Backup battery/BIOS preventing power on.

Archived from groups: ibm.ibmpc.thinkpad,comp.sys.laptops,sci.electronics.repair (More info?)

broughcut@gmail.com wrote:
> I received a ThinkPad (T23) in the post a few days ago. It had been
> left in Sleep mode and the battery was too flat to boot.
>
> I had intermittent power-on probs for a day or so. Now if I press the
> power button nothing happens, but removing the backup battery at this
> point will turn the machine on (no need to press the power button
> again). Leaving the backup battery out entirely solves the problem, and
> the machine turns on first time with no problem -- although it will not
> load the operating system, so doing away with the backup battery
> entirely doesn't seem to be an option
>
> I think the Power Manager has got stuck into thinking there's no power
> as a consequence of the extended sojourn in sleep mode with a near flat
> battery.
>
> I flashed the BIOS with the latest version to no avail (it is possible
> to power on with the backup battery installed but it takes a lot of
> messing around, diconnecting/reconnecting AC & batt etc). I have also
> tried draining the capacitor by keeping the power button pressed with
> mains/batt and backup disconnected.
>
> I have a couple of questions. Is it possible to disable the pre 'power'
> on test? Why hasn't leaving the motherboard without any power for a few
> hours already reset the system -- could this prob be due to something
> else entirely?
>
> thanks for everyone's time.

Hi...

Maybe I'm missing something here... I don't have a
thinkpad... but why don't you just replace the battery
and be done with it?

As for resetting the bios to it's defaults... is there
possibly a pair of pins to short to do this? Or isn't
there a cmos setup to restore defaults?

Good luck, and take care.

Ken

Archived from groups: ibm.ibmpc.thinkpad,comp.sys.laptops,sci.electronics.repair (More info?)

DAAAA The backup battery is working fine but it won't power up with it
plugged in?????????????????
What is the voltage of the battery when plugged in and trying to power on?
Are the wires reversed? Have you replaced it with a new one?? If that is the
case the only resolve is replace the mother board.



<broughcut@gmail.com> wrote in message
news:1113711441.181903.321810@g14g2000cwa.googlegroups.com...
> Both the backup battery and the main battery are working fine. Problem
> is, when the backup battery is powering the bios, the machine won't
> power on, even if connected to AC power (as I say, I suspect the power
> management is too blame).
>
> Without the backup battery, it powers on, but the system keeps cycling
> to back to the BIOS and asking me to set the time. If I could be done
> with the backup battery altogether that would be great, but I can't
> seem to get past the BIOS without it installed.
>

Archived from groups: ibm.ibmpc.thinkpad,comp.sys.laptops,sci.electronics.repair (More info?)

Bob Shuman wrote:
> Not clear what "backup" battery you are referring to here that is
"working
> fine", but I'd strongly suspect the on (mother) board backup battery
is weak
> or dead. Replace it with a fresh one, reset your BIOS, and then
report
> back. Or, tell us how you know that the on board backup battery is
known
> good.
>
> Bob
>

Thanks Bob. The ThinkPad's large yellow lithium "backup battery" is 3
volts and I've also tried using a different battery with the same
result. I think this is the only on board battery. One times in ten it
*can* be powered up with the backup installed, in which case the
computer works fine, so I don't think it's a terminal system board
fault.