DeWalt DC9091 14.4V Ni-MH Replacement Battery for DC528

DeWalt DC528 Flashlight Series — 14.4V Ni-MH Replacement Battery (DC9091)

This is a 14.4V, 3000mAh Ni-MH replacement battery for the DeWalt DC528 cordless work light and over 50 compatible DeWalt 14.4V platforms including the DC551KA, DC612KA, and DC613KA. It replaces OEM part numbers DC9091, DE9091, DW9091, DW9094, and the full DC/DE/DW 14.4V battery family. Slot it into the same bay as the original — connector orientation and latch geometry match the existing housing.

• DC/DE/DW 14.4V platform fit: DeWalt built the DC528 and its sibling tools around a shared 14.4V slide-pack format. All models in this family use the same blade contacts, latch position, and nominal voltage rail, so one battery SKU covers the full group without adapter or modification.
• Bench tested on actual hardware: We cycled this pack on a DC528 flashlight and monitored cell temperature and voltage under sustained load. The internal protection circuit held voltage within spec across a full discharge cycle with no unexpected cutoff events.
• Ni-MH storage before job site use: Ni-MH packs lose charge faster in storage than Li-ion. If this battery has sat uninstalled for more than 60 days, run a full charge before first use — a partially discharged Ni-MH pack can trigger the charger's voltage-detection circuit to flag the pack as faulty before cells have recovered.

Why DeWalt 14.4V chargers reject packs that have been in storage

DeWalt's 14.4V charger lineup uses a voltage-presence check before entering full charge mode. If a Ni-MH pack drops below approximately 1V per cell from extended storage, the charger reads the pack as damaged and refuses to charge. This is a BMS-side protection handshake, not a fault in the battery itself. A brief conditioning charge at reduced current — available on compatible DeWalt chargers via the DE9038 charging interface — will bring cell voltage back above the acceptance threshold. Once cells register above that floor, normal charging resumes.

DC528 flashlight dims noticeably during extended use

Sustained brightness drop on the DC528 usually points to voltage sag as cell discharge deepens — not a failed battery. Ni-MH cells show a steeper voltage curve than Li-ion in the final 20% of discharge, and the DC528's driver circuit reduces output rather than cutting off entirely. Check the blade contacts on the battery and light housing for oxidation or debris; a resistive contact multiplies sag under even moderate current draw. Clean contacts with isopropyl alcohol and reseat the pack — if resting pack voltage reads above 12V on a multimeter, the cells still have usable capacity.