GPS battery problems (Two batteries: eTrex)

IMPORTANT note. The water seal contacts the flat surface of the GPS case. Be sure the black tape is only on the vertical face.

The first step is to immobilize the batteries as above. The next step is to add dielectric grease to protect the plating on the terminals. For 2-stroke use (dirtbike), consider damping the contacts (as below). A fourth stepwould be to arrange a reliable source of external power.

If there are black deposits on the battery terminals, this is carbon buildup caused by sparking because of engine vibration. To get any life out of the batteries you must stop the movement of batteries and the lifting at the terminal connections. This problem is most common on single cylinder motorcycles, especially un-balanced engines such as 2-stroke.

Inside the battery case, the batteries are suspended between two springs. At certain frequencies (RPMs) the batteries jump around and lift off the terminals, creating a small spark each time they disconnect. After several thousand sparkings, a black carbon residue builds up between the contact and the battery terminal. Even though the batteries are not dead, the electricity can't get out thus the GPS thinks they're dead and shuts down. You can scrape the residue off the battery, but the scratches allow more oxygen into the spark, and it seems to return even faster. It's difficult to clean the contacts anyway, especially out in the woods. For this reason we advise using external power right from the start if possible. Don't contaminate the terminals, because you may need to run on batteriesto get home if your external power arrangement craps out.

At the very least tape the batteries and use dielectric grease (click here to order a 1 oz tube) on the terminals to shut out the oxygen which prevents a burning spark.

"Duracell" batteries appear to have tougher terminals and last longer under vibration than "Energizers" and"Costco".