About this replacement
AMX Panjam / Phast VPT-CP / VPN-CP — 7.2V Ni-MH Replacement Battery (57-0962)
This is a 7.2V 3500mAh Ni-MH replacement for the AMX Panjam, Phast VPT-CP, and VPN-CP survey and test instruments. It replaces OEM part 57-0962 directly. Capacity is 25.2Wh — matching the original specification from the product data.
- Panjam, VPT-CP, and VPN-CP platform fit: These three AMX instruments share the same 7.2V battery bay, connector pinout, and BMS handshake protocol. One pack covers all three. No adapter or wiring change needed.
- Bench tested on actual hardware: We cycled this pack through probe initialisation and sustained sensor logging sequences. The BMS held stable through the current spike at probe power-up and did not trip under continuous measurement load.
- Pre-deployment calibration cycle: After fitting this pack, run a full calibration cycle from the instrument menu before heading into the field. The instrument maps battery state during calibration — skipping it causes the low-battery indicator to fire prematurely on the first measurement session.
BMS lockout after the instrument sat unused in a carry case for months
Ni-MH cells self-discharge during storage, and if the pack drops below the BMS recovery threshold, the charger may show no activity and the instrument will not power on. This is a protection state — not a dead cell. Connect the battery to the charger and leave it for at least 30 minutes before assuming it has failed. Most chargers will begin a trickle recovery cycle and restore the pack to a chargeable voltage above 6.0V.
Readings resetting or dropping out mid-logging session
This happens when sustained sensor load pulls the pack voltage below the instrument's operating threshold for a split second. It is not always visible on the charge indicator because the voltage recovers immediately after the dropout. The root cause is usually a partially degraded original pack — not a charger fault. A fresh pack at full charge holds voltage steady under continuous sensor draw, and the logging session completes without reset.