https://battery-top.com/product/new-battery-for-topcon-bt-66q-rc-3-gms-2-gps-fc-100-sl90287-1/
New battery for TOPCON BT-66Q RC-3 GMS-2 GPS FC-100 - battery-top.com
Mar 20, 2026 - Battery Information: Battery Voltage: 7.4V Battery Capacity: 2500mAh Battery Type: Li-ion Condition: new Warranty: one year