I have a 2c 1200 e-tec battery and apache charger, when i charge battery it only charges to 8.26 volts when it is 90% charged and leave it on charger another 30-40 min to full charge but it never gets any higher than 8.26 volts

charger has a red and green light to charge by when you first plug in battery red light is on and charges for approx 1 hour then green light comes on to charge rest of way but it doesn't fully charge, i check voltage comming from charger with out battery hooked up and nothing, leave battery unpluged for a couple hoursand volts droped to 8.18 hooked charger up but won't go any higher, any ideas