FilterGuy
Solar Engineering Consultant - EG4 and Consumers
The required current rating of the BMS is almost always defined by the load or charge current, not by the battery. The growatt 12 k is (I think) around 95% efficient. So it will draw up to 12000W/.95=12632W. That translates to 12632W/48V= 2631.57A. (Surge current could be higher)
A 100A BMS can not handle that!
However, if you had a 4000W Inverter it would draw 4000/.95=4211W or 4211W/48V=88A. A 100W BMS would work fine for that.
For something like a 12K inverter, You are not likely to find a FET based BMS that will handle the all the current by itself. That leaves several options:
1) Use multiple banks of cells, each with it's own BMS. If the system is using 100A BMSs, it would take 3 banks of cells, each with it's own 100A BMS. If they were 150A BMSs, two banks would work.
2) Use BMSs that control large relays/contactors to turn the current on and off (Chargery is an example that can do this). I don't like this type of set-up, but people have successfully implemented them.
3) Use a BMS that provides a signal that can be issued to control the inverter to turn charge and discharge on and off. I like this type of set-up, but very few inverters have the proper inputs to accept this type of control signal (Victron may be the only inverter that can do this well)
4) Us a BMS that uses a data-com channel to control the charge and discharge. This usually requires a high end BMS and the BMS has to be programed to match the selected inverter.
A 100A BMS can not handle that!
However, if you had a 4000W Inverter it would draw 4000/.95=4211W or 4211W/48V=88A. A 100W BMS would work fine for that.
For something like a 12K inverter, You are not likely to find a FET based BMS that will handle the all the current by itself. That leaves several options:
1) Use multiple banks of cells, each with it's own BMS. If the system is using 100A BMSs, it would take 3 banks of cells, each with it's own 100A BMS. If they were 150A BMSs, two banks would work.
2) Use BMSs that control large relays/contactors to turn the current on and off (Chargery is an example that can do this). I don't like this type of set-up, but people have successfully implemented them.
3) Use a BMS that provides a signal that can be issued to control the inverter to turn charge and discharge on and off. I like this type of set-up, but very few inverters have the proper inputs to accept this type of control signal (Victron may be the only inverter that can do this well)
4) Us a BMS that uses a data-com channel to control the charge and discharge. This usually requires a high end BMS and the BMS has to be programed to match the selected inverter.
