Operating on one alternator?

[Redhook98]

Just bought (almost) a 2007 SeaRay 40DA with Cummins QSB 380s. Looks like the port alternator is dead. Reads 12.8vdc (on the Vesselview) when disconnected from shore power and motor running. No change when revving motor or operating at cruise (2350 rpm) Goes down steadily from there when everything is turned on (RADAR, displays, electronics, etc) and running for awhile. When gen is running while underway, it does up to 13.6vdc.

I need to get this thing about 2.5 hours home (appx 50 miles) in the very near future. Like as soon as I sign for it. Does the motor draw enough amps to damage or stress the charger for that amount of time? (Its a new ProNautic 1240P). In other words, is there any potential damage with running the charger (with gen) to keep a good voltage on the batteries?

Could this voltage reading because of the diode system these things are hooked to drops the customary 1 volt?? Where does Smartcraft take their voltage reading from? I am not getting a ow voltage alarm anywhere.

 

[Siboatguy]

I would just have the Alternator fixed its not a big job. And prob easy to get from local parts store...

 

[ttmott]

The alternator should be around 14 volts.
You will be just fine with the charger running. Actually, it is a charger/converter so, it's a power supply also.
Smartcraft gets it's voltage data from the engine supply voltage. It's actually the same that supplies the Smartcraft system it's voltage; the red wire in the Smartcraft wiring harnesses.

 

[Redhook98]

I would just have the Alternator fixed its not a big job. And prob easy to get from local parts store...

Can't seem to find one out here in enough time. Was going to order from SB Marine, but may not get here in time. I also have a rebuild place in my town. Just looking at worse case scenarios to ensure I am covered. Yes, it is an easy replace, but I can't source one here for some reason that will not show up until after I presumably have to go get the boat.

 

[Redhook98]

The alternator should be around 14 volts.
You will be just fine with the charger running. Actually, it is a charger/converter so, it's a power supply also.
Smartcraft gets it's voltage data from the engine supply voltage. It's actually the same that supplies the Smartcraft system it's voltage; the red wire in the Smartcraft wiring harnesses.

Thank you. Probably what I will end up doing. Then I will just pull both alternators and have them rebuilt locally. The other alternator is putting out 13.5 when running. May be going as well. Strange. Only 700 hours on these motors and excellent maintnence records. Batteries are dated for 6/21 so they are newish too.

I was not aware that the ProNautic 1240P was also a power supply. I thought they stopped doing that when they switched from the old school ferro units. ? Either way, if I keep most all 12vdc devices shut down except the GPS, there should not be much draw anyway.

 

[ttmott]

Thank you. Probably what I will end up doing. Then I will just pull both alternators and have them rebuilt locally. The other alternator is putting out 13.5 when running. May be going as well. Strange. Only 700 hours on these motors and excellent maintnence records. Batteries are dated for 6/21 so they are newish too.

I was not aware that the ProNautic 1240P was also a power supply. I thought they stopped doing that when they switched from the old school ferro units. ? Either way, if I keep most all 12vdc devices shut down except the GPS, there should not be much draw anyway.

You can also jump the two positives of the battery banks together. The good alternator and charger won't care.

 

[Redhook98]

You can also jump the two positives of the battery banks together. The good alternator and charger won't care.

That's another thing I was most likely going to do. Just make it one big battery bank.

Again, this is just to get it home so I can do it right. I am not proposing that this is a great idea. Just want to ensure I do not hurt anything else when implementing this temporary bandaid.

 

[Brite Idea]

I'm not sure if this would be your solution but doesn't running the genny with the battery charger on solve your voltage needs? When I run my genny I turn on the battery charger with everything else just to load it up.

 

[Redhook98]

I'm not sure if this would be your solution but doesn't running the genny with the battery charger on solve your voltage needs? When I run my genny I turn on the battery charger with everything else just to load it up.

Yes, it does. I was just not sure how much of a load the engine running would have on the battery charger. I.e. if the engine was sucking 10 amps just to run plus anything else 12vdc turned on, and my charger was conituousily keeping up with this over a couple hour period, is there any undue strain on the charger?