Strange power on/off problem T21

[themanwid]

Curious if anyone has come across this problem before with a T21.

Will NOT turn on without AC adapter plugged in.
As soon as AC is plugged in and laptop is turned on, ac can be removed and run perfectly on battery. I've tried multiple batteries, no success. I swapped CMOS batteries and reset the BIOS, I've switched keyboards with no luck.

Anyone have any suggestions, short of replacing the mobo???
Any help is appreciated.

Thanks.

[ryengineer]

I have but on my wife's HP. I bought a new battery from ebay (3rd party) it did the same so I returned it back and bought from another seller but no luck.

My case scenario with the battery was:

1. The laptop couldn't boot without the help of AC adapter but once it did, I could safely remove the power supply.

2. The battery could take a charge from the power supply and hold it for 2.5-3 hrs. depending on the laptop's usuage.

So I contacted HP's technical support and they gave me this reply:

"The battery is not able to provide the wattage needed for the high power drainage required during the startup process."

I was also advised to buy a genuine battery from HP parts website.
I did and it's working now.

Your case could be different though, can you charge the battery via the power supply?

[themanwid]

ya, I can charge the battery no problem.

I've tried multiple batteries that are all IBM batteries and work perfect in other laptops.

I'm guessing something is wrong with the mobo.
Thanks for the reply.

[truk]

Try booting it with the screen closed, so the power is not being drawn for the screen. You should also check for visibly loose components on the motherboard, and clean the battery contacts. Have you tried an ultrabay battery? It might help rule out a loose battery connection.