About this replacement
Akerstroms Jupiter Era 8b / Jupiter 10b Series — 3.7V Li-ion Replacement Battery (RAK3720)
This is a 3.7V, 1600mAh Li-ion cell that fits the Akerstroms Jupiter Era 8b, Jupiter 8b, Jupiter 10b, Jupiter 10bd, and over 57 additional Jupiter series crane remote controls. OEM part numbers RAK3720, AB11R, AB1504, and 933719-000 all cross to this cell. Swap it when the original battery no longer holds a charge or the remote stops responding mid-operation.
- Jupiter series compatibility: The Jupiter Era 8b, 8b, 10b, and 10bd share the same battery bay dimensions, voltage rail, and connector format — 63.20 × 38.30 × 14.00mm footprint with a single-cell 3.7V architecture. No firmware handshake is required, so the swap is straightforward.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Jupiter-series remote and confirmed the onboard BMS responded correctly to cutoff thresholds — no false low-battery flags and no dropout during button-press sequences.
- Storage and infrequent-use charging: Crane remotes often sit unused for weeks or months. Charge this battery at least once a month during idle periods. Li-ion cells discharged below 2.5V enter deep-discharge BMS lockout — a charger connected at that point may show no response at all.
Solenoid activation causing power dropout on the Jupiter remote
When a crane solenoid or relay fires, it draws a sharp inrush current through the remote's output circuit. If the battery cell has high internal resistance — either from age or a partial deep-discharge — its voltage sags below the BMS cutoff threshold at that exact moment. The remote shuts off instantly, not because the button failed, but because the cell couldn't sustain the current spike. A fresh, fully charged 1600mAh cell at low internal resistance handles the inrush without dropping below cutoff.
Remote shows low battery immediately after installing a new cell
Cells ship at storage voltage — typically 3.6V to 3.65V — not at full charge. The Jupiter remote's battery indicator reads voltage directly, and at storage voltage it registers as low rather than full. This is not a fault with the cell. Connect the remote to its charger for a full charge cycle before putting it back into service. Once the cell reaches 4.1V–4.2V, the indicator will clear.