Strategies for keeping electronics warm?

What have people tried to keep electronics' batteries warm in day hiking in winter? I'm thinking primarily about GPS units that I might want to use often, not cell phones or spot devices that could be kept in an inner layer of clothing. Has anyone tried hand/foot warmers in a small case with the device?

Steve H.

Hiking GPSes are generally designed for wider temp ranges (5F(-15C)--158F(70C) for the Garmin 60 series and 62 series) than most other consumer electronics. These are just the ratings--many devices will continue to work at lower temps.

All of the devices that you mention above (GPSes, cellphones, spot devices) are all radios and their performance will be degraded if carried close to one's body.

Batteries are also affected by the cold and may be more limiting than the devices:
* lithium primary (non-rechargeable) are best
* NiMH and lithium-ion (rechargeable) are intermediate
* alkaline are worst
The actual temperature limits and battery lifetimes depend upon the device.

Often the best option is to have the batteries in a remote battery case so they can be kept warm next to your body with the device out in the cold.

Doug

Yup, lithiums. Thanks, Doug

I usually put packages of chemical heat with GPS, camera, phone/headlamps...if really cold even with beverage bottles inside pack.

Padded camera cases or the smaller 1 liter OR insulated water bottle holders are helpful. As Doug suggested, putting the batteries closer to you helps also. Or as MtnRunr said - chem packs also help.

A caution about using body heat to keep equipment warm: You also emit a lot of moisture along with the heat. When you put a cold object in your clothing, moisture is likely to condense on and inside it, possibly causing it to malfunction. Using waterproof versions of the equipment or placing them in sealed (eg zip closure) plastic bags before putting the device in your clothing can help. (This is the same recommendation for bringing cold equipment into warm rooms.)

FWIW, Canon gives their underwater cameras (eg D30) a 14F minimum temp rating and all of their other cameras a 32F minimum temp rating. My guess is that this is due to the risk of moisture freezing inside an unsealed camera.

Note that batteries and most electronic equipment can be carried cold--they only need to be warmed up when used. (Minimum storage temps are usually lower than minimum operation temps.) One exception: LCD displays that get really cold can freeze and crack. (The minimum storage temp depends on the LCD. LCDs designed for outdoor use (eg GPS displays) generally have wider storage limits than the LCDs used on non-outdoor equipment.) Check your spec sheets for both the operational and storage temp ranges.

Doug