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Why your outdoorsy friend suddenly has a gummy bear power bank

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Re: Why your outdoorsy friend suddenly has a gummy bear power bank

#121

Post by mattmaroon »

MobiusHorizons wrote: post #100
thegrim33 wrote: post #48

Earlier quoted context omitted.

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…

Battery capacity is always measured in amp hours not watt hours, because it’s telling you more than just capacity. The rating is a measure of how many amps the battery can emit continuously for one hour. You can estimate how long the battery will last at different loads, but it won’t match up 1:1 because of efficiency differences depending on how fast the battery is discharged, and if it has a chance to recover betwe…

I can see why you would think that, but no, that’s not the case. My RV battery is 200aH but can discharge at 380 amps and drain itself in well under an hour. (That’s a peak rate which it cannot sustain for long enough to discharge itself but it can still be well above 200 the entire time.)

Most lithium batteries can drain themselves much faster than an hour.

Re: Why your outdoorsy friend suddenly has a gummy bear power bank

#122

Post by mattmaroon »

thegrim33 wrote: post #48
cenamus wrote: post #5

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.

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…

I think they really just do it because generally everything you will connect to the battery, for the most part, will be using the same voltage, and it’s just easier to do your math and in your head. Remember, most people can’t just calculate a 20% tip in their head without having to think about it for a while or use an app.

Also, in this particular instance, phone batteries are measured in miliamp hours, so it makes the thing I actually want to know, how many times can it charge my cell phone, really easy to figure out.

But as somebody who tinkers with inverters and such, I agree, it is annoying. It is still generally not that hard to do in my head, and trivial with a calculator. But I’m with you.

Re: Why your outdoorsy friend suddenly has a gummy bear power bank

#123

Post by foobarbecue »

thegrim33 wrote: post #48
cenamus wrote: post #5

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.

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…

Yeah, if you publish Ah, you should also publish voltage. Then it's just Ah * V = Wh.

Re: Why your outdoorsy friend suddenly has a gummy bear power bank

#124

Post by mbesto »

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...

Re: Why your outdoorsy friend suddenly has a gummy bear power bank

#125

Post by hinkley »

exabrial wrote: post #80

> Ultralight culture seems a little nuts to the uninitiated. I prefer "Durable, but as light as possible", not the other way around. Most ultralight gear breaks after a few uses or when it is mishandled in anything-less-than-perfect conditions, which, happens a lot outside.

The max weight is a bunch of bullshit on the ultralight gear.

Last time I moved I showed up the day before my stuff did, I slept on a camp cot I had bought for which I was 90% of the max weight. I used it on a carpeted floor for one night, it bent in two places. If I’d put the damned thing across a root it would have looked like a pretzel the next morning.

Re: Why your outdoorsy friend suddenly has a gummy bear power bank

#126

Post by wkat4242 »

codedokode wrote: post #15

Sorry for being off-topic, but why with all the advanced technology today I have to manually copy ounces and pounds into Google to learn how much it is? Instead of adding dark themes and material design, it would be better to add a unit converter. Also do you really need a power bank for a 2-day trip? In airplane mode a phone can live like 2 weeks.

Yeah for pounds it's not so bad, you just do x2 and you're in the ballpark though not 200% accurate.

Ounces are more annoying to convert.

Re: Why your outdoorsy friend suddenly has a gummy bear power bank

#127

Post by ashdksnndck »

trenchpilgrim wrote: post #115
wkat4242 wrote: post #103

Earlier quoted context omitted.

What do you use those pads for I wonder?

You put them under your sleeping bag and they make your sleep way warmer than if your sleeping bag is directly on the tent floor. https://www.nemoequipment.com/collections/sleeping-pads

That the purpose of the sleeping pad is characterized as thermal performance and not comfort is proof that I am not capable of the ultralight mindset.

Re: Why your outdoorsy friend suddenly has a gummy bear power bank

#128

Post by ashdksnndck »

hinkley wrote: post #125
exabrial wrote: post #80

> Ultralight culture seems a little nuts to the uninitiated. I prefer "Durable, but as light as possible", not the other way around. Most ultralight gear breaks after a few uses or when it is mishandled in anything-less-than-perfect conditions, which, happens a lot outside.

The max weight is a bunch of bullshit on the ultralight gear. Last time I moved I showed up the day before my stuff did, I slept on a camp cot I had bought for which I was 90% of the max weight. I used it on a carpeted floor for one night, it bent in two places. If I’d put the damned thing across a root it would have looked like a pretzel the next morning.

The designers forgot that a human is a live load!

Re: Why your outdoorsy friend suddenly has a gummy bear power bank

#129

Post by baobun »

nerdsniper wrote: post #67
esperent wrote: post #58

Earlier quoted context omitted.

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.

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.

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.

Re: Why your outdoorsy friend suddenly has a gummy bear power bank

#130

Post by adrianmonk »

SoftTalker wrote: post #71
JohnFen wrote: post #55

Earlier quoted context omitted.

> Very easy to bring crap you don't need as well. This is so true it's not even funny. I keep a spreadsheet for each trip, and among other things, I record which of the items I actually used on the trips. It was very surprising to me how many things I thought I used and therefore needed, but when reviewing the records, I never (or very rarely) actually used. Those items get cut from future loads.

I'm not a backpacker, but I presume there is stuff you normally don't use, but don't want to be without. Some amount of first-aid supplies, etc.

Hmm, my records show I only used the bear spray on 1 out of 10 trips.
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