Laptop battery does not charge

Laptop battery does not charge

With the growing complexity of laptops, notebooks and netbooks, figuring out why a laptop battery does not charge is not easy. Laptop batteries that suddenly die or notifications like “laptop battery not recognized” trigger valid reasons for suspicion. Even more – simply replacing a laptop battery is an expensive affair and certainly not always the solution. Nowadays there are many components involved in charging a laptop battery. In this story you’ll find a simplified approach to narrowing down a laptop battery problem and possible leads to a solution.

Simple laptop battery charging diagnosis

The simplified diagnosis assumes the following;

1) Laptop works on AC power – laptop battery doesn’t charge.

2) Laptop battery has worked before in the same laptop

The approach assumes the smart battery system architecture developed by Duracel and Intel. A DELL Latitude D610 business laptop is used as example.

Although the information here might not apply in all cases, it still might shed light on reasons why a laptop battery does not charge.

Diagnosis approach

The diagnosis approach is based on the observation that all laptop battery charging components are active when the laptop is powered off with the AC power adapter connected. This is true for most laptops and eliminates the involvement of the main processor in charging a laptop battery.

Laptop battery charging is managed by a second processor on the laptop motherboard. In this approach the second processor is identified as the POST (Power On  Self Test) controller. The controller executes initial test during power-on and manages laptop battery charging. Although this might not apply for all laptops, the observation mentioned earlier still stands.

When the laptop is powered-on information about laptop battery charging can be monitored through either through the BIOS setup screen or for example in Windows or Linux.

The laptop battery charging diagram below shows various components involved in charging a laptop battery. The blue and red marked text indicates click-able text and loads pages with more information.

Laptop battery charging diagram

Diagnosis diagram when a laptop battery is not charging

Laptop battery charge controller and program code

The POST controller (Power On Self Test) is a second processor or CPU on the laptop motherboard. It remains active when a laptop is powered down unless the AC power adapter is disconnected. The POST controller manages laptop battery charging and communicates with the laptop battery and AC power adapter.

The POST controller also runs test when the laptop is powered on. For DELL laptops the POST controller outputs diagnostic codes through the CAPS, NUM and SCROLL lock lights. After POST tests are completed successfully it starts the main CPU which executes BIOS program code for further testing.

The POST controller for a DELL Latitude D610 is the SMSC LPC47N354 – MacAllen III – Ultra IO controller. Unfortunately there’s little public information available but it seems this chip executes POST functions using a 8051 based micro controller. The latter is a highly popular multi-purpose embedded CPU capable of doing quite a bit of work in the lower dungeons of the DELL Latitude D610 laptop.

Laptop battery cell charging controller

The battery controller in DELL Latitude D610 batteries is the custom made BQ20864 – called a battery gauge – from Texas Instruments. The battery gauge chip tracks battery cell charge and discharge information for the laptop battery charge control circuit. There’s no public information available about this particular battery charge controller – most likely it’s protected information only available to DELL.

Windows 7 has native support for accessing battery gauge chip registers, however the feature seems to have maturity problems.

Laptop battery charge control circuit

The laptop battery charge control circuit supplies power to the laptop battery – it handles the actual charging of the battery cells in the laptop battery. The main functions performed by this circuit, among others:

  1. DC-DC voltage conversion from the AC power adapter to the Laptop batteries
  2. Start, Control and Stop the battery charging stages from bulk charge to trickle charge
  3. Communicate with the slave which is the charging controller in the laptop battery
  4. Communicate with the master which is the POST controller

For the DELL Latitude D610 the MAX1535B Battery Charger chip is the center of this circuit. The DC-DC conversion produces quite a bit of heat making it easy to locate this circuit when charging the laptop battery while powered down.

Laptop battery charging indicator LED

The laptop battery charging indicator is a multicolor LED emitting flash codes in several colors indicating the status of the charging process.

Laptop processor

The laptop processor executes BIOS program code after the POST controller completes the Power On Self Tests. During BIOS execution a laptop can generate diagnostic codes on the screen or through beeps. After BIOS tests are completed successfully the laptop processor tries to boot the operating system on the hard disk, CDROM or USB drive / stick.

The DELL Latitude D610 has a Intel Pentium M processor.

Related Batteries:

Dell Latitude C500 Battery
Dell Latitude C640 Battery
Dell Latitude C510 Battery
Dell Latitude C540 Battery
Dell Latitude C610 Battery
Dell Latitude C600 Battery
Dell Latitude C840 Battery
Dell Latitude C810 Battery
Dell Latitude C800 Battery
Dell Latitude D505 Battery
Dell Latitude D510 Battery
Dell Latitude D500 Battery
Dell Latitude D400 Battery
Dell Latitude D600 Battery
Dell Latitude D800 Battery
Dell Latitude D610 Battery
Dell Latitude D620 Battery
Dell Latitude D630 Battery

18 comments to Laptop battery does not charge

  • […] Comment (RSS)  |  Trackback Posted on November 27, 2010, 4:10 am, by brandnewbattery, under Buzz. […]

  • collaboration

    Ne’er knew this, thanks for letting me know.

  • Cassondra Szwarc

    Tips are good. I plan to try some of them out.

  • Aron Constantineau

    Thanks for the help will try using them.

  • Michael Fluty

    Hello, I found your blog in a new directory of blogs. I don’t know how your blog came up, must have been a typo. Your blog looks good, have a nice day.

  • Tony Marozzi

    Hello, this is a certainlygreat post. In principle I’d wish to jot down like this as well – taking time and genuine effort to create a brilliant write-up.!. but what can I say.!!!. I procrastinate alot and by no means appear to obtain anything done. Thank You

  • Ole Guy

    I fixed my charging problem. For about a year my Dell Latitude D610 was switching from battery power to charger intermittently. The computer is mostly in my lap, so I figured the power receptacle was cracked. Wiggling the power jack seemed to work sometimes. With the battery removed it would sometimes switch off, so I thought for sure it was a cracked connection on the motherboard. Then the battery stopped charging, but it still worked on the charger even with just a three percent charge and never switched off with the charger plugged in. In the bIOS it could not determine the charger type and I turned this warning off a year ago. After reading all the tips here and at other sites nothing worked. I did not modify or replace the battery as it was good and I have a 65 and 90 watt charger – both worked well on another D610.
    Here is what I did: first I inspected the battery bay. There was a small accumulation of dust and lint on the base of the pins and circuit board. I removed the charger and cleaned the lint off with some glass cleaner (it was convenient) and a small eyelash brush. I cleaned the battery terminals too. Dried it and waited until it was thoroughly dry just to be sure. I replaced the battery, powered it up and logged in and then connected the charger. The switching from battery to charger part was fixed. It still could not recognize the charger type and was still not charging. When I started troubleshooting the battery was fully charged and had drained to about 70 percent as I worked.
    Then I powered it down again and removed the charger and battery. I then depressed the power button for over ten seconds. I guess the idea here is to bleed off any charge and hopefully reset a circuit so it will power up and work correctly. This did not work for me – no change. The charger type was not recognized and it was not charging and was running with reduced processor power. But it was at least not switching from charger to battery power any more.
    That night, I removed the charger, powered down normally, and then removed the battery over night. The next evening I held the power button down for about a minute just to be sure to drain any residual voltage or charge from internal circuits. I thought this was a bit much, but had nothing to lose trying. I replaced the battery. Power up and logged in so I could observer the power meter. It was running with about a seventy-five percent charge. I then plugged in the 65 watt charger and watched my tray power meter. It took about fifteen seconds to start responding and blinking and then presto it was charging. As I wrote this it has fully charged.
    Clean your battery terminals in the bay and on the battery. I guess lint can short the pins and cause problems. Let it sit over night powered down with the battery and charger removed. The next day replace the battery and boot with battery power only. This allows it to boot with full processor capacity. Login and observe your power meter. Plug in the charger and see what happens. Maybe you will get lucky as I did.
    I have worked for five years around Dell Laptops (3000 of them in a K12 school). We have not experienced the charger failure problems I have read about on the web. Our charger failure rate is minimal. The 65 watt chargers have proven to be pretty durable.
    Good luck!

  • Della Blatchley

    Quite informative post article.Really many thanks! Fantastic.


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  • Laptop Technichian

    Hello, I am writing this post in an effort to help those who may have the “Charger not identified, System will not charge” problem.
    I have found through trial and error that my Dell X300 which has the aforementioned problem will charge the battery if during the POST the laptop is made to wait…
    (ie. if you have the adapter warning message turned on in the BIOS and you allow the laptop to stay on the initial POST screen where the red warning telling you that the “Adapter is not recognized, System will not charge”)

    The Laptop will then IN FACT charge the battery. I have tested this with two batteries on my system as I had purchased another regular capacity battery when I believed that my extended capacity battery was faulty and thus no longer charging. After leaving the system in the state mentioned above for a few hours I checked the battery status in the BIOS and the battery status showed as CHARGING instead of IDLE as it had shown previously, and my battery charge had went from completely exhausted to about 75%.
    I hope this will assist others in getting their batteries to charge, and while I recognize that this is NOT a “fix” it will at least provide a way to continue to diagnose the problem (and provide a last resort option to others!).

  • Victor -Procom-

    There are very good articles here, a lot of things to learn.
    Ok, now my story:
    I have two equal laptops (laptop1 and laptop2)15 months old. Suddenly laptop2 began to shutdown when working only with batt, instead the battery icon in windows said 100%. Then you connect the power adapter again, turn it on and in a minute windows said 100% charged, but in the moment that you take out the power adapter it goes off.
    So using a multimeter I saw that the bat of laptop1 had 11volts in its pinout, but the bat of laptop2 had zero. I opened the dead bat, desoldered the cells and charge them one by one with an universal li-ion little charger that I have. I soldered them again into the battery box and soldered again the charge control circuit. I used the multimeter again but zero again (cells have 3.6v in 3 pairs, so the bat has 10.8v). So I think that my charge control circuit is bad, damaged. Does anybody know what can I do for fix it? What can be bad in that circuit?
    Thank you very much.

  • surplus

    Thanks, Laptop Technichian
    I had a Dell Vostro that wouldn’t charge a new aftermarket battery but would charge an old OEM one. Your post gave me the clue to check the BIOS settings, charger alert notifications were turned off. Turning on the notifications allowed the aftermarket battery to beging charging. The machine had an OEM PA-12 power adapter. Now both batteries are charging properly.

    Hope this post may help others with the same issue

  • jalil

    my laptop dell vostro 1720 is not charging battery otherwise all things like charger pin and battery is ok.

  • Fawad ullah

    i have a problems when i plug the battery in my laptop then the charger trip

  • Anything we can do for you?

  • jada

    Hi I have a Dell inspiron mini netbook. It won’t charge, even when connected to the charger and plugged into the wall. I suspect a loose Jack connection. Is there anything that can be done?? Thanks.

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  • patti

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