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Golf power caddy/trolley battery
#11
(07-31-2019, 09:03 PM)Korishan Wrote:
(07-31-2019, 08:00 PM)bmcmullin Wrote: Hi Korishan.  Just so I'm clear, if I only feed say 16V to the pack via the P+- ports of the BMS, are you saying that some cells could still reach 4.2V?

That is correct.  So it's possible that even stopping charging at a lower voltage, stopping at 4V, it's still possible for the packs to be out of balance. Which means that you could have a 3.9V pack, and a 4.1V pack, and the bms would be "Ok, this looks good. No pack over volt limit"

Ok.  How about this idea - using a LifePo4 BMS on a LiPo battery?  Wouldn't it charge and balance up to 3.7V and then cutoff?  I realize this would leave a lot of unused capacity but if the battery provides enough capacity at 3.7V and cycle-life is the objective, wouldn't this significantly extend the cycle life?  Also, I should point out that in my application, the battery is subject to very light loads.
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#12
3.7V is waaaay to low. For non-LiFePO4's 3.7V is the nominal. You are effectively cutting your capacity by more than half.

Also, a bms is "not" a charger. So don't confuse it as such. A bms balances and manages. Don't get the terms mixed up.
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#13
(08-01-2019, 01:52 AM)Korishan Wrote: 3.7V is waaaay to low. For non-LiFePO4's 3.7V is the nominal. You are effectively cutting your capacity by more than half.

Also, a bms is "not" a charger. So don't confuse it as such. A bms balances and manages. Don't get the terms mixed up.

Yes.  I know the difference between a charger and a BMS. I was just questioning the potential, odd as it may seem.  For fun, I'm going to hook up a LifePO4 BMS to a LiPo battery and power/charge it with a 16.8V CCCV charger and monitor the pack voltages while it charges - that is - if it charges at all since the 16.8V is higher than the 14.6V  I suspect and hope that BMS will trigger from the get-go if any of the packs are at or over 3.7V.  If it does, I'll discharge the battery to get the voltages below threshold and see what happens.
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