Fire risk if I leave these lithium batteries discharging in super cold weather?

[AlaskanNoob]

About to leave the homestead for a bit and I'm going to shut down the system because I haven't yet insulated the shed where my batteries are in. But I had the bright idea of connecting my Cerbo (everything else off) to this string of 4 x 12V lithium wired up in series for a 48V bank, just so I can continue to log the various temperature sensors.

But since I'm sure if these batteries have a BMS (the newer version currently sold does, but I'm not sure about this older version), is there any fire risk when the temps drop possibly to -7F or so? Cerbo has one wired temp sensor in it and reads some bluetooth temp sensors. I would imagine it's a very small load and would think this would be manageable and they won't be getting charged, but is there still a fire risk? I'm willing to gamble with battery life being reduced with these, but I'm not willing to gamble with fire risk. I don't think there is a fire risk from potential over discharge, but I can't afford to get this wrong.

The battery manufacturer (Batteries Plus) for the newer version of this battery says it can discharge down to -4F. At 0F it can deliver 70% of its rated capacity. It usually does't get colder than -4F here, but I have seen it as cold as -7F during one winter, so if that happens, and there is a small load on the batteries at a temp just below its rated operating temperature, could that be a fire risk or would it just reduce battery life?



Many thanks for any help!

 

[MisterSandals]

I do not see a fire hazard with leaving them connected with Cerbo and BT sensors.

I think i would just disconnect everything and not worry at all.

 

[Supervstech]

I don’t know about a fire risk, but if charging that cold, the batteries will fail very quickly…

 

[AlaskanNoob]

I do not see a fire hazard with leaving them connected with Cerbo and BT sensors.

I think i would just disconnect everything and not worry at all.

Thank you. The battery part number is SLIL 12-50DCM but I can't find any specs for it. But the newer ones have a BMS and can discharge to -4F. And I did find a spec sheet for the 12AH version of ours and it also has a BMS and can discharge to -4F.

I assume when you say you would just disconnect everything, you are meaning other than the Cerbo.

So at this point I think these have a BMS (which will prevent over discharge) so I will assume that IF we drop below -4F that they will shut themselves off. And from what I've seen, the fire hazard seems to be associated with charging them at colder temps, not discharging them. So I think this should work to log our temps while we're away. Gonna give it a try.

 

[AlaskanNoob]

I don’t know about a fire risk, but if charging that cold, the batteries will fail very quickly…

Yeah, definitely won't be charging them at these cold temps for sure.

 

[MisterSandals]

I assume when you say you would just disconnect everything, you are meaning other than the Cerbo.

If there is a chance the Cerbo will discharge them to BMS cutoff, i'd disconnect that too. The BMSs will continue to discharge the batteries after cutoff, and if left long enough, will kill the batteries.

If logging the temps is worth that risk (only you have enough info to judge) then that is your call.