question

See question above

Connecting an active charger to a battery when temperature is known to be out of spec seems to me to be a marginal design. I'm unaware of any publicly available data on quantifying the impact, someone else may chip in.

Have you considered:

1) Insulation + heating system that keeps the battery above 5C, and/or

2) Installing a disconnect on the battery's wiring beyond its fuse. This way you can isolate the battery without getting to the battery when its unattended, or

3) Automatically disconnecting/disabling the charging sources when temperature is below a trigger point.

Are you likely to be using the campervan when the temperature is below 5C, or is that when its in the parking lot (and unattended)?

Thanks for the responses!

I guess that a switch to disconnect the battery is the easiest way to deal with the storage issue. If the campervan is out of use for a longer period I could check the battery every now and then, and disconnect the battery when the SOC has gone down to a level of say 60%. The remaining loads are that small that they might not cause a problem within a period of a couple of weeks. This is, however, not an ideal situation.

What also remains is the temperature problem. If I want to use my campervan again after being out of in winter, I might have to heat the battery before I am even allowed start the engine. This is not the kind of flexibility that one associates with having a campervan!

Despite the undeniable advantages of a Lifepo4-battery, this makes me thinking that I maybe better stick to my gel battery as long as no solution has been found for both issues.

Somewhere else in this forum Boekel suggested that the charger should have a possibility to keep the SOC on about 50%. In combination with a function to keep the battery at a certain minimum temperature if it is connected to a charger, this would entirely solve the problem.