Dirt Devil EVO M678 Replacement Battery 7.2V 1500mAh

Dirt Devil EVO M678 — 7.2V Ni-MH Replacement Battery (GPHC152M07)

This is a 7.2V, 1500mAh Ni-MH replacement battery for the Dirt Devil EVO M678 cordless stick vacuum. It replaces OEM part GPHC152M07 and fits directly into the M678 battery compartment. Capacity is rated at 10.8Wh, matching the original specification.

• EVO M678 compatibility: The M678 platform runs a 7.2V motor rail with a Ni-MH cell stack. The connector pinout and cell count on this replacement match what the vacuum's onboard charge circuit expects, so the charger handshake completes normally.
• Bench tested on actual hardware: We cycled this battery through the M678 vacuum under sustained suction load. The BMS held steady at operating voltage across multiple discharge cycles, and the charge circuit accepted the pack without fault codes or thermal shutoff.
• Dock charging on the M678: Remove the vacuum from the charging dock once the battery reaches full charge. The M678 dock does not switch to a true maintenance mode — leaving it docked continuously feeds a low-level trickle that degrades Ni-MH cell capacity faster than regular charge-and-remove cycles.

Suction dropping before the battery indicator reaches low on the M678

This happens when the motor draws more current than the battery can sustain at rated voltage — often triggered by a partially blocked filter, not a weak battery. The cell voltage sags under load, the motor slows, and suction falls off even though the indicator still shows charge remaining. Clean or replace the filter first. If suction recovers immediately, the battery was not the issue. If sag continues with a clean filter, the cell stack is no longer holding voltage above 6.0V under load.

M678 motor cutting out briefly then restarting on its own

This is a BMS overcurrent trip, not a loose connection. When airflow is restricted — blocked filter, full dust cup, or a stuck floor nozzle — the motor works harder and pulls a current spike the BMS interprets as a fault. The pack shuts the output, cools for a few seconds, then resets. Clear the restriction before assuming the battery is faulty. If the cutout continues with an open airpath and a clean filter, check that the cell voltage under no-load reads at least 8.4V immediately after a full charge.