Itowa Tunner 3.6V Ni-MH Replacement Battery BT3613MH 700mAh

Itowa Tunner — 3.6V Ni-MH Replacement Battery (BT3613MH)

This is a 3.6V 700mAh Ni-MH replacement battery for the Itowa Tunner crane remote control. It replaces OEM part numbers BT3613MH and BT3613MH3A. The Tunner is a handheld wireless remote used to operate overhead and industrial cranes in manufacturing and warehouse environments.

• Tunner remote fit: The Tunner platform uses a fixed 3.6V Ni-MH cell at this form factor — 60 x 38 x 16mm — with a connector and BMS handshake matched to this voltage rail. Swapping to a different chemistry or voltage disrupts the remote's power management circuit.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge sequences on the Tunner remote. The BMS accepted the cell without fault codes, and the radio transmitter held stable output voltage through repeated solenoid-activation commands.
• Infrequent-use charge maintenance: Crane remotes often sit idle for weeks between jobs. Charge this battery once a month during idle periods — Ni-MH cells left fully discharged for extended periods can develop voltage depression and fail to recover to rated capacity on the next charge cycle.

Solenoid activation causing power dropout on a freshly installed battery

When the Tunner remote sends a solenoid or relay command, the transmitter draws a short inrush current spike — higher than normal idle draw. A cell at storage voltage (typically 1.0–1.1V per cell) cannot sustain that spike without voltage sagging below the remote's cutoff threshold. The remote interprets this as a dead battery and shuts off, even though the cell is not actually depleted. Charging fully before first use brings the cell to around 1.4V per cell and eliminates the sag.

Remote showing low-battery warning immediately after cell swap

A new Ni-MH cell ships at storage voltage, not full charge. The Tunner remote reads cell voltage directly — if it sees below its low-battery threshold on startup, it flags the warning regardless of how new the cell is. This is not a faulty battery. Place the remote on charge for a full cycle before use. Once voltage climbs above the remote's detection threshold — typically around 3.6V fully charged across the pack — the warning clears and the remote operates normally.