2 4S LIFEP04 packs in parallel, 2 BMS's
- Thread starter wntrhwk
- Start date
sunshine_eggo
Happy Breffast!
You have heard wrong unless it was specific to the initial act of connecting the two batteries together. You want the voltage within 0.2V to prevent a surge that will potentially activate short circuit protection on one or both BMS. "take out" a BMS would be exceedingly abnormal. Once in parallel PROPERLY (see link #6 in my signature), should be no issues.
Good info Sunshine, thx. I had a BMS on one pack fail after discharging 30amps., guess I need to pay attention to my initial setup. Still kinda new to all the subtleties with proper battery configs.
Rednecktek
Solar Wizard
What Eggo said. Having batteries in parallel gives you two advantages. First it spreads the draw across dual BMS and battery sets so each one isn't having to work as hard, and second (as you've seen) if one dies you're not in the dark while you're trying to fix the system.
When you say the pack failed after 30a, like it smoked and died or just acted like it was dead? What happens if you try to charge it alone and run a load off it?
Always best practice to have both batteries charged to the same voltage before you connect them together or the higher charge battery will try to charge the lower battery all at once and can pop your BMS. Usually you can just throw them on a charger and it'll wake up the tripped battery and balance the batteries as they charge.
Rednecktek
Solar Wizard
Just out of morbid curiosity, when you unplug the balance lead jack from the BMS, what voltage do you get on the cell pack itself? Plugging the balance leads back in with more than 10v on the pack should reset/reawaken it. If that doesn't happen, hopefully a BMS swap is fairly easy.
Rednecktek
Solar Wizard
Huh, and not taking a charge? Hopefully the BMS can be swapped easily enough.