My battery is 12V 8AH. 2 weeks ago tomorrow of good start engine I tried to start engine but my motorcycle was scrambling to start and I found that my battery may be damaged. Maybe it is useful to know before all the time at start engine once my cluster instrument had being restarted and it seems that its voltage was low. I try to open its cells and fill with acid+water and try to charge it. I connect voltage supplier but all the time battery need more than 14.7V to charge! If I decreased voltage to 13.5 or lower the current dropped to 0.02A from 0.8A very fast. And if I increase voltage to 14.9V its current increased very fast. At the time of charging my battery completely recharged because it couldn't start carefully my cluster instrument even! Is it acceptable one undamaged battery in 0% charge charged with 15v? I sure that if this battery all time want to charge with near 15v for sure alternator can't charge it because alternator supply 13.8v! So I can hope if I charge it till 50% its charging voltage decreased? My opinion is one of its cell damaged but I want to know your opinion.