Battery life

[One Half]

Since cold saps batteries, does anyone remove their batteries and place them close to their body to keep them warm while hiking to prevent loss of charge?

[Appalachian Tater]

I'm no William Gilbert but my understanding is that cold makes batteries hold a charge better and thus deliver less current and the opposite is true for heat: they deliver more current and run out faster when warmer.

What you would want to do is keep them cold until just before you are ready to use them then warm them up.

This confirms what I am saying but doesn't go into the science behind it besides stating that heat affects the rate of chemical reactions.

http://chemistry.about.com/b/2008/01/04/cold-batteries-hold-charge-better.htm

[Panzer1]

Its too much trouble to take the batteries out of my head light. While I'm actually hiking I just keep my head light with batteries in my pack.
On cold winter nights, I will keep my head light on my head or in my pocket to keep it handy and warm.

Panzer

[Franco]

A practical answer would be that you should do that at temperature around and below freezing , otherwise the self discharging characteristics of most rechargeable batteries will be greater than what you could gain or lose by either action.
See this , for example :
http://www.pcworld.idg.com.au/article/343627/four_tips_making_your_camera_batteries_last/
BTW, do not store the camera in a warm place when hiking . If you do you will have a condensation build up and it will either freeze if you keep it out or turn into liquid when you store it in a warm place again.
Franco

[couscous]

Lithium batteries are pretty much immune to cold weather. If they stop working (somewhere below -50°F), it's probably time to come inside unless you're in the Iditarod.

[shelterbuilder]

Lithium batteries are pretty much immune to cold weather. If they stop working (somewhere below -50°F), it's probably time to come inside unless you're in the Iditarod.

Yeah, but the mushers in the Iditarod use headlamps that have a battery pack that clips to their belt underneath their parkas - that way, S&R has a few extra hours to look for the lamp-light AFTER the musher has frozen to death! :eek::eek::eek::D

[One Half]

I'm no William Gilbert but my understanding is that cold makes batteries hold a charge better and thus deliver less current and the opposite is true for heat: they deliver more current and run out faster when warmer.

What you would want to do is keep them cold until just before you are ready to use them then warm them up.

This confirms what I am saying but doesn't go into the science behind it besides stating that heat affects the rate of chemical reactions.

http://chemistry.about.com/b/2008/01/04/cold-batteries-hold-charge-better.htm


After posting this my husband told me he believes this to be true also. But he's an engineer and who knows if he holds any practical knowledge.;) I guess I will check into this. I was thinking about how if you have a weak car battery and it gets really cold you may not be able to start your car. That has happened to me. But as long as it is fairly warm, no problems. Would it be wise to remove the batteries if only to prevent accidental usage?

[SGT Rock]

Lithium works fine in cold. Supposedly these new Hybrid batteries are supposed to be rechargeable, work well in cold, and have a long storage life compared to normal NiMH. I ordered some to try them out...

http://www.google.com/products/catalog?rlz=1C1DVCB_enUS334US350&q=hybrid+batteries&um=1&ie=UTF-8&cid=16482378694086950472&ei=xVxfTOjhN4X7lwe87NSYCA&sa=X&oi=product_catalog_result&ct=result&resnum=3&ved=0CCkQ8wIwAg#

Edit----
Correction, I ended up ordering the Sanyo version of this battery: Sanyo Eneloop http://www.eneloop.info/

[Franco]

Lithium batteries are pretty much immune to cold weather. If they stop working (somewhere below -50°F), it's probably time to come inside unless you're in the Iditarod.

Not exactly. Li Ion (the type used in cameras) fail between -5 and -20c , that is between 23 f and 4 f
At around 23F the output is greatly reduced, between that and 4f it will fail completely (but then you can warm it up...)
Franco

[Spokes]

That's what bounce boxes are for....... carrying spare batteries.

[Panzer1]

Edit----
Correction, I ended up ordering the Sanyo version of this battery: Sanyo Eneloop http://www.eneloop.info/

They are still only 1.2 volts. It may not be as bright in a flashlight but it may last longer.

Panzer

[Franco]

"They are still only 1.2 volts. It may not be as bright in a flashlight but it may last longer."

The Eneloop are in fact one of if not the favourite battery at Candlepower where all the flashlight/headlamp nerds hang about . See here :
http://www.candlepowerforums.com/vb/showthread.php?t=212681

The reason why 1.2v is not necessarily worse than 1.5v is explained here :
http://www.candlepowerforums.com/vb/showthread.php?t=222784

Franco

[SGT Rock]

Lithium batteries are pretty much immune to cold weather. If they stop working (somewhere below -50°F), it's probably time to come inside unless you're in the Iditarod.

Not exactly. Li Ion (the type used in cameras) fail between -5 and -20c , that is between 23 f and 4 f
At around 23F the output is greatly reduced, between that and 4f it will fail completely (but then you can warm it up...)
Franco

Hmmm. In '08 on my winter hike I spent days below 23 and 4. And never had my lithiums give me any issues. I will admit that the lowest temp was only 6F but my Mp3 player and headlamp still worked like normal. Maybe being in contact with the human body keeps them warm enough?

[SGT Rock]

"They are still only 1.2 volts. It may not be as bright in a flashlight but it may last longer."

The Eneloop are in fact one of if not the favourite battery at Candlepower where all the flashlight/headlamp nerds hang about . See here :
http://www.candlepowerforums.com/vb/showthread.php?t=212681

The reason why 1.2v is not necessarily worse than 1.5v is explained here :
http://www.candlepowerforums.com/vb/showthread.php?t=222784

Franco

Thanks for that link Franco. I was looking at various models in this category and had a hard time sorting through the bull of advertising but decided on Enloop. I looked for some reviews and this was the only battery like this I could find one on, but didn't think to check CPF. This is the sort of thing I was looking for last night. The only other thing I wanted to know but can't seem to find is how much the batteries weigh LOL.

[Franco]

My scales measure to the nearest 5g.
Unfortunately I could only find 2x AA, I have a set of 4 in use but cannot remember in what ...
My two are about 1 oz each, 55 g for the 2.
Note that as discussed at that forum, Sanyo sell those batteries to other brands like Duracell. The white top(around the + terminal) , Made in Japan and the 2000mAh are the clues.
Sony sold some here that looked to me to be the same battery as the Eneloop.
Franco

[Kerosene]

My scales measure to the nearest 5g.My god man, invest in a decent scale (http://cgi.ebay.com/0-1-1000g-Mini-Electronic-Digital-Balance-Weight-Scale-/380253050499?pt=LH_DefaultDomain_0)! ;)

[Wise Old Owl]

http://www.climber.org/gear/batteries.html

http://www.climber.org/gear/images/BatteryLifeWarm.gif