Battery Full [Q] Galaxy Grand Quattro: battery is fine, just the prob is with the indicator

Galaxy Grand Quattro : while charging it suddenly jumps from 78% to 100% and asks to unplug the charger. When i unplug it it shows 78 or 80% back again !!! I believe that this is related to software issue. So i have done a factory reset, but no use. someone pls help if this is a known issue.. Googled abt it but dint fine anything there.. Thanx in advance.