ERGO SubBrick Lite X75 Replacement Battery 10.8V DR35

ERGO SubBrick Lite X75 — 10.8V Ni-MH Replacement Battery (DR35)

This is a 10.8V, 4000mAh (43.2Wh) Ni-MH replacement battery for the ERGO SubBrick Lite X75 notebook. It fits units carrying OEM part numbers DR35 and DR35S. Use it to restore portable computing to a SubBrick Lite X75 whose original cell no longer holds a usable charge.

• SubBrick Lite X75 fitment: The DR35 and DR35S share the same physical connector, cell count, and 10.8V nominal rail as the original ERGO pack. The BMS handshake on the X75 expects this voltage and cell configuration — swapping to a different voltage class will trip a protection fault on boot.
• Bench tested on actual hardware: We cycled this cell through charge, full-load discharge, and BMS re-initialisation on the SubBrick Lite X75 platform. The protection circuit responded correctly at both low-voltage cutoff and overcharge thresholds, and the fuel gauge IC accepted the new cell without flagging a fault state.
• Post-install conditioning on Ni-MH: After fitting, run the laptop unplugged until it hibernates at battery-cutoff, then charge uninterrupted to 100%. Ni-MH cells are more susceptible to memory effect than lithium chemistries, and this discharge-to-cutoff cycle lets the BIOS battery learn routine recalibrate against the new cell's actual capacity floor.

BIOS reporting battery health as poor after installing the DR35

The SubBrick Lite X75 BIOS reads health data from the battery's EEPROM, which stores charge-cycle history and degradation flags written by the previous cell. A fresh DR35 physically holds full capacity, but the BIOS will still display a poor health warning until it overwrites that EEPROM data. Run one complete discharge-to-hibernate cycle followed by a full uninterrupted charge. After two to three such cycles the BIOS learn routine resets the health flag against the new cell's actual voltage curve.

SubBrick Lite X75 shutting down at 20–30% charge shown on screen

This happens because the OS fuel gauge is still calibrated to the worn cell's voltage curve, not the new DR35's. When the new cell hits its actual voltage cliff under combined CPU and display load, the system cuts out even though the gauge still reads partial charge. The fuel gauge IC needs two or three full discharge-to-cutoff cycles to map its readings to the new cell's chemistry. After those cycles are complete, the displayed percentage and the true remaining capacity will track together correctly.