I got a boat passed down to me and it hasn’t run for some time. I have done everything as far as changing all the fluids cleaned carbs fresh gas and oil mix etc. I purchased a marine battery (12v 800 crank amps) and the motor turns over yet every time it reaches tdc it almost comes to a halt. Definitely not passing tdc fast enough to get it started. Should I be using 2 batteries? More crank amps?