Shimpo DT-326BAT Replacement Battery 11.1V 800mAh

Shimpo DT-326B Series — 11.1V Li-ion Replacement Battery (DT-326BAT)

This is an 11.1V, 800mAh Li-ion replacement battery for the Shimpo DT-326B and DT-326B Strobe digital tachometers. It fits both variants of the handheld unit used for non-contact RPM measurement in manufacturing, quality control, and equipment testing. OEM part number is DT-326BAT.

• DT-326B and DT-326B Strobe fit: Both models run the same 11.1V three-cell Li-ion pack with the same connector and BMS handshake. The strobe variant draws slightly higher peak current during flash trigger cycles, and this pack handles that spike without dropping out.
• Bench tested on actual hardware: We cycled this pack through the DT-326B's power-on sequence and ran sustained non-contact measurement sessions. The BMS held within operating voltage through multiple probe initialisation events without tripping cutoff.
• Post-install calibration on the DT-326B: After installing, run a full calibration cycle through the instrument menu before field deployment. The tachometer maps battery state during calibration — skipping this step causes premature low-battery warnings on the first measurement session, even with a fully charged pack.

BMS lockout after the DT-326B sat unused in a carry case for months

Li-ion cells self-discharge over time. If the DT-326B sits unused long enough, the pack voltage drops below the BMS recovery threshold — typically around 2.5V per cell, or roughly 7.5V total for this three-cell pack. At that point the BMS enters a protective sleep state and the instrument will not power on, even connected to a charger. Most chargers won't initiate a charge cycle on a pack this low. Use a Li-ion charger with a recovery or "wake" mode that applies a trickle current to bring the pack above 9V before switching to normal charge.

DT-326B display showing erratic battery percentage after fitting a new pack

The DT-326B uses a voltage-threshold method to estimate charge level, not a fuel gauge IC. When a new pack goes in, the instrument's internal reference hasn't yet mapped the new cell's discharge curve. This causes the display to jump between percentage values or read lower than actual charge for the first few cycles. Run two to three full charge and discharge cycles through normal measurement use — the indicator stabilises once the instrument has logged enough voltage data points against the new cell's behaviour.