snowranger
10 kW
Overnight usually. This is the first time it has only reached 55 volts. Do cells go out of balance so suddenly?
Ping problem 36V 12ah 2.0 Bulging
- Thread starter JinbaIttai
- Start date
snowranger
10 kW
Uh Oh... Looks like I have a problem.
That bulge on the left was definitely not there before.
That bulge on the left was definitely not there before.
BikeFanatic
1 kW
DOC, sorry to hear of your accident, the tricruser flipped EH? Hope you feel better soon, probably only hurts when you breathe 
Just unreal. No further comments. I'll keep them to myself.
snowranger
10 kW
Here are the voltages after discharging the battery 4.5 ah and after 2 hours of charge. Three cells are getting to 3.7 faster than the rest. It's going to be muscle power for a while until this gets resolved.
pre post
3.3 3.71
3.3 3.4
3.27 3.39
3.29 3.39
3.29 3.4
3.28 3.31
3.27 3.4
3.2 3.4
3.3 3.4
3.3 3.4
3.3 3.3
3.3 3.4
3.3 3.4
3.3 3.3
3.3 3.7
3.3 3.7
pre post
3.3 3.71
3.3 3.4
3.27 3.39
3.29 3.39
3.29 3.4
3.28 3.31
3.27 3.4
3.2 3.4
3.3 3.4
3.3 3.4
3.3 3.3
3.3 3.4
3.3 3.4
3.3 3.3
3.3 3.7
3.3 3.7
snowranger
10 kW
To my surprise, the pack hit 60.5 volts last night with all cells around 3.7 V. Now I'm wondering if I have a problem at all, and maybe that bulge was there from the beginning.
Has anyone heard from Ping lately? It has been almost two days.
Has anyone heard from Ping lately? It has been almost two days.
I don't have enough experience with bulged cells to know how they perform. It could be that they still can charge up to 3.7V, but have less capacity.snowranger said:
The fact that you were able to get all your cells up to 3.7V in just one night means that it wasn't very unbalanced. That could mean the bulged cells aren't too bad. When my pack was unbalanced, I had it on the charger for over 3 days, and it still didn't charge the weak cell up.
snowranger
10 kW
Ping finally responded and said to keep riding. He also asked whether the bulge is hard or soft. The one on my battery was hard, so I guess there was not a gas expansion. Hopefully, that is a good thing.
I may catch up to Dogman's 2000 miles yet.
I may catch up to Dogman's 2000 miles yet.
dogman dan
1 PW
Wow, that is good news. But I still think 12 ah is pretty small for anthing but a 250 watt motor. I've still got 8000 miles to go to get the coveted 1000 cycles though. Even if I had to buy a new battery every 3000 miles I would still be pretty happy since sla's for the range I need weighs 100 pounds.
snowranger
10 kW
To clarify, this is a 48 V 20 Ah battery. My discharge profile is 0.8 C with hill climbing at a little over 1 C.
dnmun
1 PW
what is causing the swelling i wonder? too bad i can't get him to just solder it back together and see if it will charge since we could then separate the swelling from the loss of capacity.
if the ping packs swell like this regularly and they are assembled with no excess slack for those balancing leads that run across the pack to the other side, this is gonna be a common failure mechanism. the other failed packs also had the tabs pulled to one side, possibly by the balancing wire in those cases too.
it may require more charging cycles to balance effectively, rather than longer on the charger, but that is counter intuitive.
did anyone else see similar problems with their ping packs when they opened the top? maybe just something ping would need to tell his assemblers when they secure the ribbon cable as it exits the pack. with not such a tight crimp over that edge before it goes to the BMS, and leave an extra 8-12mm of slack on the longest balancing leads to accommodate the swelling if that is common.
if the ping packs swell like this regularly and they are assembled with no excess slack for those balancing leads that run across the pack to the other side, this is gonna be a common failure mechanism. the other failed packs also had the tabs pulled to one side, possibly by the balancing wire in those cases too.
it may require more charging cycles to balance effectively, rather than longer on the charger, but that is counter intuitive.
did anyone else see similar problems with their ping packs when they opened the top? maybe just something ping would need to tell his assemblers when they secure the ribbon cable as it exits the pack. with not such a tight crimp over that edge before it goes to the BMS, and leave an extra 8-12mm of slack on the longest balancing leads to accommodate the swelling if that is common.
dogman dan
1 PW
Duuh, I got confused again. When threads get long, I lose track of who's stuff we are talking about. Mixed your battery up with the one at the start of the thread.
snowranger
10 kW
The bulge was apparently there from the start. If it is hard, there is no problem.
Ypedal
100 TW
a bulge in the packaging (tape , cardboard ) is ok.. but a bulge in a cell is not ok... :lol:
Another cell bites the dust. Repalced 2 100km ago now another has gone, looks like a neighbour to the one I replaced but will check tonight, I am guessing the swelling of the previous failures damaged the neighbouring cell, will pop the hood tonight and check.
My pack came wrapped in heat shrink which offered little give, if lifepo4 is anything like LiPo there is always some swelling when the cells are first charged. I suspect the pressure due to this initial swelling has caused all my problems. I am not sure if he heat shrinks all the packs now but I am guessing duct tape offers a bit more room for expansion.
Back to Ping for more replacements for now.
Derek
My pack came wrapped in heat shrink which offered little give, if lifepo4 is anything like LiPo there is always some swelling when the cells are first charged. I suspect the pressure due to this initial swelling has caused all my problems. I am not sure if he heat shrinks all the packs now but I am guessing duct tape offers a bit more room for expansion.
Back to Ping for more replacements for now.
Derek
Bummer. You've definitly had your share to problems. Were your previous damage cells bulged?mingonn said:
The one bulged cell I got was also next to a bad cell group. At the time, I just thought it was coincidence. Maybe it wasn't.
The other unbalanced cell I replaced wasn't bulged. It would be nice to know what is causing this.
That is interesting. The one cell from my pack that did swell happened when I took the pack apart to replace a bad cell group. The swollen cell was the next in line, so it had no compression. It sat like that for over a week while I was waiting for the replacement parts. It was during that time it swelled. Maybe it was the lack of compression that caused it. Makes me wonder if it's worth adding end plates to the pack.torrent99 said:
Also take a look at:
http://www.elmoto.net/showthread.php?t=452
and
http://www.autofocusasia.com/production_manufacturing/lion_batteries_hybrid.htm
It looks like compression may be a distinct requirement for pouch batterys such as pings.
Of the people with failed/bulged cells, how many were using the battery in a soft container/bag? Is there a correlation?
http://www.elmoto.net/showthread.php?t=452
and
http://www.autofocusasia.com/production_manufacturing/lion_batteries_hybrid.htm
It looks like compression may be a distinct requirement for pouch batterys such as pings.
Of the people with failed/bulged cells, how many were using the battery in a soft container/bag? Is there a correlation?
JinbaIttai
100 W
Dogman has quite a few miles on a ping. I wonder how tight his tool box is around the battery.
liveforphysics
100 TW
I've got Lipo packs for my helicopters 6s 5Ah that have hundreds of full cycles on them with contant drain between 10c-30c, and then rapid recharges at 2-3c. They've never had anything to help prevent cells bulging except the thin heat shrink wrap around the packs. No bulges or funny stuff going on with the cells.
I have had some very early LiPo packs that had higher internal resistance get bulging problems. We call it "puffing" in the RC world, and it's something that happens to very low quality LiPos, or Lipos with high internal resistance. The cell capacity is greatly reduced and internal resistance increases once a cell puffs. It's something that never seems to happen with modern quality LiPo cells.
I know this is a different chemistry battery, but the puffing symptoms sound very familiar to the puffing that occurs with poor quality LiPos.
I have had some very early LiPo packs that had higher internal resistance get bulging problems. We call it "puffing" in the RC world, and it's something that happens to very low quality LiPos, or Lipos with high internal resistance. The cell capacity is greatly reduced and internal resistance increases once a cell puffs. It's something that never seems to happen with modern quality LiPo cells.
I know this is a different chemistry battery, but the puffing symptoms sound very familiar to the puffing that occurs with poor quality LiPos.
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