I'm thinking of getting an Etrex of some sort and I want to mount it on my 7c...what have you guys found works best for power? I'm thinking AA's are going to get zapped real fast at -20C or below....has anyone successfully hooked it up to a sled with no battery?

rocket, definetly run your power from your sled if you are mounting your spg to your machine. I use my etrex legen all the time but i keep it in my jacket and i fin dthat it even losses battery power when it gets a bit cold, and it would not be close to -20. I have heard of some guys that use battereis, they keep there gps warm by mounting a hand warmer behind it. Not sure how good it works though. Good luck.

I think some GPS will take 12 volt AC as a power source. That's probably what you want, then you can wire right in to the power for the lights, handwarmers, etc...

I have an etrex vista, I bought the cigarette lighter power cord and installed an outlet on my sled. Used it all last year on sled and two years on a motorcycle. Just be sure you tap into a wire that is DC regulated. Check the voltage with sled running at different rpm's, voltage should stay within 13 to 14.5 volts. My Yamaha had a regulated line, Im not sure for other makes. Mt sled does not have a battery.
If you try to run on batteries they will last about 1 hour.
If your unit is cold (mine is mounted on handle bar) do not let it shut down. Since I have no battery when I kill the engine I loose power, the vista will auto shut down in 30 seconds unless you push a button, if you let it shut off cold it will not start until you warm up the batteries. Apparently it always starts on battery power even if aux. power is supplied.

I use 2000 mA rechargeable batteries in my Magellan GPS. The rechargeable batteries last about 6 hours. But just to be safe I like to plug it into my sled using the 12v adapter.
P.S. Batteries actually last longer in colder weather due to the cold temps which slow down the electron movement in the battery.

P.S. Batteries actually last longer in colder weather due to the cold temps which slow down the electron movement in the battery.
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well, that may be true, but the problem is they won't give off enough juice to power anything, so it defeats the purpose.

FishHog

You can run it from a sled that doesn't have a battery. But, if your gps unit will only allow dc current then you need to place a bridge rectifier in line between the gps unit and the wire you are branching off of from the sled. A bridge rectifier will transform alternating current to direct current or ac to dc. You can get a bridge rectifier at radio shack for around two dollars. To ensure this works make sure you test the voltage with a volt meter for dc power.

I have not done this yet but it is fully explained by the guy who runs fishweb.com and I am planning to do it as soon as I decide which gps I want to buy.

for further info look here:

fishweb.com (http://www.fishweb.com/recreation/snowmobile/stories/gps/index.html)

Rocket, there are a few good articles in this forum on powering the GPS.

http://www.snowmobileworld.com/forum/index...?showtopic=9747 (http://www.snowmobileworld.com/forum/index.php?showtopic=9747)
http://www.snowmobileworld.com/forum/index...showtopic=32937 (http://www.snowmobileworld.com/forum/index.php?showtopic=32937)
http://www.snowmobileworld.com/forum/index...showtopic=23867 (http://www.snowmobileworld.com/forum/index.php?showtopic=23867)

Honestly, I think it would be much easier to buy a kit like the one from Polaris or even better install a small 12V battery like Jim Fritch did. My rectifier works fine, but it was a fair amount of work, and you have to remember to tap a button on the GPS eveytime you shut off the sled or the unit will shut off. With a constant 12V you won't have to worry about it and word is that even a small 12V will run a GPS for 5 days w/o recharging.

So if I stuck a little 12V gel cell in there it would work? Interesting...I was hoping to be able to hard wire something in, but that might be an option. Also like the heat pack idea if I can find a GPS case that will accomodate both the unit and a heat pack.

Are there any GPS units out there that will run on AC?

None that I'm aware of. And I've ridden in -20F and not had any problems with the LCD display. If you have it mounted on the dash I think there's enough ambient heat from the engine that it's 10-20 degrees warmer right behind the windshield.

I power mine E-trex Legend with alkalines and I modified a soft case with a small pocket on the back to except a thumb warmer heat element that i wired into my spare outlet under the dash console. Works fine all day long even in the UP of Michigan.