Help What's wrong here ?: Rapid charge and rapid discharge

[AppleUser]

Have enjoyed this Core Prime for more than two years. In the past two months, three one year old batteries and even one new one show strange behavior: They rapid charge to 100% (~ 45 minutes) and with phone use, rapidly discharge again about 45 minutes.

Any ideas why?

Should I get a new similar sized phone? If so, which phone is similar or better than this Core Prime (MetroPCS).

Thanks.