Battery Sizing - What's everybody's take?

[crunchysteve]

Why charge one and run the other? Run them together and charge them together at the same time. No reason a charge circuit can't work concurrently.

Parasitic loads are fine for trickle feeds, like phone charging but, as I understand it, they're not a good idea with lithium tech. Or have I been led astray? My reasoning is charging one while riding the other to maximise charging time without a parasitic load on the working pile. Charge both while stopped for lunch. and at day's destination if enough sunlight left. Belt, braces and elastic

Sorry missed this point earlier