thanar
Member
- Joined
- Feb 12, 2018
- Messages
- 155
Cheers to the forum.
I am trying to replace the stand-by battery that is beingused in my home building elevator system for emergency lighting and lift release functions. The original battery is a sealed lead-acid 1Ah battery. The system charges the battery under 100mA and it keeps the battery charged at 13.8V. The battery is rarely used, since there are almost never power cuts, but it is being used once a month from the elevator janitor. The lead battery dies every 3 years for some reason.
I was thinking of putting together a 4S battery using 18650 cells. However, under 13.8V they would be charged only up to 3.45V per cell and they will almost definitely drift apart, since there is no balancing function at that voltage on any BMS readily available. So I was thinking that we are in need of a way to balance a battery at custom voltages. For example, it would be extra useful in this stand-by application if a balancer could bleed the cells at 3.6V, so when the weakest cell reaches that threshold (or any other adjustable is some way threshold), it would stay there and wait for the rest of them.
So, if I get one of these "balancer" boards, is there any way I could solder onto them some component that would change the bleed voltage? Change some resistors that set the balancing voltage maybe?
I am trying to replace the stand-by battery that is beingused in my home building elevator system for emergency lighting and lift release functions. The original battery is a sealed lead-acid 1Ah battery. The system charges the battery under 100mA and it keeps the battery charged at 13.8V. The battery is rarely used, since there are almost never power cuts, but it is being used once a month from the elevator janitor. The lead battery dies every 3 years for some reason.
I was thinking of putting together a 4S battery using 18650 cells. However, under 13.8V they would be charged only up to 3.45V per cell and they will almost definitely drift apart, since there is no balancing function at that voltage on any BMS readily available. So I was thinking that we are in need of a way to balance a battery at custom voltages. For example, it would be extra useful in this stand-by application if a balancer could bleed the cells at 3.6V, so when the weakest cell reaches that threshold (or any other adjustable is some way threshold), it would stay there and wait for the rest of them.
So, if I get one of these "balancer" boards, is there any way I could solder onto them some component that would change the bleed voltage? Change some resistors that set the balancing voltage maybe?