Received my batteries from Docan LF280K tiny amount of bulging.

[k490]

The batteries are here I ordered from Jenny Wu on 11/22 received there here in Phoenix today on 12/31. That was quick I wasn't expecting them just happened log in to Alibaba check the tracking it said out for delivery. I was right in the middle of cleaning out my shed I only had a chance to open one box of two and the BMS was in there. They did have slight bulging other than that they look clean. I did peel back the top little but decided doesn't really matter anyway. Whatever the outcome of this returning them would cost more than they are worth might as well just use them. I paid $85 each plus $165 for a JK BMS JK-B2A24S20P total cost including everything was $1742.

 

[Ampster]

That is nothing to worry about. Those thin Aluminum cases reduce the form factor but do require compressing. My first LFP batteries were Winstons and Thunderskys with the cast plastic shells but they took up more room for a lot less capacity so I can deal with a "tiny' amount of bulging.

 

[k490]

That is nothing to worry about. Those thin Aluminum cases reduce the form factor but do require compressing. My first LFP batteries were Winstons and Thunderskys with the cast plastic shells but they took up more room for a lot less capacity so I can deal with a "tiny' amount of bulging.

Compression debate is mind boggling. Even Will says it's not worth the trouble since the number of cycles reduced by not compressing will be 20 years away if you're charging and discharging at .5C or .3C. They will swell some as they cycle.

 

[perpetual]

check out andy's vid as well

 

[Culchee]

The batteries are here I ordered from Jenny Wu on 11/22 received there here in Phoenix today on 12/31. That was quick I wasn't expecting them just happened log in to Alibaba check the tracking it said out for delivery. I was right in the middle of cleaning out my shed I only had a chance to open one box of two and the BMS was in there. They did have slight bulging other than that they look clean. I did peel back the top little but decided doesn't really matter anyway. Whatever the outcome of this returning them would cost more than they are worth might as well just use them. I paid $85 each plus $165 for a JK BMS JK-B2A24S20P total cost including everything was $1742.

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I wouldn’t worry about it...bulging isn’t too bad... good luck with your build..

 

[k490]

Manually top balancing is this required I keep reading that it is, and some say an active balancer can do the same thing like this post. Isn't that what a balancer does? Bring all cells in the pack to the same voltage.

 

[Culchee]

Manually top balancing is this required I keep reading that it is, and some say an active balancer can do the same thing like this post. Isn't that what a balancer does? Bring all cells in the pack to the same voltage.

Have a search on the forum before you proceed... no point rushing.. there’s some stuff in the
“Resources “ that is worth a look when it comes to charging new cells..

 

[Ampster]

Even Will says it's not worth the trouble since the number of cycles reduced by not compressing will be 20 years away if you're charging and discharging at .5C or .3C. They will swell some as they cycle.

One of my reasons for compression is to reduce stress on the terminals because my pack is 3P16S and that means a bus bar straddling six cells. Even a 1/16 inch in each cell would be 3/8 of an inch movement on the last of those six cells. In my case it is worth the trouble. Maybe not so with a 1P4S 12 volt pack/

 

[k490]

I agree don't want it to put pressure on the terminals. Either have to compress or leave 1/4 inch between them for expansion or assemble end to end.

 

[Brett V]

Manually top balancing is this required

YES!
Compression is optional, I bind my cells with fiberglass filament tape and they’re just fine. Top balancing will take a while, my EVE 230’s took about 11 days but the delta never goes above 5mv.

 

[740GLE]

IMO you bought a JK BMS with active balancing for a reason, assemble the battery and let it do its thing.

If the cells are all out of whack then reassess and solve the problem.

 

[k490]

IMO you bought a JK BMS with active balancing for a reason, assemble the battery and let it do its thing.

If the cells are all out of whack then reassess and solve the problem.

I love this forum so many opinions on how to do things. I come from the RC Lipo battery experience we never did any top balancing let the balancing charger do that. We did break in the battery with lower rates in the days when they were more expensive. Later when Chinese flooded the market with cheap lipo's didn't worry about it as long as didn't burn down your house. I would charge them in my fireplace with a long cable.

 

[Ampster]

...... I come from the RC Lipo battery experience we never did any top balancing...... I would charge them in my fireplace with a long cable.

Good advice. I remember when I was trying to find a replacement for the AGMs on my e bike and the guy at the hobby store warned me about Lipo for my e-bike. I bought some Headways and ruined them but without the consequences of burning down my apartment.

 

[k490]

Good advice. I remember when I was trying to find a replacement for the AGMs on my e bike and the guy at the hobby store warned me about Lipo for my e-bike. I bought some Headways and ruined them but without the consequences of burning down my apartment.

I have seen several batteries catch fire usually from an RC airplane crashing and burning, or someone charging a battery that had been in a crash. I have flown several that had lot of bloating in foam planes. There were some that claimed you could charge them to 4.35V per cell called High Voltage batteries it worked great for 5-10 cycles then they would balloon out. Usually, 4.2V per cell was the normal cell. The power output going from 4.2V to 4.35 was amazing it really made a difference in the first few minutes of performance. I could get my pylon racer going up around 180 mph on those batteries where 4.2 go around 135-140 mph. There was a thread here someone used Lipos for a DIY solar he didn't seem to be worried. He said he only charges and discharges at low rates. Maybe he is right from my experience had to really abuse them to get an abnormal reaction. The ones I crashed got dented I saw some gas venting. I could not trust them in my house. If you kept them in a wood stove, or fireplace with a vent out the top of your house that would work.

 

[k490]

YES!
Compression is optional, I bind my cells with fiberglass filament tape and they’re just fine. Top balancing will take a while, my EVE 230’s took about 11 days but the delta never goes above 5mv.

I think I will compress for a few reasons. One I can use the busbars I got with the batteries saves me money not sure if they have enough to leave spacing. fi in the future I resell they have longer life on them for the next person. The manufacture recommends it.