Hoover S1105 Replacement Battery 3.6V 3000mAh Ni-MH

Hoover S1105 Series — 3.6V Ni-MH Replacement Battery (P-13S/F3P1)

This is a 3.6V, 3000mAh Ni-MH replacement battery for the Hoover S1105 cordless stick vacuum. It fits the S1105, S1117-981, S1117-900, and 59139115, along with seven additional models in the same family. Capacity is 10.8Wh — matching the original specification from the product data.

• S1105 family compatibility: These models share the same 3.6V single-cell Ni-MH architecture, connector pinout, and motor driver circuit. No BMS handshake is required — voltage compatibility at the cell level is what matters here.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the S1105 motor circuit. Current draw stayed within spec under normal floor load, and the cell held voltage without sag until depletion.
• Dock charging habit on the S1105: Do not leave this vacuum sitting on the charging dock after it reaches full charge. Ni-MH cells in this voltage class degrade faster under continuous trickle charge than from regular use cycles. Charge to full, then remove it from the dock.

Battery fade from leaving the S1105 on the dock continuously

The S1105 charger does not cut off cleanly when the cell reaches full charge — it transitions to a low trickle current rather than stopping. Over weeks, that trickle oxidises the negative electrode in the Ni-MH cell, reducing usable capacity. You will notice the vacuum depletes faster even on a fresh replacement if the same docking habit continues. Charge only when depleted and unplug once the indicator shows full.

Suction drops noticeably before the battery indicator reaches low

This is a motor load issue, not a battery failure. A partially blocked filter forces the motor to draw higher current than rated to maintain airflow. That elevated draw pulls the cell voltage down faster than normal cycling would. Clean or replace the S1105 filter first — if suction recovers, the cell is likely fine. If voltage still sags under normal load after a filter clean, check the cell resting voltage; it should sit above 3.4V when fully charged.