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Here's a real head scratcher...

A customer's laptop (Panasonic Toughbook) will log in and run perfectly fine while plugged in to AC power. Great. Now, if I unplug the laptop, then turn it on, it never gets past the Windows logon screen. If I plug it in, get past the Windows logon screen, then unplug the AC adapter, it keeps running for a good 3 hours.

I then tried to start it up, let it charge, then reboot without the AC adapter, even though I know this battery is full, and it still shuts down at the logon screen. Therefore, I know it is not the battery, at least it doesn't seem like it. I ran a Memtest86 on the RAM, no issues found. I ran a CHKDSK /f /r on the hard drive attached to another computer, no issues found. I also ran the Western Digital Data Lifeguard diagnostics program, again without issue. As a final struggle, I scanned for viruses on our virus checking computers with Microsoft Security Essentials, Malwarebytes Antimalware, and with Norton 2012

What type of issue should I be looking at next?


  • Safe mode works
  • Removing ALL non-Microsoft services and all Startup Items in MSCONFIG does not work
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Do you have the ability to test the battery in another laptop or another battery in this laptop? What happens precisely when a boot with the battery fails? Any error messages, or just a straight power down? – MaQleod Aug 8 '12 at 16:52
Just a straight power down. I don't have another to test it with unfortunately :( – Canadian Luke Aug 8 '12 at 16:53
Hmm, any change if you try to get to safe mode? How about if you boot into something else, such as a linux live CD/DVD/USB stick? – MaQleod Aug 8 '12 at 20:48
@MaQleod Booting from a DVD (UBCD4Win) lets me log in no issues, so it's definitely something with the current installation. Trying Safe Mode once the battery charges – Canadian Luke Aug 8 '12 at 21:01
up vote 3 down vote accepted

Check the event log, it might tell you whether something power related is going wrong.

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Actually, it was showing issues with the WLAN card, pages and pages full of entries. I disabled the WLAN card by the power switch, turned it on, and it booted twice for me! – Canadian Luke Aug 9 '12 at 16:16
if safe mode works, I would guess it is something that is loaded in normal boot that isn't in safe mode that has been corrupted or calls something that hits a hardware fault. If he's lucky, the event log will log it before the system powers down. A verbose boot might help with what exactly windows is loading just before power down, just might be hard to read it fast enough. – MaQleod Aug 9 '12 at 16:21
Side note: As I mentioned earlier with a similar network card related fix Mokubai suggested on chat, network timeouts are often the reason of an extremely slow login. @Luke, you might want to attempt to update the drivers for your motherboard WLAN card as well as check the power management options on them (the one in the device manager as well as those under the advanced settings in the network center). – Tom Wijsman Aug 9 '12 at 16:22
@MaQleod: Exactly, I guess that would be the WLAN card driver not loading. – Tom Wijsman Aug 9 '12 at 16:23
The Power settings are set to never set the adapters to sleep, but I will try updating the drivers, @TomWijsman – Canadian Luke Aug 9 '12 at 16:24

I think I have the same issue on an HP/Compaq that ran fine on XP but NOT Windows 7. I disabled he AC Battery Adapter in Device Manager and it seems to work fine now. I guess this is a Windows 7 feature not in XP.

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The facility that is responsible for reporting the battery state and supporting power management is ACPI, within which the BIOS plays a major role.

Try updating your BIOS.

Laptop batteries communicate with the embedded controller that handles power management. It's possible, but unlikely, this function of the battery has failed without any other obvious symptoms. Would really be weird for it to only make the boot process freeze, though ... You also may double check that there is no evidence of corrosion or liquid damage on the laptop's battery connector.

share|improve this answer
BIOS is up to date and won't re-update. Checking the battery and terminals, it looks good – Canadian Luke Aug 8 '12 at 18:40

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