I connected an external USB 300GB HDD to my Macbook Pro this evening and strange things started to happen, like Apple logo failed to pop up. So I took out the HD usb cable and switched off the Mac.
On OSX coming up I reconnected the USB Device and the battery suddenly went from 36% down to 0% charge.
I soon realised that the USB device had changed the state of the battery. The battery was saying Service, I plugged in the charger and it started to charge from 0% but I new it should be saying 36%.
I decided to reset the SMC and then the PMU.
After doing this OSX still reported the Service message until I pulled out the power lead and ran from the battery where it said recalculating charged percentage.
I then reconnected the mains lead and the battery state returned to normal.
All this was caused by an USB device.
On OSX coming up I reconnected the USB Device and the battery suddenly went from 36% down to 0% charge.
I soon realised that the USB device had changed the state of the battery. The battery was saying Service, I plugged in the charger and it started to charge from 0% but I new it should be saying 36%.
I decided to reset the SMC and then the PMU.
After doing this OSX still reported the Service message until I pulled out the power lead and ran from the battery where it said recalculating charged percentage.
I then reconnected the mains lead and the battery state returned to normal.
All this was caused by an USB device.