4s2p build with BMS questions  


New Member
Joined:11 months  ago
Posts: 1
23/01/2019 10:22 am  

Hello everyone.

Looking to build my first lithium pack for a heated helmet visor.  The visor will draw 1.5-2A continuous at roughly 12v fused, so my needs for a BMS will be small.  I've decided that I'd rather have a 4s battery for the job and will limit the charge to 3.9-4.0v on my imax b6 charger. My question is on the bms low cut-off voltage.  I don't want the voltage to go below 2.9-3.0v, yet I can't find an "adjustable" bms.  Do they even exist for such a small battery and discharge rate?

Micah (Vruzend Rep)
Street cred = 5 Ah Admin
Joined:3 years  ago
Posts: 484
01/02/2019 10:04 am  

They exist, but are much more rare and expensive.

A cheaper option might be to add a voltage alarm in addition to the BMS. You'd simply wire in a balance connector ( and a voltage alarm ( which has an adjustable low voltage alarm warning.

Then you use your battery like normal, but if you ever hit the low voltage warning you set in your alarm, it will beep, and you'll know to stop using the battery.

Not the most elegant solution, but definitely simpler and cheaper.


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