Random Electrical Fiddling - Part 1

I moved my 20 watt 12 volt solar panels (x2) and the charge controller downstairs yesterday.

This enabled me to hook up the old car battery I salvaged from my MR2; before it sadly went to the breakers.

This let me release one of the two Ultramax batteries. Which means I can now use one for when I'm building other projects and testing them and just cycle the two batteries when one gets a little low. :)

While I was fiddling with the solar setup I noticed that in the new position when the sun really shines down and there's no haze they get up to their full 17 volt output and the charge controller doesn't like this and stops charging the batteries. So I've added one of the two DC-DC converters I got off of eBay a while back. This restricts the voltage quite nicely to a maximum of 14 volts, but also means that the normal output has dropped to just over 12 volt.

I may have to come up with a better way of clamping the output from the solar panels without having to sacrifice 3 volts on the DC-DC converter. I'd prefer a solution that didn't kick in until the output from the panels went over 14 volts. I shall have to do some investigation. I'm sure once my copy of The Art of Electronics turns up I shall have some example circuits I can build to do the job nicely. :)

This still seems to be charging the batteries fine and if I'm reading this meter right I seem to have gathered 42 watt hours of power today. I also want to change this so it's inline with the batteries (rather than recording the raw output from the panels) and has bypass diodes to cover the batteries going back to the charge controller.

Happy the solar charger was working well enough, I dug out the other DC-DC converter to investigate why it wasn't working and it seems to be fine now. I'm guessing it must have been something to do with how it was hooked up to the solar system that was causing the problem and we had a loose connection somewhere.

It's now working fine to charge my phone off of the spare 14Ah ultramax battery.

And while I was monitoring the charging and because the soldering iron was already on I decided to hook up a couple of the little solar toy panels and see if I could power a small motor from them. By the time I'd finished the sun had disappeared behind the cottages behind me. So I'll have to wait till tomorrow (assuming it's sunny) to try it out and see if I need to hook more panels up.