Subnostr

I want a repairable, low power e-ink laptop. Something RISC5, batteries are straight 18650s, onboard mppt for direct solar charging….

Low Information Voter 1y ago

Sounds 100% doable, today! Without any custom boards, even.

You don't want MPPT at that scale, it will waste far more power than it saves. Just put a step-down buck module on the power input.

There are various RISC-V SBCs on Crowdsupply you could start with, and Waveshare make some very diy-friendly e-ink screen up to 13".

Repairable is the only dicey bit. All modern mass market stuff is surface mount. If you want through-hole and socketed ICs you're going to have to go more retro or design your own boards. If you do, pls share!

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Discussion

The Beave 1y ago

Surface mount is doable with the right soldering work station, magnification, and steady hands. Plus, components treasure up a lot less space if you want to stockpile them.

Low Information Voter 1y ago

I've known guys who've done it once for the bragging rights, but think I'd get very frustrated, myself!

True re less space, but that's most relevant if you're going full post-apocalyptic tinkerer living and working out of a backpack, covered in scrim and one embroidered meme patch. :)

All my through-hole components would still fit in a large box.

The Beave 1y ago

True.

But it is still possible and I don't let the scale frighten me off. I do prefer through hole, but, laptops really are better suited to the smallest and most dense components you can work with.

Low Information Voter 1y ago

I have some surface-mount fRAM ICs i have big plans for, but I chickened out and got tiny breakout pcbs for them :D

Very true re laptops, but that's a real tradeoff decision.

More repairable means less powerful, which means more work on the software side for equivalent functionality. Which is the way I'd jump, but others will have different priorities.

So, pics of your post-apocalyptic work backpack?

The Beave 1y ago

I'd never carry a soldering iron in my wandering pack. Less room for ammo, water, and air filters. Lol! I already know what I'd be carrying, pretty much. That's an area I've been studying and thinking about for a while.

Low Information Voter 1y ago

That makes me want to see if I can work through-hole using a sharpened tent-peg heated on campfire coals :p

The Beave 1y ago

It could be done.

atyh 1y ago

Interesting about the mppt.

At what scale does it stop making sense? I don’t really know what the efficiency of that tech is.

Low Information Voter 1y ago

Once you start having more voltage drop through the regulators and diodes than you make back in increased output, your MPPT is a liability.

The exact cutoff will be different for different projects, but I certainly wouldn't consider it for 12v or below. Unlikely to be worth it below 24v, even.

atyh 1y ago

That makes perfect sense and is great to know.

The Beave 1y ago

Would depend on your panels. MPPT controllers use significant power to calculate the maximum power point and adjust the voltage to charge the batteries or supply current to the system. The percentage of the power captured increases as the system size gets smaller, though it's not exactly linear as it does depend on the implementation between hardware and software.