SZ120p/b battery completely drained out..

I own a Sony Vaio SZ120p/b and I can't use the laptop without plugging it in to an outlet. For the month of May and June, I used the laptop at school on battery and it worked fine. But whenever I'm home it's always plugged into the outlet.
One day in July, I unplugged the cord to pack up and head for school, but for some reason I needed to check something on the laptop. So I pushed the power button to turn the laptop on, but it wouldn't turn on. Then I plugged the cord back in and tried, it turned on. From that time I figured the battery died for some "unknown" reason.

What I'm getting at is, I need new batteries but I don't want to spend $200 to get a new one. I've seen some compatible batteries on eBay selling for $40.
My question is, are they safe to use? Are there any other stores/sites that sell the batteries for cheap?

Any help/suggestion is appreciated.

Thanks.

 

You might want to read the Battery Guide for answers, but the bottom line is that 3rd party batteries are just plain dangerous and not worth risking your entire notebook.

 

Could someone tell me if this battery would work for the SZ120p/b > http://cgi.ebay.com/Genuine-SONY-VG...ryZ31518QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

This is the VGPBPS2C/S which has a 5200mAh capacity but I've seen the same model on different websites with 4800mAh capacity. Also, some of the generic ones have 4400mAh.

Which one am I suppose to use for Sony Vaio SZ120p/b?

 

it could be the motherboard

 

how would I go about fixing that?

 

The very same thing happend to my SZ150 yesterday. I unplugged ac cord and the laptop powered off as if there is no battery. Without AC power the laptop does not turn on. When plugged the power icon says "on AC power" and system does not detect battery at all. I've try to take battery off place it back again, no luck...any help appreciated? I also have the gut feeling about dead motherboard batteries don't usualy die like that, do they?

 

they do.
i have acer 662lci, year 2004 of production, so i have been using it for 3 years, and the battery died recently.
Also i have a MacBook, and his battery died after 3month from purchase, but apple has a free change program in this case.

By the way, how is it better(for laptop and battery) to use a laptop at home and at work(when you are not on the way): with AC adapter plugged, or on battery till drainage and then charging?
P.S: I know, that, if you are going to play games smoothly you should plug ac adapter.

 

Update: the dead battery does not work in a different laptop and vice versa, a different battery works ok in my laptop....

 

Update 2: While still waiting for a replacement battery, the old battery not detected by my laptop since the last week, rose from ashes. Windows now detects the battery, charging (orange LED blinks) but is on 0% all the time. Weird!