Battery

[Rathbj]

I have a 2018 sea ray XPS230 boat starts with both batteries and with battery #2. Starts intermittently on battery #1. Any ideas what it could be?

 

[Lazy Daze]

Did you load test the battery? Check connections for clean/tight, including at the switch?

 

[hottoddie]

OEM battery is know 3 years old. I suspect it's probably gone bad. Has the water level been maintained?

 

[paulswagelock]

Either corroded connections or most likely bad battery. Switch them and see if it reverses, then problem known for sure.