Racing to the Summer Solstice

By , June 24, 2018

The summer solstice seems to be a favorite time for races (or, “runs”, as they’re generally billed). The famous “Only Fools Run at Midnight” springs to mind.

This summer solstice, I ran a race of my own, trying to bring our new Nickel-Iron (NiFe) battery bank on line in time to charge during the long days of solstice sun (see Homestead Going Dark for the Summer Solstice).

I’m happy to tell you: I made it!

More or less.

Nickel-Iron battery

The Nickel-Iron battery, all topped off, tied in, and charging (Photo: Mark A. Zeiger).

Truth be told, by about 6:00 p.m. on the summer solstice itself, June 21, when the sun had moved off of our solar array, I made the last connections, took a deep breath, and pronounced the system ready to charge.

I started flipping switches and jabbing buttons. Nothing sparked, dimmed, or exploded! Best of all: the batteries began to charge!

Even though the solar panels had passed peak charging exposure for the day, the south wind blew around 25 knots, which I consider a good solid high optimal charging breeze. With lessening help from the solar array, the wind generator chugged through the night, feeding power to the new batteries, which had to charge from under almost flat to full capacity.

Early the next morning, before I felt ready to rise, the solar array kicked back in. I had the new batteries fully equalized by early afternoon. The solstice, after all, marks the middle point of a period of 4-6 days when the amount of sunlight stays constant. The sunlight on the 22nd matched the 21st; the 23rd had the same amount as well. After that, we only lose a minute a day, so we’re in really good shape for charging.

Which is a good thing. I may need to cycle the batteries a couple of times before they reach full capacity.

Trimetric charge display

The old Trimetric reflects the new normal, although the value’s still a bit low (Photo: Mark A. Zeiger).

The change over went more smoothly, and faster, than I’d expected. I dealt with a lot of complications, always balancing the need to finish in a hurry with the need to Do It Right the first time.

It didn’t help that I apparently took few notes during the first major change, back in 2015, when I installed the solar array. To make it worse, I learned that some of the notes I did write turned out to be wrong!

Nevertheless, I got it done, I ran my race, and crossed the finish line, which was to get it charging. Now I just have to clean up the unholy mess I made of the place in the process, build a few new parts, like a lid for the battery box, and a new front step for the porch, since the wire bundle displaces the old one too much.

wind generator charge controller

One major change: I moved the wind generator’s controller to the front porch, opposite the battery bank (Photo: Mark A. Zeiger).

wind generator brake

I also moved the wind generator brake all the way outside, where we can flip the switch while watching the generator (Photo: Mark A. Zeiger).

Finally, I need to tweak our system. This new bank, technically one battery comprised of 10 individual cells, charges considerably higher than the old one: 16.6-17 volts, compared to about 14.5 volts previously. This eclipses our inverter; I may need to replace it with one that has a higher fail-safe point, so it’ll actually work when the battery is fully charged, rather than shutting itself down.

I’ll let you know how it all goes.

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