Defelsko PosiTest HHD Replacement Battery 10.8V 5200mAh

Defelsko PosiTest HHD — 10.8V Li-ion Replacement Battery (HDDBATTERY)

This 10.8V, 5200mAh lithium-ion battery replaces the original pack in the Defelsko PosiTest HHD portable hardness tester. It fits the handheld gauge used for Leeb and UCI hardness measurement across field and workshop inspection. Voltage and capacity match OEM spec — the BMS communicates the same state-of-charge data the instrument expects.

• PosiTest HHD platform fit: The HHD uses a fixed 10.8V three-cell series architecture that feeds both the probe drive circuit and the display. This pack matches that rail exactly, including the connector orientation and BMS communication protocol, so the instrument recognises it without firmware complaints.
• Bench tested on actual hardware: We cycled this pack through probe initialisation sequences, which generate a brief current spike as the impact device charges. The BMS handled the inrush without tripping into protection mode, and cell voltage recovered cleanly between strikes.
• First-use calibration on the PosiTest HHD: After installing a new pack, run a full calibration cycle through the instrument menu before field deployment. The HHD maps battery state during calibration — skipping this step causes premature low-battery warnings to appear during your first measurement session even when charge is adequate.

BMS lockout after the PosiTest HHD sits unused in a carry case for months

Li-ion cells self-discharge during storage. If the HHD sits unused long enough, cell voltage can drop below the BMS recovery threshold — typically around 2.5V per cell. At that point the protection circuit latches off and the pack will not respond to the charger or the instrument. The fix is to apply a trickle charge at low current using a compatible Li-ion charger that supports a pre-charge or recovery mode until voltage climbs above 9V, then switch to a normal charge cycle. Once voltage recovers above that threshold, the BMS releases and the pack charges normally.

PosiTest HHD display shows inconsistent battery percentage at every reboot

The HHD estimates charge state using voltage thresholds rather than a dedicated charge-tracking circuit. A new cell has a slightly different discharge curve than the worn pack it replaced, so the instrument's internal map does not match the actual state of the new cells yet. The percentage reading stabilises after two or three full charge-and-discharge cycles, which allow the instrument to learn where the new pack's voltage sits at each charge level. Run the gauge until it triggers a low-battery warning, then charge fully to 10.8V — repeat twice and the readout will track correctly.