About this replacement
Electrolux PF91 Series — 32.4V Li-ion Replacement Battery (56645709099)
This 32.4V Li-ion battery pack replaces the original 56645709099 unit in the Electrolux PF91 and PF91-ALRP cordless stick vacuums. It runs at 3000mAh (97.2Wh) — matching the factory capacity spec. Fit the pack the same way as the original and the vacuum powers on without any pairing step.
- PF91 and PF91-ALRP compatibility: Both models use the same 32.4V battery rail, identical connector housing, and the same BMS communication protocol — so one cell covers both variants without any adapter or firmware workaround.
- Bench tested on actual hardware: We cycled this pack through full charge and discharge passes on a PF91 unit. The BMS held the discharge cutoff at the correct low-voltage threshold and did not trip the overcurrent protection during repeated motor start-up draws.
- Dock charging behaviour on the PF91: The PF91 charging dock does not cut power once the pack hits 100%. Leaving the vacuum docked permanently trickle-charges the cells and accelerates capacity fade. Charge to full, then remove the vacuum from the dock until the next use.
Suction dropping before the battery indicator reaches low on the PF91
This happens when a partially blocked filter forces the motor to draw above its rated current. The BMS reads that surge as a near-depletion load and reduces power output to protect the cells — even when the indicator still shows charge remaining. The vacuum feels like a weak battery, but the pack itself is fine. Clean or replace the filter first, then recharge the pack to 32.4V before testing suction again.
Motor cutting out mid-use and recovering after a few seconds
This is a BMS overcurrent trip, not a dead battery. When suction is restricted — by a blockage, a clogged filter, or a sealed floor nozzle — the motor stalls briefly and pulls a current spike that exceeds the BMS threshold. The BMS shuts off output, the motor stops, and then resets a few seconds later. Clear any blockage in the nozzle or hose, check the filter condition, and confirm the pack voltage reads above 30V before ruling out a cell fault.