Battery problem

[fireguy]

I recently replaced a dead mogul and kept the battery from the old one so I now have 2. Long story short I get dramatically different battery life with the 2 batteries in the same phone with the same settings. The old battery will last well over 24 hours and have 30 - 40% left the new battery dies on me after about 6-8 hours. Makes me think it's the battery not the phone or the running apps.