To find out why your Mac is turning off, you can look through the logs. The post Determine Shutdown Cause using Terminal has instructions on how to do this and what the codes mean.
However, based on your symptoms, it sounds like your battery is defective (given that's it's a brand new machine)
I bought a new Mac and have had it it for like 1 week now....I don't want to wait for a new MBP.
Return it for a refund or exchange.
You can try an SMC Reset as mentioned in Monomeeth's answer, but the SMC won't prevent your battery from charging and will only shutdown the system when it gets a low power reading from the battery.
So, as it stands, it's either
- a faulty SMC chip which means the logic board needs to be replaced
- a faulty battery which means the top case needs to be replaced.
There's no software or tweak that will fix either condition.
As inconvenient as it may be, this is not something anywhere close to being considered "normal." However, "not normal" doesn't mean that it's unheard of. Pretty much anything on any product can be defective from the factory; this is why you have a warranty and AppleCare.