Joke’s on them, I was listening to VNV Nation!
The past week for me had the singular focus of assembling the housing for the Tripper Trapper’s power system. It encloses a set of deep-cycle batteries, a busbar each for the battery bank and load distribution, a circuit breaker panel, and a solar charge controller.
Since material in the US is generally only available in English sizes (for some reason, the U.S. saw fit to overthrow their oppressors, but not to abandon England’s ancient system of units), I’ve had to adapt to using inches and feet. It’s odd, but manageable. The box is 21.5″ x 20.5″ x 17″, and its structure is made entirely of scrap material donated by other burners in the community.
Pictured: battery-O-fail, storage busbar, breaker rail.
I took some pictures, since watching glue dry is 99.444439% (±0.555561%) as much fun as watching paint dry, and I figured I ought to share that fun.
Wiring the battery array was much more fun. I read what I could find online about using batteries in a parallel configuration, and what I found was that for ideal performance, each battery should see equal series resistance. People have a funny way of making that look hard on the Internet; maybe they just haven’t heard of busbars.
Left: 2P configuration with equal series resistance. Centre: 4P configuration with equal series resistance, based on what I’d seen online. Right: 8P configuration used in the Powerhaus.
It looks a little haphazard, but I wanted to keep the layout somewhat symmetrical, so I put the charge and load terminals in the middle. If you trace the current path from the charge controller, through any battery, and back to the charge controller, you’ll see that whichever path you take, you go through the same resistance: the leads to the busbar, four ring terminals, 6 terminal-spacings worth of busbar, two spade terminals, and a constant amount of battery cable (since I kept them the same length). Same goes for the load, which means that this array is kept balanced by design. Since the batteries are AGM lead-acids, there is no need to apply an equaliastion charge, or to balance the cells electrically like in lithium-ion batteries.
This part of the project gave me a lot to research, and I now know a lot more about power systems as a result. The Tripper Trapper has turned out to be the most rewarding thing I’ve built to date.
