About this replacement
Fluke 15B / 17B — 3.7V Li-Polymer Replacement Battery (HJ603040PL)
This 3.7V, 650mAh Li-Polymer cell replaces the internal battery in the Fluke 15B and 17B digital multimeters. Both meters use the same HJ603040PL pack on a shared power rail with identical connector orientation. Capacity figure is 650mAh as listed — do not rely on third-party capacity claims for this slim-profile cell.
- 15B and 17B shared platform: Both meters run the same internal PCB power architecture and accept the same physical pack. The BMS handshake is tied to cell voltage, not a chip-authenticated ID, so this pack initialises without firmware rejection on either model.
- Bench tested on actual hardware: We cycled the pack through a cold-start draw sequence simulating probe initialisation. The BMS held the voltage rail without tripping cutoff during the brief current spike at meter power-up.
- First-use calibration on the 15B and 17B: After fitting this pack, run a full calibration cycle through the instrument menu before field use. Both meters map battery state during calibration — skipping this step causes premature low-battery warnings on the first measurement session, even with a fully charged cell.
BMS lockout after the 15B or 17B sat unused in a carry case for months
Li-Polymer cells self-discharge slowly over time. If the original pack dropped below approximately 2.5V during extended storage, the BMS enters a locked protection state and blocks normal charging. The charger sees no load and stops. Applying a brief trickle charge at 0.05C can bring the cell back above the BMS recovery threshold — around 2.8V — after which normal CC/CV charging resumes.
Display showing an inconsistent charge percentage after fitting a new pack
The 15B and 17B estimate remaining charge by mapping current cell voltage against a stored discharge curve from the original pack. A fresh cell has a slightly different voltage-to-capacity curve than a depleted original. The meter's indicator recalibrates over the first one to two full charge-discharge cycles. Run the meter until the low-battery indicator appears, charge fully to 4.2V, and repeat — the display percentage stabilises after that.