'08 225 ProXS. Had problems that required swapping out PCMs. Since i got my boat back, I not only get a beep when I turn the key on, it also beeps when I crank the motor. It didn't do this before.

All reservoirs, including the one under the cowl are full and I don't get a beep at any other time. My voltage is 12.1 before cranking, drops to 10.5 while cranking, then goes up to 14.1 when the engine is running.

Am I right in thinking that this is a battery problem?

I forgot to say that the battery appears to be the right one and has 1080 cranking amp capacity.