Originally Posted by dommiek
have the gps running for six to eight hours most days. I'm using a Garmin Etrex that takes x2 "AA" batteries which give approx ten hours of life.
It'll probably be a good idea to have a "gel" battery mounted somewhere on the bike as a backup...
well the idea of a "gelly" battery is that you can take the x2 AA disposable cells out regarding vibrations on the handle bar to safe the +/- contacts of the GPS from wearing sore and prevent the x2 AA from rubbing fine dust off the GPS plastic compartment (the vibrations are a serious problem while riding bad roads or off-road), the external 12Volt/3Amp battery is than the main energy source 24 hours 7 days the week ! The 3Amp battery is permanent charged while riding and last a very long time, some few days or even a week if only used for the GPS with out charging it. By hard wiring the 3Amp battery to the condenser it's getting charged any time you kick your bike in to live.
(recommendation for kick-bikes with out EL-starter or any main battery, you can fit a small diode on the charging cable between the condenser and the 3Amp battery to prevent currants leakage, this was Std. on my old KTM EGS 350 2-stroke)
Now regarding the Etrex, there should be no problem hooking it up that way, I usually never turn my Garmin 76S off over night at all while camping, just cover it up with my helmet to hide it from direct view. See all the modern Garmins can cope and run with voltage from 3Volt to 36Volt straight from a bigger Battery as far I know there is no extra volt-regulator needed, but you may check the tech-data for the Etrex, as I say the +pole of the condenser supplies safe 12Volt-DC for all your Bike electric, lamps, horn, GPS and what not is need with out blowing the items, well a extra fuse is always a good choice. Oh yes, a small switch on the dash comes handy if you don't need any GPS but is not needed.
Different set-up story on thumbers!
I run my 76S straight of the main battery with in-line fuse on my thumber-LC4 Enduro, since there is a constant 13-15Volt charge from the build in volt-regulator, works very reliably for years now, the 76S lives on a Turatech bracket right in my face on top of the handlebar cross brace, I just cover the open contacts with the supplied rubber grommet to protect this from corrosion if riding with out GPS, that's all and hassle free....
Using a small 2nd aux-battery additional to the main battery on Rally-bikes, specially for aux-equipment like "GPS, Tripmaster, extra lights, and all the other toys" is a common option, so the main bike-electric remains untouched. That way all the aux-gear runes off the aux-battery.
Last edited by spooky; 10 Aug 2008 at 12:10.