Help Mixing pouch cells

[Lucifer]

It seems to be Frozen or maybe lost its threads I don't know why some of these disappear but he has a lot of good information dark Angel.
Hopefully a moderator can chime in and help as I didn't understand why I couldn't pick up his old threads?
Plus I'm looking at battery spot welders maybe you can start a thread on your spot welder and how you got it to work so well I see some blue to capacitor spot welders for under $90 able to weld 03 pure nickel.
Have you gotten rid of the batteries that are old or unusable ?

Thanks for the reminder, (I'm a bit of a hoarder) but today put 15 pouch cells in salt water (as A W tip to quich discharge them) they will then go in the battery recycling. It's a start but I have a lot to sort. On that many of the ones I was reluctant to immediately recycle are still in pairs (cos of the PCB), as a pair they are charging but not good enough. I was thinking of using my dremel to seperate them and test them individually in case one is good and the other parasitic. Do you think its worth the effort?

All the ones I consider "Known to be good" are also in pairs, but getting great results and consistent results from each pair, still a lot to go thru tho, so for now assumed both must be good def worth keeping.

On trying some of the 36v pouch batteries that looked good and had held full voltage for ages (over a year), so tested them straight on the bike. The batteries did will, so far only got thru 3, all working at least ok. would have got further on that but the bike had some issues, like a flat tyre, and front break would not release, and some bad connections in a box on the handlebars (manufacturer fitted) and a switch broke, All fixed now, ex the switch which is on order. Shorted out n taped the wires for now.

Feel free to ask anything you like about my experience with the spot welder I bought. Nice to be able to give something back, you been v helpful. Not saying this is the best or of professional quality, don't know how it will last in the long term, but it is quick and has not struggled so far, doing just one after another, (I stop every now and then to check the battery voltages but so far they are both on their first charge still, probably being over cautious. For the price, I think its great, and not the end of the world if you decide to get a better one later, at that price still a good spare one (least I think). Looking on e-bay it looks very like you can now get even cheaper versions for as little as £10, I cannot comment on them, as I have not used one.

But it looks like a bigger Chinese company has simply decided to rip the idea of from the smaller Chinese company and made them even cheaper still. But that bit you would have to determine yourself. they might not be as good. But I would imagine there will be reviews on you tube of people who have bought them and tried them, that was the main research I did when buying mine.

Keith


Keith

 

[Lucifer]

It seems to be Frozen or maybe lost its threads I don't know why some of these disappear but he has a lot of good information dark Angel.
Hopefully a moderator can chime in and help as I didn't understand why I couldn't pick up his old threads?
Plus I'm looking at battery spot welders maybe you can start a thread on your spot welder and how you got it to work so well I see some blue to capacitor spot welders for under $90 able to weld 03 pure nickel.
Have you gotten rid of the batteries that are old or unusable ?

I Missed the bit about ME starting a thread, but the least I can do if you think this is of value, it will take me a couple of days to dig out my original research, it's still on the computer somewhere, but interrupted by a years illness between buying it and using it, during which time the design fault became known, and how to fix it. and I'll take more photos.

Be nice to start a thread where I'm not constantly asking for help LOL. and I expect you will get a lot of other input and suggestions. I'll PM you when I start the ball rolling in case you miss it.

K

 

[999zip999]

I saw your video it got a little Frankenstein there at the end Plus do you have a version in English (American ) ?
Here's the one I'm looking at it has a plug-in wall charger no battery and two good size capacitors.
Not that exact one but I'm going to look into which one I would like to purchase but that style.
Thanks for showing me that video but I want to try and buy one that works out of the box.

9 in 1 LCD Display Intelligent Dual Pulse Farah Capacitor Spot Welder Machine | eBay

This spot welder, suitable for spot welding 18650, 21700, 26650, 32650 battery assembly spot welding. Direct capacitor positive and negative charging. It is prohibited to spot weld pure nickel sheet, lithium iron monolithic aluminum and copper pole lugs as well as soft clad aluminum pole lugs.

www.ebay.com

 

[amberwolf]

Those 9Ah+ 18650 cells you asked about are fakes, as the highest real capacity you'll find is probably around 3.5-3.6Ah, typically less than 3Ah.

Larger size sells like 21700 can have around 5Ah.

If you want to buy new cells, I'd recommend places like Nkon, etc., that people successfully building good packs on here have used. Unless someone else has proven that what they got from an ebay/ali*/amazon store have been actual brand new brand name cells of the same batch and actually tested per-cell what they should in all characteristics, I would avoid those cell sources. Also, if it seems cheap it's probably that way for a reason.

If you dont' care if they're new, I highly recommend places similar to batteryhookup if there's a UK equivalent, or vehicle breakers/junkyards, and getting used EV modules. EV-grade cells are usually larger formats, MUCH better matching of cells to each other (thus less performance problems / balance issues), usually much better actual cells so they last a lot longer even under high loads near their original specs, and handle the much smaller loads bikes usually put on them very well with much less power wastage inside the cells.

Disadvantages are that the modules are hardly ever the right voltage for ebike applications, and are often rather large, so you may have to reconfigure them, and if they are pouches you either have to use them in hte original physical arrangement, unmodified, in the original housings (even if you rewire them) or make new housings that compress them properly for that specific cell model so they can't swell up under normal usage. (cylindrical cells are the only kind that doesn't have this issue, and don't require external compression from the housing). You'll also have to swap out whatever BMS is in it for something you can actually use without the EV electronics to talk to it, but that isn't much of an issue compared to the rest.

 

[Lucifer]

Started a thread as "Want a battery spot welder that works for £20"

Those 9Ah+ 18650 cells you asked about are fakes, as the highest real capacity you'll find is probably around 3.5-3.6Ah, typically less than 3Ah.

Larger size sells like 21700 can have around 5Ah.

If you want to buy new cells, I'd recommend places like Nkon, etc., that people successfully building good packs on here have used. Unless someone else has proven that what they got from an ebay/ali*/amazon store have been actual brand new brand name cells of the same batch and actually tested per-cell what they should in all characteristics, I would avoid those cell sources. Also, if it seems cheap it's probably that way for a reason.

If you dont' care if they're new, I highly recommend places similar to batteryhookup if there's a UK equivalent, or vehicle breakers/junkyards, and getting used EV modules. EV-grade cells are usually larger formats, MUCH better matching of cells to each other (thus less performance problems / balance issues), usually much better actual cells so they last a lot longer even under high loads near their original specs, and handle the much smaller loads bikes usually put on them very well with much less power wastage inside the cells.

Disadvantages are that the modules are hardly ever the right voltage for ebike applications, and are often rather large, so you may have to reconfigure them, and if they are pouches you either have to use them in hte original physical arrangement, unmodified, in the original housings (even if you rewire them) or make new housings that compress them properly for that specific cell model so they can't swell up under normal usage. (cylindrical cells are the only kind that doesn't have this issue, and don't require external compression from the housing). You'll also have to swap out whatever BMS is in it for something you can actually use without the EV electronics to talk to it, but that isn't much of an issue compared to the rest.

Yeah I thought Too good to be true.

Sorry I PM u about it, basically I didn't want to inadvertently advertise them if they were dodgy for any reason. But didn't stop to think it could serve as a warning.

So anyone else (now) reading this knows what we are talking about I put a photo below, these were being offered 8 pcs of £14 on a very well known respectable site. (Not e-bay).

SO from my admittedly limited experience I thought they looked TGTBT. I would of dismissed them out of hand except I saw in a newspaper recently that the Chinese had come out with a new Lithium battery that beat all the Japanese ones, I didn't pay much attention at the time, as reading it I guessed they would be well out of my price range. So unfortunately I cannot remember which paper it was in and when or I would link it.

I wasn't looking for these and stumbled across them accidentally, THOUGHT WOW!!! and almost bought some, then paused and thought that's TGTBT, and immediately WO thinking PM A W (sorry for that)

It never occured to me the it could serve as a warning to others.

But IF the news article was right (not everything in the newspapers is tho.... LOL). The Chinese have made a breakthrough and produced a 98000 mah cell, Of course it may not be on the market yet, the news item could be crap fed to the newspaper, and even if its all true they would probably cost a fair bit more than the ones being offered, (though the price would then tend to drop, which would be nice in a couple of years or so).

Anyone think we should start a seperate thread for these?


Keith

 

[Lucifer]

I saw your video it got a little Frankenstein there at the end Plus do you have a version in English (American ) ?
Here's the one I'm looking at it has a plug-in wall charger no battery and two good size capacitors.
Not that exact one but I'm going to look into which one I would like to purchase but that style.
Thanks for showing me that video but I want to try and buy one that works out of the box.

9 in 1 LCD Display Intelligent Dual Pulse Farah Capacitor Spot Welder Machine | eBay

This spot welder, suitable for spot welding 18650, 21700, 26650, 32650 battery assembly spot welding. Direct capacitor positive and negative charging. It is prohibited to spot weld pure nickel sheet, lithium iron monolithic aluminum and copper pole lugs as well as soft clad aluminum pole lugs.

www.ebay.com

Oh, I would just mention to be clear, first the only actual mods I did were to solder one capacitor in place, i'e two solder joints, (10 mins work) and connect it using two batteries instead of one. but thought I would give you the full info.

My other comment should be in the new thread really, so if you put something there I will get the ball rolling discussing the one you are looking at, and repeat this comment there. But basically I'm aware of this type of spot welder, and there are several sets on instructions on how to build your own, (but I know you don't want to do that). So my only comment having no experience of them is first when charged the caps may well hold potentially lethal voltage, so personally I would have preferred a better housing, bearing in mind they will be in the palm of your hand. (but that might not be an issue, just would be a concern till I knew exactly how it worked and what they were holding). The other being, that while I'm sure the makers have used caps up to the job, generally speaking Blue Caps are cheaper and less quality than black caps, when fixing things like expensive record decks (like my Linn turntable) its very often the cheap blue caps that have failed, and the solution is to remove them then replace them with new working caps, in which case its usually recommended to use the slightly more expensive but better quality black caps.

That's about all I can personally say about the one you are considering, in the other thread others may say these are not problems......because.

k

 

[Lucifer]

I saw your video it got a little Frankenstein there at the end Plus do you have a version in English (American ) ?
Here's the one I'm looking at it has a plug-in wall charger no battery and two good size capacitors.
Not that exact one but I'm going to look into which one I would like to purchase but that style.
Thanks for showing me that video but I want to try and buy one that works out of the box.

9 in 1 LCD Display Intelligent Dual Pulse Farah Capacitor Spot Welder Machine | eBay

This spot welder, suitable for spot welding 18650, 21700, 26650, 32650 battery assembly spot welding. Direct capacitor positive and negative charging. It is prohibited to spot weld pure nickel sheet, lithium iron monolithic aluminum and copper pole lugs as well as soft clad aluminum pole lugs.

www.ebay.com

On first glance this looks a better version of the same thing..... That's just first glance.
Spot Welder

 

[Lucifer]

Li po battery BMS question.

I have now got four 36v working pouch cell batteries.... YIPPEE.

But the last one had a problem, cannibalised another to make sure all good cells, charged it using bike charger... All good, checked all cells, voltage all balanced, connect to bike immediately pack output dropped to 0v, repeated several times same thing, suspected BMS, so changed it for identical one and it worked.,.... Drove a couple of miles no problem, So assume BMS is FUBAR?

I have a few identical BMS, but assume its not worth trying to fix a component, might resolder joints, surprising how many boards that are a couple of years old suffer from dry joints, but apart from that just bin it right?

Keith


WHATS A DRY JOINT?

To anyone who doesn't know, when any board is made all those components are soldered in place often by machine nowadays, but often the solder does not melt and flow as well as it should, and if you look, (often with a magnifying glass) you may notice that on most joints the solder has definitely welded itself to both the component, and to the pcb, however you may notice some joints where the joint looks different, perhaps the solder hasn't climbed up the component at all or it almost looks like the component is sitting in the middle of the solder but not definitely attached to it. Now it will at least be touching it, (or it would have never worked) when its new that works, as it all ages a hardly noticeable corrosive film covers the solder, so if there is a gap, however small between board and components this corrosion forms an insulator.... That's a dry joint, not uncommon, and easily fixed just touch the joint with a soldering iron and a bit of flux cored solder. It surprising how many things I have fixed like this, if in doubt resolder the joint.

Looking with a mag glass I do see a couple that are suspect, this isn't urgent for me so if anyone wants a photo ask and I take a pix before resoldering them, No Gt it will fix it but it literally takes seconds and cost nothing, so once the iron comes out I touch any joint that isn't immediately obviously ok.,

In fact edited this and added a photo cos I will prob forget, see the tool pointing at a vertical lie of joints, see hoe the top two have a good dollop of solder on but look at the next couple down, and you will see what I mean, suspect

 

[amberwolf]

You probably already know this, but the best place to look for a problem where it works with no load but fails under load is in the direct current path. For a BMS, this is usually in the FETs themselves, assuming they are being turned on (you can check their gate signals for that)

Assuming they are turned on, but not working, they probably got hit with a voltage spike (several ways to happen on an ebike as there's no typical safeties against them) beyond their capabilities for Vds, and POOF. FETs most often fail shorted, but sometimes they fail almost open, so they have a high resistance connection all the time (letting a ghost voltage thru similarly to when they are off, that will drop to nothing when any load is placed on them.

More often they aren't being turned on because the BMS MCU/etc sees an exceeded limit, so you still see the ghost voltage with no load, but under any load they don't pass current so the voltage drops to nothing.

For the problem of a BMS failing to turn on it's P-/C- (discharge/charge) port(s) at all, sometimes it's a cold solder joint either at a balance/sense connector pin or one of the parts between those pins and the MCU (or whatever reacts first to the sense lines for enable/disable of P-/C- ports).

More often, it's a problem with the connector's crimped contacts, either spread contacts (which then don't make good or any contact with the pin on the board), or a bad crimp or evena wire broken inside the insulation right at the back of the crimp, so it makes contact if pushed on, etc., but otherwise it doesn't.


Sometimes it's not the cells, but is a BMS that needs a switch turned on (usually this is wired to the battery case), or a temperature sensor (usually mounted in the cell block); the sensor is usually just a switch that turns itself off when it's rated temperature is reached. (usually white ceramic, sometimes stainless steel).

 

[Lucifer]

You probably already know this, but the best place to look for a problem where it works with no load but fails under load is in the direct current path. For a BMS, this is usually in the FETs themselves, assuming they are being turned on (you can check their gate signals for that)

Assuming they are turned on, but not working, they probably got hit with a voltage spike (several ways to happen on an ebike as there's no typical safeties against them) beyond their capabilities for Vds, and POOF. FETs most often fail shorted, but sometimes they fail almost open, so they have a high resistance connection all the time (letting a ghost voltage thru similarly to when they are off, that will drop to nothing when any load is placed on them.

More often they aren't being turned on because the BMS MCU/etc sees an exceeded limit, so you still see the ghost voltage with no load, but under any load they don't pass current so the voltage drops to nothing.

For the problem of a BMS failing to turn on it's P-/C- (discharge/charge) port(s) at all, sometimes it's a cold solder joint either at a balance/sense connector pin or one of the parts between those pins and the MCU (or whatever reacts first to the sense lines for enable/disable of P-/C- ports).

More often, it's a problem with the connector's crimped contacts, either spread contacts (which then don't make good or any contact with the pin on the board), or a bad crimp or evena wire broken inside the insulation right at the back of the crimp, so it makes contact if pushed on, etc., but otherwise it doesn't.


Sometimes it's not the cells, but is a BMS that needs a switch turned on (usually this is wired to the battery case), or a temperature sensor (usually mounted in the cell block); the sensor is usually just a switch that turns itself off when it's rated temperature is reached. (usually white ceramic, sometimes stainless steel).

Thank you,

Actually I didn't know. By that I mean when I initially learned about electronics 60 years ago it was a very different world (as you know). But when I got a real job, in the real world I mainly dealt with mains voltage and three phase wiring, so over time all the DC stuff got rusty, and like most things if you don't use it you loose it, and obviously what you do remember gets more and more dated. But, I was lucky enough to be given a very thorough grounding however long ago and its surprising how quickly, you can come up to speed on what at first looks like a totally different subject altogether, then each time something new "clicks" more and more comes flooding back, or your own mind understands the basic concept, then works the rest out.

Obviously as a basic BMS isn't a major expanse, so even on my limited budget its not worth doing too much work on, but you showed me a few more things that would definitely be worth checking and are easy to do. So thanks.

I hate chucking stuff away that could be easily fixed, think that was instilled in me as a child, rationing after WW2 didn't finally end in England until about 1960 when the last restrictions were lifted, (takes years to replace millions of tons of sunken ships). That war financially and industrially crippled this country. Took us about 20 years to repay the US for all the money you lent us to fight the Nazis before the Japs forced you to actually join in. Our side won but ironically even when we won we borrowed billions more from the US to help rebuild German economy. I don't think anyone there realised how much financial damage four years of all out total war did to the UK.

But don't get me wrong, we are very grateful for the vast blank checks you wrote us to help fight that war even if we did have to pay it back, we would have almost certainly lost without the US financial support. The UK fought the Nazi war machine on its own for for three years Then when Japan bombed your fleet at Pearl Harbour and you actually joined us with troops on the ground the end was inevitable, but even the last year of all out war was still at a terrible and tragic cost for both of us (and lasted even longer in the east).

Funny if you ever visit any of Europe's capitals now there is hardly any evidence now that there ever was an all out war apart from a few statues, they look unscratched. They didn't look that way in 1950, did you know that more than 12,000 tons of bombs dropped on London in the Blitz, (That's almost as many kilotons of TNT as the Hiroshima atom bomb)....... Good building repair jobs.

Keith

BTW I'm related to fieldmarshal Montgomery, my "great uncle" (I think.... my nan (grandmother) was his cousin). So our entire family has a slightly different view of the final invasion of Germany, Patton got the credit to be first to cross the Rhine which he was (but it was little more that a commando raid in reality, Monty crossed it at another point the following day leading the entire eighth army (they were not best friends).

 

[Lucifer]

Now have four working 4 pouch batteries, out of the donor batteries that I had about ten of all identical, replaced the odd cell and one BMS so result.

Now on the last one I have got working, I have another question. when the first 3 are charged (after my minor refurb) all the paired cells are identical voltage 4.1v, when charged thu BMS. On the last one, one pair of cell is just a bit down the others were all 4.1v once cell on the last pack was 3.9v. I manually charged just that pair with with my Imax, and it came up to 4.1, left it 24 hours with out BMS connected, still 4.1. so the cells are not immediately self discharging (though might over a longer time, but nothing immediately obvious). I have now re-connected the BMS to see if the situation changes.

But the question is hopefully simple, is that differential worth worrying about, assuming the BMS doesn't drain the that cell over say the next week? In which case it will need a new BMS unless I can fix this one.

So 3.9v vrs 4.1v worth the worry or not?

I do have more identical cells, removed from packs that obviously needed breaking for parts, so I could replace that pair of cell if necessary with but its a real pain and so time consuming getting a pair of cells out of one pack, I would hate to waste the time and then find it wasn't enough to be concerned about.

The other thing that might be relevant is all these packs have sat in my garage for over a year before I could do anything with them (not from choice) and they were not new when I got them, so assuming the BMS wasn't the cause of the problem (and doesn't discharge the cell now I topped it up). My plan was to use the battery on the bike, run it down a bit, then recharge it and see if it does better the second time its charged.

Any comments on this would be very welcome.

Keith

 

[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

Hi again

Been re reading some old post, now I know a bit more about these batteries I'm picking up things I missed first time round.

You said you sometimes use two BMS in a bigger pack for more cell groups, that is really the same in principle as putting two batteries in series isn't it?

SO I assume that means you can put two different finished battery packs in series then (if they are similar specs) if you want to increase the voltage. Can you confirm this for me? and any other considerations.?

Now on the same subject what about putting two finished packs in parallel ? (like jumping a car), to get more current available. This I really would like to consider having built 4 identical pouch cell packs (so far...... from several v.cheap faulty packs I picked up). The refurbed ones all work well on the bike, but my simple LED handlebar indicator tells me the available power drops when under heavy load, uphill (but still works) and immediately recovers when I throttle back, or reach the top of the hill (I'm not sure what exactly its monitoring, as it's just LED's). I was going to fit two packs on the bike and switch if I needed more range. But if I can connect them in parallel, wouldn't have to, and might have more power going uphill?

What do you think? and any other considerations to take into account, or once built can packs be used just like any other batteries?

Keith

How's the spot welder hunt going?

 

[amberwolf]

Hi again

Been re reading some old post, now I know a bit more about these batteries I'm picking up things I missed first time round.

You said you sometimes use two BMS in a bigger pack for more cell groups, that is really the same in principle as putting two batteries in series isn't it?

You can't really parallel two BMS in one pack: well, you can, but you can create problems for yourself. If you do this then each BMS may have slightly different sensing points for it's various limits even if they are supposed to be the same model/etc, and so they may turn on or off their outputs / inputs at different times, so the FETs of each may at times see the full load of the system. Depending on system wiring and BMS design you might also end up with current flows thru or voltages across things in one BMS that you don't want (or it can't take) when the other one turns off under load. If the goal is to spread the load across smaller cheaper BMSs to get more out of a pack, it's better to just use one bigger one.

Same problem happesn if you parallel two packs to get more current--if either pack can't handle the full load that suddenly gets applied to it when theo ther one shuts off, it can kill teh FETs from overheating, or even just from the current spike.

If doing it just to get more range but either one can handle the full curent, tha'ts not a problem.

You can't (shouldn't) series them either, because doing so means taht the Fets of the one that shuts off first will have to take the entire pack voltage, and they probably won't be designed for that, if you're using two lower-voltage BMS to handle one higher voltage pack. While they're on it's not a problem, but when off the switch opens and all voltage is across it...FETs don't like that and tend to blow up if it's over their ratings.

Commonly they fail shorted, so now the BMS is stuck on and can't do any protection at all no matter what happens, and it's a silent failure, meaning you don't have a way (other than manually testing the FETs regularly to make sure it hasn't happened) to even know they've failed, until cells get damaged by teh BMS not being able to protect against an exceeded limit.

Same problem happnes if you series two packs to get higher voltage.


Whether any of these actually hapepns in a particular situation depends on the specific parts and designs in the BMS, and teh actual load and conditions at the moment one of a seriesed or paralleled pair shuts off.

Fechter has posted in a few threads here and there that there *is* a way to minimize the chances of seriesed BMSes failing, and that's to install (reverse-biased, I think) schottky diodes (big enough to handle the full current required by the system) in parallel with each one. If the BMS shuts off, the diode will short around the FETs so they can't see the pack voltage and go POOF. (you'd have to search his posts to find the details of the setup).

 

[Lucifer]

Now have four working 4 pouch batteries, out of the donor batteries that I had about ten of all identical, replaced the odd cell and one BMS so result.

Now on the last one I have got working, I have another question. when the first 3 are charged (after my minor refurb) all the paired cells are identical voltage 4.1v, when charged thu BMS. On the last one, one pair of cell is just a bit down the others were all 4.1v once cell on the last pack was 3.9v. I manually charged just that pair with with my Imax, and it came up to 4.1, left it 24 hours with out BMS connected, still 4.1. so the cells are not immediately self discharging (though might over a longer time, but nothing immediately obvious). I have now re-connected the BMS to see if the situation changes.

But the question is hopefully simple, is that differential worth worrying about, assuming the BMS doesn't drain the that cell over say the next week? In which case it will need a new BMS unless I can fix this one.

So 3.9v vrs 4.1v worth the worry or not?

I do have more identical cells, removed from packs that obviously needed breaking for parts, so I could replace that pair of cell if necessary with but its a real pain and so time consuming getting a pair of cells out of one pack, I would hate to waste the time and then find it wasn't enough to be concerned about.

The other thing that might be relevant is all these packs have sat in my garage for over a year before I could do anything with them (not from choice) and they were not new when I got them, so assuming the BMS wasn't the cause of the problem (and doesn't discharge the cell now I topped it up). My plan was to use the battery on the bike, run it down a bit, then recharge it and see if it does better the second time its charged.

Any comments on this would be very welcome.

Keith

The pack referred to above, has now been sitting fully and equally charged on a shelf for a couple of days and the BMS has been reconnected for 48 hours, while the pair of pouch cells in question have dropped a a few hundredths of a volt, so I can live with that. I'll use if for a trip I have to do today, then see if the BMS charges them all equally when I recharge it. But looks done, and I think itv will settle down to being perfect once its been cycled a couple of times.

I did revive some totally dead Li ion cells from 0 volts using tips elsewhere, they appear ok, but I'm not going to actually use them in a pack due to A.W. comments, but did find that once they took their first charge the def gave back for current each time they were charged and then discharged. I have ordered some replacements, which I will check thoroughly before fitting.

I assume everyone else already knows, many fake cells do not weigh as much as the real ones, so first thing will be weigh them on my digital kitchen scales. Then still test them as some fakes now have heavier fillers to make up the weight. Ohh red cool

I think the pouch cells in question above were suffering from the same problem as the revived 18650's but to a much lesser degree as they were not flat, didn't need reviving but were a bit low to start off with.

Keith

 

[Lucifer]

The pack referred to above, has now been sitting fully and equally charged on a shelf for a couple of days and the BMS has been reconnected for 48 hours, while the pair of pouch cells in question have dropped a a few hundredths of a volt, so I can live with that. I'll use if for a trip I have to do today, then see if the BMS charges them all equally when I recharge it. But looks done, and I think itv will settle down to being perfect once its been cycled a couple of times.

I did revive some totally dead Li ion cells from 0 volts using tips elsewhere, they appear ok, but I'm not going to actually use them in a pack due to A.W. comments, but did find that once they took their first charge the def gave back for current each time they were charged and then discharged. I have ordered some replacements, which I will check thoroughly before fitting.

I assume everyone else already knows, many fake cells do not weigh as much as the real ones, so first thing will be weigh them on my digital kitchen scales. Then still test them as some fakes now have heavier fillers to make up the weight. Ohh red cool

I think the pouch cells in question above were suffering from the same problem as the revived 18650's but to a much lesser degree as they were not flat, didn't need reviving but were a bit low to start off with.

Keith

di

 

[Lucifer]

Ah finding my round the forum now, so no need to answer. As I suspected its a bit more tricky than it looks, but I found this which explains the situation.

http://liionbms.com/pdf/BPC2012Elithion.pdf

K

 

[Lucifer]

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).

Back to the first 24v bike (the 36v one in use and coming on fine). I mentioned upgrading to 36 v, its nice, everything works, but it's gutless. for all the usual reasons but also have now refurbished several 36v batteries, so it would be win win.

So first question is any idea if this controller would take 36v? You said the original controller may take it, well I got to in hidden in the frame and got it open (no easy task, glued shut), but had a look at the components. 006 shows the insides, the bigger caps are all 63v a couple of the smaller ones are 50v, so that looks like it will work with 36v battery. As to the output FET's or transistors, I struggled for some time but cannot make out what's written on them, I think the last line on them (or at least one of them) is CHN 012..

Second question, I don't mind replacing it IF I CAN GET THE CORRECT ONE, can you tell from this what I would need?

Keith

If I can't upgrade it I will just make a new battery, and sell it.

 

[amberwolf]

So first question is any idea if this controller would take 36v? You said the original controller may take it, well I got to in hidden in the frame and got it open (no easy task, glued shut), but had a look at the components. 006 shows the insides, the bigger caps are all 63v a couple of the smaller ones are 50v, so that looks like it will work with 36v battery. As to the output FET's or transistors, I struggled for some time but cannot make out what's written on them, I think the last line on them (or at least one of them) is CHN 012..

If you can go out into direct sunlight, and turn off the camera's flash, you can get much better pics of individual parts, as the camera will autofocus on them better, and it will also let you put the camera at an angle to the light to see the engraved labelling more clearly.

Once you have a bunch of well-focused pics you can then zoom in on them to read what things say.

Most likely the CHN 012 is a manufacturing plant and date, as they dont' come up in any searches with relevant results.

Besides the FETs, there are a number of parts that may be powered driectly off the battery bus, such as the LVPS that makes the 5v and 12v/etc. Most of the higher voltage cheap controllers use a big resistor to drop the voltage to the input of the LVPS, since most of the designs can't handle more than around 30v. So 24v controllers may not have this resistor (yours doesn't, AFAICT), and you may have to install one between (probably) the black wire at the lower left corner and the point that wire presently goes to. That's what that area is for down there in that corner, it even has silkscreening for the parrt, so the same design is probalby used for hihger voltage units. The resistance has to be calculated or guesstimated so that the typical LVPS current flow of a couple hundred mA or less is going to create a voltage drop across the resistor of the diffference in voltage between the battery pack and the safe voltage the LVPS can handle. There are pics of 36v controllers around the forum that show this resistor, including at least one controller test/review thread that I posted ages ago, so you could find a usable value that way, too.

The one catch is that the LVC of this controller is setup for a 24v pack, not 36v, so you would need to manually monitor voltage and stop using the system when it reaches empty (as the BMS LVC shutoff shouldn't be relied on except for emergency "something is wrong iwth the pack" shutoff, since that's all it's designed to be, it's harder on the battery to discharge it that much further every time, especially with older cells).

Second question, I don't mind replacing it IF I CAN GET THE CORRECT ONE, can you tell from this what I would need?

The only things I could tell you for sure:

--it would need the appropriate current limit to match the capability of the battery you use, so it doesn't overload the battery...but not too high a current limit for the voltage being used so the total watts remains somewhere near what the motor is likely to be able to handle. (meaning, if it was originally a 250w system, using 36v 50A is probably not a great idea :lol: ).

--needs connections for all the things listed on the label, if you want those to function; so tis' for a sensored motor, and has a PAS sensor and a throttle.

 

[999zip999]

36v should be fine. Just run till blow's. As we all do .Yes melting motors, controllers and we kill battiness. Plus we blow up spot-welders.. That is what made this forum.
Be careful batteries have stored energy and will use it. For good or bad.

 

[Lucifer]

36v should be fine. Just run till blow's. As we all do .Yes melting motors, controllers and we kill battiness. Plus we blow up spot-welders.. That is what made this forum.
Be careful batteries have stored energy and will use it. For good or bad.

LOL, Blowing things up seems normal for this game. Personally I try and avoid it (I can't really afford it). That said once I eliminate the basic obvious problems I'm serious about giving this a go, Now I got the controller out of the frame, I'm trying to work out what controller I would need to get to replace it with if and when it blows, remember I am so new to this getting my head around every new problem is a big learning curve (So many wires..... Can I just ignore, and not connect the ones I don't need?) . I have a million questions on that but I'm shattered atm, so Ill work away and prob come back and pick your brains on the replacement issue later.

My mobility issue means I could really do with a spare bike that works.

The 36v one is doing well btw.

Hows your injury recovery coming on?

K

 

[amberwolf]

(So many wires..... Can I just ignore, and not connect the ones I don't need?) .

That depends on the controller design.

For instance, most of them use N.O. ebrake switches, so leaving them unconnnected still works just like iff you had them.

But leaving PAS unconnected on a controller that requires pedalling for the throttle to operate won't work (unless you build a little circuit to constantly send a PAS signal to them anyway).

If it has a display, you probably can't operate it outside of whatever the default assist level and mode is when it turns on, wthout the display attached and working. Some come up in a "safe" mode that allows *no* motor operation until you choose an assist mode, so those don't work at all without the display.

So if you don't want a function, and know you don't ever want it, try to find a controller that doesn't have it, so you don't have to work around it.

Or find one that has options to turn off or ignore all the functions your'e not going to use.

 

[999zip999]

Maybe you could tell us more about this 24 volt bike what's what's the name on the frame how old is it what's on the handlebars that could be hooked up. They're also could be a pas that's a three wire connector and it plugs in to the round magnet around the bottom bracket so when you push well it's speed oriented the fast you pedal the more it gives it depending on what power level you put it on. But the easiest way for us to answer your questions is show us all the wires and we'll tell you what they're for plus the model and year of your 24 volt bike.
I doubt if it would be able to take 48 volts.

 

[Lucifer]

That depends on the controller design.

For instance, most of them use N.O. ebrake switches, so leaving them unconnnected still works just like iff you had them.

But leaving PAS unconnected on a controller that requires pedalling for the throttle to operate won't work (unless you build a little circuit to constantly send a PAS signal to them anyway).

OLD PAS BYPASS HACK, ages ago, I saw that someone took the wire that should go to the PAS sensor, and basically fitted a new PAS sensor on the front wheel, (think he used a speedo sensor from memory ?) instead of the original sensor the crank housing. so if the bike was moving, it thought you must be peddling, thus converting it to twist and go....... I haven't personally tried this but it sounded simple and clever.

Both the bikes I'm working on have a very similar setup, they both have a three position switch on the handlebars, that is either off, (no power) PAS, or twist and go (Now not legal for road use in the UK on new bikes). On the 24v bike the PAS selection never worked, the previous owner said a sensor in the crank case housing had failed, and that while it could be fixed by replacing it he never used that setting so didn't bother, well I don't use it either. (I can still peddle if I need to assist the electricity eg going up a steep hill), so it appears that on the 24v bike I don't need to bypass the PAS, its done it all by itself. probably as it was made before PAS was made mandatory in the UK, so was designed differently in that no attempt was made to stop you simply disconnecting it....... Least that's what I'm thinking.

I might test it by putting it back together and simply using 2 sla batteries as a power source to see what happens if I don't actually bother reconnecting the PAS on the controller. (in case the pas sensor has failed in some sort of on position). In any event its been like that for years, so I'm thinking either don't connect it or leave well alone.

SLA batteries can be handy if for no other reason simplicity when experimenting on bikes

I have a tip on SLA batteries, been given several from emergency lighting that were dead, easy fix tip if anyone wants it. the top plate on the battery can easily be removed with a knife its just stuck on with a couple of tiny spots of super glue (or similar), slide the knife gently under the top plate so you don't break it, and wiggle it focus on the glue spots. Under that plate are six rubber caps to the cells that act as seals let gas out but not the electrolyte. The gas is basically small amounts Hydrogen and oxygen released during charging, (what was the water in the electrolyte). Over time this basically dries the cells out, using a hypo, top them up with distilled water, (the water from a condenser dryer works just put thru a filter paper in case any fluff in it). Leave to stand for a while and repeat until you can see the water at the top of the cells. If any were totally dry leave overnight then repeat. Replace rubber caps glue lid back on. 75% of TOTALLY DEAD batteries given this treatment are then as good as new.

Works on sealed maintenance free car batteries too, but you have to usually drill a small hole in the to of each cell, but the solid top usually has moulding marks so you can usually see clearly where the cells are and put your holes in the exact spot you want them, then reseal the hole afterwards, (but it's only about 50% successful on them for some reason, probably sulphitation, but not done many so that might be sample size)

If it has a display, you probably can't operate it outside of whatever the default assist level and mode is when it turns on, wthout the display attached and working. Some come up in a "safe" mode that allows *no* motor operation until you choose an assist mode, so those don't work at all without the display.

So if you don't want a function, and know you don't ever want it, try to find a controller that doesn't have it, so you don't have to work around it.

Actually it was more a question of almost every cheap controller I find has loads of extra wires, that my original one never had in the first place, hence why I asked could I use one and not connect up those wires that my bike simply doesn't have. But I'm still looking for a better match atm.

Or find one that has options to turn off or ignore all the functions your'e not going to use.

 

[Lucifer]

Maybe you could tell us more about this 24 volt bike what's what's the name on the frame how old is it what's on the handlebars that could be hooked up. They're also could be a pas that's a three wire connector and it plugs in to the round magnet around the bottom bracket so when you push well it's speed oriented the fast you pedal the more it gives it depending on what power level you put it on. But the easiest way for us to answer your questions is show us all the wires and we'll tell you what they're for plus the model and year of your 24 volt bike.
I doubt if it would be able to take 48 volts.

Hi

Sorry for the slow reply, I missed your post, just seen it.

Well its and Electrobike MK2 made by a UK company called ASBikes.co.uk. (Still in business) They bought out a a newer version the MK3 which is 36 volts, but according to them its not viable to make this one 36v but from what I have read I dont think thats accurate. Its a nice folding ally frame bike, but it is so slow and underpowered it's untrue. Drive it down the road and a snail can overtake you.

There is nothing at all on the handlebars, no meters of any kind. The only thing there is a three position switch, Off, Power assist, and Twist n Go. The power assist does not work and hasnt for years. As an experiment, I disconnected the power assist wires from the original controller, and it still worked perfectly with twist and go. So the bike itself doesn't need that facility (and I wouldn't want it anyway, though I wouldn't bother removing it, I just wouldn't use it). So this test simplified matters and I ordered a controller that doesn't have it, so the new 36v controller definitely wont miss it.

I have done a fair bit of research and had a fair bit of advice, and currently I think if I replace the controller with a 36v one, and put a 36v battery on it I THINK it will work fine, I'm as sure as I can be that the motor will be more than happy, in fact I get the impression its starved of power at the moment.

Anyway sooner or later you have to actually try something instead of theorising so I have ordered one of these controllers. It only cost £10, and I have 36v batteries, so not a lot to loose to at least try it.

Cheap 36v controller from e-bay

I will keep an eye on the motor temp especially at first, but I have a gut feeling that wont be a problem, in fact I suspect its actually a 36v motor, it's got a simple 1/2" white sticky label on the motor saying "24v", but I'm dubious about that. As it was a fairly early e-bike, and as the UK was brining in "DRACONIAN" legislation covering e-bikes which had not yet gone through parliament, I sort of think the makers intentionally underpowered it, to be sure it would not fall foul of the legislation, and hence once they knew where they stood bought out a 36v version, but I could be wrong.

Thanks to advice from AW, I know the original controller is 24v, (some pictures above) and while we discussed modifying it by adding a resistor, I would have probably had to change the FET's as well (If I could read the writing on them). So in the end thought get a new controller and see what happens.

I never had any intention of going to 48v on this bike I just want it as a useable spare, so I hope 36v will deliver more current to the motor and increase the RPM a bit. It's never going to be a performance bike (and I wouldn't want or need it to be)..... I'd settle for keeping up with a fast walking pedestrian LOL. Anything more would be a bonus.

It does have a speedo, but that's def aftermarket, doesn't go through the controller, just to a sensor on the front wheel and that was broke, but while waiting for the controller to arrive I think I fixed it today. Not had chance to test it yet but I think the bike does about 10 MPH, my daughters bog standard e-scooter goes about twice as fast, that's how I judging it.

Keith

Any hints tips advice or warnings would be very welcome.

Once I totally finish all my work on these two bikes, the 36v one is already working and in use and I'm range and performance testing various 36v batteries I put together on it, using a wooden box on the rear carrier atm (another reason I would like to convert the 24v one to 36v, I got 36v batteries coming out of my ears now ). Once all batteries boxed up, tested, brakes replaced ete etc etc. Then I do have a potentially more fun project to work on, I have also 2 proper e-bikes (that don't work) one is a nice but accident damaged mountain bike, the other is a pristine Raleigh Velo (with an electrical fault). I thought I would try and make one good working decent bike from them, but this time without being under the pressure of needing to get something working ASAP, which its been up till now. The Raleigh is 36v pedelec front wheel hub motor, the mountain bike is 36v rear hub motor. So potentially a two wheel drive bike..... That will be interesting, but I'm not going to even look at them until the current work is totally finished.

 

[999zip999]

Now you can run at 36 or 48 v a motors too dumb to no voltage. What I mean by that voltage is speed you put a hundred volts on that motor it'll run in the air. but if you put it on the ground and try to push you might melt. Does the bike feel stable enough to ride at say 25 mph ? I mean is it a good bike as brakes it works you feel safe ? You could tell I'm concerned