DN50 Alternator

[gus]

I'm the proud new owner of a DN50 Alternator alternator attached to a 4107 but I need some expert advice.

The volt meter and lights flicker when the engine is running, not much but I know this shouldn't be happening..

I think I remember sometime back someone said this is caused by failed or failing diodes. Is this correct? I hope that is the only problem since it appears to be a straightforward replacement job.

I'm amazed that the diodes are  encased in alt cooling oil!! This 8V71 and DN50 Alternator is a total experience to me after owning a 4104 for five years.

[bevans6]

If the batteries are fully charged and there is no load on the system a typical DN50 and it's regulator will switch in and out, and the no-gen light will flicker on MCI's, so something like that might be happening on your bus.  You can take the back off the alternator and test the diodes with a good  digital volt meter.  The voltage is regulated by an external regulator, so if the voltage is truly varying I would suspect that as well.  Also, I might not rely on testing at idle speed, high idle would get the alternator spinning up and producing electricity in it's designed speed range.  There are good manuals on line at the delco remy site.

Brian

[gus]

Brian,

Thanks, that's just the kind of info I need. Doesn't look as if I have a problem after all - very good. I noticed the headlights flickering while at idle.

The bus has been sitting for over a year so I kind of expected some things not to work.

I think the regulator is relatively new.

I just bought the bus and haven't driven it over 50 mph yet but the voltmeter seems to flicker no matter what the engine  speed. I'm about to drive it 500 mi home so didn't want to start out with electrical problems.

Any other ideas or thoughts will be appreciated.

[Rick59-4104]

 My 4104 has the DN50, at an idle or low RPM's I get some flickering of the gauge, at highway speeds it stops...
Rick

[robertglines1]

possible corroded ground connections on battery or where ground from battery attaches to coach.Simple minor tighten might correct but should be eventually cleaned . wires on voltage regulator slightly loose or corroded

[Boomer]

Brian is right on.  Increase the RPM and put a load on the alternator (lights, A/C, etc.) and the problem should cease.

[gus]

I just got the bus home after three days on the road. Funny thing, the flickering stopped for two days then today, the last day, it started again. I'm sure the batteries are pretty well charged by now but road speed or load didn't seem to make much difference.

I did notice that the battery grounds to body are pretty corroded, that could be the whole problem right there. Now that I'm back to my shop I'll now be able to get at some of those problems. The drivers elect panel also has some pretty badly corroded terminals just like my 4104. Deja vue all over again!!

Thanks again to all. Just about the time I think I know the 4104 along comes a 4107!!

[gus]

I cleaned up all the battery grounds (they were pretty rusty) but now there is a new situation.

When I first got the bus the three batteries were not well charged. Now, after much converter and engine charging they are very well charged.

So, now the (New) generator solenoid at the driver's electric panel clicks on and off at a pretty high rate, especially at low speeds. However, when I load the electrics with the big bus heat fan motor or the marker lights the clicking stops.

Am I on the right track thinking the batteries are so well charged that the 300 amp DN50 is cutting out because it has nothing to do?

I'm used to a 100 amp truck alternator, all this extra power is new to me.

[Gary '79 5C]

Gus,
I had the DD50 for four years and never had a flickering no gen lite or voltmeter fluctuation. The voltage did dip to a low of 24.5V when idling(non fast). Back to 27.5V when driving. Just my experience, not to contradict Brian.

I have since changed this unit out for a J180 truck mounted 24V alternator. Smaller, lighter, all that I need.

FWIW, Mine did not have the orfice to reduce oil flow thru the alternator and upon changing to the smaller, non oil cooled, my engine oil pressure increased.


Gus, also start eating your Wheaties if you plan to extract that DD50 any time soon, heavy.

[luvrbus]

Blanchard Electric has a aftermarket regulator that will stop the flickering on a 50D cost around 250 bucks fwiw


good luck

[Busted Knuckle]

Gus,
I have seen the same problem over and over on the older buses with the 50 DN. Almost all our all older MCI's used to do the same thing. My dad & uncle just told all the drivers to run the lights all the time #1 for safety by making it easier to be seen (ah yeah like if they have problems seeing a bus, the lights are gonna help!) # 2 to "load" the altenator.
Always worked for us.
  BK 

[Sean]

I agree with BK.  And, yes, this is the symptom of fully charged batteries with no load.

We are adamant about running with the lights on all the time anyway, for safety.  I put a big red warning lamp on my dash, which is lit if the engine is running but the lights are off or vice-versa.  This way I can choose to have lights on or off regardless, but the light reminds me in case I just forget.

-Sean
http://OurOdyssey.BlogSpot.com

[gus]

Thanks guys, I'm learning more all the time.

Maybe the problem exists mostly with 12v versions?

Since I'm a cheapskate I don't know if it is worth $250 to me to stop the flickering!!

One other thought I had is that the new solenoid might be a momentary starting solenoid instead of the constant type. An easy mistake to make since they look so much alike. I need to check that out.

In my opinion daylight lights were once probably a safety factor but now that most vehicles have them the advantage is lost.

I've learned to be very wary of auto drivers when driving my bus even though it is this tall, solid white monster which should be super easy to see.

One of the shocks to me when I first started driving a big truck was that it seemed as if more people pulled out in front of me than when I was driving a small vehicle?? I finally decided it was because a large vehicle appears to be moving much slower than a small one and drivers think they have move time.

This is a lot more obvious when you compare small airliners landing at the same speed as very large ones, the really big ones seem to be floating in even though they are landing at the same speeds!

[Tony LEE]

Yes, I also get the occasional chattering of a relay somewhere in the bowels of the dash - when idling after a long run. Switching the low beam headlights on fixes the "problem".

24V system with the oil cooled alternator.

[gus]

Tony,

Thanks. Forgot to mention that mine is oil cooled also and 12v.

My solenoid is right next to the driver at the left wall where the major electrical panel is located.

The clicking is annoying, but from all these posts, not a real problem - much to my relief!