Gentlemen,
My ex bird reckons she's got this jacket that's heated inside. You charge it up from a normal USB phone charger for 5 minutes and it's good for 6 hours. I told her to FRO and no such thing exists as it would defy the laws of fizzicks. We don't have batteries capable of that yet. But she's adamant. Anyone heard about these things? She reckons they come from China. Sounds like a load of old bollocks to me.
You're right.
A couple of large jacket potatoes, heated in the microwave make very effective handwarmers. Then you can eat them too.
They do exist, at least one of the TV crew on PL footy last winter had one. It's not 5 min charge 6 hr use though more like the otherway round. B-) Fairly well insulated in the first place so it doesn't take much power to keep you warm.
Well heated jackets are about, but I'd imagine more charging is needed than five mins unless the charger is heavy duty and the battery as heavy as the jacket. I know a bloke who hads one and they are certainly well insulated, but as to whether they are really doing more than keeping your own body heat inside is debatable. Brian
I looked into heated socks, insoles and footwear a while ago, but they either give hardly any heat for a long time, or a lot of heat for a short time, and as to where you stick the batteries.... Brian
So, it claims to run from 5V supplied by a 10Ah USB power bank (that does not come with it). USB at 5V is going to be limited to about 2.5A, so a tad over 12W max power output.
With a 10Ah battery, they are normally quoting the cell capacity, so at the nominal 3.6V of the cell gives you 36Wh of capacity. Even if you ignore the conversion losses in the power bank boosting the output to
5V, it seems unlikely it could supply 12W for more than 3h, and 12W sounds like a fairly feeble heat output.So hours of charging, and minutes of use, sound more plausible.
They could be useful though for short term use in Winter like taking the dog for a half hour walk. Maybe more for older people who do tend to feel the cold much more readily.
Bikers tend to wear heated clothing in winter, but it plugs in to the battery/alternator.
I suspect that's the case, too. John Rumm did the math and I infer from that it's the silver lining that's doing most of the work in these things; without that I doubt the heating effect would be noticeable much at all. When I say "silver" I of course mean tinfoil or whatever it is they use to reflect the heat back in.
Is it possible they might be using supercapacitors, do you think? That was my best guess assuming she's not imagining the heating effect.
you get them in New Zealand ... re-chargable ....wife's cousin has one....I will get the name for you when she gets home....The body heats up not the arms....
Presumably not a nicad :-)
How does that help? If there's only 10 watt hours in the battery then using superconductors won't get more out of it, all it can do is make sure all of it gets somewhere. Given that one just wants heat anyway the loss in non-superconducting wires is just heat so makes no difference at all.
Cursitor Doom laid this down on his screen :
No matter what the storage medium, it will still need time to charge from a low wattage USB supply.
supercapacitors != superconductors
What?
There is only (say) 10wH in the battery, whatever you do you can't get more out of it.
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