[Feature] get battery_level in %

[n3roGit]

Could you please implement to get battery_level in % from serial?

[sussyboiiii]

You can get a battery percentage estimate using this code:

voltage = (VESC.data.inpVoltage);
batterypercentage = ((voltage-38.4)/12)*100;    // ((Battery voltage - minimum voltage) / number of cells) x 100

[n3roGit]

Is this the same calculation as the vesc software? At the moment I use a battery drain curve and interpolate the percentage

[sussyboiiii]

I don't know but this isn't the most accurate because it assumes the discharge is linear but for me it works fine.

[sussyboiiii]

Is this the same calculation as the vesc software? At the moment I use a battery drain curve and interpolate the percentage

May I ask how you use a battery drain curve on an arduino?

[n3roGit]

https://github.com/n3roGit/DPVControl/tree/mytest/DPVController

Look into the battery function in the mytest branch :)

[sussyboiiii]

Thanks, I tested it and it seems to be pretty similar to the one I am using but probably a bit more accurate. Heres a graph of both:

[n3roGit]

Oh great thanks for the feedback!

I hope someone implement to get it directly from the vest because the vesc has some filter and extra logic to get besser results

[sussyboiiii]

Yes, but the battery percentage the vesc shows me is also weird, my battery is at 3.7v per cell and 7 out of 16Ah drained and the vesc says its at 35% or below 30 with sag.

[n3roGit]

That doesn't sound optimal either. Unfortunately, I don't have any comparison values here yet. My project is still relatively at the beginning. May I ask what you have implemented with VESCUart?

[sussyboiiii]

Its a bit weird but heres the vesc function:

/**
 * Get the battery level, based on battery settings in configuration. Notice that
 * this function is based on remaining watt hours, and not amp hours.
 *
 * @param wh_left
 * Pointer to where to store the remaining watt hours, can be null.
 *
 * @return
 * Battery level, range 0 to 1
 */
float mc_interface_get_battery_level(float *wh_left) {
    const volatile mc_configuration *conf = mc_interface_get_configuration();
    const float v_in = motor_now()->m_input_voltage_filtered_slower;
    float battery_avg_voltage = 0.0;
    float battery_avg_voltage_left = 0.0;
    float ah_left = 0;
    float ah_tot = conf->si_battery_ah;

    switch (conf->si_battery_type) {
    case BATTERY_TYPE_LIION_3_0__4_2:
        battery_avg_voltage = ((3.2 + 4.2) / 2.0) * (float)(conf->si_battery_cells);
        battery_avg_voltage_left = ((3.2 * (float)(conf->si_battery_cells) + v_in) / 2.0);
        float batt_left = utils_map(v_in / (float)(conf->si_battery_cells),
                                    3.2, 4.2, 0.0, 1.0);
        batt_left = utils_batt_liion_norm_v_to_capacity(batt_left);
        ah_tot *= 0.85; // 0.85 because the battery is not fully depleted at 3.2V / cell
        ah_left = batt_left * ah_tot;
        break;

    case BATTERY_TYPE_LIIRON_2_6__3_6:
        battery_avg_voltage = ((2.8 + 3.6) / 2.0) * (float)(conf->si_battery_cells);
        battery_avg_voltage_left = ((2.8 * (float)(conf->si_battery_cells) + v_in) / 2.0);
        ah_left = utils_map(v_in / (float)(conf->si_battery_cells),
                2.6, 3.6, 0.0, conf->si_battery_ah);
        break;

    case BATTERY_TYPE_LEAD_ACID:
        // TODO: This does not really work for lead-acid batteries
        battery_avg_voltage = ((2.1 + 2.36) / 2.0) * (float)(conf->si_battery_cells);
        battery_avg_voltage_left = ((2.1 * (float)(conf->si_battery_cells) + v_in) / 2.0);
        ah_left = utils_map(v_in / (float)(conf->si_battery_cells),
                2.1, 2.36, 0.0, conf->si_battery_ah);
        break;

    default:
        break;
    }

    const float wh_batt_tot = ah_tot * battery_avg_voltage;
    const float wh_batt_left = ah_left * battery_avg_voltage_left;

    if (wh_left) {
        *wh_left = wh_batt_left;
    }

    return wh_batt_left / wh_batt_tot;
}

[sussyboiiii]

May I ask what you have implemented with VESCUart?

I'm building an e-bike and want to view speed, power consumption, temperatures etc. without the need for a phone.

[n3roGit]

oh very nice. for me it's a scooter for diving. feel free to look at content in the code if it helps you. but the webinterface and logging into a database will follow. https://github.com/n3roGit/DPVControl/tree/mytest

[sussyboiiii]

Cool project! How fast and far are you planning to go?

[n3roGit]

Yesterday I have already tested the part in the lake. Currently I'm at about 60m/minute, which is already quite fast in the water. Here I will still have to do some software sided tuning. Such devices are also rather long runners. I think I should be able to drive 4-6 hours.

[sussyboiiii]

Cool, keep it up!