Solar and truck charging of deep cycle batteries.
I've been banging this around in my head for so long I'm starting to hear rattling noises, but this time I mean it...I'm close to making the plunge and will call a few distributors next week, but thought I would present an idea here.
My plan is to build a hybrid system, one that will allow me to charge golf cart batteries from either a 100W solar panel or the truck's alternator. Furthermore, I don't plan to mount the panel on the truck. Instead it will be a remote unit on a stand of some sort that I plug into the truck using heavy duty quick connects. That way I don't have to worry about it getting damaged by low hanging branches and I can park in the shade, but have the panel in the sun (provided I can find such a place). Also, I'll be able to turn it throughout the day to get maximum efficiency out of the panel. The draw back is that the batteries will be discharging when I don't have the solar panel plugged in.
From my research on the internet, golf cart batteries can be drained as much as 50% with no harm done. However, when drained that much, they must be recharged slowly (no more that 20% of their Amp-Hour rating). The truck's alternator would probably charge them far to quickly.
The MPPT charge controller I'm think of getting is a smart charger and should work well with the golf cart batteries.
So, here is my idea. Connect the input circuit of the charge controller to the truck's electrical system. I would use a break-before-make switch to select either the solar panel, or the truck's system. Furthermore, I would incorporate a DC-DC converter to limit the current from the truck to something the charge controller can handle.
Does this sound like a reasonable design? Or, am I likely to fry components? What might I be missing? I'm starting to hear rattling again!
2000 FWC Hawk on 2006, Chevy K2500HD, Duramax.