Battery pack heat
- Thread starter silviasol
- Start date
skeetab5780
1 MW
4ah? what is that only 2 cells in parallel per string? I feel like anything under 5 cells in parallel is asking for trouble in the EV market today. I bought the 72v 11ah battery Luna has and its only 4 cells per string and even at 30a it sags pretty good even though it claims 50-60a discharge. Lets hope the cells are actually legit inside...never know
I would have bought a 20S6P if they had it. I even emailed them an asked. Prices are reasonable tho
edit: LOL I just went to the Luna site out of curiosity and they now have just added two larger 72v batteries...WTF Luna why now!!!
I would have bought a 20S6P if they had it. I even emailed them an asked. Prices are reasonable tho
edit: LOL I just went to the Luna site out of curiosity and they now have just added two larger 72v batteries...WTF Luna why now!!!
Tushar D said:
So it is normal then?
skeetab5780 said:
Actually it is a 1 parallel pack, 12 4ah cells. These are batteryspace cells which they charge $20 each for. I bought 16 of them for $140 on ebay a few years ago. Kick ass cells though, still flat as a board, not even a slight puff
Ianhill
1 MW
- Joined
- Sep 25, 2015
- Messages
- 2,918
Battery's have an internal resistance so when u ask them to do work a certain amount of energy will become heat just like a resistor, the further up the current range u go the more heat is created by the cell to a point it can not dissipated it and it starts to gather.
Heat in a battery is never good for its life span try use a higher c pack or a heatsink the latter will just help keep the electrolytes from boiling so the pack will still degrade fast or use more/larger cells and up the c rating for better heat management withing the cells.
Heat in a battery is never good for its life span try use a higher c pack or a heatsink the latter will just help keep the electrolytes from boiling so the pack will still degrade fast or use more/larger cells and up the c rating for better heat management withing the cells.
The maximum rated discharge of a cell is often limited by how hot it will get, so the rated point is often at a temperature that is just about tolerable. When you group cells together and then package up that group, then put it in a bag, the ability to dissipate heat becomes considerably less. The result is over-heating even though you're somewhat below the rated discharge.
Also, the discharge spec for a lot of Chinesium cells on the market are just outright lies...
Also, the discharge spec for a lot of Chinesium cells on the market are just outright lies...
skeetab5780
1 MW
Ya the problem is only one cell in parallel. Not a great idea IMO
Most cells don't do what they claim in the real world anyway so if its a 30a discharge cell its probably good for 15-20a
Most cells don't do what they claim in the real world anyway so if its a 30a discharge cell its probably good for 15-20a
dogman dan
1 PW
Bottom line, if they get a lot hotter than your body heat, like more than 110-120 f,, you are beating them pretty hard. If too hot to touch, then you need to back way off.
Whether that's ok to heat them up with big discharge, depends on how long you expect them to last.
And bear in mind,, beat your pack,, you might not want to bring it inside.
Whether that's ok to heat them up with big discharge, depends on how long you expect them to last.
And bear in mind,, beat your pack,, you might not want to bring it inside.
