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  1. #1
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    HP Laptop will not boot with battery

    This HP laptop, model DV2125NR, running XP Media Center, cannot boot from its battery, alone. Yet, the battery is known to be in good condition and fully charged.

    To make matters more interesting, the laptop can boot with only its AC adapter (that is, without a battery installed), and can boot with both the AC adapter and the (good) battery installed. But not from its battery, alone.

    The battery-only configuration does permit the CPU fan to run (airflow present), does permit the hard drive to run, and displays operating LEDs. However, the machine simply does not go into the boot process, nor is there any display. I suspect the laptop fails to sense the battery has a full charge, so perhaps the charging circuit interconnection is faulty, in some way.

    In addition to the original battery, a second (new) battery was purchased to aid in diagnostics. However, that battery, when fully charged and used in a battery-only configuration, does exactly what the original battery does-- runs the fan, but halts the boot process.

    What do you think is wrong?
    Last edited by alphaa10; 2015-06-06 at 12:17.

  2. #2
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    With the battery in and AC connected, does the computer continue to run when the AC is removed ?

    As it's a XP machine then the CMOS battery could be down and not loading all of the drivers - including the one for the battery.

  3. #3
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    Quote Originally Posted by alphaa10 View Post
    .... Yet, the battery is known to be in good condition and fully charged.

    ... the laptop can boot with only its AC adapter (that is, without a battery installed), and can boot with both the AC adapter and the (good) battery installed. But not from its battery, alone.

    .... a second (new) battery was purchased to aid in diagnostics. However, that battery, when fully charged and used in a battery-only configuration, does exactly what the original battery does-- runs the fan, but halts the boot process....
    Known to be in good condition and fully charged how?

    'New battery fully charged'...how do you know this?

    'New battery' means just purchased correct? Not, bought with laptop and sat around unused for years before now?

    Clean the contacts between the battery and the laptop.

    I agree with your reasoning and applaud your dx. I think it must involve the MB and its interaction with the battery. I hope cleaning the contacts works because otherwise I am at a loss to logically explain your results other than involving the MB which means running the old laptop off of AC from here on in.

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  5. #4
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    Try a hard reset...

    1. Power off the laptop, disconnect the AC adapter, all peripheral devices, and remove the battery.

    2. Hold down the power button for 15 seconds.

    3. Insert the battery, re-connect the AC adapter only, and reboot.

    After the initial boot, reconnect all of the peripheral devices, disconnect the AC adapter, and reboot.

    If it fails to boot, enter the BIOS and reload the default settings.

    If the situation continues, take a look in the Event Viewer and see what errors are being logged.
    Last edited by jwoods; 2015-06-07 at 01:12.

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  7. #5
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    Quote Originally Posted by Fascist Nation View Post
    Known to be in good condition and fully charged how?

    'New battery fully charged'...how do you know this?
    'New battery' means just purchased correct? Not, bought with laptop and sat around unused for years before now?
    Clean the contacts between the battery and the laptop...
    "New battery fully charged"-- I have charged completely the newly-purchased, newly-manufactured battery in the laptop with the problem, if its screen report of battery status is accurate. However, I am without a means to cross-check the laptop's screen report that its battery is fully charged. One prospective option is to check the battery voltage / charge status by metering the battery pack connectors. I had thought of trying to locate the pin-out diagram for the battery pack, if there is a way to test the battery directly and safely with a meter.

    Conceivably-- and your idea has considerable promise-- if the laptop's charging logic and/or connector is faulty, the battery-- despite a screen indicator showing battery is nearly 100 percent-- may not be at sufficient charge to boot. While the battery is new, it is also a cheap Chinese mport, as opposed to a more expensive Chinese import.

    In regard to battery connector conductivity, the laptop contacts appear bright and shiny under strong LED light, and appear undamaged. There is limited clearance to insert a 100-percent (anhydrous) alcohol-dampened, cotton-tipped swab, but I certainly can try that on this new battery if you still believe cleaning is important. Of course, manufacturing process quality and even storage without humidity control can alter battery values.
    Last edited by alphaa10; 2015-06-07 at 19:04.

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    The free version of HWMonitor will tell you the state of the batteries, but have you tried pulling the AC adapter after it has booted up as I've suggested in Post #2 ?

    http://www.cpuid.com/softwares/hwmonitor.html - download button lower left.

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  10. #7
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    Quote Originally Posted by Sudo15 View Post
    The free version of HWMonitor will tell you the state of the batteries, but have you tried pulling the AC adapter after it has booted up as I've suggested in Post #2 ?
    Thanks for the HWMonitor link, and I'll try that. Meanwhile, I did remove the adapter, and the laptop continues to run, although its screen dims noticeably.

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    Quote Originally Posted by Sudo15 View Post
    With the battery in and AC connected, does the computer continue to run when the AC is removed ?
    As it's a XP machine then the CMOS battery could be down and not loading all of the drivers - including the one for the battery.
    1. Disconnecting the AC adapter does not shut down operations, although it consistently dims the display noticeably, perhaps revealing insufficient charge for this "fully charged [100 percent]" battery at the moment of test.
    2. That introduces the possibility of a problem with the laptop's power connector. A wobbly power connector is a standard HP issue (over time, at least) but the basic reliability of the power connection was the first thing I checked. My definition of reliability is simple enough-- when I move the connector 2 nanometers back to where the screen brightens, the connector seems to stay in that (bright) position, so an interrupted or faulty mechanical connection does not seem the strongest suspect, at the moment.
    3. Your suggestion of a CMOS battery issue is also a prospect, since this January, 2007 laptop arrived in my collection as a basket case-- no maintenance, abused and battered. But basic life signs are still solid-- HD, CPU, and standard remedies show no problems. I'll meter the CMOS battery for voltage, first, for diagnostic confirmation, and simply replace the battery to eliminate one more failure point.

  12. #9
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    That for me confirms it's a CMOS (RTC) battery problem, but another symptom of a failing CMOS battery is the clock being incorrect on boot.

    CMOS batteries have an expected life span of ~5 years.

    The dimming of the screen will most likely be due to the Power plan for when on battery.

    From what I've seen of the DV2000 service manual (which could be similar to your DV2125NR, access to the CMOS battery is under the HDD cover but in that model it is a plug in assembly, so if you want to do this yourself then you will need to ascertain the type for your model and perhaps confirm by contacting HP Support. http://www8.hp.com/us/en/contact-hp/contact.html
    Last edited by Sudo15; 2015-06-07 at 19:52.

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  14. #10
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    Quote Originally Posted by jwoods View Post
    Try a hard reset...
    1. Power off the laptop, disconnect the AC adapter, all peripheral devices, and remove the battery.
    2. Hold down the power button for 15 seconds.
    3. Insert the battery, re-connect the AC adapter only, and reboot.
    After the initial boot, reconnect all of the peripheral devices, disconnect the AC adapter, and reboot.
    If it fails to boot, enter the BIOS and reload the default settings.
    If the situation continues, take a look in the Event Viewer and see what errors are being logged.
    In reference to your suggestion (number)--
    1. First thing I did was to reinitialize everything possible.
    2. Also done in early phase, to bleed residual voltages at likely problem points. That step did restore consistency of booting from power adapter.
    3. Done, and laptop (nearly) always boots.
    [4] After reconnecting everything, but disconnecting power adapter, the next laptop boot fails, but with active system LEDs, CPU fan and HD, and no display.

    Your suggestions for reinitialization of values are good, since reinitialization tends to be the more productive (and easier) avenue in most cases. Like the other, veteran contributors. you have covered a particular aspect of the situation thoroughly.

  15. #11
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    Sudo15, you are very close to my own findings. Here is what I already have done to confirm a startup-phase battery voltage drop.

    After pressing the start button with both power adapter and original battery connected, I allowed the laptop to proceed until it displayed the opening HP splash screen, then abruptly disconnected the power adapter plug.

    At that point, the laptop continued on its own battery power through the entire post, ending in a normal desktop display.

    However, the revelations continued. After no more than 20 seconds, my well-used and probably weak original battery messaged that I should charge the battery, and the system quickly went into hibernation. I shut down completely and disconnected the power adapter.

    Repeating the procedure for the newly-purchased battery, I first disconnected the original battery, and pressed the start button to bleed residual voltage. I substituted the new, "fully-charged" battery, and reconnected the power adapter. On pressing start once again, and after disconnection of the power adapter, the new battery sustained operations. I had enough time to open the on-screen battery meter and obtain a battery charge reading. And that reading was 100 percent!

    To test whether the reading were false, I allowed the session to continue so I could observe whether the nominally 100 percent battery seemed fully charged. And to accelerate battery depletion by application of a modest load, I also ran an anti-virus scan of the entire system. After 20 minutes, my screen display of battery power reserve was still at 84 percent.

    Now, the conclusion is inescapable-- the system has a point of resistance somewhere that sharply limits available startup current. The charging circuit itself seems normal, since otherwise, the new battery would not have performed as well under load as it did.

    Somewhat unfamiliar with the various board components of the typical laptop, I must determine where the problem lies. Yes, it could be simply a bad connection, and I certainly hope for that. But it might be a circuit board, and the cost of even used 2125 mainboards is so prohibitive, I reach the point of having to analyze cost-effectiveness of repair.

    What are your ideas about where to go from here?

    * PS-- On the CMOS battery, I was unable to test voltage because there was no exposed lead. Your suggestion that I check the CMOS battery must be limited (I suppose) to indirect measures, such as how the system performs. I did disconnect the battery, however, in order to reset CMOS to default values, then reset all original values. In earlier comments, it was suggested a weak CMOS battery would not permit proper loading of certain drivers, including possibly the driver for battery condition.
    Last edited by alphaa10; 2015-06-10 at 16:06.

  16. #12
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    You seem to have proved the old battery is kaput and the new one is OK. That leaves the motherboard as the problem at start up and all battery connection / charging is on the motherboard.

    cheers, Paul

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  18. #13
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    Given the age of the machine and the expected life span of a CMOS battery, I'd still renew that.

    While the type of battery that is fitted would cost a bit more than the standard CR2032 button cell, its cost should still be viable.

    Following a further Google on this, I did come across where a failed/failing CMOS battery was causing boot problems.

    Is the clock showing the correct time when you boot up ?

    It could well be there is a problem in the motherboard path for the laptop battery to fire up the machine completely, but if this was my machine I'd still like to eliminate what I could before condemning the motherboard.

    It's possible there could be some leakage in one of the caps on the battery circuit but as they are ceramic and not electrolytic as in a desktop, locating a bad one would need some serious diagnostics as not sure if that would be indicative by signs of a component overheating.

  19. #14
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    Quote Originally Posted by Sudo15 View Post
    Is the clock showing the correct time when you boot up ?
    Yes, time and date are correct.
    Thanks for confirming that the CMOS battery may be on the way out with 3.0v remaining.

  20. #15
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    CMOS batteries usually are 3.0v and would need to be below 2.5 -2.0v to produce the tell-tale signs, so perhaps I'm wrong - does the battery have a voltage value on it or is there anything in that manual to say what it should be ?

    I think the older ones used to be 5.0v but the more experienced guys would know more about that.
    Last edited by Sudo15; 2015-06-12 at 18:55.

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