Yanmar 3GM30F rough start

[Blackriverone]

Hi All,

I added another house battery this year and after a night at anchor I started the motor on the house batteries, not the starting battery. the motor was incredibly rough, I think it is because of load on the charging system however before I added the extra battery this did not happen.

It should be noted that starting on the staring battery the motor purred like a kitten.

My question is that by adding another house battery did I cause to much strain on the system? And should the charging system kick in as the motor is rolling over causing a boat shaking rough start?

thank you

[Cheechako]

The extra battery should have not made any difference on initial start. It would make a difference in how long it would lug down due to the alternator putting out full amps for a longer period though.
If anything, the extra battery should leave you with higher voltage each am with identical draw during the night. That could result in less alternator load if anything.

[laika]

I can't speak for every alternator out there, but usually they will kick in a minute or two after the startup. Depending on the alternator rating and that load they are under this will drop the RPMs a bit and cause the engine to idle a bit lower than it did on initial startup.

Did you see an RPM drop and how much? What's the engine idling at? You may just need to adjust the idle setting to bump it up a bit. As easy as turning a screw back by the engine-mounted fuel filter. I've got a balmar 80A alt on my 3GM and the idle will drop from about 875 to 825 after it kicks in.

[Blackriverone]

Thank you i will try that.