🚀 go-pugleaf

I can't help but wonder why nobody ever mentions solar power in 
discussions like this.  The Solarex SX-LITE panels weigh about 2
pounds and put out 18 watts, at a retail cost of $175 or so.  Admittedly
this is not cheap, but that's 1.2 amps per panel of charge
current (they're scaled for direct connection to 12V batteries,
and can be series-connected for 24).  Application is trivial...
sunlight in, two wires out.  Add a schottky to prevent dark discharge
and you're done, unless the panels are substantially more robust
than the batteries, in which case a controller is required.  
  Solarex is at 800-521-SOLA and a Bay Area distributor is Energy 
Depot at 415-499-1333 in San Rafael.
   Cheers...
  Steven K. Roberts
  Nomadic Research Labs