Is my lipo doomed?

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bart_dood   100 W

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Is my lipo doomed?

Post by bart_dood » Apr 29 2010 11:41pm

I got a batch of zippy 5Ah 22.2 lipos and two of the cells have these swirly white markings on the pouches. I took a photo.

Are my cells going to die? I have cycled them once and the voltages are all fine. Has anyone seen this before?


:(
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mwkeefer   10 MW

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Re: Is my lipo doomed?

Post by mwkeefer » Apr 30 2010 12:17am

Personally I would be more concerned with the ding than the white markings...

Seriously if you have cycled them once or twice and they haevn't puffed and the balance worked okay, then I wouldn't worry about it... We have seen some pretty knarley looking LiPos from Hobby King but they worked flawlessly.

If your charger does IR calculation, take a reading.. what is the pack IR?

-Mike
Regards,
Mike

{My Rides]
2010 Dahon Jack - GNG v1 - LYEN 6FET - 20/40A - 18S2P10AH - Nom:66.6v,1332w
2004 Hard Rock Pro Disc - Recumpence ms eDrive v4 - Astro 3220 4T - 12S2P16AH - HV110 - Left Side Drive - Gearing: 38mph
Nominal Peak Power @ 60 seconds: 5328 watts - Maximum Power: 49.8v, 120A, 5872w
2010 Downtube 8FH - Stock GNG v1 Stock Controller - EB809XC - 12-16S
2012 Downtube Nova 7spd - Stock GNG v2 - 12S2P10AH - EB809 - 12S-16S - 20A/30A,Nom VCC: 44.4, 888w

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liveforphysics   100 GW

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Re: Is my lipo doomed?

Post by liveforphysics » Apr 30 2010 1:12am

Some pack construction uses double sided tape to stick the cells together, others drible some rubber cement on and stack them.

IMO, that is dribbled adhesive that was wiped/rubbed off, leaving a wiggle of extra clean de-oxidized surface on the foil pouch.
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bart_dood   100 W

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Re: Is my lipo doomed?

Post by bart_dood » Apr 30 2010 9:11am

Thanks, that puts my mind at ease. As well as the lipo's for my ebike I ordered one more smaller Turnigy 2650mAh 11.1v lipo for my electric planes. It is completely dead. The center cell shows zero volts but I can't see any external damage to it at all, I tried in vain to revive it but I think its toast :(

At least it was very cheap.
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wasp   10 kW

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Re: Is my lipo doomed?

Post by wasp » Apr 30 2010 9:32am

bart_dood wrote:Thanks, that puts my mind at ease. As well as the lipo's for my ebike I ordered one more smaller Turnigy 2650mAh 11.1v lipo for my electric planes. It is completely dead. The center cell shows zero volts but I can't see any external damage to it at all, I tried in vain to revive it but I think its toast :(

At least it was very cheap.
yes 1 of my 8 5s 5000mah bats came with a dead cell but i was able to revive it chargeing thru balance
i used a blackberry charger and pulsed the ingoing charge
i also picked up a 3s but at 3000mah for like 15 bucks but i use mine for headlight/booster pack

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nomad85   10 kW

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Re: Is my lipo doomed?

Post by nomad85 » Apr 30 2010 9:33am

I've always had good luck with the zippy flightmax batteries, I have 12 of them in various capacities and they have all been good.
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wasp   10 kW

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Re: Is my lipo doomed?

Post by wasp » Apr 30 2010 9:37am

you can't beat those prices but shipping back under warrenty is pointless because of shipping and time frames so order extra's...

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Re: Is my lipo doomed?

Post by 999zip999 » Apr 30 2010 11:51am

great I was thinging of going lipo your surport is good I have a 48v2ah ping slim i need more power I like your networking is a great ! It took me 15min. to write plus 5min. comp. warm up.

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mwkeefer   10 MW

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Re: Is my lipo doomed?

Post by mwkeefer » Apr 30 2010 1:48pm

If you have a pack with a cell reading 0v, what is the total pack voltage? If it's 0 too then it's more than likely a solder tab which has come loose on the little pack...

If you are brave, go outside and carefully remove the shrink wrap... then remove the silicone hitemp end coat where the wires are.. finally inspect each cell in the top mounted PCB for damage to the solder joints... it should be obvious.

I don't think I ever got a 0v actual cell from HK... several where the solder had come undone and a few with dings and dents like yours...

If the cell is really 0v, don't even try to recover that cell, it will be too high of an IR to properly keep the pack in balance.

-Mike
Regards,
Mike

{My Rides]
2010 Dahon Jack - GNG v1 - LYEN 6FET - 20/40A - 18S2P10AH - Nom:66.6v,1332w
2004 Hard Rock Pro Disc - Recumpence ms eDrive v4 - Astro 3220 4T - 12S2P16AH - HV110 - Left Side Drive - Gearing: 38mph
Nominal Peak Power @ 60 seconds: 5328 watts - Maximum Power: 49.8v, 120A, 5872w
2010 Downtube 8FH - Stock GNG v1 Stock Controller - EB809XC - 12-16S
2012 Downtube Nova 7spd - Stock GNG v2 - 12S2P10AH - EB809 - 12S-16S - 20A/30A,Nom VCC: 44.4, 888w

bart_dood   100 W

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chinese crap strikes again...

Post by bart_dood » May 02 2010 9:56pm

Add lipo batteries to the list of leaded childrens toys, sulfur laden drywall and fake baby food...

I finished my bike off good enough to give it a decent ride tonight, I had previously charged the batteries up about 5 miles ago, I got about 7 miles when my voltage was at min so I pedalled the rest of the way (2miles).

When I tried the charge the cells, they didn't seem too flat. When I got to one pack it showed 3-4 volts lower than the rest. I checked the cells in the pack, most are 3.7, one is 0v and one is 2.4 volts....

I boosted the 0v cell up manually via a current controlled PSU and then a little on the 2.4 cell. Now I am balancing and I'll run a full charge and controlled discharge after this.

I suspect one or both of the fault cells will show the fault as soon as a large load is placed on it. Ironically this pack had none of the swirly marks I showed in my pics.

:(
:(

If my battery is dead I'll have to wait weeks for a replacement, how frustrating...


---UPDATE, I've been running through a sequence of balancing the pack and then doing a controlled discharge and the cells seem to be getting better, is there a chance I can rescue this pack? I will keep going and see what happens, if all looks well I'll attempt a longish ride on the set tomorrow evening.

:evil:
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liveforphysics   100 GW

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Re: chinese crap strikes again...

Post by liveforphysics » May 03 2010 12:04am

bart_dood wrote:Add lipo batteries to the list of leaded childrens toys, sulfur laden drywall and fake baby food...

I finished my bike off good enough to give it a decent ride tonight, I had previously charged the batteries up about 5 miles ago, I got about 7 miles when my voltage was at min so I pedalled the rest of the way (2miles).

When I tried the charge the cells, they didn't seem too flat. When I got to one pack it showed 3-4 volts lower than the rest. I checked the cells in the pack, most are 3.7, one is 0v and one is 2.4 volts....

I boosted the 0v cell up manually via a current controlled PSU and then a little on the 2.4 cell. Now I am balancing and I'll run a full charge and controlled discharge after this.

I suspect one or both of the fault cells will show the fault as soon as a large load is placed on it. Ironically this pack had none of the swirly marks I showed in my pics.

:(
:(

If my battery is dead I'll have to wait weeks for a replacement, how frustrating...


---UPDATE, I've been running through a sequence of balancing the pack and then doing a controlled discharge and the cells seem to be getting better, is there a chance I can rescue this pack? I will keep going and see what happens, if all looks well I'll attempt a longish ride on the set tomorrow evening.

:evil:

The problem here was what happened above, when you poked current in a dead cell to bring it up to normal voltage. This isn't NiCd. When a cell reaches a <2.0-2.5v SOC (state of charge), it's having irreversable chemical changes happen. The cell is junk. You can poke it up to whatever voltage you want, but it's only going to be a liability that takes out the other good cells in the pack with it.
Cells need to be matched as closely as possible in Ri and capacity to make a pack work. Once a cell has seen very low voltage, you gotta cull it or it will just take out other cells with it.
Each carcinogen vapor exposure includes a dice roll for cancer.

Each mutagen vapor exposure includes a dice roll for reproductive genetic defects in your children.

Each engine start sprays them into a shared atmosphere which includes beings not offered an opportunity to consent accepting these cancer experiences and defective genetics life experiences.

Every post is a free gift to the collective of minds composing the living bleeding edge of LEV development on our spaceship.

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Hyena   100 GW

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Re: Is my lipo doomed?

Post by Hyena » May 03 2010 5:34am

Sounds like bad luck irrespective of those white markings!

Incidently I pulled apart a HK pack once (can't remember if it was turnighy or zippy) and the cell that was DOA reading 0 volts had been marked with pen on side large flat side of the pouch. This wasn't visable as it was in the middle of the pack and I only saw it when I cut the cell out, but it looks like that cell was identified as being sick and the bastards went ahead and used it anyway ( I assume it must have died in transit and they didnt assemble/ship a blatently dead cell)
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bart_dood   100 W

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Re: chinese crap strikes again...

Post by bart_dood » May 03 2010 1:04pm

"
The problem here was what happened above, when you poked current in a dead cell to bring it up to normal voltage. This isn't NiCd. When a cell reaches a <2.0-2.5v SOC (state of charge), it's having irreversable chemical changes happen. The cell is junk. You can poke it up to whatever voltage you want, but it's only going to be a liability that takes out the other good cells in the pack with it.
Cells need to be matched as closely as possible in Ri and capacity to make a pack work. Once a cell has seen very low voltage, you gotta cull it or it will just take out other cells with it."

Well what I did was charge the cells up to some reasonable point like 3.7-3.9 with balance on, then do a discharge at a rate of 4 amps. I would watch the bad cell voltage which dropped faster than the rest, I let it drop to 2.9-3.0 volts and then I would run through the balance charge again, back up to 3.7-3.9.

On the first cycle the bad cell would drop quite quick, but after a couple of cycles it got better and better with each cycle. I did a balance charge on the pack to about 4-4.1 volts last night before I went to bed and today I will try a 5 amp discharge, again I'll keep an eye on the bad cell voltage to make sure I don't go under 3.0 volts, I'll time the discharge and measure how long it takes, this will give me an idea of how much capacity is in the faulty cell.
Another indicator is how close the cells are voltage wise as they discharge, I'll watch this too.
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Ypedal   100 GW

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Re: Is my lipo doomed?

Post by Ypedal » May 03 2010 1:37pm

Have an emergency exit plan when working with cells like this.. this ain't no joke, when they go.. they really GO!!!!!... :o .. fun to experiment with.. not to be left unsupervised at any point now or in the future..
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liveforphysics   100 GW

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Re: chinese crap strikes again...

Post by liveforphysics » May 03 2010 6:21pm

bart_dood wrote: Well what I did was charge the cells up to some reasonable point like 3.7-3.9 with balance on, then do a discharge at a rate of 4 amps. I would watch the bad cell voltage which dropped faster than the rest, I let it drop to 2.9-3.0 volts and then I would run through the balance charge again, back up to 3.7-3.9.

On the first cycle the bad cell would drop quite quick, but after a couple of cycles it got better and better with each cycle. I did a balance charge on the pack to about 4-4.1 volts last night before I went to bed and today I will try a 5 amp discharge, again I'll keep an eye on the bad cell voltage to make sure I don't go under 3.0 volts, I'll time the discharge and measure how long it takes, this will give me an idea of how much capacity is in the faulty cell.
Another indicator is how close the cells are voltage wise as they discharge, I'll watch this too.

You're begging for more pack failure my friend. It's damaged. You can always wake a cell back up a bit, but it's damaged. It's not going to match it's buddies, and that means it's going to be taking them down with it in the pack.
Each carcinogen vapor exposure includes a dice roll for cancer.

Each mutagen vapor exposure includes a dice roll for reproductive genetic defects in your children.

Each engine start sprays them into a shared atmosphere which includes beings not offered an opportunity to consent accepting these cancer experiences and defective genetics life experiences.

Every post is a free gift to the collective of minds composing the living bleeding edge of LEV development on our spaceship.

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Re: Is my lipo doomed?

Post by Hyena » May 03 2010 7:33pm

Ypedal wrote:Have an emergency exit plan when working with cells like this.. this ain't no joke, when they go.. they really GO!!!!
Haven't you seen Lukes destructive lipo videos, I chew on old cells when I run out of chewing gum now :lol:
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Hmm can't explain this..

Post by bart_dood » May 03 2010 10:21pm

Ok so I ran the risk and charged up all the packs in my office at work today under the desk!

The pack with the bad cell in it I did a controlled discharge down to about 3.6 volts each cell and then I charged it back up to 4.2 and it seemed to match the rest, at least voltage wise.

I put them on the bike and strapped on a multimeter connected to the cell directly through the BMS, I didn't want to run the suspect cell less than 3.0 volts.

I ended up riding 14 miles in total, hills and some headwind, these are the voltages of the pack with the questionable cells:

C1 3.79
C2 3.77
C3 3.79
C4 3.67
C5 3.78
C6 3.79

According to my watts up my average power consumption was 305 watt hours, so I'm quite frugal with the juice. Peak amps were around 23-24 amps, my setup is not designed for speed.

The bad cell is C4 and its still off from the rest but not terrible, I am doing another controlled discharge and re-balance again and I'll try it again tomorrow or the day after.

Oh yeah, I ran across a lycra coming the opposite direction, I went another 0.5 miles and then turned around, I caught him up and blew past him, I stopped a mile and a half up the road where I turned around again. His expression was somewhere between anger and confusion!!
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nomad85   10 kW

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Re: Is my lipo doomed?

Post by nomad85 » May 03 2010 11:07pm

I would just buy another pack, its not worth dying for...
E-bike#2- Trek Xtracycle 45 mph top speed(@74v)
Trek 850/9C 9x7 rear motor / 74v 10Ah Lipo
Mileage since 10/20/08: 9500 miles as of 8/10

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Re: Is my lipo doomed?

Post by bart_dood » May 03 2010 11:19pm

nomad85 wrote:I would just buy another pack, its not worth dying for...

Yeah I'm already planning on fixing the pack by replacing the cell, but at least I can do some limited miles while I get a replacement.
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nomad85   10 kW

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Re: Is my lipo doomed?

Post by nomad85 » May 03 2010 11:20pm

true, just be careful :wink:
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Re: Is my lipo doomed?

Post by liveforphysics » May 04 2010 9:36am

Hyena wrote:
Ypedal wrote:Have an emergency exit plan when working with cells like this.. this ain't no joke, when they go.. they really GO!!!!
Haven't you seen Lukes destructive lipo videos, I chew on old cells when I run out of chewing gum now :lol:
LOL!!! LiPo chewing gum! I love it!
Each carcinogen vapor exposure includes a dice roll for cancer.

Each mutagen vapor exposure includes a dice roll for reproductive genetic defects in your children.

Each engine start sprays them into a shared atmosphere which includes beings not offered an opportunity to consent accepting these cancer experiences and defective genetics life experiences.

Every post is a free gift to the collective of minds composing the living bleeding edge of LEV development on our spaceship.

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Re: Is my lipo doomed?

Post by Ypedal » May 04 2010 10:02am

8)
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bart_dood   100 W

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Re: Is my lipo doomed?

Post by bart_dood » May 10 2010 10:32pm

124,000 miles on my daily driver EV. Chevy Volt :)

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