Batteries - How long do they last?



I’ve been trying to find the best batteries for a small handheld GPS that I use. This is a Garmin Geko 201, which I chose for its miniscule size and weight.

I used a data logger to measure battery voltage with the GPS unit sitting on a window-sill where it has a partial view of the sky. However I was concerned that the measurements are a bit unreliable since the GPS flashes a low battery warning and turns itself off when it thinks the battery is too low. Also it may be possible that varying satellite positions may affect power consumption, particularly as I have the GPS set to use EGNOS (Euro WAAS) which may depend on which satellites are in view.

So instead of using the GPS to measure battery performance I decided to use a torch (flashlight in USian). The nearest one to hand was a Peli Versabrite. (6000 CP, 5 Lumens, 2xAA, 0.6A, 1.8W). I used AAA batteries instead of AA since the GPS takes AAA batteries.

Battery life measurements

2 x AAA in Peli Versabrite.

Here’s the results.

Battery duration test
Battery duration test