Mercruiser 3.0 not keeping charge on batter

[Emmywatts]

Hello, I have a 2005 Bayliner 185 with a 3.0 Mercruiser engine. I seem to have issues with the battery not keeping a charge. I think it might be the connectors, but don't know what to purchase to replace them? Does anyone know what type of Connectors I need?

 

[alldodge]

Howdy
Were going to need more info to advise

Need to measure the voltage output of the Alternator when its running.

What is the battery voltage before motor starts, and after motor is running around 1500 RPM or more?

 

[Scott Danforth]

also, once the battery is charged, is there current between the battery + and the cable (motor off, and key switch off)

is there a battery switch?