Amazon.com: Gomadic Portable AA Battery Pack Designed for The Garmin etrex 10 20 30 - Powered by 4 X AA Batteries to Provide Emergency Charge. Built Using TipExchange Technology : Electronics
Gomadic High Capacity Rechargeable External Battery Pack suitable for the Garmin etrex 10 20 30
Garmin eTrex 10 - How to Remove Battery Compartment - YouTube