Yeah that charged fine, its just this one battery I charged it without balancing and it completed fine now at 8.3
Think it must be a loose connection on the battery.
*edit*
I just rechecked with the other battery and its now doing the same with that which is really weird because I charged one battery fine then swapped straight away to the other then got the error. The Charger is an Overlander RC6-VSP and it's brand new Looks like I'll have to return it.