About this replacement
DeWalt DC528 Flashlight Series — 14.4V Ni-MH Replacement Battery (DC9091)
This is a 14.4V Ni-MH replacement battery rated at 1500mAh (21.6Wh) for the DeWalt DC528 cordless work light and compatible 14.4V platforms. It replaces OEM part numbers DC9091, DE9091, DW9091, DC9096, DW9096, and over 20 additional cross-references in the same voltage family. The pack slots into the DC528's battery cradle and restores full light output to the job site.
- DC528 and 14.4V platform compatibility: DeWalt's 14.4V tools and accessories share a common battery rail and connector geometry across this generation. The DC528 flashlight, DC551KA, DC612KA, DC613KA, and 50-plus additional models all draw from the same 14.4V bus — same connector, same BMS handshake protocol, no adapter needed.
- Bench tested on actual hardware: We ran this pack through charge and discharge cycles on a 14.4V DeWalt platform and monitored the BMS for cell balancing and protection response. The pack accepted a full charge without thermal anomaly and held stable voltage under a sustained low-draw lighting load.
- Ni-MH storage between jobs: Ni-MH cells lose charge faster in storage than Li-ion. If the flashlight sits unused for more than two weeks on site, top the pack off before taking it into the field — a partially discharged Ni-MH left sitting will reach a state where the charger's acceptance threshold rejects it.
Why the DC528 dims under sustained load even with a charged pack
Ni-MH cells develop elevated internal resistance as they age or after deep-discharge events. Under a continuous lighting load, that resistance causes measurable voltage sag — the pack reads 14.4V at rest but drops noticeably under draw. The DC528's bulb or LED driver receives less voltage and output dims. If the pack is new and this still happens, check the battery cradle contacts for corrosion or debris — contact resistance adds directly to the sag on a 14.4V rail.
Charger blinking red on a new or stored 14.4V Ni-MH pack
DeWalt's 14.4V chargers run a voltage check before entering the charge cycle. If cell voltage has dropped below roughly 10V after long storage, the charger reads the pack as faulty and blinks red rather than starting a charge. This is a protection circuit response, not necessarily a dead pack. Try a "recovery" or "force charge" mode if your charger supports it — or connect the pack to a compatible charger that allows manual override. If the cells recover above the acceptance threshold, the charger will switch to normal mode and complete the cycle.