Electrical issue

[Timbo]

Good morning all, I have a crazy thing going on with the main power coming up to the console. When I turn things on they are fine but if I go to start my starboard engine I loose everything the engine will start to turn over but then stops I will have no power to anything for about a minute then things will start working again. I checked the battery connections and all is tight and no corrosion I'm a little stumped, my port side engine starts with no problem. Any insight to what may be causing this issue would be great. Thanks

[biggerseagar]

You might looking a the connections at your circuit breaker for your starboard engine.

Roger

[Timbo]

Would that cause all my things to go out or just the motor not to turn over.

[biggerseagar]

It would cause the motor not to start.

[Timbo]

That's what I thought, how likely is it that a battery switch could go bad.

[mmwjr]

The starboard battery provides power to helm so it the voltage is dropping off it all drops off. Put a volt meter on the battery and check it voltage while someone tries starting the engine if it drops to 10V or less the battery is bad.

When you checked the battery connections did you check the negative battery cable where it attaches to the engine? Often overlooked.

[Timbo]

If I put the battery switch to both wouldn't that eliminate the low battery thing, I can start my port engine on either bat one or bat two. If the battery was weak wouldn't it crank like real slow and then die. When I try to start it spins fine for like 5 seconds and then just stops dead and everything is dead at that time but the port engine still cranks with no problem while everything else is still dead. This is why I'm baffled so much.

[mmwjr]

Return (ground) to is common to the switch so if lose, corroded it will impede starting. A bad connection gets hot real fast causing an increase in resistance and reduces current flow.

Check ground connection to block.

Other common points are the slave and starter soleniod which can develop pitted contacts over time but I would not expect the helm power to drop off with these.

With dual engines you can swap part between them if you suspect anything else to test before replacing.

IMO start with the ground.

BTY if one battery is bad and the switch is set to both the bad one will drag the good one down so using the both position doesn't always work however switch to batt 2 should if batt 1 is bad.

[Timbo]

Well checked all battery connections one seemed loose so I tightened it, checked all other connections all seemed good, the funniest thing is before I did anything I tried starting the engine and it started and ran fine. I let her run for a good twenty minutes or so with no problems, I did notice my volt meter jumps a lot on the side and if I turn the blower on it drops below 12 volts on the gauge.
Having the marina check it out this week I will keep you all posted as to what is found.
Thanks for all the help hopefully I fixed the problem and they find nothing but I have a feeling its going to be a few more boat units out of my pocket.

[shrew]

This sounds like a simple draw issue. IF you have a bunch of things running, then start the engine on the same battery, the surge in cranking amps could cause a voltage drop and the devices to shut themselves off. This occurs to me if I start my GPS and Radar before start the motor.

Solution. I shut off all the 12 volt devices, then start my motor, then start things like GPS and Radar.

[Timbo]

OK the marina tested all the electrical systems and everything is good but they found that the circulator pump was leaking a little bit and that the oil lines were starting to leak. All in all I guess I shouldn't complain after all I got the boat for a song and with what I put into it I still haven't reached the fair market value.
Thanks all for the input.