Have been reading about issues with the 12V Lead Acid battery installed in Bolts and Konas. It needs to be kept charged during storage or the car won't start and so on. According to the Bolt manual the Li-Ion battery (with very low self-discharge) can be left for up to a year with a ~50% SOC, but the 12V lead acid battery needs to be disconnected and put on a trickle charger. (Presumably by disconnecting the 12V battery you remove all the parasitic loads from the Li-Ion battery as well.) Why is that 12V battery necessary? Why not just a high-voltage DC to 12VDC converter instead of a 12VDC battery charging circuit? A separate battery seems like an unnecessary complication to me. (And just add a switch to disconnect all the little parasitic loads for long-term storage.) Do all EVs have a separate 12V lead acid battery? Do the Teslas?