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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

#271

Post by cess11 »

WithinReason wrote: post #258
dreadnip wrote: post #164

Earlier quoted context omitted.

I’ve met people on trail with 5-6 pound baseweights. Crazy world out there.

does that include food and water?

No, it's likely a bag, a hammock, a small gas bottle with burner and pot, and perhaps sleeping bag, tarp and some gadgets and eating utensils, plus an extra set of clothes. I.e. the core equipment you're going to reuse indefinitely. Perhaps they weigh in things like reusable bottles and the like too.

Personally I'm not into paying a premium for "ultralight" and similar so I might have misinterpreted something when glancing at people that seem to be. For me part of the hiking experience is getting used to carrying weight and living off equipment that would work in a crisis or adjacent to armed conflict, i.e. my basic gear clocks in at about twenty kilos or so, though that's enough to feed and 'house' about four people. Two field kitchens, teepee-style storage tent as well as a large pyramidal tent for sleeping, field spade, handheld radio units for the family/team, fishing equipment, &c. Usually I carry ~10 liters of water, a liter of ethanol, food, spare clothes and whatnot on top of it.

I find that lowering weight into the single digits doesn't give me that much extra range consistently over several days so I'd rather set up camp close to the area where I'd need it and leave some weight behind while I take on the more demanding trail or climb. At the end of the day it's going to be an endurance activity rather than a sprint anyway, at least for a non-athletic button pusher in his forties, like me.

Clearly people that mostly roam areas close to cities or that have joint issues or similar would have reason to make other decisions.

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

#272

Post by vidarh »

spuz wrote: post #266
vidarh wrote: post #265

Earlier quoted context omitted.

> 1000 (gram) calories The "(gram)" make no sense here. We commonly use "kilo" as shorthand for kilogram", but kilo is just a prefix indicating 1000 and never indicates "kilogram" when given as a prefix to another unit, and so there's no implied/left out "gram" in 1 kilocalorie.

1 kilogram Calorie is the amount of energy needed to raise the temperature of one kilogram of water by 1 degree. 1 gram calorie is the amount of energy needed to raise the temperature of 1 gram of water by 1 degree.

I see there's some use of it after having done some searches, so I'll concede it makes some minor sense as a means to disambiguate due to the Calorie/calorie confusion. Especially as "calorie" and "gram calorie" then means the same thing. This is actually the first time I can recall having seen anyone use it, though, and so for me at least it confused matters rather than clear it up...

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

#273

Post by numpad0 »

beAbU wrote: post #249
nwallin wrote: post #170

Earlier quoted context omitted.

> 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.

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.

So that's why it doesn't align with existing industry units and always requiring conversions...

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

#274

Post by numpad0 »

esperent wrote: post #58
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…

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.

Internal voltage is chemistry dependent. In other words, cell manufacturer invariant. It's 3.7V for NMC, 3.2 for LFP, 2.3 for LTO, 3.0 for Na-ion.

Technically speaking, the pack voltage as well as Ah rating should be that of the pack and not cumulative total of the pack; two NMC 18650 in series should be 7.4V 2600mAh, not 3.7V 5200mAh. But denoting as if all cells are in parallel allow this figure to be maximally inflated and so that's what manufacturers do.

High voltage charging etc are not relevant. Though, high voltage assembled battery packs should be marked in that high voltage amp-hour ratings.

The technical reason why amp-hour rating exist is because there are parameters dependent on amperage than energy or voltage, such as thickness of the wire to be used in the device or cycle life of the cell. Voltage of a battery also kind of change proportionate to remaining energy in it, and values like 3.7 for NMC or 1.5 for Alkaline is a 50%, averaged, state.

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

#275

Post by numpad0 »

NedF wrote: post #92
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.

> Wouldn't surprise me if it was just half that, This was openly crowdfunded in Japan. Please explain the lie/scam for us? How does Makuake rip people off? https://www.makuake.com/project/haribo_dcglobal/ Is this comment anything more than the normal shit HN negativity? Nihilism is so cool, thinking is so hard, if I try I might fail. Sure you might be right. Just want to know where the scam is here?

Makuake is supposed to be a crowdfunding site but it's more of Groupon now. Lots of "projects" are just rebadges from AliExpress, profiting from the fact that English proficiency of Japanese consumers as well as appetite for foreign sold product is effectively zero, virtually unexisting those websites.

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

#276

Post by londons_explore »

In a typical hike, not only do I care about weight and capacity, but also recharge speed from AC.

I often will be stopping at a cafe for lunch, and in the 45 mins I'm there I want my phone to charge from 15% to 90%, and I also want my battery to recharge from 15% to 90% to give me another 3 days hiking before the next recharge stop. That involves carrying a dual-output USB adaptor where both outputs are fast charging, two cables, a battery bank and my phone.

Thats a lot of stuff to carry, when someone would ideally make a single AC adaptor with a built in battery and cable such that when plugged in to AC it recharges both itself and an attached phone, and when unplugged from AC it discharges itself into the phone.

With clever design, some of those bits of electronics can be combined and casings and heatsinks shared making the whole setup smaller, lighter and cheaper. By integrating the battery charging logic into the AC adaptor, the temperature of the adaptor and output towards the phone can be used to adjust the charging speed to maximize use of the flyback transformers saturation current.

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

#277

Post by numpad0 »

invalidator wrote: post #137
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…

There's a technical reason for it: the voltage sags when the battery is discharged quickly. Ah is relatively constant, but Wh decreases significantly with faster discharge rates, so it can't specified as a single figure.

That's a bit cursed mental model tbf... The voltages of batteries, in the first place, is function of state of charge. 100% = 4.2V, 0% = ~2.7V, 50% is 3.7V(by volume or something. 2.7 is also technical absolute minimums, cutoff voltage is usually more like 3.2V. Please don't abuse the battery in the ranges between 3.2 to 2.7V, let alone below).

Charge/discharge current capacity is constant throughout, at least so battery manufacturers say, at 1-20x the amp-hour capacity depending on the cell. Usually 5x or less.

Since energy = voltage x current, instantaneous W capacity is higher at first, reducing as it becomes supply side limited rather than load side limited.

But all those is irrelevant to why everyone uses mAh, it's because products with biggest numbers sell fastest. Marking capacity in Wh is noble, but it's a clearance worthy sin if you ask the shelves.

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

#278

Post by bregma »

numpad0 wrote: post #273
beAbU wrote: post #249

Earlier quoted context omitted.

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.

So that's why it doesn't align with existing industry units and always requiring conversions...

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.

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

#279

Post by askvictor »

B-Con wrote: post #260

Probably not. The community is always hungry for ways to trim weight, any new offering in the field is interesting, but since the battery is one of the most critical items, well, people tend to be conservative and stick to established models. Most ultralight folks go light so they can cover more ground while being more comfortable. Experienced ultralighters consider how a weight reduction introduces risk against that…

> it gives you charging parallelism (shortening down your recharging time

How do two independent power banks achieve this?

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

#280

Post by Xylakant »

askvictor wrote: post #279
B-Con wrote: post #260

Probably not. The community is always hungry for ways to trim weight, any new offering in the field is interesting, but since the battery is one of the most critical items, well, people tend to be conservative and stick to established models. Most ultralight folks go light so they can cover more ground while being more comfortable. Experienced ultralighters consider how a weight reduction introduces risk against that…

> it gives you charging parallelism (shortening down your recharging time How do two independent power banks achieve this?

I believe the parent means you can charge the powerbanks in parallel.
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