Hi,
You can add your own battery. Please look at the code here:
specifically
static struct bq27426_platform_data mangoh_yellow_battery_gauge_platform_data = {
.energy_full_design_uwh = 4800000,
.charge_full_design_uah = 1200000,
.voltage_min_design_uv = 3300000,
};
modify the code to meet your battery requirements., rebuild and deploy on your unit.