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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.

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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!

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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.

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The battery percentage is going up while I'm using it, so that's a pretty positive sign.

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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.

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@mike Dang. I wonder if there's a market for a proper 12V USB-C charging dohig.

@stibbons there are such things out there in the world, but they seem to be a bit pricey right now. I'm not a sure I can afford to try a few out and see.

The inverter plus my existing PD USB-C charger is working pretty well so far, even if it's not likely to be that efficient.

The Pinebook is pretty light on power use and I'm definitely packing the inverter anyway, so I'm not sure it's a setup that needs too much refining. It'd be sweet to have but far from essential.

@mike 12VDC-230VAC-5V barrel connector? Very efficient power delivery 😆

@ThermiteBeGiants Not quite, last step is ~60W USB-C PD negotiated power delivery probably somewhere in the 12-15V range.

@ThermiteBeGiants sure does!

There are 12V PD adaptors out there but they're around $50 right now and I'm not in a hurry to experiment given I have exactly one device with me that needs it.

I'll have the inverter anyway, so fuck it, this is good enough.

@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 I don't thing there's a high risk of that happening to me haha

@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 @dadegroot @mike it’s like reading the bodybuilding.com forum thread about how many days there are in a week 😆

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

@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!

@brendantcc you're going to be terribly disappointed when I tell you it's just GNOME3 with the Dash to Panel extension.

@mike you're a bad person and should feel bad :)

@mike

> how best to switch between solar and alternator charging

big knife switch. like the one traditionally used to allow the lightning down to Frankenstein's monster.

@Nikolai_Kingsley @mike nice, I’ll see that and raise you two key triggers that have to be turned by two people at the same time

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