I have four 280 ah batteries on the way. My intention is to get four more so I can build a 24 volt system. My question is, if I have an eight S BMS can I temporarily use it for just four batteries or must it be hooked up to eight ?
Assuming you mean cells, LiFePO4 3.2V.four 280 ah batteries on the way.
If you run a 8S BMS with just 4 cells the BMS will think that 4 cells have 0 volts and shut down (which is what it is supposed to do).I intend to get 8 cells eventually but for now I will have just four cells.
If you run a 8S BMS with just 4 cells the BMS will think that 4 cells have 0 volts and shut down (which is what it is supposed to do).
If you decide to build a 4S battery without a 4S BMS, then YOU are the BMS. Its a lot of work and takes a lot of vigilance and a bit of luck. Having a little monitor like an ISDT BattGo with low cell warning (audible beeps), it can keep you from being a bad BMS.
I was a BMS for few months when i first got my cells and had not decided on a BMS. Its possible but there are risks.
I'll do that, send a message. Thanks.I have an Overkill 4S BMS and another JBD 8S to 20S BMS that can be wired for various cells. Since JBD and the Overkill BMSs are similar it is worth an email or phone call to Steve at Overkill to confirm and get the wiring diagram. His email is Support@OverkillSolar.com
There is also a group at Reddit for Overkillsolar.
You could get a good start on top balancing your cells in the mean time. This always takes a lot of time and patience too.No sense in damaging things just because I'm impatient. I kinda figured that it was possible to use the batteries without a BMS but I don't need to right now.
Good idea !!You could get a good start on top balancing your cells in the mean time. This always takes a lot of time and patience too.
The BMS needs to be appropriately sized to your charge and discharge amps. The battery size is secondary.I wonder if the Overkill 120 amp BMS is appropriate for these batteries ?? It would limit me to 1440 watts.
Thanks for reminding me that a 12 volt battery is more than 12 volts. ;- ) 1536 W should be sufficient. I hope to be able to run my induction cook top when we lose power. This happens a lot lately.The BMS needs to be appropriately sized to your charge and discharge amps. The battery size is secondary.
12.8V x 120A = 1536W