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Why your outdoorsy friend suddenly has a gummy bear power bank

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258 points arnon | 8 comments | 21 Sep 25 12:31 UTC | HN request time: 0s | source | bottom

https://archive.ph/1G2Ut
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mbesto ◴[21 Sep 25 22:58 UTC] No.45327428[source]▶
This is a very poorly researched article. A few things worth considering:

- 20,000 mAh is the rated capacity. Anyone who has tested 18650 batteries (which are the cells typically used in these battery packs) knows the rated capacity != tested capacity.

- Watthours is more important than amp hours

- Tested watt hours as typical loads is more important than amp hours

- It's very normal to see tested capacity to be roughly 70~80% of rated capacity.

- This commenter said they got "At 18W average, I pulled out 55.4Wh" on the Haribo [0]

- The generally considered "gold standard" for ultra light batteries in this range is the Nitecore NB20000 Gen 3, which regularly tests around 56 Wh.

So yes the conclusion is correct - you get roughly the same amount of capacity for a typical load (18W phone) for a cheaper price and slightly less weight. Very curious what battery cells the Haribo uses.

[0] - https://old.reddit.com/r/Ultralight/comments/1li5rxw/20000ma...

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coin ◴[22 Sep 25 00:12 UTC] No.45327839[source]▶
> Watthours is more important than amp hours

I'd go a step further and say that amp hours is meaning less since voltage is not specified. The only valid battery capacity unit of measure is watt hours. While most battery packs use a single 3.7 lithium ion battery, Apple's first gen MagSafe battery pack used two internal batteries in series, throwing off everyone's amp hours only comparison.

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nwallin ◴[22 Sep 25 00:57 UTC] No.45328092[source]▶
> The only valid battery capacity unit of measure is watt hours.

I would also accept Joules. But yes, the unit should be a unit of energy.

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1. beAbU ◴[22 Sep 25 06:43 UTC] No.45329848[source]▶
You are probably making a joke, but just in case and for those that don't know, a joule _is_ a watt hour.

1 joule is 1 watt-second to be precise. So 1Wh is 3600 joules.

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2. numpad0 ◴[22 Sep 25 09:37 UTC] No.45331042[source]▶
So that's why it doesn't align with existing industry units and always requiring conversions...
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3. bregma ◴[22 Sep 25 10:45 UTC] No.45331599[source]▶
Thank goodness SI units are power-of-ten based so converting between watt hours and joules is just a matter of moving the decimal place. Oh, and throwing in an ancient Sumerian constant approximating the number of Earth rotations as it revolves around the sun once.
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4. lotsofpulp ◴[22 Sep 25 11:07 UTC] No.45331775{3}[source]▶
Do seconds have anything to do with the Earth rotating around the sun? I thought a second just has to do with the Earth’s rotation on its axis.

Also, I wonder how usable a unit of time that was not based on a day would be, since so much of our life revolves around that cycle.

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5. numpad0 ◴[22 Sep 25 11:15 UTC] No.45331836{3}[source]▶
No, Watt-second-hour = 3.6 kJ, so J to Wh is moving the decimal place couple steps AND dividing by 3.6. The actual units used in circuit designs is mAh, so the decimal has to be moved for another time then divided by 3.7[V] again. That's too much for a smooth-brained man like I am.
6. tnlnbn ◴[22 Sep 25 12:16 UTC] No.45332352{4}[source]▶
Yes, seconds are related to the Earth rotating around the sun. Simplifying slightly, the normal definition of a day relates to how long for Earth to rotate on its axis until the same spot on the Earth points at the sun again.

Compare Mean solar day vs Stellar day vs Sideral day - the difference is less than 5 minutes or so.

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7. ◴[22 Sep 25 12:45 UTC] No.45332648{5}[source]▶
8. lotsofpulp ◴[22 Sep 25 12:58 UTC] No.45332795{5}[source]▶
Thanks, I see now from:

https://en.wikipedia.org/wiki/Solar_time

I was thinking along the lines of the ancient Sumerians arbitrarily deciding to divide 1 day into 24 hours, and 24 hours into 60 minutes, and 60 minutes into 60 seconds, and how that doesn't have anything to do with how humans came up with the concept of 1 year (the Earth rotating around the sun).