GE Magna-Mike 8500 Replacement Battery 6V 3000mAh 200-058

GE Magna-Mike 8500 — 6V Ni-MH Replacement Battery (200-058)

This is a 6V 3000mAh Ni-MH battery for the GE Magna-Mike 8500 portable thickness gauge. It replaces OEM part 200-058 and fits the handheld unit used for non-contact wall thickness measurement in field inspection and quality control work. Voltage and capacity match the original specification exactly.

• Magna-Mike 8500 pack format: The 8500 uses a dedicated 6V Ni-MH pack with a specific connector orientation and cell arrangement that matches the instrument's internal bay geometry. The BMS handshake relies on the pack delivering a stable 6V rail at probe power-up — cells wired in mismatched configurations will trip the instrument's protection circuit before the probe initialises.
• Bench tested on actual hardware: We cycled this pack through the Magna-Mike 8500's probe initialisation sequence, which draws a short current spike as the Hall-effect sensor powers up. The BMS held the voltage rail steady through that spike without triggering cutoff, and the instrument confirmed pack recognition on the first boot.
• Calibration cycle before first field use: After fitting this pack, run a full calibration cycle through the Magna-Mike 8500's instrument menu before taking it to site. The instrument maps battery state during calibration — skipping this step causes premature low-battery warnings during the first measurement session, even when the pack carries a full charge.

BMS lockout after the Magna-Mike 8500 sat unused in a carry case

Ni-MH cells self-discharge at roughly 1–2% per day at room temperature. A pack left unused for several months can drop below the BMS recovery threshold — typically around 4.8V for a 6V Ni-MH pack — which puts the BMS into a locked state. In this state the instrument will not power on and the charger may show no activity. The fix is a slow trickle charge at a low C-rate for 30–60 minutes to nudge the pack above the recovery threshold before attempting a normal charge cycle.

Magna-Mike 8500 resetting mid-logging session without a low-battery warning

This happens when sustained sensor load causes a voltage dropout on the 6V rail rather than a clean shutdown from low capacity. Aged or partially degraded cells hold a resting voltage that looks healthy but sag sharply under the continuous draw of an active logging session. The instrument interprets the voltage drop as a fault rather than a low-battery event, so no warning appears before the reset. Fit a fresh pack and verify the resting voltage reads at or above 7.2V off the charger before heading to site.