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Why your outdoorsy friend suddenly has a gummy bear power bank

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258 points arnon | 2 comments | 21 Sep 25 12:31 UTC | HN request time: 0.448s | 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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1. foobarbecue ◴[21 Sep 25 22:58 UTC] No.45327424[source]▶
Yeah, if you publish Ah, you should also publish voltage. Then it's just Ah * V = Wh.
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2. baq ◴[22 Sep 25 06:52 UTC] No.45329907[source]▶
…just remember V is a rather complicated function of many parameters instead of some fixed value.