Used GL820 with AC Adapter Power Supply ; USB Cable and DC Battery B-517 | eBay
Amazon.com: Battery Replacement for GRAPHTEC GL220 Data Logger Part NO B-517 : Health & Household
Amazon.com: APC Back-UPS 450VA BE450G Compatible Replacement Battery by UPSBatteryCenter : Health & Household
Amazon.com: DMU12-3 12V 2.8Ah Replacement Battery by UPSBatteryCenter : Health & Household
Synergy Digital Equipment Battery, Works with Graphtec B-517 Equipment, (Li-Ion, 7.4V, 2200 mAh) Ultra High Capacity, Compatible with Graphtec B-517 Battery - Walmart.com