3na consumes the total charge in each of her two batteries
each night! She has over 100' of coolneon in her, but she
also uses five separate inverters, which consume nearly
an amp! So the 7 Amp-hour battery lasts about 7 hours.
Her color guns don't last even that long!
She'd eat a dozen D batteries per night or more if I'd have
gone the disposable route. Since she uses large capacity
rechargable batteries all I needed was a charger, and
since there is plenty of sunlight in the desert a solar
charger made sense.
I found a good deal on solar cells on the internet and
built one panel for charging the 12V battery and one for
the 6V battery. I found a circuit design for a gel-cell
battery charger which reduces the charge to a trickle
when the battery is fully charged.
Soldering solar cells is much harder than it seems. I had
to use 4% silver solder and a fairly powerful soldering
iron. Ultimately, the trick turned out to be to scratch
the surface to be soldered with an X-acto knife.