Kinryo KC3411A 4.8V Replacement Battery 2000mAh Ni-MH

Kinryo KC3411A / KC3412A Series — 4.8V Ni-MH 2000mAh Replacement Battery (KC0402A)

This is a 4.8V, 2000mAh Ni-MH replacement battery for the Kinryo KC3411A, KC3411B, KC3412A, KC3412B, and over 24 additional compatible models in this instrument series. It replaces OEM part numbers KC0402A and 5441-1445. The pack restores power to surveying and field measurement instruments that have degraded or failed batteries.

• KC3411 and KC3412 series compatibility: These models share the same 4.8V four-cell Ni-MH architecture, connector pinout, and BMS handshake protocol — the same pack runs across all variants without modification.
• Bench tested on actual hardware: We cycled this pack through probe initialisation loads and sustained sensor draw. The BMS held stable across both events with no spurious cutoff or voltage dropout at the measurement circuit.
• Post-install calibration cycle: After fitting this pack, run a full calibration cycle through the instrument menu before heading into the field. The instrument maps battery state during calibration — skipping it causes premature low-battery warnings during your first measurement session, even with a fully charged pack.

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

Ni-MH cells self-discharge over storage. If the KC3411A or KC3412A sat unused long enough, the pack voltage can drop below the BMS recovery threshold — typically around 4.0V for a 4.8V four-cell pack. When this happens, the charger may show no activity and the instrument may not power on at all. Reactivation usually requires a controlled trickle charge at low current (around 50–100mA) until the pack climbs back above the BMS re-initialisation threshold before a normal charge cycle can resume.

Readings resetting or dropping out during a live logging session

This is not a firmware issue — it is a voltage dropout under sustained sensor load. During a logging session, the instrument draws continuous current across the measurement circuit, and a degraded or partially charged cell in the pack can sag below the instrument's minimum operating voltage. The processor resets to protect data integrity, which looks like a random restart. Charge the pack fully, then verify cell balance — if the dropout persists at the same point in a session, one cell in the pack has diverged and the pack needs replacement.