Laptop battery problems

This is my first post on the forum, and it's about a long-suffered battery problem.

I've had my Gateway laptop for about 3-4 years now, and there have been no problems except for a battery-related one. After 3 years, I noticed that my battery was charging only up to 70 percent, or 60 percent. A major problem is that when I plug it into it's AC Adapter, it can run for about 30 minutes while surfing the web, but lasts about 5 minutes while playing downloaded games. After that, the screen goes black, but audio keeps playing. It seems to me like the computer keeps working but the screen stops functioning.

A few days ago, to try to remedy the problem, I bought another battery, thinking that it must have just been the wear and tear over the years. I got the battery, it all fit well, and it was charged up to 67%. I let the battery charge up to 100%, and thought I could leave the charger in and that the laptop wouldn't fail as usual. I was wrong, and 5 minutes into playing a game, the screen went black.

I decided to cut my losses and settle with the new battery, and go back to the old method of charging to the highest percent, playing or using my browser, and then powering it off and charging it up again for a later use. Even that hadn't gone as planned, as that when my computer got to around 54%, it shut off completely.

I'm not sure why this is happening. I'm hoping to fix the problem soon as it's really hindering my work.

Here are my computer's specs:
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System Information
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Time of this report: 2/21/2014, 22:15:38
Machine name: CONSHEA-PC
Operating System: Windows 7 Home Premium 64-bit (6.1, Build 7601) Service Pack 1 (7601.win7sp1_gdr.130828-1532)
Language: English (Regional Setting: English)
System Manufacturer: Gateway
System Model: P-7805u
BIOS: Ver 1.00PARTTBL
Processor: Intel(R) Core(TM)2 Duo CPU P8400 @ 2.26GHz (2 CPUs), ~2.3GHz
Memory: 4096MB RAM
Available OS Memory: 4090MB RAM
Page File: 1893MB used, 6286MB available
Windows Dir: C:\Windows
DirectX Version: DirectX 11
DX Setup Parameters: Not found
User DPI Setting: 144 DPI (150 percent)
System DPI Setting: 96 DPI (100 percent)
DWM DPI Scaling: Enabled
DxDiag Version: 6.01.7601.17514 32bit Unicode

To review:

I've had this computer for a long time, battery started to have problems

Battery A only charges up to 49% at most, and when plugged in, shuts off after a few minutes.

Battery B charges up to 100%, but when plugged in has the same affect. Also, when Battery B reaches around 50%-56% it turns off completely.

Please help!

 

Did you follow the manufacturers recommended initial charging cycle? Batteries have memory circuits, if not charged correctly they do not preform up to snuff.