Got my Elite 5 HDI last year. When I first used it on ice I put the screen brilliance up to 10 (all the way up) and let it run to see how long it would last, got a good solid 7 hours out of it before the battery voltage became marginal. I normally run it with a 6 or 7 brilliance and sleep it if I move but it is on just about all day and have never had it die on me. The unit goes on the boat during the soft water season. I do use the ice pack with Elite 5 in the summer when fishing in the canoe. I also put the charger on the ice pack battery every couple of months during the summer.