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;     } } 

Answer 2

API 21 onwards we can get the instantaneous battery current in microamperes, as an integer. Developer docs

BatteryManager mBatteryManager = (BatteryManager) getSystemService(Context.BATTERY_SERVICE);     Long avgCurrent = null, currentNow = null;     if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.LOLLIPOP) {         avgCurrent = mBatteryManager.getLongProperty(BatteryManager.BATTERY_PROPERTY_CURRENT_AVERAGE);         currentNow = mBatteryManager.getLongProperty(BatteryManager.BATTERY_PROPERTY_CURRENT_NOW);     }     Log.d(TAG, "BATTERY_PROPERTY_CURRENT_AVERAGE = " + avgCurrent + "mAh");     Log.d(TAG, "BATTERY_PROPERTY_CURRENT_NOW =  " + currentNow + "mAh"); 

Using mBatteryManager you can get the instantaneous current reading.

Measuring Device Power and reading power consumption and the available properties on NEXUS devices. Android open source docs