My phone keeps shutting off by itself (android)?

[Avery]

Its an optimus v. I got it last year for Christmas and now probably daily it will either restart or completely turn off and wont charge. I don't have many apps running, I literally only use twitter and my messaging and browser apps. My new monthly plan starts on the 7th of February, should I just use my moms old phone? She got the galaxy s III and her old phone she only had for 3 months. Thanks.

[Android Core]

you either have a battery issue or low RAM issue or a defective phone

Take it to the wireless carrier store... they will determine what is wrong and tell you either 1) its fixed--here you go... 2) buy a new battery.... 3) get a free warranty replacement due to defect