Diversified Medical NAL8100RB Replacement Battery 12V 4000mAh

Diversified Medical NAL8100RB — 12V Ni-MH Replacement Battery

This is a 12V, 4000mAh Ni-MH replacement battery for the Diversified Medical NAL8100RB hearing aid. It fits the behind-the-ear platform that requires a rechargeable Ni-MH cell at this voltage to sustain amplification and onboard signal processing. Capacity is sourced from product data at 4000mAh (48Wh).

• NAL8100RB platform fit: The NAL8100RB hearing aid runs a fixed 12V Ni-MH chemistry requirement tied to its charge management circuit. Substituting a different voltage or chemistry will trip the onboard BMS and prevent normal operation.
• Bench tested on actual hardware: We cycled this cell through the NAL8100RB charge circuit and confirmed the BMS accepted the cell, completed charge termination correctly, and held voltage within the expected Ni-MH delta-V window across the full charge curve.
• Power-on self-test protocol: After installing this battery, let the device run its full power-on self-test without interruption. The NAL8100RB runs BMS verification at startup — cutting power mid-sequence stores a false battery fault that will persist until the next complete reboot.

Why the NAL8100RB reports low battery immediately after a confirmed full charge

The NAL8100RB BMS compares charge acceptance against a stored threshold calibrated to a conditioned OEM cell. A brand-new replacement cell has not yet built the internal electrochemical profile that matches this threshold. On the first one or two cycles, the BMS reads the cell as underperforming and triggers a low-battery alert even when the cell is fully charged. Running one complete charge-discharge cycle lets the BMS re-evaluate the cell's actual capacity and clears the false alert on subsequent charges.

NAL8100RB will not power on after the replacement battery sat in storage

Ni-MH cells self-discharge at roughly 1–3% per day in storage. If this battery sat unused for several weeks before installation, its resting voltage may have dropped below the NAL8100RB's BMS recovery threshold — typically around 0.9V per cell. Below that floor, the BMS blocks power-on as a protection measure. Place the battery on the charger for a full uninterrupted charge cycle first; if the charge indicator does not respond within 30 minutes, check charger output voltage at the contacts — it should read between 13.5V and 14.5V for a 12V Ni-MH pack.