Lithium hab battery in sub zero weather

[Dolmen]

I rely on my Lithium hab battery to maintain my cab battery via a votronic battery maintainer (battery master) as I have no solar. The system is working perfectly and at the rate of drain I have seen to date it would be many months before the lithium battery was depleted, however, with the current sub zero temperatures I am wondering what effect it will have on the lithium if any ie will the lithium battery lose some charge just because of the cold weather or can it only lose what is being drained from it by the cab battery, I am not expecting any problems, just not sure how all this works so apologies if its a stupid question.

 

[Raul]

All the way back to OP original question whether the battery will lose charge in cold weather:
I turned charge and discharge off about 6 weeks ago and the soc was 45%. Yesterday when I turned it back on I did notice the SOC was 39%. Since the bms had not seen any current leaving the battery, I am guessing that it has reduced the SOC based on temperature? Anybody know whether the bms does this or not?

Yes the bms guestimates the energy left for that moment in time, based on temp, voltage and previous amp taken out.
If you bring the same battery with the same SOC to a 25degC, the estimate will rise, and internal resistance will change to. All test and rating figures are at a specific temperature, usually 25C. Lithium plays well above 15C and bellow 35C.

 

[ED O'DARAC]

I rely on my Lithium hab battery to maintain my cab battery via a votronic battery maintainer (battery master) as I have no solar. The system is working perfectly and at the rate of drain I have seen to date it would be many months before the lithium battery was depleted, however, with the current sub zero temperatures I am wondering what effect it will have on the lithium if any ie will the lithium battery lose some charge just because of the cold weather or can it only lose what is being drained from it by the cab battery, I am not expecting any problems, just not sure how all this works so apologies if its a stupid question.

Hi, we have a lithium power station in the van as a backup system and it is standalone, so not being charged or depleted. It has just stood for six months and I switched on to check it this morning and it still has 100% power available, so they don't self-drain like our old lead acids or gels. Very stable.
This is in the extremely cold Moho garage. (By the way.)
Best wishes

 

[Tombola]

they don't self-drain like our old lead acids

this is true, you can get months with very little reduction if disconnected

 

[Ian_H]

Yes the bms guestimates the energy left for that moment in time, based on temp, voltage and previous amp taken out.
If you bring the same battery with the same SOC to a 25degC, the estimate will rise, and internal resistance will change to. All test and rating figures are at a specific temperature, usually 25C. Lithium plays well above 15C and bellow 35C.

Will a victron shunt get confused if the heater comes on, as there is current flowing to the battery but not charging the cells? Although I guess an hour at 4A won't make much difference (well 4Ah!) to the SOC

Hi, we have a lithium power station in the van as a backup system and it is standalone, so not being charged or depleted. It has just stood for six months and I switched on to check it this morning and it still has 100% power available, so they don't self-drain like our old lead acids or gels. Very stable.
This is in the extremely cold Moho garage. (By the way.)
Best wishes

I'm sure it's still close to 100%, but as Raul says the SOC is just the bms's guesstimate. It's calculated, not measured directly.

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[Raul]

Will a victron shunt get confused if the heater comes on, as there is current flowing to the battery but not charging the cells? Although I guess an hour at 4A won't make much difference (well 4Ah!) to the SOC

I'm sure it's still close to 100%, but as Raul says the SOC is just the bms's guesstimate. It's calculated, not measured directly.

Yes the victron shunt will count those 4A as going in the battery instead of heaters. It will re sync when it reaches absorb and resets to 100% SOC.

 

[jwells]

Just a follow up on the below freezing low solar current issue, I now have the Victron solar controller low temperature warning set to stop charging at low temperature (adjustable!)
Don't have to worry about it anymore! Yeah!!! Time to get my life back!!

 

[Guigsy]

All the way back to OP original question whether the battery will lose charge in cold weather:
I turned charge and discharge off about 6 weeks ago and the soc was 45%. Yesterday when I turned it back on I did notice the SOC was 39%. Since the bms had not seen any current leaving the battery, I am guessing that it has reduced the SOC based on temperature? Anybody know whether the bms does this or not?

I've been leaving mine charge and discharge on. I've got quite a high parasitic power draw in my van. I think the discharge is low enough that the BMS can't see it. So after a few weeks, the BMS still thinks the battery is charged. But in reality it's quite heavily drained. My external Victron shunt is keeping much better tabs on the real discharge level. This is only really relevant when the van is sat for long periods over the winter.