HB5D1H Cricket Pillar Replacement Battery 3.7V 800mAh

Cricket Pillar / M615 — 3.7V Li-ion Replacement Battery (HB5D1H)

This is a 3.7V, 800mAh Li-ion cell that fits the Cricket Pillar and M615 smartphones. It replaces the original HB5D1H battery when the existing cell has degraded or failed. Physical dimensions are 42.50 × 35.50 × 5.00mm — confirm these against your existing cell before installing.

• Pillar and M615 compatibility: Both models share the same battery bay dimensions, connector pinout, and BMS handshake protocol, which is why a single cell covers both. The charge IC communicates over the same NTC thermistor line on each device.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the M615 platform. The BMS accepted charge current without fault flags, and the thermistor line reported temperature accurately across the full cycle.
• Fuel gauge recalibration tip: On first use after installation, run one complete discharge-charge cycle with fast charging disabled. This gives the fuel gauge IC time to map the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell.

Sudden shutdown at 20–30% on the Cricket Pillar after a cell swap

The fuel gauge IC in the Pillar uses a stored discharge curve from the old cell to predict remaining charge. A new cell with a different internal impedance hits a voltage cliff at a higher state of charge than the IC expects. When modem activity or screen load pulls current, the cell voltage drops below the shutdown threshold before the gauge reaches 0%. One full discharge-charge cycle — taken to 3.0V under load and charged back to 4.2V — forces the coulomb counter to resync to the new cell's actual curve.

OS percentage jumping erratically after battery replacement

Erratic percentage readings on the M615 or Pillar after a swap are almost always the coulomb counter recalibrating. The IC is still referencing charge-state data from the previous cell's history. It corrects itself after one or two full discharge-charge cycles. If the jumping persists past three cycles, check that the connector is fully seated — a loose pin on the NTC line causes the IC to misread cell temperature and distort the state-of-charge estimate.