alternator problem

[Dick Simonis]

This is a Powerline link. They seem to use heavier components and support higher temperatures. They may have a more efficient alternator fan design for diesel pusher configurations but they did not mention it. Dick has a good point here and it is well worth a check with them, especially if they have built a specific configuration for the pusher design. Anyone who does marine components certainly studies reliability and strives for providing a long life.

http://www.hdpsi.com/24HD%20Series%20Alternators/24HD%20Alternator.htm

The boat environment is terrible for corrosion but heat wise it is actually quite good. The exhaust is a wet exhaust, the engines are small displacements and they use wet heat exchangers. In addition they constantly pull cool air in from the deck vents to feed the air intake. The current demands are high but the temperature of the environment is probably quite stable compared to our pushers. They also tend to run the diesels at a constant high cruise RPM range which helps with all of this alternator fan cooling flow. Hope there is a pusher design....

Later Ed

Ed, you may be thinking more like a powerboater.  We seldom ran our engine at cruising speed unless we were charging batteries than it went off.  Most engine running time was used at anchor for charging batteries and we'd cram as much power as possible in the shortest period of time.  In fact our Powerline had the smallest pulley available so it would put out max current at the lowest possible RPM...just a little above idle. It was common to see the DC output in the 100A to 130A range when charging batteries and powering the 2,000 W inverter to run the microwave and etc.

 Also, the engine room on the boat had no ventilation except for a cowl in the cockpit and the engine (3-53 detroit) ran at ~200F pretty much the same as our Cat.  Granted the exhaust was water cooled but everything else was the same temp as our MH.

I can't speak for all DP's but our engine room seems quite cool when I pop the hatch after a run.  

Just saying, the way we need to run out alternators just does not seem right.

I believe Powerline has differant fans available for, as you know, engines like our 3-53 were quite content running in either direction.

[Keith Moffett]

Ed and all
Thanks alot for all the suggestions.  Some great info. on what to look for and I will go back over the connections, fuses and so on.  Mostly its nice to know that it may not be something I didnt do or did wrong.
Keith

[Bruce Benson]

A couple of notes on short alternator life:

Using the inverter at a high current flow rate while driving (i.e. cooking in the microwave or convection oven) has not worked well for us.

Connecting the two smaller wires (14ga or so) incorrectly on the alternator has not worked well for us.  Check the installation, one wire is always hot and one is switched by the ignition.  Consult the WM schematic and be certain you have it wired correctly.  Clue - the alternator should never be warm after sitting overnight.

We have found that the alternator is easily rebuilt and the price has been the low $200 range.

[Edward Buker]

Dick,

I was thinking of my relatives motor sailer. He ran the diesel to maintain hull speed with sails up and he also had a compressor on the engine for refrigeration cold plate, so the engine ran often. The diesel while running pulled a lot of air that gets exhausted out the wet exhaust after combustion. The engine room maintained a workable temperature under relatively constant conditions. The 3-53 you had pulls over 200cfm at 1800 RPM which provides constant cool air intake to the engine room. You probably ran lower RPM but you get the idea.

I do think our DP engine compartments are well ventilated, especially at speed. I do think that when we have run hard and come to a stop or are at low speed the exhaust manifolds radiate a lot of heat and at that point there is little air flow around the alternator. This is probably the time that we get a peak heat cycle while under a charging load. I think if we had a big fan running in front of the alternator, proportional to the engine rpm, it would make a difference in not having periods of very high temps.

You are right, that having to be conservative in the way we run these alternators really means they were not designed for the larger constant loads that big battery banks represent while suffering the alternator cooling capability of a diesel pusher configuration. They are just adapted for our use given they were available. Good thing our heart lung machine in the later years does not rely on one of these :-)

Later Ed

[Keith Moffett]

A final update on this;
The shop that rebuilt the alternator a few days ago also went through the charging system, batteries and connections finding no problems.  I had them look at the batteries and draw test them as severely as possible but they held up fine.
Turns out that the 10 ga. wire connecting the diodes on one bank was out of position and rubbing on the stator.  When this shorted it took the whole unit.  
I had called Leece Neville who refered me to their lead tech where I left a message.  He never called back.  Dont have much hope for compensation there.
The shop also tore apart the original alternator and the same wire was positioned only slightly differently.  I wonder if this might be a common cause for alternator failure in our coaches.

Keith

[Joel Ashley]

On our old coach, when I replaced the alternator, I did so with a Powerline unit from Camping World.  I think very highly of their product, and would also recommend Powerline as an option, like Dick and Ed do.

Joel