Operating with bad alternator?

[Richard Scott]

Just went thru a survey for a 2007 Sea Ray 40 Sundancer with Cummins QSB 380 motors. Appears to be no voltage coming from port alternator (readings on gauges). Stayed at 12.8 when initially running, but went down when operating longer during seat trial. (Starboard alternator is charging fine and stayed at about 13.7vdc).

Anyway, I need to get the boat south about 50 miles out of the marina it is currently at to my marina. I have the option of replacing where it is at, and it doesn’t look to complicated. But worst case scenario, can I operate it with the genny running and battery charger on to get it that far? or is that too much of a draw on the battery charger. (ProNautic 1240P) Not sure what the load is of a running QSB 5.9 on the batteries. When running during the sea trial, I noted the gauge was reading appx 13.6vdc with genny running and charger on. Just don’t want to overload the charger with this type of use.

 

THANKS!

Topic

[Richard Scott]

Follow-up

Just a quick follow-up on this. Had to connect both battery banks together to get the boat home in order to inspect/troubleshoot. Did not want to run with battery charger. Turned out the sense/excite wire was sitting in the plug on that alternator but was broke. Casual observation during the survey would not show a broken wire. A new connector fixed that issue. No rebuild or new alternator needed. Just wanted to close this out.

2 users thanked author for this post.

Rob Schepis, Tony Athens

[Richard Scott]

I did not look. My mistake. I had assumed the seller would have no issue with getting a replacement installed as part of an agreement. Now I am up against a hard stop and need to get it out soon. Luckily SB Marine has them in stack, and they look no harder than a truck alternator to change out. Hell, they are a truck alternator. Lol! I’m just looking at worse case scenario in case I am not able to get to it in time.

[Rob Schepis]

The charger should be more than capable for the load — Didn’t you look at the display on the charger to see how many amps it was putting out?

I would just get the alternator rebuilt and replaced before heading out.

1 user thanked author for this post.

Richard Scott

[Author]

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