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Why your outdoorsy friend suddenly has a gummy bear power bank

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258 points arnon | 1 comments | 21 Sep 25 12:31 UTC | HN request time: 0s | source

https://archive.ph/1G2Ut
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cenamus ◴[21 Sep 25 13:07 UTC] No.45322381[source]▶
20Ah for 23 bucks? Seems like it's almost too good to be true. Wouldn't surprise me if it was just half that, would explain the price and weight.
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thegrim33 ◴[21 Sep 25 14:56 UTC] No.45323306[source]▶
Man it drives me crazy when people/products use Ah instead of Wh as a way to specify battery "capability".

Without knowing more details about the battery, "20Ah" alone does not convey enough information to determine how long the battery could power a given load for. If I need to power a 100 watt lightbulb, will a 20Ah battery power it for an hour? 10 hours? 10 days? No way to know.

Wh is the unit of stored energy, Wh is what I want to see. Even the official Amazon product page for it doesn't list a Wh figure.

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esperent ◴[21 Sep 25 16:13 UTC] No.45323988[source]▶
Isn't that 20Ah figure always relative to the internal voltage of the lithium batteries, 3.7v? At least that's what I always assumed.
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nerdsniper ◴[21 Sep 25 20:17 UTC] No.45326275[source]▶
10 years ago most of these battery packs were relative to the 5V output voltage, so they advertised lower amp-hours. That stopped making sense with fast charging at higher voltages so they restandardized on 3.7V.

But watt-hours would make infinitely more sense for all batteries.

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1. baobun ◴[21 Sep 25 23:09 UTC] No.45327497{3}[source]▶
Huh, I didn't get that memo so have been played a fool assuming 5v until now. Advertising mAh corresponding to a different unadvertised voltage than the output is just misleading advertising.