Laptop dies randomly and suddenly when using battery

[Winter Blue]

My laptop I use for school, a HP G6-2235US, has been randomly dying when on battery. What it is being used for has no effect. It can be idling, running MS Office, or playing a game and it will just die. Once it dies I can just press the power button and it will power back on just fine.

During the time it has been doing this I have replaced the Battery and upgraded the APU and RAM, leaving the MOBO and HDD. The latest bios installed.

What would be causing this?

Any help would be appreciated!

 

[digitaldoc]

Did you replace it with a 3rd party battery? Some of them are not too good.

 

[Winter Blue]

Yes I did, but it is the same symptoms as when I had the old battery.

 

[digitaldoc]

Is the power supply cable firmly inserted? Sounds like the laptop is only intermittently getting power.