First live test of the car's dual battery switch! It works! The backup battery is getting charged when the engine is running as long as the primary is full.

Unanswered questions at this point are how best to switch between solar and alternator charging, and whether the battery box will ever leave the car.

For the first part, right now it's just going to be yanking the plug out of the battery feed and swapping in the panel. Simple and probably effective enough but I'd kinda like a big solar on/off switch somewhere. Maybe.

Everything is simpler if the battery stays in the car but maybe it's too inflexible. I'm about 50/50 on this issue.

Minor note about my wiring here - the most cost effective way I found to get all the cabling was to buy some discounted, shitty jumper cables and cut them up. I have hidden many sins under heat shrink wrap but hey, it works!

Final test for today, charging the laptop via an inverter off the battery, as 5v USB just doesn't cut it for recharging a Pinebook - which is the only general purpose computing device I'm planning to take with me.

Kinda weirded me out a bit when I realised I only ever need to run one wire anywhere since the car's actual body is the common ground.

@mike Unless you end up working on pre-1955 American cars, where a lot of them had the body wired to the positive charge instead.

@dadegroot @mike I have a tractor built 1958-1963 that has positive ground. Aggravating for sure.

@ThermiteBeGiants @dadegroot @mike Well, I just spent some time googling pros and cons of negative vs positive ground. And mostly I've learned I never want to read car enthusiasts talking about electricity.

@stibbons @ThermiteBeGiants @mike IIRC positive ground tends to mean the body rusts less, but the wiring corrodes more, or something like that.

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@dadegroot @rfox @stibbons @ThermiteBeGiants how much deterioration could we possibly be talking about over a decade or two here? Can't be that significant right?

@mike @rfox @stibbons @ThermiteBeGiants yeah it's not much, but I presume measurable, as the car industry change polarity, presumably because there's more metal in the body and thus a bit of rust there was less of an issue.

@dadegroot @mike @rfox @stibbons more to the point, basically every other field of electrics and electronics uses the negative ground convention. Cheaper to buy polarised components that way!

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