To start this off, I bought a c&d 135ah batt from him in March, when I got it I put it on the charger to make sure it had a full charge. Well it jumped from 12-15 volts also instantly. Being the Noob I was I thought **** that's normal. But now with my research and experience, I bought a xs power d3100 and never had a problem of anywhere like that. Same charger also. So I contacted boom after buying it and let him know it was a bad battery. His response was that I must have ruined it and there's nothing he can do... This was a while ago and being the good guy that I am I tried to work it out with him. But nothing. Now he won't even reply to my texts or messages on here. If wondering I had a 240 amp alt.