Originally Posted by Paulz
I’m confused on correct extreme cold winter storage of my 2017 Zion srt. 2 eco trek lithium batteries , one agm , and agm starting battery. It will be stored in unheated garage with -30 temps . I understand the winterization of van but not the electrical.
Are you quoting Celsius or Fahrenheit at -30? Regardless -30C is -22F. Lithium Ion Phosphate batteries if their internal core temperature goes below -4F (-20C) the batteries will be permanently damaged. I'm not clear if incremental or absolute. This is what I got from the company that distributes my batteries, Elite Power Solutions.
"Temperatures below -4°F (-20°C) will cause the electrolyte to freeze which will cause permanent damage to the batteries if it does not kill them entirely. If storage temperatures will go below -4°F then you will need to heat the batteries to above -4°F to prevent damage to the battery. There is no exception to this."
As I mentioned batteries in use or being charged I have observed to be 10-15 degrees F. or so above the ambient air temperature. Also my unheated former garage that I could not store my van in always was almost 20F above ambient temperature. So you may have dodged a bullet if your core cells of your batteries have not gone below -4F or maybe your batteries have been incrementally damaged as in life of the battery or maybe your storage space has not gone down below -4F long enough to lower the battery temperature by the factors mentioned.
Electrical is a method of applying heat to keep the batteries above -4F (-20C) either directly with heating pads or indirectly by heated space. The latter can be by any fuel source. Directly by heating pads can be from the batteries themselves as long as you have a shore power connection of 15a.
Early on the Class B manufacturers and battery companies were ignorantly marketing to Americans with the -20 temperature confusing Celsius with Fahrenheit saying or implying it was -20F. ARV was the first to correct that and I confirmed that directly as I mentioned above. I don't know if Roadtrek ever did.