Krups BioCare Jet Pack 2.4V Replacement Battery RS-MH 3941

Krups BioCare Jet Pack — 2.4V Ni-MH Replacement Battery (RS-MH 3941)

This is a 2.4V, 1100mAh Ni-MH replacement battery for the Krups BioCare Jet Pack electric toothbrush. It matches the original cell format and connector used in the BioCare Jet Pack handle. Install it when the original cell no longer holds a charge or brushing power has noticeably dropped.

• BioCare Jet Pack compatibility: The BioCare Jet Pack uses a dedicated 2.4V Ni-MH cell sized at 56.80 × 17.10 × 17.10mm. That voltage rail and connector match this battery directly — no adapter, no modification needed.
• Bench tested on actual hardware: We cycled this cell through the BioCare Jet Pack's inductive charging base and confirmed the BMS accepted charge normally, maintained stable motor draw at full brush speed, and held voltage above the low-charge cutoff threshold without premature shutdown.
• Dock charging on the BioCare base: Remove the toothbrush from the charging base once it reaches full charge. The BioCare base delivers a continuous trickle charge — leaving the handle docked permanently stresses Ni-MH cells and accelerates capacity fade faster than regular partial-charge cycling.

Brushing power dropping before the low-battery indicator triggers

Ni-MH cells in toothbrushes experience voltage sag under brush motor load before the indicator circuit reads them as low. The motor draw pulls the cell voltage below its nominal 2.4V transiently, which slows brush head oscillation even though the battery still shows charge. This is a symptom of a cell that has lost usable capacity — not a faulty motor. Replacing the cell restores the voltage headroom the motor needs to sustain full oscillation speed.

Toothbrush not charging after new battery is installed

Inductive charging on the BioCare base is sensitive to physical alignment between the coil in the handle and the coil in the base. If the handle is not fully seated — even a few millimetres off — the coupling is too weak to transfer enough current to charge the cell. Check that the brush head is removed before docking, then reseat the handle firmly until it sits flush. If the charging indicator still doesn't activate, verify the base has power and try a different outlet before concluding the cell is the issue.