[MetroMPG]

I want to put a solar panel on the ForkenSwift to trickle charge its 48v battery pack. The car often sits unused for days at a time, and when it is used, it's for short trips only. So using a panel isn't an outrageous idea in this case; it could measurably reduce grid energy consumption.

I don't want to modify the panel itself (12v nominal, 85w, rated for 21v peak, open circuit).

I also don't want to modify the pack (eg. to split it into four 12v pairs, wired in parallel for 12v charging).

Instead, what I was thinking was "rotating" output from the panel to pairs of 6v batteries using an automated relay circuit that switches sequentially through the 4 pairs of batteries every N minutes (where N is a small value, say 2, to minimize the chance of unbalancing the pack as light conditions change).

I've read a small amount about the "555" timer integrated circuit, and it seems (to my non-expert electronics mind) like it might be a suitable foundation for this idea, in combination with some standard 12v relays.

Any of you electronics wizzes willing to guide me in setting up such a circuit?