Alternator Output on start up Mainship 400

[Sailinggod]

Mainship 400 alternator not charging for 4 minutes after start

On my Mainship 34, 6lYA-STP engine, an intake manifold pre-heater goes on for the first 4 or 5 minutes to heat the air intake when the engine is cold to avoid smoking diesel. My alternator shows no charging until this time expires, then fine after that. So it may be by design.
Cheers

 

[thirsty boy]

Alternator

I have a 2006 Mainship pilot. I had that Issue and found out that the heaters were drawing the power. When they shut off, the output came back to normal. I disconnected them and have not had any issues at start up.

 

[rgano]

I have a 2006 Mainship pilot. I had that Issue and found out that the heaters were drawing the power. When they shut off, the output came back to normal. I disconnected them and have not had any issues at start up.

If you have not done so, consider removing the heaters and plugging the holes (Yanmar sells a plug - go figure) because the coils could deteriorate and end up getting sucked into your zero clearance engine with catastrophic results.

 

[gilbertpark]

I have twin Yanmers (4JH DTE) in my boat. When I start them up the charging light stays on for both of them. If I increase the revs to 2000 to 2500 rpm then the lights go off and don't come on again when I go back to tick over. I do have a Victron system but have never looked at the voltage when the charging lights are - I will when I next use the boat.

As its both engines I doubt anything has failed as it would be unlikely in both engines.

 

[Bacchus]

I believe those heaters only operate in cold temps. Don't recall what the temp is.
I pulled mine last year on a 15 YO Yanmar and they looked like new... that makes me believe they don't even kick in at initial start unless the temp is low enough, or they would have some discoloration.

Here is an excerpt from the Yanmar manual that states the air- preheaters' operations are controlled by coolant temp.

 

[davidla]

The heater answer may be the best one in my case. I have noticed that at engine start the amp drawer recorded on the BMV shunt stays high for the entire four minutes. It routinely pulls 35 amps during the whole four mins. Whereas a normal start (on a different engine) might show a dip to 50 amps and then back to nothing immediately.
Thanks all