Cold Batteries and Silica Gel

[JNorton]

I've heard that there are severe limitations when using alkaline batteries in near-freezing conditons. Does anyone know if NiMH or Lithium Ion batteries perform better in more extreme conditions?
Also, anyone have experience using Silica gel and have a technique for recharging the stuff in the field?
James Norton

 

[Scott Brady]

NiMH batteries store well in cold, but perform poorly (as do most batteries), even at 32 degrees, NiMH batteries lose 20% of their capacity (though voltage is not affected at that temp.)

For charging, I would recommend this...

 

[droppdwn]

I lived in the Philippines for nearly two years and used only the disposable silica gel around my computer, camera, and electronic components the entire time. They would collect about 10oz of water ever month (inside an air-conditioned house!) If you're planning on being in a VERY humid or rainy environment like the Amazon, I'd suggest saving your money for Pelican cases instead. You _can_ buy 'rechargeable' silica gel (maybe at a pool supply place?) that changes color. Then you can pop it in an oven and bake it back to dry.

Otherwise I’d place all my camera equipment in a nice air-tight case and toss a couple of silica gel packets in on top of it (I'd steal them form my wife's shoe boxes personally). Hope this helps.

A few links for silica for sale on the web:
http://www.jakesmp.net/CSD_Silica_Gel/CSD_Silica_001_M.html
http://www.drierite.com/default.cfm

I can’t even begin to help with batteries/recharging systems because I’m in the middle of deciding on solar :sunflower panels myself. That Brunton that Scott posted is pretty cool because it (supposedly) generates 900mA. You can get lower current ones for less. With that flexible one you could use little suction cups in a back/side window of say a 4runner and charge batteries all day long while driving OR parked.

I like this universal (1.2V-14.4V batteries / 100V-240V AC OR 12V DC input) battery charger, and plan on ordering one very soon:

http://www.thomas-distributing.com/mh-c777plus.htm

And it should connect nicely to a panel once I find a nice, tough one. Uni-solar makes them for the military.

 

[JNorton]

Silica Gel

Thanks for the response. Concerning the disposable packets, is there a way to determine if they are used up? How about methods for recharging the re-useable gel in the field: Without an oven, that is.
How'd you determine that they collected 10oz. of water a month? What quantity were you using of the small, shoe-box style packets?
James Norton

 

[Scott Brady]

Chad,

Great suggestions. I have used silica packs in my Pelican cases (that house my camera gear) for a few years now.

I am seriously concidering solar options for the truck now, and have a few interesting ideas (including the big roof area over the cab). I have read of many challenges in using solar cells on an OHV though, including tree damage and cracking from rough roads at high speeds. That is why I keep coming back to the Brunton...

 

[droppdwn]

Oh crud, sorry guys. I've been busy lately and not keeping up... In the Philippines they sell dessicant everywhere. The ones we were using came in little plastic tubs. Dessicant at the top, a thin one-way permeable membrane layer of some sort, and then the rest as a collecting tub for the water collected. I just happened to measure it one day at right around 10oz before I threw it out and replaced it with fresh dessicant. The other stuff I found on the web turns color red to blue or vice-versa, I don't remember.

I've changed my mind mine lately too. I used to be really concerned about humidity and electronics. I think that it eventually shortens the life of electronics, but short of dropping gear in a puddle or getting caught in a rain storm, I no longer worry about it. That being said the movers threw a BUNCH of packets in every box that left the Philippines.