Shark XBT779 SV780 Replacement Battery 18V 3000mAh

Shark SV780 / VX33 / Pet Perfect II — 18V Ni-MH Replacement Battery (XBT779)

This is an 18V Ni-MH replacement battery rated at 3000mAh (54Wh), carrying OEM part number XBT779. It fits the Shark SV780, VX33, and Pet Perfect II Hand Vac cordless stick vacuums. When the original cell degrades and suction weakens noticeably before the low-battery indicator triggers, this is the direct replacement.

• SV780, VX33, and Pet Perfect II compatibility: These three models share the same 18V battery rail, connector housing, and BMS handshake protocol — that is why one cell fits all three. Swapping between models does not require any adapters or firmware changes.
• Bench tested on actual hardware: We cycled this cell through repeated motor-start loads and monitored BMS response during sustained suction. The protection circuit held within spec on each draw cycle and did not trip under normal operating conditions.
• Dock charging on Shark stick vacs: Remove the vacuum from the charging dock once the battery reaches full charge. Shark SV780 units left on the dock continuously pass a slow trickle current through Ni-MH cells, which degrades capacity measurably faster than charge-and-remove cycles. Charge only when depleted.

Suction dropping before the battery indicator reaches low

Ni-MH cells in cordless vacuums lose voltage under motor load before the resting voltage drops enough to trigger the low-battery indicator. The SV780 motor draws harder when the filter is even partially restricted, which accelerates voltage sag mid-clean. The result is noticeably weaker suction while the indicator still shows charge remaining. Clean or replace the filter first — if suction recovers, the battery is not the cause. If it does not, the cell is likely below 15V under load.

Motor cutting out and then recovering a few seconds later

This is a BMS overcurrent trip, not a dead battery. When the filter is blocked or the brush roll is jammed, the motor draws current above the BMS threshold and the protection circuit shuts the output briefly. The pack resets itself after a few seconds, which is why the vacuum restarts without any intervention. Check the filter and brush roll for hair or debris before replacing the battery — a clean airpath brings the draw back within the BMS limit. If the cutout persists after clearing the restriction, the cell itself may be causing the excess draw through internal resistance.