LiPo battery care and basic information

[bandaro]

forgive my lack of knowledge, but that charger in the post above.
could i just buy several lipo packs to get my 24v 20 or 30amps. then just charge them a couple at a time? if that is so, could i also build up some sort of connection board so that i just plug each battery into its slot to build them up into 24v 20amp? then i could just wire my motor up to the board? would this be a safe reliable way to do it?
if that is possible how many batteries of what type would i need?
what i would really like is for some one with exp to jump up and say buy this do that and bingo. but i need to learn at the same time

sure can. i am going to have my batteries charged in 4 sets of 3s, making a 12s1p pack for the discharge. planning on charging via some balancing tabs i shall solder in, then have each set of batteries going to a board that i can discharge from. i am only charging as 4 sets of 3s as the rc chargers are generally limited to 50w, and the charger i have charges up to 5A each set, so 3s is the highest voltage that can take the full 5A charge ((3.2x3)x5=48w) so its fastest as 4 sets.

in regards for your board, its a nice neat way, but make sure that the set of batteries you are charging are isolated from the other batteries, otherwise the power will flow into the rest of the pack, effectively charging the whole pack at once, but not very well, possibly leading to smoke. this means you will need to solder plugs into the wires, so you can isolate a set. alternatively, you could charge all of your pack at once, with the cells rigged in parallel for the charge, and series/parallel for the discharge.

what i would recommend for you to do is get 4 packs of 6s 5000mah lipo's to make a 22.2v 20Ah total, then have a 6s charger, such as the one im getting here: http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=11170 or a more powerful one if funds allow, and charge as 4 sets of 6s, then have the plugs from each battery on a board, and a second board that plugs over the first board that is rigged in parallel, going to the speed controller, so when that top board is unplugged, each 6s pack is isolated. by having a board holding the connectors its a single plug/unplug to isolate the packs, rather than 3 connectors to unplug. could make the top board a front cover of the battery box even, so its easy to get the cells out if need be.

it may be cheaper to buy the total 24 cells in a different configuration (ie 8x3s packs on special) but if you are not confident soldering directly on the cells, then go the 6s packs. alternatively, people are having success with power supplies set to the max pack voltage ( so for lipo: 4.2vx6=25.2v), and charging the pack as a single unit, letting the cells try to balance themselves out. i found this to be a bit more expensive for my configuration, and i understand the cells and circuitry so would prefer to manually monitor exactly what my cells are doing, but a meanwell supply or the like could be a great alternative for a charger, and charge faster than the linked charger.

 

[daddz]

forgive my lack of knowledge, but that charger in the post above.
could i just buy several lipo packs to get my 24v 20 or 30amps. then just charge them a couple at a time? if that is so, could i also build up some sort of connection board so that i just plug each battery into its slot to build them up into 24v 20amp? then i could just wire my motor up to the board? would this be a safe reliable way to do it?
if that is possible how many batteries of what type would i need?
what i would really like is for some one with exp to jump up and say buy this do that and bingo. but i need to learn at the same time

sure can. i am going to have my batteries charged in 4 sets of 3s, making a 12s1p pack for the discharge. planning on charging via some balancing tabs i shall solder in, then have each set of batteries going to a board that i can discharge from. i am only charging as 4 sets of 3s as the rc chargers are generally limited to 50w, and the charger i have charges up to 5A each set, so 3s is the highest voltage that can take the full 5A charge ((3.2x3)x5=48w) so its fastest as 4 sets.

in regards for your board, its a nice neat way, but make sure that the set of batteries you are charging are isolated from the other batteries, otherwise the power will flow into the rest of the pack, effectively charging the whole pack at once, but not very well, possibly leading to smoke. this means you will need to solder plugs into the wires, so you can isolate a set. alternatively, you could charge all of your pack at once, with the cells rigged in parallel for the charge, and series/parallel for the discharge.

what i would recommend for you to do is get 4 packs of 6s 5000mah lipo's to make a 22.2v 20Ah total, then have a 6s charger, such as the one im getting here: http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=11170 or a more powerful one if funds allow, and charge as 4 sets of 6s, then have the plugs from each battery on a board, and a second board that plugs over the first board that is rigged in parallel, going to the speed controller, so when that top board is unplugged, each 6s pack is isolated. by having a board holding the connectors its a single plug/unplug to isolate the packs, rather than 3 connectors to unplug. could make the top board a front cover of the battery box even, so its easy to get the cells out if need be.

it may be cheaper to buy the total 24 cells in a different configuration (ie 8x3s packs on special) but if you are not confident soldering directly on the cells, then go the 6s packs. alternatively, people are having success with power supplies set to the max pack voltage ( so for lipo: 4.2vx6=25.2v), and charging the pack as a single unit, letting the cells try to balance themselves out. i found this to be a bit more expensive for my configuration, and i understand the cells and circuitry so would prefer to manually monitor exactly what my cells are doing, but a meanwell supply or the like could be a great alternative for a charger, and charge faster than the linked charger.

that helps a bit, but also confuses a bit not your explanation, just my lack of knowledge. right now i have pretty much decided on a ping 24v30ah as soon as my tax comes in, or several smaller ones if the price works out ok. or 1x 20ah to use, and 1x 10ah, as a reserve, my current batteries are 22kg so i will still cut weight even carrying a reserve supply
i reckon i will change my mind about clikkitysix more times before i hand over the cash though

 

[Arlo1]

WHos going to be the first to try this? http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=11941&Product_Name=Turnigy_nano-tech_6000mah_6S_25~50C_Lipo_Pack

 

[steveo]

WHos going to be the first to try this? http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=11941&Product_Name=Turnigy_nano-tech_6000mah_6S_25~50C_Lipo_Pack

will it be really worth it? ... 1000mah extra .. and usless increased c rating.... unless we are building a drag car with lipos ... then thats a different story

-steveo

 

[Arlo1]

WHos going to be the first to try this? http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=11941&Product_Name=Turnigy_nano-tech_6000mah_6S_25~50C_Lipo_Pack

will it be really worth it? ... 1000mah extra .. and usless increased c rating.... unless we are building a drag car with lipos ... then thats a different story

-steveo

Uhm well with my current set up of 10ah 24s I am hitting the limits of the C rating from time to time! I would thing if someong had to build a light bike for say the 2011 international ebike race they might want the highest c rating possible as well as the quicker charge capabilitys and the higher amount of expected cycles!

 

[El_Steak]

Just spent some time reading through this list of Lipo fires reported on RCGroup. Burned houses, garages, cars...

http://www.rcgroups.com/forums/showpost.php?p=1936756&postcount=4

I keep my 12 packs in Lipo Bags at all time (while riding and while charging), but I'm not sure those bags would be enough to contain a fire (I have 4 bags, each one with 3 x 6s 5000ah packs).

All the vids I've seen of those Lipo bags containing a fire are with smaller 1500-2000ah cells. Anyone ever had a real-life experience of a couple of large cells (5000ah+) bursting in flames inside one of those Lipo bags?

 

[Doctorbass]

Just spent some time reading through this list of Lipo fires reported on RCGroup. Burned houses, garages, cars...

http://www.rcgroups.com/forums/showpost.php?p=1936756&postcount=4

I keep my 12 packs in Lipo Bags at all time (while riding and while charging), but I'm not sure those bags would be enough to contain a fire (I have 4 bags, each one with 3 x 6s 5000ah packs).

All the vids I've seen of those Lipo bags containing a fire are with smaller 1500-2000ah cells. Anyone ever had a real-life experience of a couple of large cells (5000ah+) bursting in flames inside one of those Lipo bags?

Impressive list of bad events!!!!

I still worri about Lipo.. Me and my wife bought a new house 4 months ago.. with a garage as well. I ve built an aluminum box for all my 12 lipo (4s 3p) 6" x 6" x 8" in 1/8" thick aluminum.

but i promissed myself to ALWAYS charge them outside the house!!! also.. i ll chrge them with my 1700W DC PSU .. that s 1.3C charge rate.. but for safer method i always charge to 4.1V ( LiLo) and never discharge lower to 3.4V/cell.

 

[El_Steak]

Looks like the Lipo safety bags I've been using are pretty much useless...

[youtube]ZEkewCjiDs0[/youtube]

That looks exactly like the bags I got from Hobby King... Tabarnak!

Ammo Box maybe ? For you canadian folks, Princess Auto has some nice ones for 13$ !

http://www.princessauto.com/surplus/hand-tools/tool-holders/8023569-ammo-box

 

[joera]

This is a fantastic thread, very informative.
I just purchased a eZee conversion kit with the 14Ah polymer upgrade.
I was wondering what you guys suggest for winter or long time storage?
Like 3 or 4 months. I’ve heard that it’s best to keep the battery charged
At 50%, is this true? And is there any other tips for storage.

 

[xXNuggettXx]

Hey guys, brand new to the forum and also to the Ebike world. I had a question about building a LiPo pack. I know I want somewhere in the range of 50V 10Ah. According to this thread each cell has maximum "safe" voltage of 4.2V. However, in looking into the Turnigy batteries for sale on Hobbycity (http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=9180&Product_Name=Turnigy_5000mAh_6S_25C_Lipo_Pack) each cell is only 3.7V. Which should I trust when designing a pack? I know I can check them once I get them but I wanted to know what to expect before hand. I thought that they were supposed to stay between 3.3V and 4.3V or else they may go boom so should I use those two numbers as boundary values? Thanks in advance.

 

[bart_dood]

Hey guys, brand new to the forum and also to the Ebike world. I had a question about building a LiPo pack. I know I want somewhere in the range of 50V 10Ah. According to this thread each cell has maximum "safe" voltage of 4.2V. However, in looking into the Turnigy batteries for sale on Hobbycity (http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=9180&Product_Name=Turnigy_5000mAh_6S_25C_Lipo_Pack) each cell is only 3.7V. Which should I trust when designing a pack? I know I can check them once I get them but I wanted to know what to expect before hand. I thought that they were supposed to stay between 3.3V and 4.3V or else they may go boom so should I use those two numbers as boundary values? Thanks in advance.

The safe voltage is the maximum you can charge to, some people like to live dangerously and go to 4.3 volts per cell, others are conservative and run perhaps 4.1 volts.
3.7v is the nominal voltage, it changes over the discharge of the pack. The 3.3 volts you mention is the lower end, for lipos if you go too low you change the chemistry and wreck the cells and they can't be fixed.
The less you deeply cycle the batteries the better, you'll get longer like and better balancing.

I have a pack just like the one you describe, zippy flightmax. I charge to about 4.22 volts per cell and only run them down to about 3.75 volts before re-charging.

 

[xXNuggettXx]

Thanks bart_dood for your reply. If you don't mind me asking, what configuration is yours setup in? I was thinking about buying the 5000mAh Turnigy batteries and doing a 11s2p setup. Is there some advantage to going with a lower capacity battery and adding more in parallel (obviously this would add more weight to the pack)? Also, would you recommend the Zippy's over the Turnigy's?

 

[El_Steak]

Is there some advantage to going with a lower capacity battery and adding more in parallel

Not in the case of Lipo. The C rate is so high that even a single 5Ah in series can deal with the current that almost all the ebikes controllers out there will be able to suck from it.

I don't think its a good idea to go with an odd number like 11cells. You'll have to deal with different pack sizes and wont be able to put all packs in parallel should you wish to balance charge them with a single RC charger. 4 packs of Zippy or Turnigy 6s 5ah 20C (12s2p) would give you the 50V 10ah you are looking for around 200$. You'll also have to factor in the shipping cost from HK and you'll need some connectors / wiring as well as a charging solution (RC chargers / powersupplies with BMS, etc.) and something to monitor the cells voltages (battery medics, cell logs, etc.)

 

[xXNuggettXx]

Thanks El_Steak,

I think that's solid advice and what I'll probably do. I was thinking about using these as cell monitors (http://www.chargery.com/cellMonitor.asp). I guess I would need one for each pack. Do you have any reccomendations on chargers? This is where things start to get hazy for me. I'd also be happy to see a thread on e-sphere that talks about chargers for n00bs but I can't seem to find one. Thanks again.


Now all I have to do is talk Methods into giving me one of his crazy 100V 100A controllers. He's the one that got me into ebikes but he told me he doesn't build them anymore. I think if I annoy him long enough I may be able to get one out of him.

 

[El_Steak]

I was thinking about using these as cell monitors (http://www.chargery.com/cellMonitor.asp). I guess I would need one for each pack.

I would instead recommend the "CellLog" from hobby king. There's a model that supports logging through USB and the other cheaper doesn't. I use the cheaper one. The CellLog will give you readings for all your cells and has a low and high voltage alarm output. You could also use them in the upcoming CellLog BMS from Gary: http://endless-sphere.com/forums/viewtopic.php?f=14&t=17168&start=225#p305199

You will need 2 celllogs, one for each parallel string in your pack (2 packs in parallel and 2 packs in series).

Do you have any reccomendations on chargers? This is where things start to get hazy for me. I'd also be happy to see a thread on e-sphere that talks about chargers for n00bs but I can't seem to find one. Thanks again.

I don't think theres yet a fully "plug and forget" charging solution for Lipo like you have for a Ping pack.

I've seen 3 approaches to charging:

1- RC charger with all your packs in parallel.
When you want to charge, you unplug your packs from series configuration (2s2p) and connect them all in parallel (1s4p). Using parallel adapters for your discharge and balance leads, you can then charge your pack using a single RC charger. This is cheap, but rewiring your pack for each charge cycle is annoying and dangerous. If you make a mistake you can easily short it out. (search the forum for KFF and you'll see).

2- Several RC chargers for each parallel strings.
In this case you would use 2 RC charger, 1 for each parallel group in your pack. The advantage is you don't have to change the connections (you can leave your pack in 2s2p). You will need isolated chargers however or use a seperate power supply for each charger. This is a bit more expensive and you have to deal with more chargers and powersupplies. Look up doctorbass, he recently modified a Turnigy quad charger to do just that.

3- Bulk charging with Powersupplies.
You can by cheap Meanwell power supplies, adjust their voltage to match your pack and "bulk charge". You plug the power supply directly in the pack and it will supply current until the pack voltage raises to the same as the PS output voltage. This is cheap and you don't have to rewire your pack in any way. However, you will have to closely monitor each cell group in your pack to make sure none are going over 4.2V. You will also need another method to balance your cells should they become unbalanced (a Hobby King battery medic could help with that).

soon- BMS
There are a couple of BMS in development for Lipo. These will work with bulk chargers but will provide high voltage protection and automatic cell balancing. This will solve pretty much all the Lipo charging issue. Search the forum for Lipo BMS and you'll find the information in multiple threads.

Now all I have to do is talk Methods into giving me one of his crazy 100V 100A controllers. He's the one that got me into ebikes but he told me he doesn't build them anymore. I think if I annoy him long enough I may be able to get one out of him.

Check with LYEN on the forum, he seems to have pretty good controller offerings.

 

[Arlo1]

If I have a 4s lipo pack with one cell mesuring 0.000 volts and super low resistance is it shorted?

 

[Ypedal]

If I have a 4s lipo pack with one cell mesuring 0.000 volts and super low resistance is it shorted?

I've had to deal with this a few times, using the ballance leads to tap into that single cell i charged it up slowly ( 1 amp ) to 3.0 ~ 3.3 v .. remove the charger, let it sit a while, if it keeps the voltage, charge it up !.. if it drops to 0 again.. consider it toast.

 

[Arlo1]

If I have a 4s lipo pack with one cell mesuring 0.000 volts and super low resistance is it shorted?

I've had to deal with this a few times, using the ballance leads to tap into that single cell i charged it up slowly ( 1 amp ) to 3.0 ~ 3.3 v .. remove the charger, let it sit a while, if it keeps the voltage, charge it up !.. if it drops to 0 again.. consider it toast.

Haha I did better I hooked up a 12 volt motorcycle battery to the one cell and it would not climb above 1.8 volts I had to stop bacause after about 1 minute there was smoke coming off my 14 gauge jumper wires lol. It must be shorted internaly!

 

[MadRhino]

One of the packs that I received from HobbyKing was wrong: one cell in the pack was dangerously low (2.54v), with all the other cells around 3,7v. I've put this pack aside with a red tape on, and did not attempt to charge it, since I have more packs than needed right now.

Today, I checked the bad pack and it is now balanced. The low cell recovered by itself, in about 10 days on the shelf. Should I trust it? Or is there some test I should do to make sure? Is this situation common?

All the other packs are perfect, I've put them all to cycle after balancing and they keep their balance almost perfectly. I have 12 packs 8s and 12 packs 6s, all Zippy 5.8A 30c. It is one of the 6s that was wrong.

 

[Gregory]

I'd guess it was a bad connection on the balance taps when you tested it and the cell was at 3.7V all the time - either at the JST headder or where the balance tap is soldered to the cell.

The JST -XH connectors are known to be unreliable.

Cells don't just balance themselves while sitting on the shelf open circuit.

 

[Gregory]

... using the balance leads to tap into that single cell i charged it up slowly ( 1 amp ) to 3.0 ~ 3.3 v .. remove the charger, let it sit a while, if it keeps the voltage, charge it up !.. if it drops to 0 again.. consider it toast.

Haha I did better I hooked up a 12 volt motorcycle battery to the one cell and it would not climb above 1.8 volts I had to stop bacause after about 1 minute there was smoke coming off my 14 gauge jumper wires lol. It must be shorted internaly!

Attention lipo beginners do not do this - Obviously Arlo must be kidding here and wanted to ruin the cell and should have used the sarcasm or smiley. I just want to emphasise to noobs the proper way to try revive a dead lipo is to trickle the tiniest current you can into the cell, check, cycle, check. And do it in a flame proof area.

Arlos’ way is dumping huge amps into an empty, possibly damaged lipo cell.
Also if charging via the balance taps (22awg?) on HK lipo they are only good for a few amps continuous.

 

[MadRhino]

I'd guess it was a bad connection on the balance taps when you tested it and the cell was at 3.7V all the time - either at the JST headder or where the balance tap is soldered to the cell.

The JST -XH connectors are known to be unreliable.

Cells don't just balance themselves while sitting on the shelf open circuit.

Thanks, that's what logic dictates. I will charge it and put it to cycle with the others, altough the bad balance connection could eventually cause erroneous safety shutoff some day.

 

[vanilla ice]

..stay between 3.3V and 4.3V or else they may go boom so should I use those two numbers as boundary values?

If you stay between 3.6 and 4.1v you don't loose all that much capacity compared to running from 3.3 to 4.3v.. Have a look at a discharge graph to see what you lose. There is no one right way to go. Its up to you what values to pick, everything is a trade off. Just like with other chemistry, you will gain life span by giving up a little capacity.

Also temperature effects the cells, so taking a conservative course with your max/min voltage gives you more leeway there. A cell charged up to 4.1v in a cold garage at night may turn out to be 4.2 when you go to use it the next day.

 

[deVries]

Link http://endless-sphere.com/forums/viewtopic.php?f=14&t=9170&start=195#p284110 from here, to this previous post...

Can I charge 5 LiPo packs at the same time using ONE DC power supply to power all 5 chargers? I assume the 5 LiPo chargers isolates itself with each LiPo pack while all 5 chargers can share the main/source 12-14v DC Power Supply without any problems??? Correct or No?

Not correct. These chargers do not have isolated outputs. The negative output is common with the negative 12-14V input. If you have the packs separate, and not connected in series, then yes, you can do use multiple units driven from a common 12V input source, to charge the packs at the same time.

-- Gary

Is it possible to use three 12-14v cheap car battery chargers (with enough output amps to support each 4s LiPo charger) AND then the negative outputs would not share any of the negative commons from the three separate car charger inputs... Therefore, the 3 in series 4s3p packs to make a 12s3p battery can be left connected in series AND be charged simultaneously by the three 4s LiPo chargers each having its own 12-14v car charger making three inputs, one each from one of the three auto chargers. This effectively isolates each 4s3p pack from each other to charge in series as a 12s3p battery?

Will this work to charge three 4s3p packs connected in series simultaneously & safely?

Thanks!

 

[Crash Machine]

Sorry to break into this post with yet another question but I've read till my eyes are blurred the last couple of days. Is there a good configuration that will match the voltage of my 48v Ping pack(53 volts actually)? 14s is what I understand :? . Odd number? I would like to start by paralleling 10 Ah of Lipo to raise the C rating of the 15 Ah Ping battery. I have an X5 (40 amps) that is very hungry .
I also like to do rather long distance rides,2300 miles across the southeast last summer maybe across the country this summer. So I figured out I need about 50 Ah to make daily riding less of a chore. So 35 Ah or more of whatever battery composition I choose. Lipo is so much lighter it seems like the logical choice. But I hate to give up the dependable 15 Ah Ping battery. Thanks in advance.