Pretty much what I was gonna say. You can have a battery that will charge up to 13 or more volts but when you place a load on it, ie turn the key, it drops down to 9 volts and won't do squat. Make very sure your connections at the batt are clean and tight, you'd be surprised how a tiny bit of corrosion or being slightly loose can starve the starter of full juice. If you go to a local parts store they'll usually test it for free, Nate
