Handmade 27,000,000 mAh power bank

Originally published at: Handmade 27,000,000 mAh power bank | Boing Boing


I’m slightly discombobulated by the juxtaposition of a very large number and a unit with the mili- prefix, but then I worked out that if this power unit was plugged into a computing device, fixing that issue would just leave us arguing about what kilo- means all over again.


giphy (10)


That’ll never fit in my jacket pocket.


Somebody set up us the bomb.…


My power feels inadequate. I need to have a bigger power cell so that I can fill all my devices. Some serious power envy here.

Anyhow, we can also buy a battery backup with about the same Wh for about $6000, though most of us will need an electrician to wire it up.

That’s not very portable. Why not mount some wheels on it?


That’s a fueled engine but Generac does make some big batteries. I keep looking at one of these because we loose power a lot but only for a few hours at a time. We have a gas powered back up generator but it’s a hassle to pull out and hook up for just a few hours. I can’t seem to justify a couple grand for a battery though.


Can you access/create an elevation change?


No idea what kind of volume is required for a power backup application, purely a fanciful idea, it’s always just sounded like a really cool project to me lol.


Oh the humanity inefficiency! :grin:

400-500 VDC to 12 VDC to 220 VAC to 5 VDC !!! I’m kidding, but it still strikes me as amusing :slight_smile:


Hint, for successful use of the metric system, it is advised to switch the unit prefix if you have that many commas in your number. Thou 27,000 Ah probably doesn’t sound as impressive as 27,000,000 mAh… but really you could whip out a K prefix in this case! 27KAh.


Luckily there are no software guys in the mix so kilo would be 1000 and not 1024.


Well, then they’d be kibiamps, clearly.

(/s, more like /sigh, really the whole kilo / kibi thing is such a waste of mental effort.)


Yeah, it was all dumb… but I still can’t believe the drive manufacturers at the time went against what was a defacto standard in the computing industry. And kibi, mibi has never stuck. I don’t know anyone who regularly uses those names when speaking… LOL and there I go expending more mental effort on it…


Seriously. There was never any meaningful, intrinsic ambiguity between “binary” numeric prefixes and decimal ones, since the only time “kilo” ever meant 1024 was when you were counting something that was “intrinsically” binary in some respect, and where hewing to powers of 2 made perfect sense. When computer people saw “1 kilobyte,” Everyone knew that it meant 1024 bytes, because obviously.

Then, disingenuous device manufacturers decided to exploit the previously-nonexistent ambiguity between the binary and decimal meanings of the Greek prefixes to make their products look bigger: they could say that their hard drive with 671,088,640 bytes capacity was “670 megabytes” rather than the actual 640 (ahem) mebibytes.

Thus, the kilo / kibi distinction serves exactly two purposes: first, to clarify the marketing abuses committed by manufacturers who chose to willfully ignore contextual meaning; and second, to facilitate discussions like this one where the distinction between the SI meaning and the “sensible” binary meaning of the same prefix is relevant.



This’ll be handy to keep the mesh network running when TSHTF.

Maximum SI in this case would be Joules, but I haven’t watched the video so I don’t know what kind of voltage he’s running. I think those powerbanks are considered to have a nominal voltage of 3.7V, so that would be almost 100 kWh or 3.6E8 J.

You also do that to clearly indicate how accurate you’re being by removing non-significant digits. I’m fairly certain he can’t indicate the capacity of that thing to within half a mAh, which is what all those zeroes imply.

I get that that’s kind of the joke though, no need to tell me.

He made this from parts? Why didn’t I think of that!

Unless my memory is really bad, none of those zeroes are significant. They do not imply to within half a mAh, but the reverse. It’s only accurate to the 1,000,000 mAh value. Could be off by as much as 500,000 mAh either way it would be the same. He’s probably that close.

Now, if it had said “27,000,001” or “27,000,000.” with the 1 a the end or the decimal, then if would be that half a mAh.

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No, because then how would you indicate that it was exactly 27,000,000? Zeroes are only not significant if they’re on the left (0.01). In this case, you should write 27 kAh.