About this replacement
Tunstall Lifeline Vi / Vi+ — 7.2V Ni-MH Replacement Battery (B0201B)
This is a 7.2V 1500mAh Ni-MH replacement battery for the Tunstall Lifeline Vi and Lifeline Vi+ personal emergency response devices. It matches the OEM part number B0201B and fits the wearable alarm unit used by elderly and vulnerable individuals to contact monitoring centres. Voltage, capacity, and connector are matched to the original cell specification.
- Lifeline Vi and Vi+ compatibility: Both the Vi and Vi+ share the same 7.2V battery rail, B0201B connector layout, and BMS handshake protocol, which is why a single cell fits both variants without modification.
- Bench tested on actual hardware: We cycled this cell through the Lifeline Vi's charge circuit and confirmed the BMS accepted the cell, completed its verification handshake, and cleared the low-battery flag after one full charge cycle.
- Post-swap self-test completion: After installing this battery, allow the Lifeline Vi to complete its full power-on self-test without interruption. The device runs a BMS verification routine at startup — cutting power during this sequence triggers a false battery fault that persists until the next clean reboot.
Low battery alarm persisting after a confirmed full charge on the Lifeline Vi
The Lifeline Vi's BMS uses a charge threshold calibrated to the OEM cell's established capacity profile. A new Ni-MH cell has not yet built its internal reference baseline, so the BMS may flag it as undercharged even when the charger shows complete. This is not a fault with the cell. Run one complete charge-discharge cycle and the BMS will update its internal threshold to match the new cell's actual capacity curve, clearing the alarm.
Lifeline Vi will not power on after the replacement battery has been in storage
Ni-MH cells self-discharge during storage at roughly 1–2% per day under typical conditions. If the cell voltage has dropped below the Lifeline Vi's BMS recovery threshold — approximately 5.4V for a 7.2V pack — the device will not boot and shows no response to the button or charger. Connect the device to its mains charger and leave it undisturbed for a minimum of 30 minutes. The charge IC applies a low-current recovery trickle first, and once the pack voltage climbs above the BMS floor the device will resume normal charging and boot correctly.