Mastercraft x-45 Voltage sensitive relay on starter?
 

Trying to trouble shoot an electrical problem.
It’s on my second boat (2007 mastercraft x-45)

When running the batteries seem to get a little low (even though volt gauge says 14.5). Once the batteries appear to be low the engine idles a little rough and is prone to stalling. The starter will not engage with the key switch. The solenoid makes no sound. If you jump it with some pliers across the starter terminal it turns over with full force. The problem is very intermittent and frustrating to track down. I have dual batteries and a perko switch. My question is if anyone knows of some voltage sensory relay that might make it so the voltage from the key doesn’t make it to the starter if it thinks voltage is a little low.

check your alternator output ( probably ok if your seeing 14.5 volts) and check your grounds ( start by cleaning them)