I finally put together the little charger I’ve been wanting to build since my Solar Energy Educator colleague Bill Rock showed me the one he made as a demonstration project with his students. When Anne Pope, the executive director of my local sustainability organization Sustainable Flatbush, asked me to get some solar going at SF’s eco fair at the Flatbush Frolic this past Sunday, I knew it was the perfect moment to break out my wire strippers, roll up my sleeves and blow a few fuses.
The original plan for this charger comes from a Popular Science DIY article from July 2007. With guidance from Popular Science–and especially from Charlitron who shared his version of it with lots of illuminating supporting material—I present the Sustainable Flatbush Suncharger.
Stay tuned for much more detail for those of you who really want to build this thing! Like, how do you solder a guitar plug onto a cigarette socket????
10-watt photovoltaic (PV, aka solar-electric) panel:
Voltage: max. power 17.6V, open circuit 21.6V
Current: max. power 0.57A, short circuit 0.61A.
Pop Sci used a 5-watt panel, probably to keep costs down, but if I’m bothering to build it, I want to get more out of it! The charge controller can handle an even bigger panel, too.
4 amp charge controller:
I love this elegant little thing. Here is the spec sheet from the manufacturer. The charge controller keeps the battery from overcharging or discharging too deeply, both of which can ruin the battery.
The Pop Sci article used a 10A meter, which doesn’t do much when the panel is only rated at around .6 amps! If about .7 is all you’re going to get at peak power, then the 1 amp meter will do the trick.
In the video you’ll see that I used a cheap multimeter to measure current for now, but I’m going to add an analog panel meter like this one between the panel and the controller. I’m also going to add a meter or two between the battery and the load to put numbers on what this baby can actually do.
I got connectors at Radio Shack.