E-SEEK M310 Replacement Battery 7.4V 1800mAh BP-7V4-1A8

E-SEEK M310 / M310S — 7.4V Li-Polymer Replacement Battery (BP-7V4-1A8)

This is a 7.4V, 1800mAh Li-Polymer battery for the E-SEEK M310 and M310S portable field instruments. It replaces OEM part BP-7V4-1A8 directly. The slim 76.52 × 56.00 × 14.76 mm cell fits inside the M310's battery bay and powers the unit through survey and data-collection sessions.

• M310 and M310S compatibility: Both models run the same 7.4V power rail and use identical battery bay dimensions and connector pinout. The BMS handshake protocol is shared across the two variants, so a single replacement cell covers either unit without modification.
• Bench tested on actual hardware: We ran the BP-7V4-1A8 replacement through charge, discharge, and probe-initialisation cycles on the M310 platform. The BMS held within spec during sensor power-up current spikes and did not trigger a false low-voltage cutoff under sustained logging load.
• First-use calibration on the M310: After fitting this battery, run a full calibration cycle through the instrument menu before field deployment. The M310 maps battery state during that calibration pass. Skip it, and the fuel gauge starts from stale reference data — causing premature low-battery warnings before the cell is genuinely depleted.

M310 BMS lockout after the instrument sat unused in a carry case for months

Li-Polymer cells self-discharge slowly in storage. If the M310 sits packed away long enough, the cell voltage can drop below the BMS recovery threshold — typically around 2.5V per cell, or 5.0V across the 2S pack. At that point the BMS enters a protective sleep state and blocks both charging and power-on attempts. Connect the unit to its OEM charger and leave it for at least 30 minutes before pressing the power button — most BMS circuits on this chemistry require a trickle pre-charge pulse to exit sleep mode. If the charge LED does not respond after an hour, the cell has dropped below the hard cutoff and will not recover.

M310 shuts off the moment USB data transfer to PC begins

USB data transfer activates the M310's serial interface, which draws additional current on top of the display and active sensor load. An ageing or partially discharged cell can hold a resting voltage that looks acceptable on the status screen, but sags below the BMS cutoff threshold the instant combined draw spikes. The instrument interprets this as a critical voltage event and shuts down to protect the cell. Charge the battery to full before any transfer session and check that the USB cable is not also attempting to draw charging current in reverse — some PC ports and hubs create a conflicting charge/discharge condition through the data port.