[StarLite Mk V] Battery doesn't charge to 100%

[rbm78bln]

Hi all!

The issue is easily summarized: The battery doesn't charge to 100%, eventhough it's selected in the BIOS settings. This behaviour is independent from the selected charging speed, max charge level is honoured, just doesn't ever reach a hundred percent, even if selected. Max. charge varies (even while constantly plugged in) between 94 and 97 percent. Please find a few screenshots attached.

The device is brand-new, so this shouldn't be a hardware issue.

Please help.

PS: Coreboot is 24.06, Distro is Arch, Kernel is 6.9.7-arch1-1

[Sean-StarLabs]

There's nothing wrong there; it's just the overcharge protection.

If you're interested:

static uint16_t calculate_charging_current(int16_t temperature)
{
    uint8_t charge_level;
    uint8_t stop_charging   = false;

    switch (emem_max_charge) {
    case 0xaa:  // 60%
        charge_level = 60;
        break;
    case 0xbb:  // 80%
        charge_level = 80;
        break;
    default:    // 100%
        charge_level = 100;
        break;
    }

    /*
     * We stop charging if any of the below conditions are met:
     *  Any alarm bits are set
     *  The battery reports that it's fully charged
     *  The battery has charged to target level
     */

    /* Alarm bit(s) set */
    if (CONFIG(BATTERY) && check_battery_alarm())
        stop_charging = true;

    /* Fully charged */
    if (CONFIG(BATTERY) && battery_is_fully_charged())
        eram_battery_overcharge_protection = 1;

    /* Charged to target level */
    if ((charge_level < 100) && (eram_battery_relative_state_of_charge >= charge_level))
        eram_battery_overcharge_protection = 1;

    /* Overcharge protection active */
    if (eram_battery_overcharge_protection) {
        /* Check if the battery has drained 5% */
        if (eram_battery_relative_state_of_charge < (charge_level - 5))
            eram_battery_overcharge_protection = 0;
        else
            stop_charging = true;
    }

    if (temperature >= 450)     /* 0.0C */
        stop_charging = true;

    /* If there isn't a battery online, trickle charge */
    if (!eram_battery_status)
        return 256;

    if (stop_charging)
        return 0;

    if (temperature < 150 || emem_charging_speed == 2)  /* Below 15.0°C or charging speed 0.2C */
        return eram_battery_design_capacity / 5;    /* 0.2C */

    if (eram_battery_voltage >= (CONFIG_LIMITED_CHARGING_VOLTAGE / 100 * 95) ||
        emem_charging_speed == 1)               /* Voltage >= 95% of limited charging voltage or charging speed 0.5C */
        return eram_battery_design_capacity / 2;    /* 0.5C */

    return eram_battery_design_capacity;            /* 1.0C */
}

[rbm78bln]

Thank you, great to know!