this post was submitted on 29 May 2024
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I have a 100 W rigid solar panel including a charge controller that I currently only use for camping to charge batteries (also useful in an emergency at home). It strikes me as a waste that I could be generating more clean energy with equipment that I already have, but I don't have anything in mind to use this energy for.

Obviously I could try to tie it into my home to run more of my household on solar, or buy more/bigger batteries to charge, but with 100 W of generation, it's probably not worth it without a significantly increased investment.

I tried searching around online, and I found plenty of discussion for what to do with a whole house that generates excess capacity (mainly sell to the grid), but nothing really on what to do with small scale DC generation.

Anyone here have thoughts?

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[โ€“] [email protected] 4 points 7 months ago (1 children)

3 years seems pretty good for using a car battery outside of it's preferred use case. I guess that depends on how good/bad you were about deep cycling it.

Currently, the batteries I'm using are my power tool batteries, which are 18V so they charge through a dedicated (12V) charger, and I have a little USB A/C and low powered inverter that uses them. I probably wouldn't necessarily want to put my lithium batteries through every day cycling, though.

I've thought about generating hydrogen with it to use for experiments and such, but idk if I have the space for that.

[โ€“] [email protected] 1 points 7 months ago* (last edited 7 months ago)

3 years seems pretty good for using a car battery outside of it's preferred use case.

Better than that :) They were junk car batteries when I got them, and I still got 3 years out of them. But yeah, they didn't get deep cycled much or at all since there were 2 in parallel and the loads I had on them were very small (5-6 500 mAh cell phone chargers and occasionally some LED rope lights).

When I eventually hooked an inverter up to charge my laptop or run a lamp during power outages, they started to show their age with the extra current draw. I think that's what finally did them in.

Yeah, lithium batteries wouldn't like that kind of daily cycle without some kind of charge/discharge limiter to keep them in the 30-70% range. That's basically what hybrid and EV battery managers do to prolong their useful lifespan. I think LiFePO4 lithium batteries would tolerate that better (they're the ones typically used in e-bikes), but they're not cheap. I've also found it difficult / expensive to find solar chargers for them (to be fair, mine is 48v 20AH so finding any aftermarket charger for it has been a challenge lol).