Help Mixing pouch cells

[Lucifer]

Hi hope I have this in correct place.

Being on a pensioner on a tight budget, but being known to be good at fixing things, I have now collected (free) four electric bikes that need fixing. I'm focusing on the two I have actually got working (with homemade SLA battery packs). (one is 24v one 36v). Next I Bought a lot of cells very cheap. (Li-Pol and 18650). I have got as far as making two different 24v packs one from 18650 cells and one from the pouch cells (both packs made from identical cells atm).

So first problem, the one made from pouch cells suddenly cuts out, disconnect it and start again, and works till it cuts out again, cuts out under load, I suspect the BMS, but could it be the pack not delivering enough current? And ideas?.

The 18650 cell battery I built (temporary without a BMS atm) appears to work ok, but I expected more power, (it has 7 sets of 5 cells). Would more cells per pack eg 7 sets of 9 give me more power, or just extend range?

Now the big question I also bought a lot of pouch batteries, trouble is most are not marked, and various sizes,they appear to be old e-bike batteries or similar, most have only one or two duff cells, I'm thinking of replacing the duff cells, with good ones from other packs, trouble is they are different size and shape, so far from identical. Any help or advice on this (even don't do it) would be welcome. I have loads of these so to me it would be well worth the effort. Literally any hints on any safe way to mix and match would be very welcome

Thankyou... optimistically in anticipation







Note: I'm a pensioner, new to all this inc computers and forums, so be nice.... LOL

 

[amberwolf]

So first problem, the one made from pouch cells suddenly cuts out, disconnect it and start again, and works till it cuts out again, cuts out under load, I suspect the BMS, but could it be the pack not delivering enough current? And ideas?.

By cut out, do you mean that power actually shuts off, no voltage at the contorller input? (this is the BMS turningg off the output to protect the cells ffrom damage).

Or just that the assist stops, but power remains on? (this is the controller LVC preventing operation to not stress the battery. )

In either case, if it was fully charged and all cells equal voltage, it means the cells can't handle the load beng placed on them. That usually means problematic cells or interconnects, or both, with recycled-cell packs. Paralleling more cells may help, depending on the condition of the cells.

If you start out with all cells equal voltage at full charge, but the cells end up at different voltages partway thru the discharge (somewhere between empty and full, or even when i'ts all empty), then the cells aren't all the same characteristics (capacity, internal resistance, etc), so the diffferent seriesed groups of cells won't behave the same and the pack wont' deliver power as well ro as long as if all the groups were matched to each other.

If it wasn't fully charged and/or the cells weren't equal voltage during the problem, but it works fine until it reaches that point, the pack doesn't have enough capacity to do the job you want for the length of time / distance you want, so you need more parallel cells, or higher capacity cells.

The 18650 cell battery I built (temporary without a BMS atm) appears to work ok, but I expected more power, (it has 7 sets of 5 cells). Would more cells per pack eg 7 sets of 9 give me more power, or just extend range?

What specifically do you mean by "more power"?

Do you mean the voltage sags a lot while it's under load? If so, more paralleled cells will help with that (and give more range).

If instead you mean that there's little or no voltage sag but the motor just doesn't push as hard as you want it to, you probably need a bigger (higher current) controller (and depending on the motor, possibly that too). Using higher current you might need more parallel cells, too.

Now the big question I also bought a lot of pouch batteries, trouble is most are not marked, and various sizes,they appear to be old e-bike batteries or similar, most have only one or two duff cells, I'm thinking of replacing the duff cells, with good ones from other packs, trouble is they are different size and shape, so far from identical. Any help or advice on this (even don't do it) would be welcome. I have loads of these so to me it would be well worth the effort. Literally any hints on any safe way to mix and match would be very welcome

Pouch cells are tough to work with, espeically when taking packs apart taht you don't know how they were assembled.

Any phsyical damage to them can cause improper operation, up to and including puffing, leaking, and risk of fire. They have to built into packs that are compressed along the cells' flat faces sufficiently so that they can't swell up during charge or discharge, as that changes their properties and causes problems. (cylindrical cells do this with the casing of each cell, so they are the only kind that don't require this)

Often packs are glued together, or tough sticky tape is applied between cells, and getting them apart can damage both good and failed cells. If you have lots of cells, then I'd discard any that are damaged in any way (it's just safer, since you can't know what will happen until it does, whcih could be in thirty seconds or never).

There are a bunch of pack repair threads around the forum over the years, especially RC LiPo pouch packs, that have some info on methods attempted boht successfully and not, to do these repairs.

Mixing cells can work, if you have some idea of what they are capable of so you can parallel cells where needed to beef up weaker types to match the capabilities of the rest of the cells ina pack. Won't really matter if you use stronger/better cells in place of failed ones in a pack; those will just be less stressed than the rest of the pack. If you are not usingg the pack any harder or longer than the weakest cell in the pack, then it doesn't require any better cell than that to fix it.

You can do some basic testing of cells to see what they are capable of and if they're "good enough" for the purpose, before assembling them into a pack. You might need to buy some equipmment dependign on what you already have.

you can also test within the pack after it's assembled or before it's disassembled; this can be easier to test as all you need is the bike and a voltmeter to measure each cell while under load (i'ts just harder to fix because you have to at least partly disassemble the pack to do so).

 

[999zip999]

Young grasshopper first put a balance conne
ctor 4s 5s 6s 7s 8s . If bigger than 8s then get two. Then you can get a cell meter and if you have a 16s pack you get to 8s if you have a 14-s pack you'd get two seven s's and one of your pack so you know what's going on with the BMS yes this is your observation table or buy a Bluetooth BMS
The main thing is used quality known cells use the cells that you know that they have capacity if there's no capacity there's no volume of energy even though they might fully charge they'll discharge that fast Mattch cells.
Be careful this is not a game those cells are live and can make fire as you know a 9-volt battery for a radio can make fire so what are you making. Be careful it's not a game

 

[Lucifer]

see below, have not worked out how you did those quotes yet

Thank you for taking the time to ans.

have not worked out hou you got those quotes form my post (a hint for next time would be great)

You ask "
By cut out, do you mean that power actually shuts off, no voltage at the contorller input? (this is the BMS turningg off the output to protect the cells ffrom damage)."

First on the bike I'm working is twist and go (not pedlec, or elect assist) the controller is built into the frame, and I have not got to it yet. My first experiment was to use two good 12 volt SLA batteries in series, to literally just replace the original 24 volt battery which is dead, this worked, (confirming the bike was worth the effort) so at the moment I have left everything else exactly as is so that I did not introduce more variables. My first test was with my Li-po pack, made from the best 7 pairs of cells salvaged from a 36 v li-po pack (with a new 7s BMS). I cannot measure voltage at the controller, cos cant get to it easily, but I think I can answer the question as the voltage coming out of the pack I built dropped to Zero. when I totally disconnect it and it went back to about 28 v (What it had fully charged). So sounds like BMS turning off, I bypassed the BMS took the voltage from the + and - of the charged pack direct to the bike, went round the block a few times and it did not cut out but had less power than my SLA's. also felt like the pack was running out of steam, however after I stopped for a few mins it worked again

Next tried my homemade 18650 pack, this one was not quite finished so had not fitted the BMS yet, but due to the dissapointing result above decided to do straight to trying the pack without the BMS, I had learnt mor by the time I built this pack, all theses cells have been well tested inc their capacity with an Imax B6, the all readily charge to over 4v (even when I tell the Imax 3.7) and the all hold well over 2 amps each, these were also salvaged from a 36v bike battery, seven packs of 5 (charged each pack with the Imax due to no BMS fitted yet, this worked much better but I expected more speed, (I'm not a speed freak, just it was slower that I expected as in noticeably slower than my daughters xami e-scooter which does about 18 mph, so I would guess at 15 mph).

For both these packs I have more identical cells, with the pouch cells I would have to take the pack apart (in which case I would now test how much each holds and could then rebuild it with 7 x 3 (most will fit in the case), With the 18650 I could add an extra 4 to each pack of five, and that would still fit in case (only started with 5 as they were in groups of 5 in the doner pack).

Prob a bit exhaustive, but should contain what you need.

"You ask "
What specifically do you mean by "more power"? Do you mean the voltage sags a lot while it's under load? If so, more paralleled cells will help with that (and give more range). "

Yes the Lipo pack sags under load, and then sometimes cuts dead, till disconnected. So from your first I assume thats the BMS protecting the cells, so they are not good enough ?

Reading you reply on Lipo Pouch cells IF I HAVE THIS RIGHT, If I have a defective pouch in a pack for any reason, and the rest test ok,. I can safely replace it with any other good pouch, but obviously the finished pack will be as good as the least powerful?

One more question, I read that I can bypass the BMS on load (hence my test), no risk other than to the battery cells? of which I have hundreds, so not overly worried about that at the moment, providing the thing does not burst into flames.

Thank you again for your time, (AH just seen those quote marks above) And smilies, I'm getting it now LOL

 

[Lucifer]

Young grasshopper first put a balance conne
ctor 4s 5s 6s 7s 8s . If bigger than 8s then get two. Then you can get a cell meter and if you have a 16s pack you get to 8s if you have a 14-s pack you'd get two seven s's and one of your pack so you know what's going on with the BMS yes this is your observation table or buy a Bluetooth BMS
The main thing is used quality known cells use the cells that you know that they have capacity if there's no capacity there's no volume of energy even though they might fully charge they'll discharge that fast Mattch cells.
Be careful this is not a game those cells are live and can make fire as you know a 9-volt battery for a radio can make fire so what are you making. Be careful it's not a game

Thank you "Grasshopper", I'm totally new to this and its like learning chinese, I'm now well into my 70's a retired pensioner, but I did qualify as an electrical engineer over 50 years ago, obviously none of this existed then, and never came across any of it during my working life, I retired before they invented this technology, so its all new to me, and I'm keen to learn about it having given up driving and having mobility issues. But I'm picking it up.

Remember Grasshopper "Woman who cook beans and pees in the same pot, is very unhygienic" LOL,

But seriously thank you, while I'm not sure it helped with the problem, it was interesting, not ready to experiment with 2 x BMS in a pack yet but interesting. And yes I have lit a fire with a 9v battery and a wire wool pad (used to be a Scout leader) and as it happens was watching some You-Tube videos of packs exploding only last night. Scary stuff.

Dr. Keith Maltman (not medical) LOL

 

[amberwolf]

have not worked out hou you got those quotes form my post (a hint for next time would be great)

Press the Reply button on the post you want to quote.

Then put your cursor where you would like to reply to a piece of my post, and press enter, and it will make a gap for you to type in.

I cannot measure voltage at the controller, cos cant get to it easily, but I think I can answer the question as the voltage coming out of the pack I built dropped to Zero. when I totally disconnect it and it went back to about 28 v (What it had fully charged). So sounds like BMS turning off, I bypassed the BMS took the voltage from the + and - of the charged pack direct to the bike, went round the block a few times and it did not cut out but had less power than my SLA's. also felt like the pack was running out of steam, however after I stopped for a few mins it worked again

That usually means the cells just arent' up to the task, either because they have problems or just arent' meant to provide that much power. Verifying the balanc eof the pack, what all the different cell groups' voltages are at cutout (preferably while actually under at least some load), will hlep tell you if it's because of one or more groups, or if it is a general thing.

the all readily charge to over 4v (even when I tell the Imax 3.7)

That sounds like either the Imax is not working correctly, the balance connections are high resistance, or the cells themselves are high resistance so they reach a high voltage during high current (but would then drop in voltage once the current stops).

If htey are Li-Ion and not LiFePO4, 4.2v is most commonly full, and 3.6-3.7v is half full, dropping to around 3v+ for empty.

LiFePO4 is full about 3.4-3.6v, and quickly drops to around 3.2v, where it will stay for most of the capacity (discharge curve), the drops to around 2.4-2.8v for empty.

(the cells can be discahrged a bit lower than that, but there is very little capacity there and it is hard on them)

and the all hold well over 2 amps each,

2A, (amps) or 2Ah (amp-hours)? the first is a current capability, and the second is capacity. They are completely different things despite the one term containing the other's name.

these were also salvaged from a 36v bike battery, seven packs of 5 (charged each pack with the Imax due to no BMS fitted yet, this worked much better but I expected more speed, (I'm not a speed freak, just it was slower that I expected as in noticeably slower than my daughters xami e-scooter which does about 18 mph, so I would guess at 15 mph).

Speed is determined first by the motor winding x wheelsize x any gearing between motor and wheel, vs the voltage applied to it. It is next limited by total power (v x a = watts) vs air resistance and rolling resistance, once you get to speeds about 15mph+ where pushing thru the air starts to get noticeably harder.

All other things equal, smaller wheels are slower but push harder (more torque), same as smaller gears in front on a bike (or bigger in back) do.

Yes the Lipo pack sags under load, and then sometimes cuts dead, till disconnected. So from your first I assume thats the BMS protecting the cells, so they are not good enough ?

Probably. Could be just one cell or cell group--what voltages do the individual cells (or groups of paralleled cells) each have when under that load, or during the first stage of charging? They should all be equal, and if they are not, those that are different from the majority are problematic in one way or another.

Reading you reply on Lipo Pouch cells IF I HAVE THIS RIGHT, If I have a defective pouch in a pack for any reason, and the rest test ok,. I can safely replace it with any other good pouch, but obviously the finished pack will be as good as the least powerful?

Essentially, yes, as long as no other cells are damaged in the process.

One more question, I read that I can bypass the BMS on load (hence my test), no risk other than to the battery cells? of which I have hundreds, so not overly worried about that at the moment, providing the thing does not burst into flames.

Yes, though the latter risk is a real risk if the pouches get damaged, overheated, etc.

If you have a place to test away from buildings, trees, etc., it is safer to do that way, especially since the cells you are using are of unknown condition and while it is unlikely, could already be damaged in ways that could lead to a fire (you have no way of knowing and there is no useful test to tell, until they do).

 

[Lucifer]

Press the Reply button on the post you want to quote.

Then put your cursor where you would like to reply to a piece of my post, and press enter, and it will make a gap for you to type in.

Cool easy, thanks

That sounds like either the Imax is not working correctly, the balance connections are high resistance, or the cells themselves are high resistance so they reach a high voltage during high current (but would then drop in voltage once the current stops).

I might not have made that clear, I have actually 3 Imax chargers, and having hundreds of 18650 cells to sort through. I have been using all of them, I fully charge individual cells on the Imax (s) the cells read 4.2v on a meter afterwards, (not balanced charging for a pack) left them a couple of weeks to see if the self discharged, still read 4.2 (also have three meters, def read 4.2v) then discharged them on the Imax to measure what they held. Then individually charged them again, each time I told the Imax to charge to 3.7 volts, every time every cell charged to 4.2 volts? So far I have been working mainly with INR18650 29e SAMSUNG SDI 6 II4T cells, as I had about 60 of them all identical, all looking good as new from 36v bike batteries. (literally got hundreds of green mixed ones as well from matika power tool batteries), from memory I think the green ones did actually stop at 3.7v fully charged (well the ones that passed my test), but the blue Samsung ones all charged to 4.2v regardless of which Imax I used (I also bought some very cheap 18650 chargers, which charge 4 cells at a time, to speed this process up, but no other features), they also charge these cells to 4,2v before the led changes from red to green. ? So I assumed these cells were better cells that wanted to charge to 4.2 v? Once charged they do not drop, they hold at 4.2v ? All 60 of them? Does this make any sense?

Accidentally backspaced and removed the quote part

So "2A, (amps) or 2Ah (amp-hours)? the first is a current capability, and the second is capacity. They are completely different things despite the one term containing the other's name. "

The latter being delivering 2 amps for one hour (2x1 = 2ah) capacity, will have to download some instructions for the I-Max to see what number it's actually giving me, I assumed it was giving me the capacity of the cell, unless you know?

Yes, though the latter risk is a real risk if the pouches get damaged, overheated, etc.

Even when using as opposed to charging? Just confirming this as I read elsewhere in a couple of places that it was ok to bypass the bms on loads (I looked it up), but cannot remember where I read it, or confirm that the authors knew what they were talking about. TBH I thought it would be ok myself, so I only did a quick search superficial for BMS Bypass on load, found three places that said it was fine long as you realised the BMS would not protect your cells, so as that appeared to confirm what I thought, I gave it a try. No one mentioned any fire risk.... Or I would have done a lot more research before trying it. So there is a fire risk?

If you have a place to test away from buildings, trees, etc., it is safer to do that way, especially since the cells you are using are of unknown condition and while it is unlikely, could already be damaged in ways that could lead to a fire (you have no way of knowing and there is no useful test to tell, until they do).

For experimental charging, I use a large steel Gas BBQ in the garden, with opening lid, fireproof and waterproof by design, but ventilated.... perfect, (I disconnected the gas bottle just in case, but in fact as intense as the things are when they explode, believe it or not they are no where near hot enough to go through a calor gas bottle, but as it only takes a second to remove the Gas bottle, it made sense). Just run out an extension lead, connect it up, close the lid, go for tea.

This could be a good tip for others who might not have thought of it as a safe battery experimental charging point.? Leave it up to you if you think its worth putting on the forum somewhere, might already be there.

My immediate objective is to get anything working and useable (I now have mobility issues), But I can see that once I get to that point I will probably get addicted to this, interesting hobby, I have two very nice, bigger, much better e-bikes in the garden, (given to me free because the owners couldn't get them fixed) they obviously need more work, (I assumed if you can build one of these bikes from scratch, which people do, they must be fixable, so I accepted them). But for now I focussed on the two that at least just work with my SLA packs. They will obviously both work once I make a good battery for each of them. In theory fairly straightforward (In theory). They also both have the advantage for me that they are twist and go (I need a new hip..... at least lol), and they are the folding type co I can legally fold them and take them on public transport, trams and busses etc. (yeah... welcome to old age). WHEN I get them both working, I will look into over volting the 24 volt one, the motor should take it, and I'll get the controller out inspect it, and source a suitable more powerful replacement before doing it. But only once the other bike is also useable. As I really need transport to get about.

Such a long way from my GXSR, with its "power commander and other not for road use components" (196 mph in theory, I never got above 180) LOL

Thank you again, very helpful, I will now do a lot more experimenting, I think Ill stick with the 18650 for now, appear more immediately promising. Come back to the lipo packs later, I thought they were more powerful so was very motivated to work with them, and I was then lucky enough to pick up several LiPo 36 volt bike battery pouch packs, someone had been collecting to build a powerwall (and had given up) so I got them cheap. If and when Im sure I dont need whats left over, I can always sell it on, I will have at least tested it all for someone by then.

Keith

Keith

 

[Lucifer]

Decided to put away all the lipol pouch packs for now, focus on 18650's .

So before storing the pouch batteries, I can spend some time on them.

1) would you chuck any swollen cells even if it still holding full charge? Time consuming getting them off the pack, so if they are safe to store I'll leave them for now. If a fire risk, I'll reluctantly have to remove them.

1a) Was thinking of making a 12v pack for each bike for lighting etc, (can buy case, strips, and BMS from china for under £10 or e-bay, looks like and 12 v sla when put together). So assuming they are safe, (if not bin). Think its worth keeping any cells that still hold full charge but look less than perfect for such a pack, or waste of time?

2) Most of the pouches are still in packs charged to 36v (or more), think I should discharge them? If so to what? even though different size and type they are all in pairs, 10 pairs of cells per pack. As this will take time, I only want to do it if its essential from a safety point of view. Alternatively, I can cut off all the wires and insulate them if that will do. (Empty lemonade bottles, remove both ends, hot air gun, becomes big shrink wrap).

So battery building, simplified by forgetting the pouch cell considerations for now (other that storing them).

3) If I build the batteries using all what I think are higher spec blue samsung cells, I can use a maximum of 7 x 7 = 49 per 24v pack. (Have a lot more but also want to build 36v batt for another bike). But I also have hundreds of mixed green batteries from Matika Power tools (assorted makes, but probably all the same spec, as they came out of exactly the same type of battery packs). When I was testing them they did not hold as much as the blue samsung cells. But they are all good, hold charge, (all over 1500 ma on the imax discharge test). There is space for more cells in the case so I think adding 2 of these cells to every group of blue samsung cells, (making 9 in total 7 blue 2 green, per group) will produce a better battery overall than just the 7 samsung cells?

Yes, will do if i'm right but if not in simple terms what have I misunderstood?

Keith

History lesson..... Just for fun

"When I went to college pretty much the only thing that run on a battery was a torch"

Even my first two cars still had hand cranking starting handles. Buyers thought "new fangled" car batteries were not reliable, if you couldn't start the car by hand WHEN they let you down. LOL.

By the late 50's early 60's you could actually buy transistor radios that ran on batteries and they only cost about £30, but that's equivalent to about £800 now. So for "quite a while" they were nowhere near as common as you might think. I remember saving up to buy my mum a red Dansette Radio, it was her pride and joy.

 

[Lucifer]

VERY SIMPLE LAST MIN SAFETY QUESTION

Once cells have been visually inspected, charged, discharged, tested, and recharged, monitored to ensure the dont get more than at most slightly warm to the touch when charging (as in keep touching them and eventually notice a hardly noticeable increase in temperature) . When would you say they are now safe enough to just charge on the kitchen worktop, using "just" normal precautions. I assumed they by now they are ok and have just started charging some of my previously tested 18650 cells that I had discharged to store. This was very much an after thought, I wasn't concerned about them by now. But would you still be more concerned than if they were new cells? When would you consider such cells safe enough, to simply charge using just the usual precautions, (as opposed to also a fire proof box in the garden)?

Keith

 

[999zip999]

If your pout cells are puffed recycle them. If you're 18650 sales won't fully charge or discharge below 2.5 volts recycle them. For your 18650 cells match voltage match AH and match I.R. that's why a lot of people don't go through the effort of charging and matching cells as they can be boughten pretty cheap new.
From places like battery hookup you can buy batteries that have been professionally built used and you only have to put a BMS on it.
A BMS will not balance in out of balance pack you want to balance your pack before you put a BMS on.
As they have just small baby bleed resistors. Most of the time here's something for you a Bluetooth BMS that attaches to your phone so you can see the voltage of each cell group in parallel and total voltage. It's a beautiful thing.
24v e-bike sounds like a Walmart . 48 volt is good for an e-bike. In USA.

 

[Lucifer]

If your pout cells are puffed recycle them. If you're 18650 sales won't fully charge or discharge below 2.5 volts recycle them. For your 18650 cells match voltage match AH and match I.R. that's why a lot of people don't go through the effort of charging and matching cells as they can be boughten pretty cheap new.
From places like battery hookup you can buy batteries that have been professionally built used and you only have to put a BMS on it.
A BMS will not balance in Alabama balance pack you want to balance your pack before you put a BMS on.
As they have just small baby bleed resistors. Most of the time here's something for you a Bluetooth BMS that attaches to your phone so you can see the voltage of each cell group in parallel and total voltage. It's a beautiful thing.
24v e-bike sounds like a Walmart . 48 volt is good for an e-bike. In USA.

Thanks.

In in UK btw, but even here 24 v bikes are scarce, its is old but here twist n go are illegal now but a few older ones (like this one) are still around,and they are legal as they were made before the law was introduced. But the main advantage of this bike was I got it for peanuts. I thought once i had it reliably working I could then think about upgrading the electrics.

I'll look up battery hookup, not heard of it, or any similar service here in England, but they might exists, batteries here are EXPENSIVE. Being new to this I didn't know bluetooth BMS existed, I think someone else mentioned that, but I didn't get what it does until now, so will look into that as well. Being a pensioner, money is really tight, but time is available in plentiful supply. Kinda changes how you prioritise things. But thanks for the info on cells/packs, and the ideas to look into probably for future use, but interesting none the less.

I have only built two packs so far, (one hasn't got a BMS yet the 18650 pack) the other I did balance before connecting the BMS, so I got that part right.

Don't know what Alabama balance pack means, not heard of it? sounds American? so we might have another name for it?

Keith

 

[Lucifer]

48 volt is good for an e-bike. In USA.

Here the maximum legal e-bile is 250 watts, (Stupid IMHO) but that's the law, anything else is illegal, so 36v is very common, I'm certain there are "LOTS" of bikes well over the 250 Watt legal limit, as these e-bikes are all fairly new at the moment the police are not bothering about them, but as the number on the roads increase it's only a matter of time before they have crack down. As its only the 250 Watts and under that are exempted from our Road Traffic Act, if you were caught on an illegal bike, they could hit you with a lot of fairly serious charges, No road tax, No insurance, No Mot, no vehicle type approval, incorrect driving Licence, Incorrect vehicle group, to name a few. So from my point of view keep it legal (or at the very least so you would have to strip it down to prove it wasn't legal....) LOL

 

[amberwolf]

Then individually charged them again, each time I told the Imax to charge to 3.7 volts, every time every cell charged to 4.2 volts?

That probably means the Imax isn't working the way you want it to, either because it's not designed to or it's not setup right, or not in the right mode. You'd have to check it's manual for the specifics of how to charge to just a certain votlage rather than full, as I don't know that charger well enough to say.

from memory I think the green ones did actually stop at 3.7v fully charged (well the ones that passed my test), but the blue Samsung ones all charged to 4.2v regardless of which Imax I used (I also bought some very cheap 18650 chargers, which charge 4 cells at a time, to speed this process up, but no other features), they also charge these cells to 4,2v before the led changes from red to green. ? So I assumed these cells were better cells that wanted to charge to 4.2 v? Once charged they do not drop, they hold at 4.2v ? All 60 of them? Does this make any sense?

If hte charger is actually able to set to charge to a specific voltage, and doens't, it's a charger issue for whatever reason.

If the charger is set to charge to a voltage and a cell doesn't reach taht voltage, its' a cell issue, most likely that they aren't the right chemistry adn can't charge that full. (or that they are much higher capacity than whatever capacity limit has been set in the charger, if any).

Accidentally backspaced and removed the quote part

Ctrl-Z (hold the key marked CTRL and press Z once) is "undo".

So "2A, (amps) or 2Ah (amp-hours)? the first is a current capability, and the second is capacity. They are completely different things despite the one term containing the other's name. "

The latter being delivering 2 amps for one hour (2x1 = 2ah) capacity, will have to download some instructions for the I-Max to see what number it's actually giving me, I assumed it was giving me the capacity of the cell, unless you know?

If it says A, that's amps. If it says Ah, that's Amp-hours.

Even when using as opposed to charging? Just confirming this as I read elsewhere in a couple of places that it was ok to bypass the bms on loads (I looked it up), but cannot remember where I read it, or confirm that the authors knew what they were talking about. TBH I thought it would be ok myself, so I only did a quick search superficial for BMS Bypass on load, found three places that said it was fine long as you realised the BMS would not protect your cells, so as that appeared to confirm what I thought, I gave it a try. No one mentioned any fire risk.... Or I would have done a lot more research before trying it. So there is a fire risk?

There is always a fire risk anytime a cell is used outside it's abilities in a way that damages it. (the damage has to be in specific ways, but since we can't see inside the cells without destroying them we can't know if they are or not).

The phrase "BMS would not protect your cells" means exactly that--it does not protect them being used outside their abilities, and so can't protect them from damage.

Whether the risk is acceptable or manageable depends on the cells, situation, how much control you have over what happens in the system, and how good you are at manually managing the system to prevent excursions outside the cell limits.

I don't use a BMS on my SB Cruiser trike (or CrazyBike2 before it) primarily because the cells I use are very well-matched, so they are always the same as each other. So if I monitor whole-pack voltage, and divide that by the nubmer of series cells, I can predict that every cell will be that voltage, and so prevent over or under voltage events manually or by setting voltage limits in the charging hardware and the controller. Similarlly, I can set current limits that ar well within the limits of the cells, and ensure they are nevver used even near those limits much less beyond them.

if the cells were not well-matched, and not much more capable than I need them to be, I would not easily be able to safely do this without a BMS to manage the system for me. Eventually they will get old and worn out enough that they won't be well-matched and I'll have to either lower the system limitations to compensate or use a BMS or replace them with new well-matched cells. (probably the latter, since cheap used EV modules are getting more commonly available from places like Batteryhookup; I have no desire anymore to do what you're doing and make packs with lots of smaller cells :lol: ).

For experimental charging, I use a large steel Gas BBQ in the garden, with opening lid, fireproof and waterproof by design, but ventilated.... perfect, (I disconnected the gas bottle just in case, but in fact as intense as the things are when they explode, believe it or not they are no where near hot enough to go through a calor gas bottle, but as it only takes a second to remove the Gas bottle, it made sense). Just run out an extension lead, connect it up, close the lid, go for tea.

Personally, I'd move the bottle away from it, just because bad things happen unexpectedly and sometimes unpredictably.

If you poke around you'll find that old BBQs and ovens and the like have commonly been used for storage and testing sites. :lol: I used to do so until someone stole my BBQ (including the stuff that was in it...but they didn't get my gas bottle because I had put it away to keep it safe from any potential battery incidents) along with a bunch of other stuff.

I do keep some old cells and packs in metal filing cabinets, and some old thickwall steel cabinets, outside in some sheds...just in case.

They also both have the advantage for me that they are twist and go (I need a new hip..... at least lol), and they are the folding type co I can legally fold them and take them on public transport, trams and busses etc. (yeah... welcome to old age).

Yes; I built the SB Cruiser heavy-cargo trike to do all my travelling and shopping, etc with (especially to take the dogs places, as St Bernards don't typically fit in the average bicycle trailer). No need for the other transports for me, 99.99999% of the time.

WHEN I get them both working, I will look into over volting the 24 volt one, the motor should take it, and I'll get the controller out inspect it, and source a suitable more powerful replacement before doing it. But only once the other bike is also useable. As I really need transport to get about.

The controller may take it too, at least to 36v, but it might have an HVC that turns it off above about 30v (some do).

 

[amberwolf]

1) would you chuck any swollen cells even if it still holding full charge? Time consuming getting them off the pack, so if they are safe to store I'll leave them for now. If a fire risk, I'll reluctantly have to remove them.

I don't trust swollen pouch cells in use, but I had quite a few old RC Lipo pouch packs with swollen cells that were donated to me, stored in an old oven for years (because i forgot about them :lol: having intended to use them for containment storage testing that I never got around to) and they never failed just sitting there. But it doesn't mean they can't.

Most fire risks are during charging or discharging, when current is flowing. But they *can* fail just sitting there not even connected to anything, it's happened to people on this forum and elsewhere, though very very rarely.

1a) Was thinking of making a 12v pack for each bike for lighting etc, (can buy case, strips, and BMS from china for under £10 or e-bay, looks like and 12 v sla when put together). So assuming they are safe, (if not bin). Think its worth keeping any cells that still hold full charge but look less than perfect for such a pack, or waste of time?

I would not keep any physically damaged cells, simply because you cannot know what damage has occured inside, and whether or not it will fail catastrophically, or when.

Similarly, any cells that heat up "significantly" in charge or use are either damaged, too-aged, or being used beyond their actual capabilities (regardless of their original specs). Some people intentionally use cells at high rates that heat them up, and just build the pack with cooling built into it or knowing they will have to let it cool down periodically, etc....but this is hard on the cells, ages them faster, and increases the risks of damage that could result in a fire. So I don't recommend it. I like my batteries to not generate noticeable heat. (actually prefer that in the entire system, since heat is wasted power that could have been used to move me farther ).

2) Most of the pouches are still in packs charged to 36v (or more), think I should discharge them? If so to what? even though different size and type they are all in pairs, 10 pairs of cells per pack. As this will take time, I only want to do it if its essential from a safety point of view. Alternatively, I can cut off all the wires and insulate them if that will do. (Empty lemonade bottles, remove both ends, hot air gun, becomes big shrink wrap).

Assuming the BMS is unplugged from the cells so it can't drain them over time (if it's powered off the balance connector rather than the main thick wires) then the packs should be fine just sitting there in whatever cool storage you have, until you get around to them. Mostly people store things at about half charge, as higher voltages can degrade things faster, as do higher temperatures.

3) If I build the batteries using all what I think are higher spec blue samsung cells,

You can check the specs and actual performance testing for many cells at Flashlight information

But they are all good, hold charge, (all over 1500 ma on the imax discharge test).

Just to be sure, is that ma, or mah?

There is space for more cells in the case so I think adding 2 of these cells to every group of blue samsung cells, (making 9 in total 7 blue 2 green, per group) will produce a better battery overall than just the 7 samsung cells?

Are they the same chemistry? If not, they may not have the same charge voltages, so you'd have to not charge them any hihger than the lowest voltage chemistry, and not discharge them any deeper than the highest voltage chemistry, limiting the total capacity available by some small amount.

Otherwise, paralleling more cells doesn't hurt, as long as the total characteristics for each parallel group are the same as every other parallel group. (meaning if you have cells with different capacities or internal resistances, setup the groups so that the average of each characteristic is equal between every group, so that they all discharge and charge the same and don't become unbalanced, making the pack perform less well than otherwise).

"When I went to college pretty much the only thing that run on a battery was a torch"

Even my first two cars still had hand cranking starting handles. Buyers thought "new fangled" car batteries were not reliable, if you couldn't start the car by hand WHEN they let you down. LOL.

By the late 50's early 60's you could actually buy transistor radios that ran on batteries and they only cost about £30, but that's equivalent to about £800 now. So for "quite a while" they were nowhere near as common as you might think. I remember saving up to buy my mum a red Dansette Radio, it was her pride and joy.

I guess you might be a bit older than I am; I grew up in a time of battery-powered devices of various kinds; the cassette player was the most advanced portable audio technology, but I didn't get one of those till I was in my 20's)

 

[999zip999]

Talk to text I usually read before I print but sometimes it escapes me Alabama. That means out of balance I fixed the typo. The way those old nipple cells as fast as you can best to discharge them down to zero. Yes get rid of them they can reverse polarity and fire can start yes I'm trying to scare you. I'm 65. Yes I've had a battery fire in my garage it makes a lot of black soot that you can't be washed off it's almost permanent and when the fireman comes and puts it out all the heat goes to your ceiling and if you got any fiberglass or graphite fishing rods up there or Atomic titanium skis Herman Meyer style melted. So be careful I'm also going to write about my battery charger in this thread at the top.
I went downstairs to balance my 72 volt 8ah it doesn't have a BMS and it never goes out of balance . Till just now when I was using my balance charger and I moved the bike in the ground from the power supply to the charger unit came off and I let it sit for a little bit not knowing and it started smoking I turned it off and barely was able to save it I had to put New balance wire a 5S.
This is through the balance wires only and it can do up to 9s and I think 8 amp through each balance wire even though I try to keep it under five amps

 

[999zip999]

If you have a BMS or if you don't have a BMS I always put balance wires on so you could know the voltage of each group and I have a picture. Right now it's set up for 4s 5s and 6s and it says it balances it but it would take a while.
The last pic is of my 84 volt charger. As you can see it's three chargers they're all mean well 24 volt you can hit up to 27 maybe 28 volts on the first one and on the second one it would be 56 and the third one will be 84 volts they seem pretty indestructible but these are 10 amp we should probably be too much for used cells or of cells have not known quality. I just use it as the 56 volt tap and the 84 volt tap.

 

[Lucifer]

That probably means the Imax isn't working the way you want it to, either because it's not designed to or it's not setup right, or not in the right mode. You'd have to check it's manual for the specifics of how to charge to just a certain votlage rather than full, as I don't know that charger well enough to say.





If hte charger is actually able to set to charge to a specific voltage, and doens't, it's a charger issue for whatever reason.

If the charger is set to charge to a voltage and a cell doesn't reach taht voltage, its' a cell issue, most likely that they aren't the right chemistry adn can't charge that full. (or that they are much higher capacity than whatever capacity limit has been set in the charger, if any).




Ctrl-Z (hold the key marked CTRL and press Z once) is "undo".



If it says A, that's amps. If it says Ah, that's Amp-hours.





There is always a fire risk anytime a cell is used outside it's abilities in a way that damages it. (the damage has to be in specific ways, but since we can't see inside the cells without destroying them we can't know if they are or not).

The phrase "BMS would not protect your cells" means exactly that--it does not protect them being used outside their abilities, and so can't protect them from damage.

Whether the risk is acceptable or manageable depends on the cells, situation, how much control you have over what happens in the system, and how good you are at manually managing the system to prevent excursions outside the cell limits.

I don't use a BMS on my SB Cruiser trike (or CrazyBike2 before it) primarily because the cells I use are very well-matched, so they are always the same as each other. So if I monitor whole-pack voltage, and divide that by the nubmer of series cells, I can predict that every cell will be that voltage, and so prevent over or under voltage events manually or by setting voltage limits in the charging hardware and the controller. Similarlly, I can set current limits that ar well within the limits of the cells, and ensure they are nevver used even near those limits much less beyond them.

if the cells were not well-matched, and not much more capable than I need them to be, I would not easily be able to safely do this without a BMS to manage the system for me. Eventually they will get old and worn out enough that they won't be well-matched and I'll have to either lower the system limitations to compensate or use a BMS or replace them with new well-matched cells. (probably the latter, since cheap used EV modules are getting more commonly available from places like Batteryhookup; I have no desire anymore to do what you're doing and make packs with lots of smaller cells :lol: ).




Personally, I'd move the bottle away from it, just because bad things happen unexpectedly and sometimes unpredictably.

If you poke around you'll find that old BBQs and ovens and the like have commonly been used for storage and testing sites. :lol: I used to do so until someone stole my BBQ (including the stuff that was in it...but they didn't get my gas bottle because I had put it away to keep it safe from any potential battery incidents) along with a bunch of other stuff.

I do keep some old cells and packs in metal filing cabinets, and some old thickwall steel cabinets, outside in some sheds...just in case.


Yes; I built the SB Cruiser heavy-cargo trike to do all my travelling and shopping, etc with (especially to take the dogs places, as St Bernards don't typically fit in the average bicycle trailer). No need for the other transports for me, 99.99999% of the time.





The controller may take it too, at least to 36v, but it might have an HVC that turns it off above about 30v (some do).

Thanks very much, very helpful, no questions this time, I'm going to read that all again several times let it sink in, and give it some thought, have to say this forum is amazing. These little buggers are certainly "A BIT" more complicated than they appear at first. Probably glad I didn't read all this before I jumped in at the deep end (which would have been very wise though) but might have put me off. Now however I'm past that, the kitchen looks like a science lab LOL very determined to learn a lot more.And take a week off the project, and devote it to avoiding by sorting and disposing of a lot of the pouch cells, I have lots so anything that looks less than perfect Ill recycle.

Keith

 

[Lucifer]

If it says A, that's amps. If it says Ah, that's Amp-hours.

The Imax measures the discharge in MilliAmps the number slowly increases until it reaches the voltage you told it to discharge the cell to, then it stops (this can take hours) and shows the total ma e.g. 1500 ma so 1.5A, which I had "assumed" was what the cell held, i.e. its capacity.

On discharging cells to recycle imperfect ones (thinking of a lot here) could I safely connect a 12 v bulb in series with say a 100 ohm resistor, (have lots of both from something else) and then literally leave them on the BBQ overnight to go flat, (then meter them to confirm they are flat)?

Yes; I built the SB Cruiser heavy-cargo trike to do all my travelling and shopping, etc with (especially to take the dogs places, as St Bernards don't typically fit in the average bicycle trailer). No need for the other transports for me, 99.99999% of the time.

Cool I bought as a later project, a Pashley 3 wheel bike, was thinking of motorising it, put it on one side in garden for now, someone then dumped a running machine, so I salvaged a hench 30v torque monster of an electric DC motor from it complete with drive belt etc. (size of a car starter motor). No questions on this atm, but had a similar idea, attach trailer also for dog so I can get him to some country side to exercise him. Obviously I'll have to master the basics first. In hindsite I wished I had also salvaged the electronic control for the running machine, bit large like a dashboard, but I could have probably adapted them into a variable speed cruise control, as well as a throttle, but too late they are gone now. But will come back to this project when I know better what I'm doing.

Gotta learn to walk before I can cruise. LOL

K

 

[Lucifer]

I'm trying to scare you. I'm 65. Yes I've had a battery fire in my garage it makes a lot of black soot that you can't be washed off it's almost permanent and when the fireman comes and puts it out all the heat goes to your ceiling and if you got any fiberglass or graphite fishing rods up there or Atomic titanium skis Herman Meyer style melted.

Job done LOL. As I mentioned to Amberwolf, taking a week off progress, to focus on recycling anything dubious. I also asked him this so hope that doesn't offend anyone. To discharge a lot of dubious cells quickly (which are stored in mu garage, (ITS ATTACHED TO TH HOUSE) I was thinking of 12v bulb in series with 100 ohm resistor, could knock a dozen of these up in minutes. Put it on the BBQ put my shunt across the terminals and leave it overnight to flatten the cell. Any comments?

Once the disposal bit has been done I am going to re-read everyones post, look a few things up, and get started again.

K

 

[Lucifer]

Talk to text I usually read before I print but sometimes it escapes me Alabama. That means out of balance I fixed the typo. The way those old nipple cells as fast as you can best to discharge them down to zero. Yes get rid of them they can reverse polarity and fire can start yes I'm trying to scare you. I'm 65. Yes I've had a battery fire in my garage it makes a lot of black soot that you can't be washed off it's almost permanent and when the fireman comes and puts it out all the heat goes to your ceiling and if you got any fiberglass or graphite fishing rods up there or Atomic titanium skis Herman Meyer style melted. So be careful I'm also going to write about my battery charger in this thread at the top.
I went downstairs to balance my 72 volt 8ah it doesn't have a BMS and it never goes out of balance . Till just now when I was using my balance charger and I moved the bike in the ground from the power supply to the charger unit came off and I let it sit for a little bit not knowing and it started smoking I turned it off and barely was able to save it I had to put New balance wire a 5S.
This is through the balance wires only and it can do up to 9s and I think 8 amp through each balance wire even though I try to keep it under five amps

I have had to repair fire damage before (not caused by batteries). I found the soot impossible to remove and the smell. In the end I diluted some oil based undercoat, with turps (white spirit/Kerosine) so fairly thinned down and runny, and painted the whole room with a couple of coats of that, which didn't remove it but successfully sealed it all in, then took about a week with all the windows open to get rid if the smell of that (LOL) then redecorated. End result was as good as new, but a serious pain.

 

[amberwolf]

The Imax measures the discharge in MilliAmps the number slowly increases until it reaches the voltage you told it to discharge the cell to, then it stops (this can take hours) and shows the total ma e.g. 1500 ma so 1.5A, which I had "assumed" was what the cell held, i.e. its capacity.

Capacity is measured in Ah (or mAh, because the unit of time (hours) is required to do this. (how many amps over how much time = capacity)

Without that, it's just an instantaneous current measurement. (how many amps)

If the charger manufacturer decided to just ignore the correct unit and use the wrong unit on their display, then it's probably showing you capacity despite this. It is not terribly uncommon for marketers, sellers, manufacturers, etc., to just decide to do something wrong because they think it's cool or is cheaper or will sell more things, etc.

On discharging cells to recycle imperfect ones (thinking of a lot here) could I safely connect a 12 v bulb in series with say a 100 ohm resistor, (have lots of both from something else) and then literally leave them on the BBQ overnight to go flat, (then meter them to confirm they are flat)?

If you really need to discharge failed cells before disposing of them, you can dump them in a bucket of saltwater and they'll discharge themselves to zero that way. Less labor intensive.

Cool I bought as a later project, a Pashley 3 wheel bike, was thinking of motorising it, put it on one side in garden for now, someone then dumped a running machine, so I salvaged a hench 30v torque monster of an electric DC motor from it complete with drive belt etc. (size of a car starter motor). No questions on this atm, but had a similar idea, attach trailer also for dog so I can get him to some country side to exercise him. Obviously I'll have to master the basics first. In hindsite I wished I had also salvaged the electronic control for the running machine, bit large like a dashboard, but I could have probably adapted them into a variable speed cruise control, as well as a throttle, but too late they are gone now. But will come back to this project when I know better what I'm doing.

Gotta learn to walk before I can cruise. LOL

I started out with a treadmill motor design for the original CrazyBike2. Not sure if there are any images left in the thread about taht version of the bike, lots have been lost in server cahnges in the intervening 13-14 years since then. Might still be on the old electricle.blogspot.com site where I was documenting things before I came here. But I had a drivetrain all worked out and was building it (but didn't have the high voltage battery system I'd need to properly drive the motor), then someone gave me some powerchair motors with gearboxes, and those were so much easier to use I went right to those without testing the treadmill drive. (I think I still have the motor and drivetrain bits in a box somewhere).

I have the bits of a second treadmill's powertrain that was going to become assist on a big cargo trailer, but I've gotten some hubmotors wheels more suited to that since then that don't require much modification of the trailer....saved the motor and it's control system to use on the lathe instead, someday, to replace the AC motor that has no speed control.

The electronics for the treadmill would be designed to convert AC to DC for the motor system and probably would not work from a battery, if they are like the two machines I've had apart so far.

4QD over there in the UK makes good brushed controllers (I used a 2QD on my first powerchair motor system for CrazyBike2), and Curtis golfcart controllers can be had used pretty cheaply, if you need something to drive the treadmill motor. Usually 36v systems.

 

[Lucifer]

I don't trust swollen pouch cells in use, but I had quite a few old RC Lipo pouch packs with swollen cells that were donated to me, stored in an old oven for years (because i forgot about them :lol: having intended to use them for containment storage testing that I never got around to) and they never failed just sitting there. But it doesn't mean they can't.

Most fire risks are during charging or discharging, when current is flowing. But they *can* fail just sitting there not even connected to anything, it's happened to people on this forum and elsewhere, though very very rarely.



I would not keep any physically damaged cells, simply because you cannot know what damage has occured inside, and whether or not it will fail catastrophically, or when.

Similarly, any cells that heat up "significantly" in charge or use are either damaged, too-aged, or being used beyond their actual capabilities (regardless of their original specs). Some people intentionally use cells at high rates that heat them up, and just build the pack with cooling built into it or knowing they will have to let it cool down periodically, etc....but this is hard on the cells, ages them faster, and increases the risks of damage that could result in a fire. So I don't recommend it. I like my batteries to not generate noticeable heat. (actually prefer that in the entire system, since heat is wasted power that could have been used to move me farther ).




Assuming the BMS is unplugged from the cells so it can't drain them over time (if it's powered off the balance connector rather than the main thick wires) then the packs should be fine just sitting there in whatever cool storage you have, until you get around to them. Mostly people store things at about half charge, as higher voltages can degrade things faster, as do higher temperatures.


You can check the specs and actual performance testing for many cells at Flashlight information



Just to be sure, is that ma, or mah?

on the ma mah, Ill get to the bottom of that after my week devoted to recycling and disposing. Be happier once I get that done.

Wow, I'm getting so much info I nearly missed this, and it's a big post to miss. First thing I'll disconnect all the BMS from all the packs (not done that yet, didn't know). Then as mentioned a week recycling anything looking dubious. Of the "swollen!" Li PO packs, most are not swollen at all, but even the ones that are mainly are just slightly puffed,(some are very puffed, as in doubled in size, so they can go, shame because they are still holding charge, but better safe than sorry. I might separate the slightly puffed ones (less than doubled in size, but no tension in the pouch), put them in my brick built shed at the bottom of the garden, I have an old (KEY TYPE no electronics) small safe in the loft which isn't used, but looks pretty fireproof, so I could put them in that, and come back to them, the obvious problem with that is as you said "Just forgetting about them".

Are they the same chemistry? If not, they may not have the same charge voltages, so you'd have to not charge them any hihger than the lowest voltage chemistry, and not discharge them any deeper than the highest voltage chemistry, limiting the total capacity available by some small amount.

I obviously wrongly assumed that all 18650 cells had the same chemistry, (I did jump in at the deep end), So no idea, So I will have to look the cells up somewhere on the net and find that out

Otherwise, paralleling more cells doesn't hurt, as long as the total characteristics for each parallel group are the same as every other parallel group. (meaning if you have cells with different capacities or internal resistances, setup the groups so that the average of each characteristic is equal between every group, so that they all discharge and charge the same and don't become unbalanced, making the pack perform less well than otherwise).




I guess you might be a bit older than I am; I grew up in a time of battery-powered devices of various kinds; the cassette player was the most advanced portable audio technology, but I didn't get one of those till I was in my 20's)

Yeah about ten years older, surprising what a difference that makes. At college, we cross wired the emitter and collectors of glass valves to make a single "Dual Nand Smitt trigger" or as it's better known a flip flop, connected a cascade of these devices, to make a ripple counter, then build and-gates, or-gates, inverters etc out of them. Stick loads of transistorised versions of these circuits into a semiconductor and you have a TTL logic chip, stick thousands of them circuits into a bigger chip and you get a gate array. Put thousands of arrays in an IC and "eventually" you get a Z80 CPU, etc. etc etc. And all that happened over a fairly short time (see Moores Law). LOL

I remember when a 16k static ram chip cost £16,000 and that was when £16k was a lot of money, as in you could buy a house with it and have change.

At college we actually built a basic computer, out of glass valves it was the size of a ping pong table, threw off more heat than my central heating system, and the program was hard wired into, and the huge thing could only answer one question, that had been set by the tutor to achieve..... But it worked. LOL

Now I'm back to struggling to learn how to make a battery feels like it's gone full circle, and its a bit harder than a LeClanche cell this time. LOL

Sorry if this is all Latin to you, just assumed you had an electronics background.

K

 

[Lucifer]

Capacity is measured in Ah (or mAh, because the unit of time (hours) is required to do this. (how many amps over how much time = capacity)

Without that, it's just an instantaneous current measurement. (how many amps)

If the charger manufacturer decided to just ignore the correct unit and use the wrong unit on their display, then it's probably showing you capacity despite this. It is not terribly uncommon for marketers, sellers, manufacturers, etc., to just decide to do something wrong because they think it's cool or is cheaper or will sell more things, etc.

That probably clarifies that, I was suspecting something like that. Also more than suspect my 3 Imax B6's are in fact Chinese rip offs , and they got the unit wrong in translation. LOL

If you really need to discharge failed cells before disposing of them, you can dump them in a bucket of saltwater and they'll discharge themselves to zero that way. Less labor intensive.

F******** brilliant and so obvious thanks, should have thought of that myself. that will save a load of time.

I started out with a treadmill motor design for the original CrazyBike2. Not sure if there are any images left in the thread about taht version of the bike, lots have been lost in server cahnges in the intervening 13-14 years since then. Might still be on the old electricle.blogspot.com site where I was documenting things before I came here. But I had a drivetrain all worked out and was building it (but didn't have the high voltage battery system I'd need to properly drive the motor), then someone gave me some powerchair motors with gearboxes, and those were so much easier to use I went right to those without testing the treadmill drive. (I think I still have the motor and drivetrain bits in a box somewhere).

I have the bits of a second treadmill's powertrain that was going to become assist on a big cargo trailer, but I've gotten some hubmotors wheels more suited to that since then that don't require much modification of the trailer....saved the motor and it's control system to use on the lathe instead, someday, to replace the AC motor that has no speed control.

The electronics for the treadmill would be designed to convert AC to DC for the motor system and probably would not work from a battery, if they are like the two machines I've had apart so far.

I actually looked at it, it was easy to separate the mains transformer and rectification from the low voltage side, two separate boards in fact, but dismissed the idea at the time (as it was a big board), regret it now, but gone anyway. But did get a fantastic motor and drive chain.

4QD over there in the UK makes good brushed controllers (I used a 2QD on my first powerchair motor system for CrazyBike2), and Curtis golfcart controllers can be had used pretty cheaply, if you need something to drive the treadmill motor. Usually 36v systems.

Thanks, that's a bit of a longer term project, if I'm not careful I start too many different projects at the same time, at the risk of never actually finishing any of them. Once the challenge has gone, I easily loose interest, I'M being strict with myself now (well stricter), try and remain focussed on one project at a time. Don't acquire anything for other projects except the current one UNLESS "Its def gonna be of use, AND its rare or hard to usually get hold of, OR it's stupidly cheaper than it should be). This is helping me keep focussed on one thing ("helping" LOL).

K

 

[Lucifer]

You can check the specs and actual performance testing for many cells at Flashlight information

Hi Again, I took a look at the above, perhaps it's me but couldn't immediately see what I wanted (prob too impatient), So I went here because I know how to navigate (its fantastically simple, quick and informative, it's a fantastic data base, it's v cool, well worth adding to your list if you don't already have it.

A Cell Database that I knew of (Start point...... really worth a look)

My better Blue Cells

These are the Samsung (BLUE) cells

The Best of my Matika Green cells

The Matika cells are mixed abut include these GREEN cells (These ones are Sony)

But I cannot see where it refers to the chemistry of the cells, I have been there before, and I thought they all had the same chemistry.
So as you raised the chemistry question, can you see if they are the same please? I did try, I'm not being lazy,

Links 2 and 3 take you straight to the data on the two diff cells I'm thinking of mixing. Top link is to look up any cell

Keith

 

[Lucifer]

Hi anyone

Anyone know an easier way to measure a cells internal resistance other that Ohms and Kirchhoffs Laws ? Is there a cheap gadget ?