Colgate Omron ProClinical A1500 Replacement Battery 2.4V 600mAh

Colgate Omron ProClinical A1500 — 2.4V Ni-MH Replacement Battery (GP75AAH2A1H)

This is a 2.4V, 600mAh Ni-MH cell that replaces the internal battery in the Colgate Omron ProClinical A1500 electric toothbrush. It matches OEM part number GP75AAH2A1H and restores the brushing mechanism to normal operating power. Dimensions are 55.52 × 15.00 × 14.40mm — verify against the existing cell before fitting.

• ProClinical A1500 fit: The A1500 runs a single Ni-MH cell at 2.4V to drive the oscillating brush motor. This cell matches that voltage rail and physical footprint. The internal charging circuit expects Ni-MH chemistry — substituting a different chemistry will misread charge state and shorten cell life.
• Bench tested on actual hardware: We cycled this cell through the A1500's inductive charging base and confirmed the charge circuit accepted it without fault. The motor drew expected current at full charge, and the BMS handled termination correctly at capacity.
• Base charging practice for the A1500: Remove the toothbrush from the charging base once full and only return it when charge is noticeably low. The A1500's inductive base delivers a continuous trickle when the brush is docked — leaving it seated permanently accelerates Ni-MH capacity fade faster than normal partial-charge cycling.

Battery fade from continuous dock charging on the A1500

The ProClinical A1500 charges inductively through its base stand. The base does not cut power once the cell reaches full charge — it continues delivering a low-level current. Over months, this trickle overcharges the Ni-MH cell and causes voltage depression, where the cell appears charged but delivers less usable capacity per cycle. The fix is simple: use the toothbrush off the base until brushing power noticeably drops, then recharge fully and remove again.

Brush motor running weak even with a freshly charged new cell

A new Ni-MH cell does not reach full capacity on its first charge cycle — this is normal chemistry behaviour, not a fault with the cell or device. The A1500's motor may feel sluggish for the first two to three full charge-and-use cycles while the cell conditions. Run the toothbrush until the motor slows noticeably, then charge fully. By the third cycle, resting voltage should stabilise at approximately 2.4V and motor speed will reach normal operating level.