EEVblog Electronics Community Forum

Electronics => Projects, Designs, and Technical Stuff => Topic started by: antenna on November 11, 2022, 04:59:44 pm

Title: Electric hand warmers
Post by: antenna on November 11, 2022, 04:59:44 pm
I have been looking at rechargable hand warmers online but I am curious if they are safe.  I thought lithium ion batteries did not do well in hot enviroments.  Are these things safe to use or will they choose a random day to burn the house down?
Title: Re: Electric hand warmers
Post by: james_s on November 11, 2022, 06:53:37 pm
Safety depends on how the specific product is designed. I doubt the heat is a problem, the battery is likely on the cuff or back of the hand, not inside the glove, and it's not going to be scorching hot. It is certainly possible to design one that is safe, the biggest risk is always the charging system. A poorly designed charger that overcharges the battery can start a fire.
Title: Re: Electric hand warmers
Post by: bidrohini on November 12, 2022, 05:04:39 pm
You may find some more information at the following links:
https://www.consumer.org.hk/en/press-release/20110114-2 (https://www.consumer.org.hk/en/press-release/20110114-2)
https://www.ocoopa.com/blogs/ocoopa/how-to-safe-use-usb-hand-warmer (https://www.ocoopa.com/blogs/ocoopa/how-to-safe-use-usb-hand-warmer)
Title: Re: Electric hand warmers
Post by: antenna on November 13, 2022, 05:33:51 pm
I ended up going with a liquid fuel warmer.  Thanks
Title: Re: Electric hand warmers
Post by: james_s on November 13, 2022, 07:47:20 pm
Liquid fuel is certainly more dangerous than electric, but if used properly either is unlikely to cause a problem.
Title: Re: Electric hand warmers
Post by: richnormand on November 14, 2022, 09:49:26 pm
No safety issues from my perspective on lithium batteries used for heated gloves.

I have these:
https://www.motionheat.ca/ (https://www.motionheat.ca/)
Initially made for oil workers in northern Alberta. They had to be rugged, wear resistant and last the whole shift.
Used for ski and using the snowblower in -35C temperatures.  Great in the car without a heated steering wheel on those mornings too.

The battery is in a small pouch at the glove entrance where there is no heating so it does not get warm.
For ski I got the wire harness the goes through the coat sleaves to a pocket inside so I am not disturbed by the weight at my hands/wrists while in motion.

They are in their fourth or fifth year and the lithium batteries are still up to the job.
They still last about 6 hours on the mid setting.