Adding low temperature protection to a BMS

[Jim T]

I have found a nice 300 amp LiFePO4 BMS for a 12.8V battery on Battery Hookup but it does not appear to have low temperature protection. Thinking I might be able to add it to the BMS by installing a small temperature switch that opens at freezing and adding it in series to one of the voltage sense leads. This way when temperature drops to low the BMS will detect an open at one of the sense leads going to one of the cells and simply shut down. Would this work?

 

[sunshine_eggo]

I have found a nice 300 amp LiFePO4 BMS for a 12.8V battery on Battery Hookup but it does not appear to have low temperature protection. Thinking I might be able to add it to the BMS by installing a small temperature switch that opens at freezing and adding it in series to one of the voltage sense leads. This way when temperature drops to low the BMS will detect an open at one of the sense leads going to one of the cells and simply shut down. Would this work?

Yes, but that "small temperature switch" needs to be able to handle the full input/output current of the battery.

 

[bestconcreteblock]

Yes, but that "small temperature switch" needs to be able to handle the full input/output current of the battery.

I think the OP is talking about putting it in series with one of the voltage sense leads.

 

[sunshine_eggo]

I think the OP is talking about putting it in series with one of the voltage sense leads.

I see that now. Not sure that a cell reading going to 0V would cut off charge. Would have to test.

 

[Jim T]

Yes, but that "small temperature switch" needs to be able to handle the full input/output current of the battery.

I don't think you understood what I said. The temperature switch would not drop any current what so ever. It would go in series with one of those tiny voltage sense wires.. when the switch opens the BMS would shut down because of the open sense wire.