Battery %

The battery icon on my 15" Retina Macbook Pro is telling me that my battery is 100% charged. This is the OS X icon which is there by default.

However, the FREE Battery Health app available on the Mac App Store is telling me my battery is only 97.9% charged. The iStat Pro widget I have installed is telling me my battery is also 98% charged.

The power cord has been attached to my computer constantly the past few times I've used my Macbook Pro and yet it seems by battery isn't actually reaching 100%.

I am going to try and callibrate my battery by allowing it to run down to 5% and then charge fully and see if this changes anything. Just seems odd the OS icon is telling me one thing, yet apps are telling me something else.

Not a major problem, just a strange annoyance triggering my OCD tendancies and just wondered if anyone else has seen this happen with their MacBooks.

Thanks in advance in for your help.