Did you check static battery voltage ??? That sounds like battery voltage to me. A new Marine deep cyle battery carries between 13-14 volts. They are not a 12 volt battery like a car battery and that's why they require a special marine battery charger.
On the other hand, if it shows 12+ volts and then you start it and it goes up to 13.4, then it may be charging.
Yeah, battery is a new marine 640 CCA. Was reading -12 so I charged it up to 12.40 w/ car charger and then with the new regulator she popped right up to 13.44. Response was immediate, so I like it.
thanks CC