XO Troubleshooting Battery

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{{OLPC}}{{Translations}}
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This is the portion of the [[XO Troubleshooting Guide|XO Troubleshooting Guide]] for diagnosing problems with the battery and power on an [[Hardware_specification#Laptop_Hardware|XO laptop]].
 
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=Start Here=
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= Introduction =
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What problem are you experiencing with your laptop ?
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==The laptop won't run using the battery==
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This is the portion of the [[XO Troubleshooting Guide|XO Troubleshooting Guide]] for diagnosing problems with the battery on an [[Hardware_specification#Laptop_Hardware|XO laptop]]. The Help activity and XO manual for release [[Releases|8.2.0+]] also has a "Battery charging" chapter [http://www.laptop.org/8.2.0/manual/XO_ChargingBattery.html].
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If the laptop functions fine using a known good test battery, the battery should be replaced.
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If the laptop doesn't function from a known good test battery, see [[#Diagnosing_Battery_Problems|Diagnosing Battery Problems]].
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This page details <em>only</em> problems that actually reside within the battery. Note that if you are having problems running an XO from battery power, or having problems charging a battery, such problems could be the fault of the laptop (the battery itself may be fine). Problems that are localised to the laptop itself are discussed at [[XO Troubleshooting Power]].
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==The battery light is flashing red==
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How can you tell whether a particular problem is due to a faulty battery or faulty laptop? This is easiest when you have two XOs. Let's say you have laptop A including battery A, which is exhibiting a problem. You also have laptop B with laptop B, which is your personal XO which you trust to be functioning well. Take battery A and place it in laptop B, and take battery B and put it in laptop A. Testing both laptops will then give you a strong indication as to where the problem resides. Does the problem "follow" battery A into laptop B? If so, the problem resides within the battery (you're on the right page). Or does the problem remain within laptop A even when running from battery B? In such case, the problem resides within the laptop (see [[XO Troubleshooting Power]]).
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If the battery light is flashing red, this usually indicates an error with the battery. Try a [[XO_Full_Reset|full reset]]. If the problem persists, then the battery should be replaced.
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If the replacement battery shows the same flashing red battery charge light, see [[#Common Causes for lack of battery presence|common causes for lack of battery presence]], below.
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If you only have one XO available to you, it is suggested that you have a quick read of both this page and [[XO Troubleshooting Power]]. You should be able to make an educated guess as to which page is the most appropriate for your problem. If in doubt, follow the diagnostics outlined on both pages.
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It is possible to obtain more information about the battery, and possibly repair it.  See [[#Battery LED is flashing red|below]].
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= Start here =
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==The laptop can't charge the battery==
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<b>First, take a quick look at the battery, especially the black connector which contains the contacts that electrically connect the battery to the laptop.</b> Dried green crystals have been spotted around the connector on non-functional batteries on some occasions.  This is from decomposition of the contact metal due to electrolysis in water.  This may be cleaned with baking soda mixed with water, using a toothbrush. Wash your hands well afterwards. This may recover the battery, unless the contacts have become badly corroded.
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If the laptop can charge a known good test battery, the battery should be replaced.
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:If the battery is a LiFePO4 battery, with a yellow label, see the [[XO_LiFePO4_Recovery_Procedure|LiFePO4 recovery procedure]].
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If the laptop can't charge the known good test battery, see [[#Diagnosing_Battery_Problems|Diagnosing Battery Problems]].
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<b>Perform an [[XO Full Reset]].</b> If you know the problem is localised within a battery, this is unlikely to make any difference. Nevertheless, lets do it now to be sure.
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==The laptop won't run using the power adapter==
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<b>Disconnect the battery, and connect the laptop to AC power</b>. Now turn on the laptop. After the system has loaded, insert the battery.
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If the laptop runs fine using a known good power adapter, the power adapter should be replaced.
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If the laptop can't run from a known good power source:
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<b>Does the battery LED start flashing red?</b> If so, jump to [[#Battery LED is flashing red]].
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* Does the battery charge LED indicate the laptop thinks it has power ? With a battery inserted, the battery LED should turn yellow or green within a minute of applying power.  In this case, the laptop probably has a [[XO_Troubleshooting_PowerOn|startup problem]], not a power problem.
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* Otherwise, the motherboard needs replacement.
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:Suspect components are the fuse F1 (2A) and diode D21 (3A schottky) on the motherboard protecting the DC input.  If the fuse was blown, check diode D123 (3A schottky) and diode D118 (38V zener) to see if they are OK.
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==The laptop emits a high pitched whine when using the power adapter==
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<b>Does the battery LED start flashing yellow?</b> If so, see [[#Battery LED is flashing yellow]].
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''Working on this one''
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: <em>For more information on the battery LED, see [http://wiki.laptop.org/go/Power_management#Battery_LED].</em>
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=Diagnosing Battery Problems=
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<b>Is there no apparent response in the battery LED?</b> See [[#Battery detection diagnostics]]
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Charging of the battery, and interpretation of the front panel buttons, is under the control of a separate microprocessor in the laptop, the Embedded Controller (EC).  In order to ensure that battery communications are being properly handled, we must first establish that the EC is operating correctly:
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==Did the EC boot?==
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Now fully charge the battery, and wait for the battery LED to go green. Now disconnect AC power and discharge the battery while the system is running, keeping an eye on the percentage charge.
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Follow the [[XO_Full_Reset|Full Reset procedure]], and check to see if the battery LED flashes orange momentarily after reapplying power.
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If it didn't flash at all, you probably have a broken motherboard.
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<b>Does the system shut down abruptly with over 10% of charge remaining?</b> If so, see [[#Laptop shuts down abruptly with significant charge remaining]].
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If it flashed another color (red or green), then you probably have a problem with the LED driver circuitry.
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==Does the EC recognize the battery?==
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Now, starting with the battery completely discharged, perform a [[#Capacity test]] of the battery.
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When a battery is inserted into the laptop, the EC reads information about that battery from a integrated circuit inside the battery.  If the EC does not receive valid information from this read, it will either assume that a battery does not exist, or report an error.  The following tests tell if the EC is talking the battery correctly.
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===Does the battery light respond to changes in external power?===
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<b>Is the battery capacity significantly lower than that of the rated specification?</b> If so, see [[#Battery capacity is significantly degraded]].
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When you apply external power, the battery led should light up in one of four states:
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* solid '''green''' - indicates a fully charged battery
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* solid '''yellow''' - indicates a battery being charged
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* solid '''red''' - indicates a battery in dire need of charging
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* '''flashing red''' - indicates a battery error.  See [[#The battery light is flashing red|above]] and a detailed explanation [[#Battery LED is flashing red|below]].
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If the battery light does not indicate one of these states (e.g. nothing lights up) then the battery is not being recognized.  If you get a solid battery light then the EC has successfully read the battery gauge.
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= Battery LED is flashing red =
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If the battery light stays unlit then either the battery is not recognized or the data read has confused the EC.  Use one of the following methods to manually check for battery presence to determine the problem.
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===Checking for battery presence===
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Lets start with the case that has the most solid diagnosis available: you have the laptop running with the battery inserted, and the laptop is also connected to AC power.  The laptop seems to run fine with AC power connected, but the battery LED is flashing red (to be clear: the battery LED briefly is illuminated briefly as red, and then turns off, and this cycle repeats), and the laptop may not be able to be run from battery power alone.
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The following methods may be used to manually check for battery presence.
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====Using Linux====
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This flashing-red pattern means that the Embedded Controller (EC) has detected a problem with the battery. To understand this further, we can ask the EC for the error code. From the [[Ok]] prompt:
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Linux has an interface to the laptop's battery subsystem.  Its available via sysfs at <tt>/sys/class/power_supply/olpc_battery/</tt>.  The value of 'present' indicates if the EC thinks a battery exists. To check this value use the 'cat' command in the terminal app or at a vtty:
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  cat /sys/class/power_supply/olpc_battery/present
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  ok ec-abnormal@ .
 +
 
 +
'''Note''' the '.' at the end.  An error code will be returned.
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====Using OpenFirmware====
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Now run:
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You will need a [[Activation_and_Developer_Keys|developer key]] for the laptop.  [[Open Firmware]] has command that will talk to the EC and read the current battery info.  This command is <tt>watch-battery</tt>.  At the Open Firmware command prompt do:
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  ok watch-battery
  ok watch-battery
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If EC thinks a battery exists you should see a single line that gets updated with various pieces of battery information. If a battery does not exist then that will be indicated with a 'No battery' rather than battery status info.
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And hit escape. An error message will be printed. This message is a human-readable interpretation of the error code.
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====Using OpenFirmware and batman.fth====
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Now identify the section below that corresponds to the error code/error message and follow the instructions for potential solutions.
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You will need a [[Activation_and_Developer_Keys|developer key]] for the laptop. [[#Batman.fth|Batman.fth]] has commands that can interrogate the state machine of the EC's 1-wire interface.  This allows you to see what's happening on the 1-wire bus.  The command for this is <tt>see-bstate</tt>.  If a battery is not detected the numbers printed will cycle between 0,1 and 2.  Numbers other than that indicate the EC has detected a battery.
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==Common Causes for lack of battery presence==
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==Wrong Pack setting (code 02) ==
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There are a number of possible causes for lack of battery presence.  Here they are, in the order in which they should be checked.
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===Unplugged cable===
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This error indicates battery EEPROM corruption.  Using [[#Batman]], use bat-dump-banks to examine the content of the EEPROM. Please send this information to OLPC techsupport or the developers list.
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[[image:Keyboardstep2a.jpg|thumb|The battery connector in the bottom part of the laptop]]
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Check to see that connectors CN21 and CN22 on the motherboard are firmly plugged in. There is a second connector, hidden in the bottom part of the laptop.
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===Broken Wire===
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== LiFePo4 Overtemp (code 0b) ==
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If no batteries are detected, a break or bad connection between CN22 on the motherboard and the data pin on the battery connector results in no 1-wire communication (seen as this problem).  Check continuity of the cable with an ohm meter.
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''add pictures''
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The battery got too hot.  Turn off the system remove the battery and let things cool.
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===Bad data in battery EEPROM===
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== Bank 1 Invalid ==
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Normally if the data in the EEPROM has been corrupted a flashing red LED error will result.  However, depending on the corruption it may be possible to confuse the EC.  Use a known good battery to ensure that the problem is with the battery and not the laptop.
+
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A battery in this condition can be detected by watching the output of <tt>see-bstate</tt>.
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This message can be produced when the memory in the gas gauge has become corrupted, causing the battery identification data to be lost. <b>This fix should only be attempted on batteries that are labelled as ''Made by BYD Company Limited'' on the label printed on the internal-facing side of the battery.</b>
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===One-wire Communication Error===
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This problem can be fixed with batman. [[#batman.fth|Load batman, according to the instructions on this page]], then attempt to fix the problem with:
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The sensor inside the battery could be malfunctioning or the output from the EC could be corrupted from a manufacturing defect. If the laptop cannot communicate with the known good battery, and you have already checked for an [[XO_Troubleshooting_Battery#Unplugged_Cable|unplugged cable]] or [[XO_Troubleshooting_Battery#Broken_Wire|broken wire]], then the error is in the laptop motherboard and it will need replacement.
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ok batman-start
 +
ok bat-set-life-byd
 +
ok batman-stop
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==Battery LED is flashing red==
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Now remove and insert the battery.
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Flashing red LED indicates that the battery subsystem has detected an error.  [[Open Firmware]] has a command that will read the error code from the [[Embedded_controller|EC]].  The command for this is 'ec-abnormal@'.  At the [[Open Firmware]] prompt use the following to view the error code.
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ok ec-abnormal@ .
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'''Note''' the '.' at the end.  This is required to print the error code.
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Note that these same set of symptoms can also be indicative of other non-ID problems, so this may not solve your problem. If the problem remains after attempting this fix, you will need to examine the battery banks and contact OLPC tech support.
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''The error conditions should be listed...''
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== Bank 0 Invalid ==
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==Battery fails to charge?==
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First, using a serial console, save the output from the batman command:
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===Checking the actual charge level===
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  ok bat-dump-banks
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olpc-pwr_log is a Linux bash script that allows you to measure the amount of charge delivered to or extracted from the battery. It can be used to determine if the battery is performing at its rated capacity.
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===Laptop abruptly shuts off before battery is capacity reaches < 10%===
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This may be useful later. Plus, OLPC would appreciate seeing this information posted to the devel mailing list in cases where the repair worked.
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See [[#Checking the actual charge level|above]].
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=Software Tools=
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There could be many causes of this error. One case found in Nicaragua had all bytes in bank 0 shifted left by one byte. The EC was then confused when reading a strange value from the status byte.
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==olpc-pwr_log==
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This was successfully solved with:
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Currently this tool (a Linux script) is located at [http://dev.laptop.org/~rsmith/olpc-pwr_log http://dev.laptop.org/~rsmith/olpc-pwr_log]
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-
To use olpc-pwr_log follow the following procedure:
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ok bat-fix-error-2
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# Copy (or download) [http://dev.laptop.org/~rsmith/olpc-pwr_log olcp-pwr_log] to the XO.  It does not need any special priviledge
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It should be safe to try this repair technique for any case of Bank 0 Invalid, but it may not be able to solve the particular problem you are seeing. After running the command, perform a full reset (disconnect AC power, remove and reinsert battery).
-
# Start it
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-
The script will wait until it detects a battery and then begin to log various parameters via the olpc-battery subsystem. If your battery is really low and the [[Embedded_controller|EC]] is using trickle charge rather than main charge then the script will appear to be still looking for a battery even though the yellow charge light is on.  Once the EC finishes trickle charging it will report that a valid battery is present and the script will continue.
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If that didn't fix your problem, you can try a more invasive Bank 0 reset. This is only valid for XO-1 and XO-1.5 batteries at this time, <b>don't try it on a battery that originally arrived in a XO-1.75 laptop.</b>
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The output of the script is both to the screen and to a file. The file name is 'pwr-<date>-<gauge ID>.csv'.  Gauge ID is a unique ID number that is contained in the gas gauge of each battery.
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  ok bat-reset-bank0
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More details can be found [[XO_Power_Draw|here]]
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After running the command, perform a full reset (disconnect AC power, remove and reinsert battery). If the error condition cleared, the system will now be confused regarding the percentage of battery power remaining - you need to complete a full charge or a full discharge before things regain synchronization.
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==batman.fth==
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= Battery LED is flashing yellow =
-
Batman.fth is a forth script that is available from [http://dev.laptop.org/pub/firmware/scripts/batman.fth http://dev.laptop.org/pub/firmware/scripts/batman.fth]To use it you must load it at an [[Open Firmware]] (OFW) prompt. Getting to an OFW prompt requires a [[Activation_and_Developer_Keys|developer key]]. To use:
+
This indicates the battery is being trickle charged. This is normal but only occurs for a very low batteryLeave the XO plugged in and normal charging will resume after trickle has finished. It may take up to an hour before normal charging commences.
-
# Place [http://dev.laptop.org/pub/firmware/scripts/batman.fth batman.fth] on a USB key
+
Trickle charging occurs when the battery voltage is lower than 5.4V. This can be monitored with the <tt>watch-battery</tt> firmware command detailed below.
-
# Insert the USB key into the laptop XO (while it is turned off)
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# Start the laptop
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# Enter [[Open Firmware]] by pushing the ESC key while the laptop is starting up.
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# At the 'ok' prompt, type:
+
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fload u:\batman.fth
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-
The batman script may be stored on devices other than a USB key.  It is loaded with the 'fload' command, which must specify the storage device where bathman.fth is located:
+
If trickle charging persists after an extended period of time, go to the [[#OK prompt]] and run:
 +
ok watch-battery
-
USB disk:
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If watch-battery reports 0V 0A 0C and trickle charge, it may be worth testing the battery with a multimeter. See the [[#Multimeter test]].
-
  fload usb:\batman.fth
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SD card:
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  fload sd:\batman.fth
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NAND flash (root directory):
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  fload nand:\batman.fth
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Once loaded you run the commands in the script just like any other OpenFirmware command.  If you turn off the laptop, you have to repeat the loading process.
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= Battery detection diagnostics =
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=== Key tools in batman.fth ===
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If the system provides no apparent response in the battery LED when a battery is inserted, here are some diagnosis steps.
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The following is a list of useful tools in batman.fth with a brief note how to use them.  Some of these commands require that the EC be put into reset prior to running them so that the EC battery management system is disabled.  The 1w-init command does this.  After the 1w-init command is used all keyboard, touchpad and button activity is disabled.  Including the power button.  Any command requiring a 1w-init will require that any further commands be invoked using the processor serial port.  To power off the laptop afterwards, you will have to remove both external power and the battery.
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* 1w-init
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Power off the laptop, remove the battery, power on the laptop again and go to the [[#OK prompt]]. Now run:
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: Put the EC in reset and prepare the system so that [[Open Firmware]] can talk directly to the gas gauge chip in the batteryAll keyboard, touchpad and button activity is disabled after this command.  Required prior so some of the other commands.
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  ok watch-battery
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* see-bstate
+
 
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: Continually prints the EC 1-wire communication state machine index.  Useful for determining if the EC can talk to the battery gas gauge.
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Is a battery reported? If so, your problem is not related to battery detection, and must be related to battery charging or usage, discussed elsewhere on this page.
-
: Does not need 1w-init.
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 +
Power off the laptop, remove the battery, power on the laptop again and go to the [[#OK prompt]]. Now run:
  ok see-bstate
  ok see-bstate
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* bat-recover
 
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: Does PWM on the charge enable line resulting in a psuedo-current limited charge of the battery.  Streams the battery temperature, currrent, voltage and accumulated charge register (ACR) to the screen.
 
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: Automatically runs 1w-init
 
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ok bat-recover
 
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* bat-set-low
 
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: Zeros out various values in the battery's gas gauge EEPROM forcing the EC to resync with the state of the battery.  Useful if your battery is marked as full when it really is not.
 
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: Needs 1w-init
 
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ok 1w-init bat-set-low
 
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==Linux battery subsystem==
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This command continually prints the EC 1-wire communication state machine index. In other words, it's a low-level dump of the EC's communication with the battery. Before the battery is inserted, you will see a repeated pattern (usually "0 1 2" or "0 1 3").
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 +
With see-bstate still running, insert the battery and examine any change in the output. If there is no change in the output, it means the battery did not respond, see the "incorrect speed setting" section below.
 +
 
 +
If there is some change in the output, it means that the system did detect some form of battery presence, but the communication was not enough to identify the battery.
 +
 
 +
== Incorrect speed setting in battery EEPROM ==
 +
 
 +
If there is no change in see-bstate output when inserting a battery, you are possibly seeing a problem of <b>incorrect speed setting in battery EEPROM.</b>
 +
 
 +
The gauge chip in the battery can support two different 1-wire speed modes, selected by a setting in the EEPROM. Open Firmware only offers support for the low-speed mode, which is configured by default in our batteries.
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 +
If the battery EEPROM becomes corrupted in such a way that the speed setting is switched to high-speed, the system will fail to see the battery. <tt>watch-battery</tt> and <tt>see-bstate</tt> will behave as if no battery has been inserted.
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 +
This can be corrected with one-wire interface equipment, which is readily available and quite cheap. Some OLPC deployments have obtained such equipment and use it to correct problems such as these. Such devices are able to reprogram the battery EEPROM, removing the corruption and going back to low-speed mode. If purchasing such equipment, be sure to buy a device that supports high-speed more - not all do.
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 +
Firmware versions Q2F01 and newer for XO-1, and all firmware versions for XO-1.5 and XO-1.75 try very hard to avoid this condition, by detecting it before the EEPROM is written and enforcing low-speed mode.
 +
 
 +
If a large number of batteries are encountered in this state in your project, please contact OLPC; there is a possibility that a special EC firmware could be produced to reprogram batteries in this condition.
 +
 
 +
= Laptop shuts down abruptly with significant charge remaining =
 +
 
 +
The reason for this may be that the Laptop fails to (fully) charge the battery. Please continue in the following section: [[#Battery capacity is significantly degraded]]
 +
 
 +
= Battery capacity is significantly degraded =
 +
 
 +
If you have determined that the battery capacity is degraded through one of the following methods:
 +
* You have noted that the laptop shuts down abruptly while the battery still has a significant amount of charge
 +
* You have tested the capacity of the battery and have found it to be much lower than the rated capacity of 2800mAh
 +
* The battery refuses to charge (the battery behaves as if it is completely discharged, i.e. it cannot power the system alone, but connecting AC power causes the battery LED to go green immediately)
 +
 
 +
In this case, if the battery is a LiFePO4 battery with a yellow label, it could be that the battery cells have become inbalanced. See the [[XO LiFePO4 Recovery Procedure]]. Note that this problem was common on early XO-1 batteries, but is rarely seen on more recent models.
 +
 
 +
If you reach this point and the LifePO4 recovery procedure doesn't help, you're unfortunately at the end of the road. It seems that the battery's internal resistance is too high to allow charging. You should discard the battery in an appropriate recycling facility.
 +
 
 +
= Techniques =
 +
 
 +
== OK prompt ==
 +
 
 +
Some of the procedures on this page require you to have access to the Open Firmware [[Ok]] prompt. This may require a developer key to "unlock" the machine. See the [[Ok]] page for directions.
 +
 
 +
== batman ==
 +
 
 +
NOTE: batman is incompatible with XO-1.75. Any repairs done with batman must be performed on a XO-1 or XO-1.5 laptop.
 +
 
 +
Batman is a set of utilities for battery diagnostics and repairs. Some of the batman commands are included in recent firmware versions, others must be loaded from an external file. See [[Batman]] for more info.
 +
 
 +
== Capacity test ==
 +
 
 +
All recent OLPC OS versions include a tool called olpc-pwr-log which can be used to measure the capacity of the battery.
 +
 
 +
# Ensure that your battery is fully discharged
 +
# Power on the laptop with no battery inserted
 +
# Open a terminal.
 +
# At the terminal, run:
 +
#* For 2012 OS versions and newer: <tt>systemctl stop powerd.service</tt>
 +
#* For pre-2012 OS versions: <tt>stop powerd</tt>
 +
# At the terminal, run <tt>olpc-pwr-log</tt>
 +
# Insert the battery when prompted
 +
# Wait until charged
 +
 
 +
olpc-pwr-log will periodically report information about the battery. The final column shows the net accumulated current that has been delivered to the battery since olpc-pwr-log was started. In recent software versions this value is presented in microamp hours (uAh), divide by 1000 to obtain the value in milliamp hours (mAh).
 +
 
 +
Once the battery has fully charged and the battery LED is green, look at the value printed in the last column. This tells you how much charge was delivered to the battery during the charging process, which is representative of the capacity of the battery.
 +
 
 +
A brand new battery would be expected to have a capacity of 2800mAh or more. As the battery is charged and discharged during its lifetime, the capacity will gradually decrease. However, it is rare to find a battery with a capacity lower than 2000mAh even after extended use.
 +
 
 +
More details can be found in [[XO power draw]].
 +
 
 +
== Multimeter test ==
 +
 
 +
Checking the voltage of the battery with a multimeter acts as a simple health check for the battery, and may help with other diagnostics.
 +
 
 +
The battery has three terminals that connect to the laptop, you need to measure the voltage across the middle terminal and the one closest to the center of the battery. If your multimeter probes are too big to enter the terminals, find a couple of thin paperclips (or another type of thin wire) and feed them into the terminals, then you can connect the multimeter to the clips.
 +
 
 +
For a good battery with some charge, expect a reading between 1V and 7V. If the multimeter reports 0V here, it suggests that there is a bad connection between the cells and the battery connector, or that the protection circuit has permanently failed. Both cases would indicate that the battery is permanently damaged and cannot be recovered.
 +
 
 +
= Tips =
 +
 
 +
== Estimates ==
 +
A battery is a chemical device whose characteristics change with age, history, and ambient temperature.  The charge amount shown in the frame is only an estimate.  Do not worry if your battery shows (for example) 96% charged, or does not reach 100% charge.
 +
 
 +
== Minimizing battery depletion ==
 +
Even when powered off (by choosing Shutdown from the Home view), the XO has slight power draw, losing about 2% charge a day.  If you won't be using the XO for a while you can avoid this by removing the battery from the XO after powering off.
 +
 
 +
== Examining battery information from Linux ==
 +
 
 +
Some of the diagnostics on this page require Open Firmware [[Ok]] prompt access, which requires that security is disabled. If you cannot disable security to reach this prompt, some of the diagnostics can be made from a Linux terminal. However, note that many repairs require [[Ok]] prompt access, so this diagnostic access is of limited value.
 +
 
 +
# cd /sys/class/power_supply/olpc-battery
 +
# ls
 +
 
 +
For example, to read the "flashing red error code" normally accessed with <tt>ec-abnormal@</tt>, you can now type:
-
''More information needed here''
+
# cat error
[[Category: Repair]]
[[Category: Repair]]
-
[[Category: Hardware]]
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[[Category: Battery & Power]]
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[[Category: Cleanup]]

Current revision as of 18:32, 6 October 2012

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  english | español HowTo [ID# 275220]  +/-  


Contents

Introduction

This is the portion of the XO Troubleshooting Guide for diagnosing problems with the battery on an XO laptop. The Help activity and XO manual for release 8.2.0+ also has a "Battery charging" chapter [1].

This page details only problems that actually reside within the battery. Note that if you are having problems running an XO from battery power, or having problems charging a battery, such problems could be the fault of the laptop (the battery itself may be fine). Problems that are localised to the laptop itself are discussed at XO Troubleshooting Power.

How can you tell whether a particular problem is due to a faulty battery or faulty laptop? This is easiest when you have two XOs. Let's say you have laptop A including battery A, which is exhibiting a problem. You also have laptop B with laptop B, which is your personal XO which you trust to be functioning well. Take battery A and place it in laptop B, and take battery B and put it in laptop A. Testing both laptops will then give you a strong indication as to where the problem resides. Does the problem "follow" battery A into laptop B? If so, the problem resides within the battery (you're on the right page). Or does the problem remain within laptop A even when running from battery B? In such case, the problem resides within the laptop (see XO Troubleshooting Power).

If you only have one XO available to you, it is suggested that you have a quick read of both this page and XO Troubleshooting Power. You should be able to make an educated guess as to which page is the most appropriate for your problem. If in doubt, follow the diagnostics outlined on both pages.

Start here

First, take a quick look at the battery, especially the black connector which contains the contacts that electrically connect the battery to the laptop. Dried green crystals have been spotted around the connector on non-functional batteries on some occasions. This is from decomposition of the contact metal due to electrolysis in water. This may be cleaned with baking soda mixed with water, using a toothbrush. Wash your hands well afterwards. This may recover the battery, unless the contacts have become badly corroded.

Perform an XO Full Reset. If you know the problem is localised within a battery, this is unlikely to make any difference. Nevertheless, lets do it now to be sure.

Disconnect the battery, and connect the laptop to AC power. Now turn on the laptop. After the system has loaded, insert the battery.

Does the battery LED start flashing red? If so, jump to #Battery LED is flashing red.

Does the battery LED start flashing yellow? If so, see #Battery LED is flashing yellow.

For more information on the battery LED, see [2].

Is there no apparent response in the battery LED? See #Battery detection diagnostics

Now fully charge the battery, and wait for the battery LED to go green. Now disconnect AC power and discharge the battery while the system is running, keeping an eye on the percentage charge.

Does the system shut down abruptly with over 10% of charge remaining? If so, see #Laptop shuts down abruptly with significant charge remaining.

Now, starting with the battery completely discharged, perform a #Capacity test of the battery.

Is the battery capacity significantly lower than that of the rated specification? If so, see #Battery capacity is significantly degraded.

Battery LED is flashing red

Lets start with the case that has the most solid diagnosis available: you have the laptop running with the battery inserted, and the laptop is also connected to AC power. The laptop seems to run fine with AC power connected, but the battery LED is flashing red (to be clear: the battery LED briefly is illuminated briefly as red, and then turns off, and this cycle repeats), and the laptop may not be able to be run from battery power alone.

This flashing-red pattern means that the Embedded Controller (EC) has detected a problem with the battery. To understand this further, we can ask the EC for the error code. From the Ok prompt:

ok ec-abnormal@ .

Note the '.' at the end. An error code will be returned.

Now run:

ok watch-battery

And hit escape. An error message will be printed. This message is a human-readable interpretation of the error code.

Now identify the section below that corresponds to the error code/error message and follow the instructions for potential solutions.

Wrong Pack setting (code 02)

This error indicates battery EEPROM corruption. Using #Batman, use bat-dump-banks to examine the content of the EEPROM. Please send this information to OLPC techsupport or the developers list.

LiFePo4 Overtemp (code 0b)

The battery got too hot. Turn off the system remove the battery and let things cool.

Bank 1 Invalid

This message can be produced when the memory in the gas gauge has become corrupted, causing the battery identification data to be lost. This fix should only be attempted on batteries that are labelled as Made by BYD Company Limited on the label printed on the internal-facing side of the battery.

This problem can be fixed with batman. Load batman, according to the instructions on this page, then attempt to fix the problem with:

ok batman-start
ok bat-set-life-byd
ok batman-stop

Now remove and insert the battery.

Note that these same set of symptoms can also be indicative of other non-ID problems, so this may not solve your problem. If the problem remains after attempting this fix, you will need to examine the battery banks and contact OLPC tech support.

Bank 0 Invalid

First, using a serial console, save the output from the batman command:

ok bat-dump-banks

This may be useful later. Plus, OLPC would appreciate seeing this information posted to the devel mailing list in cases where the repair worked.

There could be many causes of this error. One case found in Nicaragua had all bytes in bank 0 shifted left by one byte. The EC was then confused when reading a strange value from the status byte.

This was successfully solved with:

ok bat-fix-error-2

It should be safe to try this repair technique for any case of Bank 0 Invalid, but it may not be able to solve the particular problem you are seeing. After running the command, perform a full reset (disconnect AC power, remove and reinsert battery).

If that didn't fix your problem, you can try a more invasive Bank 0 reset. This is only valid for XO-1 and XO-1.5 batteries at this time, don't try it on a battery that originally arrived in a XO-1.75 laptop.

ok bat-reset-bank0

After running the command, perform a full reset (disconnect AC power, remove and reinsert battery). If the error condition cleared, the system will now be confused regarding the percentage of battery power remaining - you need to complete a full charge or a full discharge before things regain synchronization.

Battery LED is flashing yellow

This indicates the battery is being trickle charged. This is normal but only occurs for a very low battery. Leave the XO plugged in and normal charging will resume after trickle has finished. It may take up to an hour before normal charging commences.

Trickle charging occurs when the battery voltage is lower than 5.4V. This can be monitored with the watch-battery firmware command detailed below.

If trickle charging persists after an extended period of time, go to the #OK prompt and run:

ok watch-battery

If watch-battery reports 0V 0A 0C and trickle charge, it may be worth testing the battery with a multimeter. See the #Multimeter test.

Battery detection diagnostics

If the system provides no apparent response in the battery LED when a battery is inserted, here are some diagnosis steps.

Power off the laptop, remove the battery, power on the laptop again and go to the #OK prompt. Now run:

ok watch-battery

Is a battery reported? If so, your problem is not related to battery detection, and must be related to battery charging or usage, discussed elsewhere on this page.

Power off the laptop, remove the battery, power on the laptop again and go to the #OK prompt. Now run:

ok see-bstate

This command continually prints the EC 1-wire communication state machine index. In other words, it's a low-level dump of the EC's communication with the battery. Before the battery is inserted, you will see a repeated pattern (usually "0 1 2" or "0 1 3").

With see-bstate still running, insert the battery and examine any change in the output. If there is no change in the output, it means the battery did not respond, see the "incorrect speed setting" section below.

If there is some change in the output, it means that the system did detect some form of battery presence, but the communication was not enough to identify the battery.

Incorrect speed setting in battery EEPROM

If there is no change in see-bstate output when inserting a battery, you are possibly seeing a problem of incorrect speed setting in battery EEPROM.

The gauge chip in the battery can support two different 1-wire speed modes, selected by a setting in the EEPROM. Open Firmware only offers support for the low-speed mode, which is configured by default in our batteries.

If the battery EEPROM becomes corrupted in such a way that the speed setting is switched to high-speed, the system will fail to see the battery. watch-battery and see-bstate will behave as if no battery has been inserted.

This can be corrected with one-wire interface equipment, which is readily available and quite cheap. Some OLPC deployments have obtained such equipment and use it to correct problems such as these. Such devices are able to reprogram the battery EEPROM, removing the corruption and going back to low-speed mode. If purchasing such equipment, be sure to buy a device that supports high-speed more - not all do.

Firmware versions Q2F01 and newer for XO-1, and all firmware versions for XO-1.5 and XO-1.75 try very hard to avoid this condition, by detecting it before the EEPROM is written and enforcing low-speed mode.

If a large number of batteries are encountered in this state in your project, please contact OLPC; there is a possibility that a special EC firmware could be produced to reprogram batteries in this condition.

Laptop shuts down abruptly with significant charge remaining

The reason for this may be that the Laptop fails to (fully) charge the battery. Please continue in the following section: #Battery capacity is significantly degraded

Battery capacity is significantly degraded

If you have determined that the battery capacity is degraded through one of the following methods:

  • You have noted that the laptop shuts down abruptly while the battery still has a significant amount of charge
  • You have tested the capacity of the battery and have found it to be much lower than the rated capacity of 2800mAh
  • The battery refuses to charge (the battery behaves as if it is completely discharged, i.e. it cannot power the system alone, but connecting AC power causes the battery LED to go green immediately)

In this case, if the battery is a LiFePO4 battery with a yellow label, it could be that the battery cells have become inbalanced. See the XO LiFePO4 Recovery Procedure. Note that this problem was common on early XO-1 batteries, but is rarely seen on more recent models.

If you reach this point and the LifePO4 recovery procedure doesn't help, you're unfortunately at the end of the road. It seems that the battery's internal resistance is too high to allow charging. You should discard the battery in an appropriate recycling facility.

Techniques

OK prompt

Some of the procedures on this page require you to have access to the Open Firmware Ok prompt. This may require a developer key to "unlock" the machine. See the Ok page for directions.

batman

NOTE: batman is incompatible with XO-1.75. Any repairs done with batman must be performed on a XO-1 or XO-1.5 laptop.

Batman is a set of utilities for battery diagnostics and repairs. Some of the batman commands are included in recent firmware versions, others must be loaded from an external file. See Batman for more info.

Capacity test

All recent OLPC OS versions include a tool called olpc-pwr-log which can be used to measure the capacity of the battery.

  1. Ensure that your battery is fully discharged
  2. Power on the laptop with no battery inserted
  3. Open a terminal.
  4. At the terminal, run:
    • For 2012 OS versions and newer: systemctl stop powerd.service
    • For pre-2012 OS versions: stop powerd
  5. At the terminal, run olpc-pwr-log
  6. Insert the battery when prompted
  7. Wait until charged

olpc-pwr-log will periodically report information about the battery. The final column shows the net accumulated current that has been delivered to the battery since olpc-pwr-log was started. In recent software versions this value is presented in microamp hours (uAh), divide by 1000 to obtain the value in milliamp hours (mAh).

Once the battery has fully charged and the battery LED is green, look at the value printed in the last column. This tells you how much charge was delivered to the battery during the charging process, which is representative of the capacity of the battery.

A brand new battery would be expected to have a capacity of 2800mAh or more. As the battery is charged and discharged during its lifetime, the capacity will gradually decrease. However, it is rare to find a battery with a capacity lower than 2000mAh even after extended use.

More details can be found in XO power draw.

Multimeter test

Checking the voltage of the battery with a multimeter acts as a simple health check for the battery, and may help with other diagnostics.

The battery has three terminals that connect to the laptop, you need to measure the voltage across the middle terminal and the one closest to the center of the battery. If your multimeter probes are too big to enter the terminals, find a couple of thin paperclips (or another type of thin wire) and feed them into the terminals, then you can connect the multimeter to the clips.

For a good battery with some charge, expect a reading between 1V and 7V. If the multimeter reports 0V here, it suggests that there is a bad connection between the cells and the battery connector, or that the protection circuit has permanently failed. Both cases would indicate that the battery is permanently damaged and cannot be recovered.

Tips

Estimates

A battery is a chemical device whose characteristics change with age, history, and ambient temperature. The charge amount shown in the frame is only an estimate. Do not worry if your battery shows (for example) 96% charged, or does not reach 100% charge.

Minimizing battery depletion

Even when powered off (by choosing Shutdown from the Home view), the XO has slight power draw, losing about 2% charge a day. If you won't be using the XO for a while you can avoid this by removing the battery from the XO after powering off.

Examining battery information from Linux

Some of the diagnostics on this page require Open Firmware Ok prompt access, which requires that security is disabled. If you cannot disable security to reach this prompt, some of the diagnostics can be made from a Linux terminal. However, note that many repairs require Ok prompt access, so this diagnostic access is of limited value.

# cd /sys/class/power_supply/olpc-battery
# ls

For example, to read the "flashing red error code" normally accessed with ec-abnormal@, you can now type:

# cat error
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