Blackberry Battery Issue

[Nate607]

Hello guys,

I bought a new Blackberry Bold 9780 a month ago and the battery has been acting weird since the i bought it. It switches off by saying battery drained when the indicator shows 25%. I don't even see any red or yellow indicator of battery low. I think the shop owner replaced the battery with a used one because the battery doesn't seem that new. Has scratches. I think he replaces it when he took it for upgrading to newer versions of OS6. He took it for about 20 minutes. When it switches off even though it shows 25% then i plug it into charger to turn it on and it then shows batter 0%. It charges normally from 0% to 75% but then it shoots up from 75% to 100% in a minute. If i let it charge for several hours more even though it says 100% then sometimes it goes till 0% before switching off and when i let it charge till about 60 or 70% then it will go till 0% before charging. Also my battery drains fast. If i unplug it at 7am when its 100% then it will switch off by 7pm with only normal usage of BBM. No 3G and no apps running in the background. I have tried installing many versions of OS6 but no change in the battery so now I am using latest OS6. Any ideas on how to fix it? Do i need a new battery?