No power from alternator , just started leaving campground

neoneddy · July 24, 2018, 10:04:48 AM

Heading out from gooseberry falls this morning I noticed my Voctron monitor didn't show a good charge coming from the DC side.

We had been making good power from solar all morning, so we're not stuck stuck, but no AC on the road.

I checked the battery connection, looked good , checked the voltage regulator, I see there is a button to press, it was in.

Any ideas? My volt meter was left on I guess (me) so it's dead at the moment.

Update: I'm leaning towards a diode replacement, looking for ideas on best practices and where to buy. Hoping NAPA sells them.

neoneddy · July 24, 2018, 10:49:51 AM

Checked the relays in the back, specifically the field relay. It was clicking.

luvrbus · July 24, 2018, 10:59:09 AM

Check the Field on the alternator it should be magnetized,those are not hard to trouble shoot about the only thing that goes wrong to prevent charging is the diode pack goes bad

neoneddy · July 24, 2018, 11:02:10 AM

How can I test that? Running or not?

luvrbus · July 24, 2018, 11:12:11 AM

Quote from: neoneddy on July 24, 2018, 11:02:10 AM
How can I test that? Running or not?

You do it with the engine running or not running the field requires DC to make the magnetic field,if it is magnetized check the diodes on the rear of the alternator

eagle19952 · July 24, 2018, 11:41:56 AM

Quote from: luvrbus on July 24, 2018, 11:12:11 AM

You do it with the engine running or not running the field requires DC to make the magnetic field,if it is magnetized check the diodes on the rear of the alternator

yup, just hols a screw driver/pocket knife to the axis point of the rotor shaft. if it sticks, it's the diodes or that which energizes the field .

neoneddy · July 24, 2018, 11:56:06 AM

I opened the access hatch in the back under our bed and poked at it with a few metal items (hammer, wrench, etc) nothing was sticking. I tried it with engine off, master switch on and then when running, still the same.

I have a small string of 24v led lights I could use a simple " power / no power" indicator. Are there any tests I could perform at the regulator? (inside back entry door bay).

Seems like one way or another, there is no field fix for this. We could cut our trip short or just roll on with no AC. Solar panels (1950 watts) are keeping us topped up for the moment.

One last thing , if it matters. I've attached a screen grab for our DC power monitor graph. It shows us making good power and tailing off as the batteries charged until we stopped at our camp site. Would something like the fields just stop working suddenly? To me that seems more like a relay or something else.

eagle19952 · July 24, 2018, 12:05:40 PM

Quote from: neoneddy on July 24, 2018, 11:56:06 AMTo me that seems more like a relay or something else.

me too.

neoneddy · July 24, 2018, 12:46:58 PM

So, with the engine running, I took my test light and checked the Field wire and the positive wire on the voltage regulator, both were making power. Does that tell us anything? I'll try and find a store to get a battery for my multi meter at the next stop.

luvrbus · July 24, 2018, 01:06:25 PM

Ok if you have power to field the relay is working,the way those work is the diodes turn the AC current to a DC current,I would guess the diode pack is bad,you can check the field winding with a meter if they are good it will read between 3.9 and 4.2 resistance,that is a gear driven alternator right ? and it is spinning

Lee Bradley · July 24, 2018, 01:57:11 PM

If I'm reading the posts correctly, you have power to the field post and no magnetic field. That nothing is attracted to the case. I would disconnect the field wire and check for current draw. The field coil should pull about 10 amps if no draw the field coil has an open somewhere.

neoneddy · July 24, 2018, 03:08:39 PM

I don't have a way currently to measure the draw on that wire. However I did notice a change in engine pitch when I connected and disconnected the field relay. Similar to how the engine would not down a tick when you put any other electrical load on it.

I can't tell for sure if it's spinning as it's gear driven.

Also good news, an air bag spring a leak.

Lee Bradley · July 24, 2018, 04:04:37 PM

The solar on bus will shut down the alternator when the batteries are at full charge. The solar system on bulk will run at 28.8 volts and the bus system is at 27.5 so the solar voltage is high enough that the regulator shuts off the alternator. Charge light comes on and the tach quits. Try running the AC to drop the system voltage and see if the alternator powers up.

neoneddy · July 24, 2018, 05:30:21 PM

@lee I've had that before , on my monitor I can track exactly how much the alternator is contributing.

Solar brought me from 52% this morning to 85% this evening, it's combining both systems, house and coach.

@everyone , the Mrs noticed the DC system contributed a little here and there. So there is that, I've never been able to measure it. I did get new battery for the multimeter. I'll start following the rabbit trail this evening and tomorrow.

neoneddy · July 24, 2018, 06:05:33 PM

New question for the audience.

http://www.delcoremy.com/The-Latest/2013/March/Tech-Tip-Flash-the-Field

Could this have happened? I'm not seeing any magnetism.