About this replacement
Custom Battery Pack 4/5F6-3S1P — 3.6V Ni-MH Replacement Battery
This is a 3.6V, 500mAh Ni-MH replacement battery pack built to the 4/5F6-3S1P specification. The pack measures 50.40 x 37.00 x 6.30mm and replaces OEM packs matching that part number. Check your original pack label against part number 4/5F6-3S1P before ordering.
- 3S1P cell configuration: Three Ni-MH cells in series deliver the 3.6V nominal rail. Single-parallel arrangement keeps the footprint flat and the capacity at 500mAh — matching the original pack's voltage and physical envelope so the replacement fits the same bay.
- Bench tested on actual hardware: We cycled the pack through charge and discharge on the bench and confirmed cell balance across all three positions. The BMS held within expected cutoff thresholds, and the pack reached rated voltage without anomalous heat.
- First-cycle conditioning for Ni-MH packs: Ni-MH chemistry ships at storage voltage — typically 30–50% of rated capacity. Run one complete charge cycle before first use. Devices with a capacity indicator won't read accurately until the pack has completed at least one full charge-discharge cycle to calibrate the gauge against the new cells.
Pack running at lower voltage than rated on first installation
Ni-MH packs are stored and shipped at reduced voltage to slow self-discharge during warehousing. A fresh 4/5F6-3S1P pack will often measure 3.0–3.2V at the terminals before the first charge, not the rated 3.6V. This is normal and not a sign of a faulty cell. Charge the pack fully before measuring terminal voltage or trusting any device capacity readout.
Pack not accepted by device after swap
Some devices run a voltage-range check at power-on — if the pack voltage is below the acceptance threshold, the device rejects it before drawing any current. This trips most often with a fresh replacement pack still at storage voltage. Connect the pack to its charger first and bring it to full charge before installing it in the device. Once at 3.6V, the device should clear the check and initialise normally.