GPS eats batteries....get these. I bought some and they last a long time. You'll save money in the long run. I have an Eagle Accu-Nav (about 8 years old...ancient, but it works well). It uses six alkaline AA batteries over the course of a day long hunt (intermittent use). When I got the MAHA 1800's I tried them by sitting the GPS on my deck and let it run continous. I figured they would last about 2 hours. They lasted 5 and a half hours. I was amazed.
These aren't cheap, but they are good. Definitely pay the extra few dollars and get the 12V cord for use in the truck.
http://www.thomas-distributing.com/mh-4aa180.htm
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