Rowenta Dentasonic 2.4V Replacement Battery 1100mAh

Rowenta Dentasonic Series — 2.4V Ni-MH Replacement Battery (RS-MH 3941)

This is a 2.4V, 1100mAh Ni-MH replacement battery for the Rowenta Dentasonic, Dentacontrol Duo, Dentacontrol 707, and CuraMed Dentasonic electric toothbrushes. It replaces the internal cell that powers the sonic vibration motor. When the original cell can no longer hold a charge, brush speed drops before the indicator triggers — this battery restores full motor output.

• Dentasonic and Dentacontrol platform fit: These models share the same internal cell bay dimensions (56.80 × 17.10 × 17.10mm), voltage rail, and connector configuration, which is why one cell covers the full range. No adaptation is needed between variants.
• Bench tested on actual hardware: We cycled this cell through the inductive charging base and confirmed the BMS accepted charge without flagging a fault. Motor draw under load stayed within the cell's discharge curve across multiple cycles.
• Dock charging practice for Ni-MH cells: Remove the toothbrush from the charging base once it reaches full charge and only return it when noticeably weaker. Continuous trickle charging from an inductive base accelerates capacity fade on Ni-MH cells faster than partial-cycle use does.

Battery fade from continuous dock charging on the Dentasonic base

Rowenta's inductive charging bases keep the toothbrush in a low-level trickle charge whenever it sits docked. Ni-MH cells degrade faster under continuous trickle current than they do from normal charge-discharge cycles. Over weeks, this compresses the cell's capacity even when the brush appears fully charged. The fix is to use the base for charging only — lift the brush off once it's full and dock it again only when power starts dropping.

Brush vibration weak on first use after fitting new cell

A freshly installed Ni-MH cell often delivers reduced motor speed on the first one to three cycles — this is normal cell conditioning, not a fault with the battery or the brush. The cell's internal resistance is slightly elevated until it has been fully charged and discharged a few times. Run two or three complete charge-and-use cycles before judging performance. After conditioning, resting voltage should read approximately 2.4V and motor speed should return to full output.