About this replacement
Cedar CD-100M — 6V Ni-MH Replacement Battery (5N-70KACL)
This is a 6V 2000mAh Ni-MH battery for the Cedar CD-100M survey and measurement instrument. It replaces OEM part 5N-70KACL and fits directly into the CD-100M battery compartment. Capacity matches the original 12Wh specification.
- CD-100M platform fit: The CD-100M runs a 6V Ni-MH cell pack with a specific connector pinout and BMS handshake that gates power to the measurement module. This replacement matches that voltage rail and connector geometry, so the instrument powers on and communicates with the pack without throwing a battery fault.
- Bench tested on actual hardware: We cycled this pack through instrument startup, active sensor logging, and data transfer. The BMS held voltage within the CD-100M's operating window across all three load states, and the cell temperature stayed within Ni-MH safe limits throughout.
- First-use calibration requirement: After installing this pack, run a full calibration cycle through the CD-100M instrument menu before field deployment. The instrument maps battery state during that calibration sequence. Skipping it causes premature low-battery warnings on your first measurement session in the field.
BMS lockout after the CD-100M sat unused in a carry case for months
Ni-MH cells self-discharge during storage. If a pack sits unused long enough, cell voltage drops below the BMS recovery threshold and the pack enters a protection lockout — the instrument won't power on and the charger shows no activity. This isn't a dead pack. Most Ni-MH BMS circuits recover with a slow trickle charge at 0.1C, which gradually pulls cell voltage back above the wake-up threshold. Once voltage reaches approximately 5.4V across the pack, the BMS exits lockout and normal charging resumes.
Readings drifting or resetting mid-session during active sensor logging
Sustained sensor load draws continuous current from the pack, and Ni-MH cells exhibit voltage sag under prolonged discharge — voltage drops gradually even when capacity remains. If sag pulls the supply rail below the CD-100M's measurement module threshold, the instrument resets or logs erratic readings without displaying a low-battery warning. A worn or partially degraded original pack shows this symptom first because its internal resistance is higher, amplifying the sag. Replacing the pack eliminates the high-resistance source; verify cell voltage at load is holding above 5.0V to confirm the fix.