Hioki Z1000 LR8400 Replacement Battery 7.2V 3600mAh

Hioki LR8400 / MR8880-20 — 7.2V Ni-MH Replacement Battery (Z1000)

This is a 7.2V, 3600mAh Ni-MH replacement battery for the Hioki LR8400 data logger and MR8880-20 memory HiCorder. Both instruments run on the Z1000 pack, which powers the measurement circuitry, sensor inputs, and onboard storage during field deployment. Capacity is 25.92Wh.

• LR8400 and MR8880-20 compatibility: Both units draw from the same 7.2V rail and use an identical connector and BMS handshake, so one Z1000 pack covers either instrument without modification.
• Bench tested on actual hardware: We cycled the pack through full charge and discharge on the LR8400 platform and confirmed the BMS reported state-of-charge correctly across the load profile produced by active sensor channels logging at standard intervals.
• Post-install calibration before field use: After fitting this pack, run a full calibration cycle through the LR8400 instrument menu before deploying it on-site. The instrument maps battery state during that process, and skipping it causes premature low-battery warnings during the first real logging session — even when the pack is fully charged.

BMS lockout after the LR8400 sat unused in a carry case for months

Ni-MH cells self-discharge at roughly 1–2% per day at room temperature. A pack stored for three to six months inside a closed case can drop below the BMS recovery threshold — typically around 5.0V for a 7.2V six-cell pack. When voltage falls that low, the protection circuit locks out charge input to prevent cell reversal. The instrument will not power on, and the charger shows no activity. Leaving the pack on charge for 30–60 minutes at the charger's trickle rate usually recovers enough cell voltage to let the BMS release the lockout and resume normal charging.

LR8400 shuts down mid-logging session with no low-battery warning

This happens when sustained sensor load pulls pack voltage below the instrument's cutoff threshold faster than the state-of-charge indicator updates. The display may still show two or three bars before the shutdown occurs. It is more common with aged cells where internal resistance has risen — voltage sags sharply under load even though resting voltage looks acceptable. Check resting voltage with a multimeter after charging: a healthy Z1000 pack should read 8.4–8.6V at full charge with no load applied.