Hi All,
As we all know, batteries are the bane of off-grid systems. I'm trying to figure out what the best deal for batteries is, measured by cost per year.
It seems like folks with money buy batteries like Surettes and the rest of us use all sorts of things, with golf cart batteries being very common. I myself have used golf cart batteries for the last six years. Either this year or next I'm going to have to replace them so I thought I'd start a debate here.
Here is my very limited experience. I got my batteries a little over six years ago at a cost of about US$1000. This works out to $166.66 a year, or $13.88 a month. Now, I realize that there are other costs like fuel for the genny that I didn't keep track of.
I think a key factor is how you use the batteries. I made sure I had a bank large enough to really meet my needs ( 10 batteries). I made sure I had a reasonably efficient charging system that had enough power for a reasonable recharge time (160 amps from an alternator). On a cloudy day, I run the genny for a short time in the morning, until the voltage gets up around 14V. Then in the afternoon, after I've gotten whatever I might from solar and used most of my electricity for the day, I run it again to 14 or so V. So I never go days without a charge. Further, the solar and charger I had in the beginning were inadequate, so the batteries weren't all that well treated for a couple of years, especially in terms of absorption charge. I really wish I had kept records of fuel consumed. With the next bank I'm going to. I am adding even more PV panels, so the next set will be treated much better. I expect to get a couple more years out of them next time.
I have two friends with expensive high quality batteries. One got 10 years out of his last set of Surettes, but his cost/year is much, much higher than mine. He goes several days without charging and runs his genny less than me for sure. The other it is hard to say, he didn't treat his batteries well, leaving them flat for long periods etc. His cost/year is way higher, but I don't think his experience is relevant.
So here is my hypotheses: Golf cart batteries, properly sized and charged, can provide a better value in terms of cost/year. Thoughts?
Jonathan