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A comment on Why your outdoorsy friend suddenly has a gummy bear power bank. Parent comment

Re:Why your outdoorsy friend suddenly has a gummy bear power... by mikestew on Sunday September 21, 2025 @12:24PM (#45324108)
If your 100W light bulb is a USB bulb running at 5V (to make the math a bit easier), with 20 Ah you’ll get 100Wh, ergo it’ll run your bulb for a hour. You just need to specify the voltage. There are numerous online calculators to do this math for you.

https://www.inchcalculator.com/ah-to-wh-calculator/

Watt-hours won’t save you, because we don’t know what voltage your bulb needs. Don’t assume it’s 120/240V.

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Re:Why your outdoorsy friend suddenly has a gummy bear power... by SR2Z on Sunday September 21, 2025 @02:00PM (#45325099)
I mean, I know what voltage/wattage my devices need. I have no idea what voltage the battery bank is going to offer.
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Re:Why your outdoorsy friend suddenly has a gummy bear power... by SamBam on Sunday September 21, 2025 @04:50PM (#45326509)
...by that logic if my 100W bulb is running on 10V, with my same 20Ah I'll get 200Wh, so I'll get a bulb of the same wattage, with the same battery, running twice as long? Magical double energy!

...this is why we should measure the total energy in Wh, not Ah.

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