When we approached a couple of solar power companies about upgrading our solar system, we were quoted about $6000 (arg!) for something similar to our current system, and anything from $8000 to about $15000 to upgrade it. None of them attempted to save money and waste by making use of the components we already had. Hmm…what to do?
In the spirit of self-sufficiency, we figured we could cobble something together ourselves for a lot less dosh, with second-hand components and the working bits of our old system. We knew people who had done it (admittedly, they knew a lot more about practical electricity than we did) and our neighbours lent us a heap of old Grass Roots magazines, that had a few useful articles. Actually, the most useful-looking article was missing the second page, but the first page was quite good. And of course there is Google.
So this is how we gave our ailing solar system an $820 facelift, and made it comparable to systems for which we’d been quoted over $6000. I’ve included my embarrassing mistakes, which resulted from being a bit more enthusiastic than knowledgable.
The inspiration for this whole thing came from the time we picked up our first bantam chooks from a man who turned out to be a former world skydiving champion. He’d wired his caravan with second hand solar batteries and panels, and generously showed us how he did it. But our solar system was still staggering along adequately, so the idea went on the back burner for a few months.
Then one evening not so long ago it dawned on us that our batteries weren’t holding charge. The house lights had been getting dimmer and dimmer at night, and the power to the DVD player cut off one too many times just before the climax of the movie. It was time to do something about the solar system.
Buying the batteries
So imagine our delight when we saw an ad in the paper for second hand batteries, the same capacity and voltage as our current dodgy ones, for $390. (We’d been quoted over $1000 for new, only slightly higher capacity batteries). I was a bit wary about second hand batteries (how do you check they’re OK etc?) but Felice had some long conversations with Bernie, the talkative Irishman who was selling them, and we went back and forth to Google checking the brand and the suitability for small solar systems. We ended up knowing Bernie’s life story, and that apparently the batteries were previously backup batteries, kept fully charged for their whole life. We didn’t know Bernie from a bar of soap, but since we moved here, we’ve never had a bad experience with dodgy second hand things, so we handed over $390 plus $30 for the courier to Lismore, and lugged home 500Ah worth of bright yellow, and good condition, 12V AGM batteries.
Where are the connectors?
The batteries were made up of 6 2V cells, in 2 plastic boxes of 6V each. Unfortunately, when we got them home, we realised there wasn’t anything connecting the cells to each other. So what we had was a set of 6 2V cells, and not yet a 12V battery. Embarrassing mistake number 1: we’d assumed the batteries would come connected together, so didn’t check first. A quick call to Bernie told us that he’d assumed we had an installer (ha ha!) who would sort the connectors out, so when we told him the awful truth, he gave us some instructions for making them ourselves. And they worked! Here is what we did:
We had some old 3/4 inch copper pipe in the garage, left here from the previous owners. We cut it into short lengths to match the distances between the terminals on each cell, and sandpapered it because it was covered in garage crap – corrosion, mouse poo, and who knows what else.
Then we bashed them flat with a heavy hammer. At first, we thought we might be able to get away with only flattening the ends, but the rounded pipes wouldn’t fit on the batteries, so we ended up doing the whole thing.
Finally, we drilled holes in each end to take the bolts that go into the terminals.
We’re lucky enough to have a couple of hand drills passed down from an old friend of the family, so we don’t need to turn on the generator to drill things. I thought they might not be able to drill the metal, but they went through like the copper was (hard!) butter. (Embarrassing mistake number 2: drill the hole larger than the bolt that needs to go through it. I ended up drilling each hole twice, because the first one was too small. )
So finally, we could bolt the connectors to the big yellow plastic boxes. Et voila!
Later, we stole the connector covers from our old failing batteries and squeezed them on. They don’t quite fit, but we’re hoping they’ll give some protection against chicken poo. Cassie has been seen investigating the battery top as a potential nest.
Next step: the regulator… Part 2