Battery suitable for Garmin Edge 820 - 600 mAh 3.7 V battery - BatteryUpgrade
Replacement Battery 361-00043-00 For Garmin Edge 820 Edge 520 Edge 500 200 205 Edge820 GPS Garmin Edge 520 Plus Battery
Garmin Edge 200/205/500 and Edge Explore 820 Battery
Garmin Edge 820 Review | Trusted Reviews
Amazon.com: NP99sp NewPower99 Battery Kit for Garmin Edge 820 and Garmin Edge Explore 820 with Tools, Video Instructions, Long Life Battery : Electronics