What he said ^^^^.
A weak and/or failing 12V Auxiliary Battery is the bane of EVs. It's been the cause of the vast majority (90%+?) of odd behaviors in the more than half-dozen EVs I've driven since 1997. Hooking up a high-quality, multi-stage battery tender/charger (that's AGM compatible) periodically, greatly reduces said behavior.
A weak and/or failing 12V Auxiliary Battery is the bane of EVs. It's been the cause of the vast majority (90%+?) of odd behaviors in the more than half-dozen EVs I've driven since 1997. Hooking up a high-quality, multi-stage battery tender/charger (that's AGM compatible) periodically, greatly reduces said behavior.