Getting the battery current values for the Android Phone

Question

I am trying to collect power usage statistics for the Android G1 Phone. I am interested in knowing the values of Voltage and Current, and then able to collect statistics as reported in this PDF.

I am able to get the value of Battery voltage through registering for an intent receiver to receive the Broadcast for ACTION_BATTERY_CHANGED. But the problem is that Android does not expose the value of current through this SDK interface.

One way I tried is via sysfs interface, where I can view the battery current value from adb shell, using the following command

$cat /sys/class/power_supply/battery/batt_current
449 

But that too works only if the phone is connected via USB interface. If I disconnect the phone, I see the value of batt_current as '0'. I am not sure why the value of current reported is zero. It should be more than zero, right?

Any suggestion / pointers for getting battery current value? Also please correct me if I am wrong.

Answer 1

You could just look at the source code for the Current Widget. It has hard coded path's to where certain platforms store the current values.

/*
 *  Copyright (c) 2010-2011 Ran Manor
 *  
 *  This file is part of CurrentWidget.
 *    
 *  CurrentWidget is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  CurrentWidget is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with CurrentWidget.  If not, see <http://www.gnu.org/licenses/>.
*/

package com.manor.currentwidget.library;

import java.io.File;

import android.os.Build;
import android.util.Log;

public class CurrentReaderFactory {

    static public Long getValue() {

        File f = null;      

        // htc desire hd / desire z / inspire?
        if (Build.MODEL.toLowerCase().contains("desire hd") ||
                Build.MODEL.toLowerCase().contains("desire z") ||
                Build.MODEL.toLowerCase().contains("inspire")) {

            f = new File("/sys/class/power_supply/battery/batt_current");
            if (f.exists()) {
                return OneLineReader.getValue(f, false);
            }
        }

        // nexus one cyangoenmod
        f = new File("/sys/devices/platform/ds2784-battery/getcurrent");
        if (f.exists()) {
            return OneLineReader.getValue(f, true);
        }

        // sony ericsson xperia x1
        f = new File("/sys/devices/platform/i2c-adapter/i2c-0/0-0036/power_supply/ds2746-battery/current_now");
        if (f.exists()) {
            return OneLineReader.getValue(f, false);
        }

        // xdandroid
        /*if (Build.MODEL.equalsIgnoreCase("MSM")) {*/
            f = new File("/sys/devices/platform/i2c-adapter/i2c-0/0-0036/power_supply/battery/current_now");
            if (f.exists()) {
                return OneLineReader.getValue(f, false);
            }
        /*}*/

        // droid eris
        f = new File("/sys/class/power_supply/battery/smem_text");      
        if (f.exists()) {
            Long value = SMemTextReader.getValue();
            if (value != null)
                return value;
        }

        // htc sensation / evo 3d
        f = new File("/sys/class/power_supply/battery/batt_attr_text");
        if (f.exists())
        {
            Long value = BattAttrTextReader.getValue();
            if (value != null)
                return value;
        }

        // some htc devices
        f = new File("/sys/class/power_supply/battery/batt_current");
        if (f.exists())
            return OneLineReader.getValue(f, false);

        // nexus one
        f = new File("/sys/class/power_supply/battery/current_now");
        if (f.exists())
            return OneLineReader.getValue(f, true);

        // samsung galaxy vibrant       
        f = new File("/sys/class/power_supply/battery/batt_chg_current");
        if (f.exists())
            return OneLineReader.getValue(f, false);

        // sony ericsson x10
        f = new File("/sys/class/power_supply/battery/charger_current");
        if (f.exists())
            return OneLineReader.getValue(f, false);

        // Nook Color
        f = new File("/sys/class/power_supply/max17042-0/current_now");
        if (f.exists())
            return OneLineReader.getValue(f, false);

        return null;
    }
}