About this replacement
Teletec AK1 / AK4 — 9.6V Ni-MH Replacement Battery (FW24)
This is a 9.6V 2000mAh Ni-MH replacement for the Teletec FW24 battery pack. It fits the AK1 and AK4 crane remote control units used on industrial crane and hoist systems. Capacity is rated at 19.2Wh, matching the original pack specification.
- AK1 and AK4 platform fit: Both models run the same 9.6V rail and use the same FW24 pack format, so one cell configuration covers both remotes. The connector pinout and BMS handshake are identical across the AK series.
- Bench tested on actual hardware: We cycled this pack through solenoid activation sequences on a crane remote test rig. The BMS held voltage above the dropout threshold during repeated relay inrush events without tripping.
- First-use charge on crane remotes: Ni-MH cells ship at partial storage voltage — typically around 7–8V for a 9.6V pack. Run a full charge cycle before the first operational use, especially on safety-critical crane installations where a low-voltage dropout during an E-stop sequence would be a problem.
Why crane remotes drop out during solenoid activation
Solenoid and relay coils draw a short, sharp inrush current at the moment of activation — often three to five times the steady-state draw. On a depleted or aged Ni-MH pack, this spike pulls the pack voltage below the BMS cutoff threshold for a fraction of a second. The remote's microcontroller interprets that as a dead battery and shuts down. A fully charged 9.6V pack with healthy cells will hold above 9V under this inrush load; anything sagging below 7.5V during activation is a cell-capacity problem, not a charger or remote fault.
Remote shows low battery immediately after fitting a new cell
Ni-MH packs leave the warehouse at roughly 60–70% of nominal voltage to prevent self-discharge damage during storage and shipping. The AK remote reads pack voltage on boot and flags anything below its threshold as low. This is not a faulty cell — it is a cell at storage voltage. Connect to the Teletec charger and run a full charge cycle; the low-battery indicator will clear once the pack reaches approximately 9.6V resting voltage.