geem
Well-known member
A friend has lithium batteries from Sterling. He has been using the default Sterling charge settings.
He is having problems since he installed a high output Balmar alternator and regulator to charge the lithium. He has minimal solar, hence the alternator charging.
The alternator is designed to charge lithium, so no problem there. The problem is with the batteries.
The Sterling default charge voltages are wrong. If you have these batteries, change the settings. They are too high.
I would suggest BMS settings per cell
over voltage protection (OVP) 3.65v
Balance voltage start 3.45v
Alternator.
charge setting maximum 3.5v
Absorbtion time 30mins
Float 3.35v ( effectively no charge)
Ditto for Solar
charge setting maximum 3.5v
Absorption time 30mins
Float 3.35v
One of things to be aware if if you buy drop in batteries is that the balancers are generally passive. There are exceptions such as Fogstar Drift that uses active balancing at up to 2A.
Passive balancers, balance at a mV level. If you have a cell that has high voltage, they are pretty useless at correcting the imbalance. You can introduce a longer absorbtion time to give the balancer time to try and correct the voltage but this must be done at above 3.45v per cell or it has little to no effect.
Having a small lithium bank is also not great. The temptation is to charge the battery to 100% so you maximise the stored capacity. Charging above circa 80- 90% tends to put you in the area of cell voltage spikes where the passive balancer needs to perform. It is far better to have a larger capacity bank, ideally using two batteries maximum. Multiple parallel lithium batteries can have their own problems where the batteries go out of balance due to differing resistance in connecting cables and terminal connections.
Charging to 80% ensures that the battery doesn't get a BMS high cell voltage trip and shut down charging.
Charging with a high output charger such as a Balmar alternator sounds great, but if one cell on one battery has a high voltage trip, then the BMS with stop the charging. The remaining lithium battery, assuming you have two batteries, is now getting the whole charge from your high output charge source. So for two batteries you have just doubled the charge rate to the remaining battery. This will possibly put you over the manufacturer’s recommended maximum charge rate, heat up the battery and BMS quickly and likely cause a similar high voltage trip on this battery as well.
He is having problems since he installed a high output Balmar alternator and regulator to charge the lithium. He has minimal solar, hence the alternator charging.
The alternator is designed to charge lithium, so no problem there. The problem is with the batteries.
The Sterling default charge voltages are wrong. If you have these batteries, change the settings. They are too high.
I would suggest BMS settings per cell
over voltage protection (OVP) 3.65v
Balance voltage start 3.45v
Alternator.
charge setting maximum 3.5v
Absorbtion time 30mins
Float 3.35v ( effectively no charge)
Ditto for Solar
charge setting maximum 3.5v
Absorption time 30mins
Float 3.35v
One of things to be aware if if you buy drop in batteries is that the balancers are generally passive. There are exceptions such as Fogstar Drift that uses active balancing at up to 2A.
Passive balancers, balance at a mV level. If you have a cell that has high voltage, they are pretty useless at correcting the imbalance. You can introduce a longer absorbtion time to give the balancer time to try and correct the voltage but this must be done at above 3.45v per cell or it has little to no effect.
Having a small lithium bank is also not great. The temptation is to charge the battery to 100% so you maximise the stored capacity. Charging above circa 80- 90% tends to put you in the area of cell voltage spikes where the passive balancer needs to perform. It is far better to have a larger capacity bank, ideally using two batteries maximum. Multiple parallel lithium batteries can have their own problems where the batteries go out of balance due to differing resistance in connecting cables and terminal connections.
Charging to 80% ensures that the battery doesn't get a BMS high cell voltage trip and shut down charging.
Charging with a high output charger such as a Balmar alternator sounds great, but if one cell on one battery has a high voltage trip, then the BMS with stop the charging. The remaining lithium battery, assuming you have two batteries, is now getting the whole charge from your high output charge source. So for two batteries you have just doubled the charge rate to the remaining battery. This will possibly put you over the manufacturer’s recommended maximum charge rate, heat up the battery and BMS quickly and likely cause a similar high voltage trip on this battery as well.
