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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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cenamus ◴[21 Sep 25 16:44 UTC] No.45324359[source]▶
Yeah, but pretty much every power bank uses lithium ion batteries (or used to, at least), so you use 3.7 average volts.
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syedkarim ◴[21 Sep 25 20:29 UTC] No.45326347[source]▶
Lithium NMC, which I think is the most common, is 3.7V. Lithium iron phosphate, which some power packs do use, has a nominal voltage of 3.2V.
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1. addaon ◴[21 Sep 25 21:14 UTC] No.45326708{3}[source]▶
And LTO, which is what I actually want, is 2.3 - 2.4 V.