Re: Etrex Legend - battery life problem

David Lee wrote: 
Jean wrote...

I have an eTrex Legend that I bought last Christmas and I've been using
Energizer NiMH batteries (2100 mAh rating) in the unit.

When I have the unit on for more than a couple hours (as when
geocaching), the unit nearly always reports that the batteries are low -
despite the fact that I always start out with fully charged batteries.

If I turn the unit off, let it sit for about 5 to 10 minutes and then
turn it back on, the "batteries low" message doesn't pop up and the unit
functions normally. I can continue this process (ie, turn it off when it
reports low batteries, let it sit, then turn it back on) and geocache
for several more hours. Does this sound like (a) a problem with the
GPSr, (b) bad batteries, and/or (c) a bad battery charger?


What sort of battery charger are you using? Unless it is a "smart" charger using -dV or dT detection it will only fully charge batteries of the capacity for which it was designed, since cheap chargers just charge with a constant current for a fixed period of time. Hence with such a charger upgrading to higher capacity batteries will not increase the amount of charge available to your GPSR - the batteries will simply be undercharged. Even if you do have a "smart" charger, there is no guarantee that it will be able to supply a full charge to more recent high capacity cells. The reason is that most of these chargers have a "safety timer" that cuts off the charging current after a fixed time to prevent over-charging, in case -dV detection fails to detect full charge. You will need to check your charger manual or specifications to find out the maximum charge that it can suppy (charging current x time = mAh) and compare this with the charge capacity of your batteries.

David



The Energizer charger I'm using came with the batteries. I would hope that it is a smart charger ... the Energizer web site gave no specifics for this model (model CHCAR), but one blurb in the general FAQ's indicated that their chargers are kinda smart (they stop charging depending on change in temp, change in voltage, elapsed time).

Jean
.

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