Keeping batteries working in the cold

[andrewa]

My question is aimed particularly at snow sports.

Once a battery gets cold, does it lose its charge entirely , or does the charge improve again when it is warmed?

I'm thinking largely of GoPro batteries and drone (DJI Spark) batteries.

On Bogong last weekend, my GoPro batteries were next to useless - it got down to -4, but I stored them inside some gloves, which probably made f... All difference!

I know I can keep them inside my clothing, but it's not v comfortable sleeping with them in my down jacket chest pocket!

I was thinking of other ways to keep them warm, and wondered about those stick on instant heat pads that are used medically, and which keep warm for 12 hrs. I'm not sure what temp they get to, but presume it is less that 46c, which is the hottest you can tolerate on your skin. Thinking about putting 1/2 of one of those in a small foam envelope with the batteries at night, or even sticking a bit of one on the drone battery to improve battery life ( the drone's a new toy for next weekend on Bogong).

? Any other thoughts

A

[ofuros]

I usually keep them close to my body during the day & in my make shift sack/pillow wrapped
in something soft during the night. Heat from my boof head keeps them alive & kick'n.

[Tortoise]

I was thinking of other ways to keep them warm, and wondered about those stick on instant heat pads that are used medically, and which keep warm for 12 hrs. I'm not sure what temp they get to, but presume it is less that 46c, which is the hottest you can tolerate on your skin.

I wash up with 60 degree water (no gloves). I checked the hand warmers I use ('Hothands'), which at times can be almost too hot for my bare skin. It says they can get up to 70 degrees, which I think is about right. I expect the stick on ones don't get as hot, but it'd be worth checking.

[andrewa]

46c is the maximum comfortable temperature skin can tolerate (we did an experiment at medical school). I don't know what your hands are made of!

I now know why I blew up so many mercury thermometers by running them under the hot tap when I was trying to feign a temperature and wag school!

So, once cold, I know that batteries fizzle, and seem to recover somewhat once warmed a bit, but don't know whether the loss in charge is recoverable by bringing back up to 20c+, or whether the charge is lost.

A

[Tortoise]

I have more problems than I thought!

[CasualNerd]

So, once cold, I know that batteries fizzle, and seem to recover somewhat once warmed a bit, but don't know whether the loss in charge is recoverable by bringing back up to 20c+, or whether the charge is lost.

A

Everything I read (and people were posting here) suggests batteries recover ok once warm. Just don't charge them at low temperatures, I know from personal experience my phone battery never recovered from one morning of charging while walking below zero this year. It just dies suddenly, displayed charge level never accurate etc.

[eggs]

Not as cold as snow - but on the OT I ran low on normal batteries [not rechargeable].
To keep them going longer I did sleep with them, and finally heated them a little on the cooker to eek out a little more life.

[ChrisJHC]

To keep them going longer I did sleep with them

Does your wife know?

[eggs]

Yes. She was with me on that trip.

[keithy]

Andrew

Lithium based batteries (like those in your gopro / drone) will be have their discharge capacities negatively impacted by cold temperature. For example, when discharging at a normal rate of around C/5, the discharge capacity drops by around 20% at -10°C. This gets worse if you have a higher discharge rate (which you would experience in a drone) of say >C instead of the C/5 rate, then your battery's capacity at that temperature (-10°C) drops by >50%.

This is due to the negative impact of cold temperatures on electrolyte conductivity.

The good news though, is that the capacity drop is usually only experienced during the exposure to cold temperatures. It should not degrade the battery's long term capacity (all other things being equal).

However, as I have previously posted a reply to Casualnerd in this post viewtopic.php?f=21&t=19706&start=60#p330558, when you start getting below freezing temperatures, be careful not to recharge your drone/gopro batteries with a powerbank. Charging a lithium ion battery below freezing (<0°C) is not good. It can shorten your battery life and lead to battery failures. See the previous post on the longer reply.

What I do with my lithium batteries when it is below freezing is to put them in a pouch in my sleeping bag (for overnighters) or in an insulated baggie in my pack. But usually before use, they will be on my body somewhere to warm them up.