Electric Gloves

[KirstinS]

Dad has a pair of Warmawear electric gloves that he uses for skiing. He really suffers with cold hands but says these work a treat. Only issue is they use 9v batteries which last an hour or two at best so its very expensive. Cheap 9v are a waste of time and last about 5 mins

A quick look on ‘net shows most quality PP3 9v to be around 500mah tops. Cheap 9v can be as low as 50mah. Rechargable 9v are about 500mah mark but often more like 300mah

I have tons of 18650 lion cells knocking about

My thought is I can solder him up some rechargeable packs by series 2 x 3.7v 2900mah Panasonic 18650 cells up into a pack that is 7.4v 2900mah nominal (8.4v hot off charger). They will fit into the battery compartment just

The voltage is bit low on paper but I wondered how fast alkaline 9v tail off from 9v in reality ? Particularly on such a high drain use as this. I’ve no idea of the c rating of a 9v alkaline. I believe most 198650 are 1C

I think that in the real world although my packs will not produce as much heat in the glove at the outset – after 20mins use the 9v and my packs will be about equal. But mine will last 4 to 5 time longer and hopefully give a full days skiing use

Anyone able to provide any input here ?

Many thanks
Kirstin

 

[Emo Rider]

I Canada, you can get a set of heated grip that you can slide your hands into. Used mostly for snow mobiles, they are hard wired into the machines electrical system. you might be able to modify for said purpose.

 

[Alan Quay]

I picked up a heated body warmer and insoles from Maplin last year. They work a treat.

As for your battery idea, it should work. You might want to measure the current with a 9v alkaline first, then compare with the lithium. It's possible that the alkalines internal resistance is the limiting factor as far as current goes. It would also pay to measure the resistance of the heating element.

You don't want burned fingers.

 

[KirstinS]

Thanks mike - excellent point about the resistance. Didn't think of that possibility

 

[Alan Quay]

Out of curiosity, I tested a reasonable quality alkaline pp3, by shorting and measuring the current. It gave around 5amps, but with a massive voltage sag.

 

[Scimitar]

I'd not trust old 18650s until I was sure what current was being drawn and how far down the voltage went in what time. You must, for the sake of your old fella, if nothing else, measure and be sure.

 

[KirstinS]

Just to confirm it worked just fine

My testing was basic - I simply left both gloves on in the middle
Of the concrete garage floor

I just measured the voltage on my 2500 7.4v packs every 10 min till
I got bored. Voltage dropped slowly - I guessed about 5 hours constant use to get down to 3.2v

Then recharged

hen I tested again wearing them for an hour. They do get slightly less hot than pp3 as expected . But only
True for first 20mins or so and then pp3 voltage drops as it empties


Then went skiing

We both wore then and they both worked a treat for a full days use (turning off when not required) never got below 7v per pack

 

[Alan Quay]

Thanks for the update, nice to see a positive conclusion to thread!

 

[Scimitar]

Excellent!