Garmin Etrex 20 Lithium Battery Test

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    BC Bob


    Locale: Vancouver Island

    I bought a 4-pack of AA "Energizer Ultimate Lithium" batteries to test. I'd like to use lithium batteries on backpacking trips because of their longer life, lighter weight, and better performance at low temperatures.

    Weights on my scale (2 AAs):

    Energizer Rechargeable: 54 g
    Duracell Alkaline: 49 g
    Energizer Ultimate Lithium: 29 g

    First test. The first 2 lithium batteries lasted about 5.5 hours. They died at the beginning of my third day hike. I called Garmin tech support to discuss. They suggested a hard reset in case some unknown glitch was causing a battery drain. A bad battery is also a possibility (though I'm skeptical of that). Backlighting was never used. I had both the GLONASS and WAAS options turned ON. I know they drain the batteries faster.

    Second test ended today. GLONASS and WAAS were OFF for the duration of the test. Backlighting was never used. Over 6 weeks I did 17 day hikes ranging from 2-5 hours, plus two 1-hour bike rides for a total of 57.1 hours on the 2nd pair of batteries (I kept track of the times in a spreadsheet to keep it accurate). I'm pretty impressed with 57.1 hours. I didn't expect over 40.

    GPS alone gives me accurate tracks and decent position "lock on" times I think.

    Third test. I might try turning GLONASS back on to see if that caused most of the drain in the first test.

    Bob Gross
    BPL Member


    Locale: Silicon Valley

    You might be getting higher battery drain from GLONASS and WAAS, and I doubt that those options get you much. WAAS was designed and built purely for airliners to use to improve their vertical positioning accuracy on landing. It has little use for a hiker.


    Michael Driscoll
    BPL Member


    Locale: Monterey Bay

    WOW I had no idea one could get tracking times like that… I have always thought the 20 was a sweet spot in the GPS world… could you say again batteries used for 2nd test…

    Billy Ray


    Locale: the mountains

    I got 5 days with Li Batts in my eTrex 30 last spring in the canyons of Utah… approximately 8 hours per day as I tuned it on when I started hiking in the morning and off when I got to camp… 8 x 5 = 40

    Glonass and WASS off and screen light were off.


    jimmy b
    BPL Member


    Thanks for starting thread. Very helpful knowing I can get such extended battery life.

    Did you hold off on the hard reset before doing the second test to isolate the possibility of a "glitch" drawing down the battery? I would think your third test would take care of that. If not it seems Billy Ray's results back up the theory of longer life associated with turning the extra features off.

    So for those in the know, could you explain the difference in having the GLONASS and WAAS off…in layman's terms please. Thanks


    BC Bob


    Locale: Vancouver Island

    Batteries are below. I'm starting another test today on a day hike. I've got GLONASS turned back ON. I agree with BG that GLONASS doesn't help much (at least where I hike) but I'd like to see if that was what drained the batteries so fast in the first test.

    I also wonder if 19 day hikes & bike rides would be the same as seven 8-hour days backpacking, i.e., would leaving it on for 8 hours at a time affect (reduce) battery life.Energizer Ultimate Lithium AAs

    BC Bob


    Locale: Vancouver Island

    Jimmy, I did the hard reset after I finished the first test and before I started the second. It was suggested by Garmin tech support. Hard to know if it made any difference (I'm skeptical). I think it's just the last ditch effort to correct a problem. It's like computers. If it starts acting goofy, hit the reset and see if that fixes it.

    Please see the links in my first post for explanations of GLONASS and WAAS. That's about all I know on those.

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