Mt. Whitney Portal Store & Hostel Forums General Mt. Whitney Portal Store Message Board Battery Life

I have gone back and forth between AA batteries and AAA (Duracell) and rechargeable batteries for my GPS unit and headlamps and I seem to be having problems with longevity with any of them. Kurt talked about keeping the batteries warm, which I do, but to have batteries go out after only a few uses with a GPS unit or headlamp with an expiration date 2013 is crazy. Any ideas? Or is just easier to buy fresh batteries for each trip? What typically should the life be of a rechargeable battery be once on the trail?

Expiration date of a battery really has nothing to do about how long it lasts in use. The date (in your case) just tells how much shelf life the battery has endured before you put it into use. I had a digital camera that would on occasion EAT batteries. For instance, when in Wash. D.C., bought new batteries just after lunch, and had them go away 4 hours later.

One word can solve all your problems, Lithium! They actually do last over 5X as long as normal batteries they weigh much less and work in -40F to 140F.

I use nothing else in everything I have! I don't think duracell makes any yet though.

Look for the energizer ones in AA or AAA.

That's a loaded question full of variables including but not limited to:

1) The power consumption of the device or more accurately the rate of discharge of the cell.

2) The state of charge of the cells. Not all chargers always deliver a full charge.

3) The age and condition of the cells.

4) The temperature of the cells.

5) The capacity of the cells.

6) The time span since the cells were charged. One downside of NiMH cells is their relatively high self discharge rate. The newer LSD (Low Self Discharge) cells keep their charge longer at the cost of some capacity.

For environmental reasons I prefer rechargables. My Garmin Vista HCx will run 11+ hours on two fully charged, conditioned, 2000 mAh Sanyo Eneloop AA cells above 40 degrees F. But YMMV. A lot.

One more small but important point. Some of the newer headlamps with advanced electronics sip power even when switched off. Remove the cells or interrupt the circuit with a piece of plastic when storing.

when weight and performance come first: Lithium for the TV remotes use the regulars

+1 on the Lithium batteries in the winter.

With lithium batteries I've been able to keep the GPS unit out on the harness of my pack without fearing it dying.

I use NiMH extensively; but when it counts I use Lithium.
They are light and last a long time - but they die fast. On devices with a "gauge" indicator it will go from fully charged to empty in nothing flat.
For when it matters, I typically carry a new set of Lithiums for each device for each day. Thankfully, I usually only have two or three day trips.

I use a combination of Lithium ion (custom to particular devices), NiMH (AA size) and Lithium primary (AA size) on a case-by-case basis.

As stated elsewhere in this thread, older NiMH batteries have a high self-discharge rate and are often useless after as little as a week. Capacity is adequate but really only for short trips because of the self discharge issue. (They are also rather heavy.)

The Li-ion custom batteries for my digital cameras hold their charge but are fairly limited in capacity. For instance, in 2005 when I had a Nikon Coolpix 4500, I had to carry 4 of its Li-ion batteries to last 10 days in Philmont. My Nikon D200 eats its pair of Li-ion batteries in 3-4 days, as well.

I also have the auxillary pack for the D200 that carries 6 AA batteries instead of the two custom Li-ions. On our second (2007) trip to Philmont, I had a set of six Lithium primary AA cells in it and that set of batteries lasted until the last day of a 10-day trip, somewhat over 1,000 images. (as a counter example, I recharged the Li-ions 4x in 14 days, about 2,500 images on a recent vacation in Cambodia and Vietnam)

In my old Garmin GPS II+, normal AAs last at best one day. A set of four Lithium AAs last 2-3 days at 8-12 hours per day, or a whole trip of intermittent use.

I also second the sharp "knee" in the discharge curve for the Lithium primaries. They can read full one minute and flat less than five minutes later.

Basically, it's a matter of "using the right tool for the job." When I'm in or near civilization, I'll use the rechargeable batteries to cut down on waste. When I'm in the back country, especially on a longer trip (5 dayr or more), I'll pack the Lithium AAs for lighter weight and longer use life. In those cases, it's worth the extra cost and the small amount of trash generated.