Tripod Data Systems: Using the Power Log

Using the Power Log

Summary

Recon's operating system includes a built-in utility which can be used to determine whether the battery is performing correctly. This article explains how to enable power logging on Recon and how to use a power log to evaluate a battery's performance.

More Information

A common concern with any handheld device is battery performance. Recon's operating system includes a built-in utility (awcbatlog.exe) which can be used to evaluate a battery's performance. This utility checks the battery voltage at one minute intervals and records the results in a log file as \System\pwrlog.txt.

To create a power log on Recon, choose Start> Programs> Utilities> Battery Log. This will open a window on Recon notifying you that power logging has been enabled:

Power logging will continue until this program is closed. If you want to continue working with Recon while power logging is running, you can minimize the logger program by clicking on the desktop icon in the lower right corner. Note that logging pauses when Recon is powered off or allowed to go to sleep. If you want a continuous power log so that you can measure battery life, you will need to configure Recon to never go to sleep (Start> Settings> Control Panel> Power> Schemes and select "Never" under "Switch state to suspend" for the Power Scheme "Battery Power").

Once power logging is complete (for instance, the batteries have been allowed to completely run down), transfer pwrlog.txt to the PC and open it in a text editor such as Word or Wordpad. A Recon power log looks like:

# This log file contains power log information.
#
# System Specs:
#
# Serial #: FS16A07230
# Board #: FR2A533136788
# OS Version #: 4.1.8.0
# Processor Type: Intel(R) PXA250 (B2)
# Processor Speed: 200 MHz
# Ram Size: 64 MB
#
# Each line contains one entry in the following format:
Time , OnAC , Volts , BatPercent , ADCcount, LightOn, DC Brightness, AC Brightness, Current Brightness
2004/04/20 11:20:56, 1, 2604, 100, 26097, 1, 20, 31, 31
2004/04/20 11:21:56, 1, 2612, 100, 26172, 1, 20, 31, 31
2004/04/20 11:22:56, 1, 2611, 100, 26171, 1, 20, 31, 31
2004/04/20 11:23:56, 1, 2617, 100, 26223, 1, 20, 31, 31
2004/04/20 11:24:56, 0, 2483, 50, 24937, 1, 20, 31, 20
2004/04/20 11:25:56, 0, 2478, 50, 24893, 1, 20, 31, 20
2004/04/20 11:26:56, 0, 2504, 50, 25140, 0, 20, 31, 0
2004/04/20 11:27:56, 0, 2502, 50, 25123, 0, 20, 31, 0

Each line in the power log contains 9 fields separated by commas. These fields include the time and date, external power status, display light status, battery voltage (millivolts), estimated battery charge percentage, and other system parameters. In the above example, external power was removed after 4 minutes and the display light timed out 2 minutes later.

If your Recon is running firmware version 4.1.6 or older, the format of the power log is simpler:

# This log file contains power log information.
# Each line contains one entry in the following format:
Time , OnAC , Volts , %Battery , ADCcount
2003/12/11 14:53:19, 1, 2819, 100, 28160
2003/12/11 14:54:19, 1, 2820, 100, 28172
2003/12/11 14:55:19, 1, 2820, 100, 28173
2003/12/11 14:56:19, 1, 2822, 100, 28188
2003/12/11 14:57:19, 1, 2822, 100, 28193
2003/12/11 14:58:19, 0, 2748, 100, 27477
2003/12/11 14:59:19, 0, 2738, 100, 27382
2003/12/11 15:00:19, 0, 2734, 100, 27348
2003/12/11 15:01:19, 0, 2731, 100, 27318
2003/12/11 15:02:19, 0, 2729, 100, 27295
2003/12/11 15:03:19, 0, 2725, 100, 27261
2003/12/11 15:04:19, 0, 2723, 100, 27243
2003/12/11 15:05:19, 0, 2722, 100, 27230
2003/12/11 15:06:19, 0, 2720, 100, 27215
2003/12/11 15:07:19, 0, 2718, 100, 27195

Each line in the power log contains 5 fields separated by commas. The first field is the time and date; the second field indicates whether Recon was on external power; and the third field reports the battery voltage (millivolts). In the above excerpt, external power was removed 5 minutes after power logging was started. Over the next several minutes, the battery voltage dropped from 2.748v to 2.718v.

If you have concerns about the performance of your Recon battery, follow these steps to obtain a complete power log:

Connect Recon to AC power, turn Recon off, and allow it to charge for at least 12 hours.
Configure Recon to never go to sleep. Choose Start> Settings> Control Panel> Power> Schemes, and select "Never" under "Switch state to suspend" for the Power Scheme "Battery Power".
Configure Recon to not use the display light while running on battery power. Choose Start> Settings> Control Panel> Display> Display Light, and move the "Brightness on battery" slider all the way towards the left.
Disable or remove any power-consuming CompactFlash cards (such as Bluetooth, 802.11, or GPS cards). CompactFlash memory cards do not consume significant power and do not need to be removed.
Remove AC power, and choose Start> Programs> Utilities> Battery Log.
Set Recon aside until the batteries die.
Reapply AC power, connect Recon to the PC via ActiveSync and copy \System\pwrlog.txt to the PC.

If you open pwrlog.txt in a text editor such as Word or Wordpad, you can determine how many hours elapsed between starting power logging and battery death. With properly charged newer batteries at room temperature, no backlight activity, no power-consuming CompactFlash cards, and no software running other than the power logging utility, you can expect your batteries to last at least 30 hours.