On Fri, 13 Apr 2012 13:52:53 -0700, mike wrote:

On 4/13/2012 11:18 AM, David wrote:
My daughters laptop has stopped charging the battery. The battery is
fine in another identical laptop so I dont believe it is a battery
problem. The battery from the 'other' laptop will not charge in the
problem one.
You don't say...can we assume you've tried swapping the power supplies?
Yes, tried the obvious things. The power connector is 2 pin, or rather
the coaxial type power connector. New power supply does not help.
How many contacts on the power plug? One of the causes of not charging can
be that the computer cannot verify the CORRECT power supply. If the
communication line to the PS is faulty, that can happen. Your socket
is already damaged, maybe the comm pin came loose? Or shorted to the
power and blew up the sensor?
Same thing happens at the battery. IF one of the several contacts
is faulty, you get weird symptoms. Shine 'em all up and compare the
signals to the good laptop. I've seen bent or broken pins and
solder joints around the pin can fracture and open up. Does not take much
resistance at these currents to confuse the charge controller.
Good point. I haven't looked around the battery connector. OK, I
haven't tried all the obvious things! The way the battery physically
connects should give reasonable protection from movement. I will check
the soldering of the pins though.

There are some fets between the power and the battery. Compare to the
good one to see if something is open there.
The two connectors are about 4 inches apart so there is a lot going on
between them! I'll try following some tracks to see if I can find a
difference.

I believe the easy solution is a new motherboard. The original
supplier no longer has any spares available.

The laptop was sold in the UK by Novatech but I think it is 'generic'
It has a model number L51II0 on the label on the base. It also has
'Made in China' 63GL51013-10 CM-2.

The motherboard was made by Uniwill. The only codes I am aware of are
ML 94V-0 E251244 and a date (?) code 0704- 171. This is about right
for when it was bought.

I have tried Googling but the best I have come up with are some
"ex-equipment" sold for spares.

I have had problems in the past with the power connector on the board
but I believe these have been resolved (mostly by a U-shaped wire from
the back of the pin to the board to allow a little flexing). It worked
fine for some months before the charging problem appeared.

It is running Vista and the icon in the system tray initially shows
charging when the cord is plugged in but after about 4-5 cycles it
stops moving.
I don't know if there's any real sensing in this circuit.
May be that the computer turns on the icon when it sends the control
voltage to turn on the charger, but doesn't verify that it happened.
The info bubble may be open-loop indication of the control signal logic.
Later it senses a problem and turns off the icon?????
Agreed, you never know which moving indicators mean anything with
Microsoft!

There's a program called PCWizard. It can talk to the battery on many
laptops and tell you what it thinks the battery status/condition is.
Compare the two laptops. There may be some useful conclusions.
I'll try that.

The info bubble continues to show 'plugged in: charging'
but no power goes into the battery (% shown remains constant).

I would appreciate any suggestions for a source or any ideas for what
might be wrong.