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HELP!! First trip no charging off House Alternator
Hey all, left Prevost last night maiden voyage home, all was well, couple days ago noticed red light on dash, top, above battery light…it went away.
Last night did 140 miles, batteries according to Techlink showed charging, all good…ran off batteries last night, today got the light again, had intermittant charging going down the road now nothing! Light is on full time on dash. I do understand that light is for house alt according to Marathon, I suspect maybe regulator as it has been kinda intermitant.
I am no electrical guru and only have some of my tools with me, to make matters worse I hve a small cut on my generator flexible coolant line so do NOT want to run that….have auto gen disabled at inverter.
I just bought a cheap multi meter at a camping world I pulled off at, all connections except possibly one on house alt look good.
1st question…..What can I test?
My options are to continue 400 miles home where I can sort it out or try and fix myself, if regulator is roached not sure what I could do about that on the road!
2nd questions, right now house batteries are at 12.3 and 24.4 pulling 8 and 1 amps respectively…..if they get too low can I just kill battery power in the bay and just run home….dont care if fridge gets warm…..
Thanks for any advice……ahh the FUN begins!!!
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37 Replies
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What is your alternator set up? Do you have a dedicated house alternator?
Generally if a coach does not have OTR which I suspect is the case with yours you wil have the large 50DN as the house alternator and a second smaller alternator for the chassis.
The 50DN is easy to check, and since the regulator is external if it is found the alternator is OK changing the regulator is a simple operation. Do you feel comfortable doing electrical checks?
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Jon, yes 50 dn massive oil cooled for house, smaller for chassis.
Do I feel safe doing electrical test….hmm…well my dumbass just fried the Vanner monitor in engine bay I think (or it was already roached) More on that later…. ( I understand monitor is for chassis and inconsquential)
Yeah I think I can do a quick test….I had a look at connections and they sem good except for one which looks a little dodgy…I think it is the field one???
But if you can walk me through anything would greatly appreciate it.
Just fired genset and hose is weeping pretty good, I can do a quick patch job field repair with some hose clamps I am sure but would rather not run it until I can properly replace the hoses!
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Jon, is proper procedue to disconect the field and then test positive to field (NOT the gorunded one) to see if alternator makes voltage…?
Not sure I have a thick enough gauge wire to feel safe doing that…probably try and just get back to home base where I have all my resources…I really hope the alt. is ok….looks like a bear to replace!
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Yes, that is the procedure. If you have the field hooked to the positive 24 volt terminal your alternator voltage should ramp up in an uncontrolled manner. Obviously disconnect the jumper before it reaches 30.
If you toasted the Vanner for the chassis (how do you know? it might just need to have the CB reset) you really do need it. Your lights are 12 volt, your DDEC may be 12 volts and you may have lost the ability to maintain the 12 volt charge.
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Jon, thank you so much for the help…truly!
So the Vanner EQ is ok, just the vanner *monitor* (EM70D) I think which is just the tell tale device for the chassis…and pretty sure it is fried chicken now, smoke rolling out of it…has two 3 amp inline fuses going to it, 24v one is toast. I read another thread on here that it also happened to someone else.
All chassis electrical ok and charging fine according to VMSpc going down the road, green light on Vanner equalizer when engine running.
Have gen running now and its not spitting coolant so cooling things down (its a 100* in CA) and charging house batteries while taking a break, my inverters say charging is in bulk but my techlink screen does not showing charging amps….just batt at 13.3 and 26.1 now…
Have a lot to learn on the electrical side of things!
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G-Man,
13.3 & 26.1 is equal to float voltage. Maybe someone has cut back the charging voltage on your Trace’s. You have a lot going on, the best bet would be to try to fix the gen leak so you can get your house back, but with the gen running now and showing bulk, you should be seeing about 14.4 – 28.8. That’s why I think your inverter charge settings have been adjusted way down, they could be at 7.5 each when they need to be at 30 or at least 15 for full tilt charging assuming your other electrical loads are not too high.
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Tom, had all 3 a/c’s going and am sure fridge was running and maybe a few other small loads, not sure. Marathon told me at one point few days ago when I had a issue with Techlink that when they set up the trace inverters they had them built to Marathon specs with a few chips inside (iirc) so am wondering if I reset the Traces to factory default does it get me back to how Marathon wanted in from the factory?
Will be back home tonight and can sort out generator easy, can hook up to shore power but only 15 amp…so that will probably only be enough to run very light loads and hopefully charge the house.
I will get alternator tested this weekend and hope it is just the regulator.
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G Man I have new 50DN if u need one
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Peter, you are a Prince! But!
Alternator is putting out juice, about 70 v at idle 90 + at high idle. have 25v at ign source on regulator but I think my buddy who is helping me said the relay is NOT closing….the relay that the house alt. connects to, it is mounted just to the left of the regulator.
Going to do a bit more testing and report back.
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Very curious about the relay and what activates it to charge the house batteries from the alternator…I think I searched an old post where Tom changed the regulator but also found the relay to be bad and had to replace that to get power back to batteries from alternator.
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The voltages you state confuse me. I would expect to see voltages more like the range of 24 to 28 volts.
But, assuming there is no isolator, but there is some means of separating the two banks when the alternator is not charging I would look for a relay circuit. One of my previous coaches had a 4th terminal connection on the alternator for a relay which was nothing more than a solenoid like the firewall mounted ones on old cars. When the alternator was not charging the circuit was open, when it was charging the solenoid closed allowing charging current to the house. My later coaches had an isolator.
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With voltages of 80 or 90 I would look first at the main cable coming off your alternator. The one that is as big as your thumb. It has a sleave over the last few inches. The cable can break and the sleave can hide the break from sight. You can feel it though. This will cause eratic voltages like you are seeing.
I only know this because I had it happen to me. It may not be your problem but worth looking.
Davy
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G-man,
Not sure if this will help or not… I have an 07 Marathon and have had house alternator issues off and on for the past year…
On you tech link house Battery screen when you have the bus running and some load on the house side.. like an AC or two or the convection… does the lower right Charging value have a number in green? If it does then the Alternator is working… if it doesn’t you might have a problem. From what Marathon has told me that value goes up and down based on what you are using inside the coach while running down the road mine goes from 0 when I have nothing much on and just unplugged to well over a 100 if we have a couple ACs and are using the micro…
The first two times I had issues it was a bad connection on the relay wire on mine it’s purple and on the back of the alternator.
Good luck and hope that helps a bit
Bill
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Bill that is helpful, I will take a look at that wire. Last time it worked it showed erratic charging voltage of about 230-255 amps or so then quit and light on dash came on.
Light was also temporarily on dash for a very short period of time a few days prior when I was inspecting coach.
So…it seems something is dodgy, a wire relay not sure and unfortunatly I have no time next few days to dig into it, but will later this week. I am curious what activates the relay to have the alternator charge the house….inverters play any part in this?
Thanks Glenn
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Glenn,
I am not by any means an expert on this but from what I have been told is the house alternator output is determined by usage or draw… We have been in Canada and Alaska for the last 2-3 weeks and not running any roof air or much more than lights and a TV or so and my charging has shown 0…. But as soon as you turn on the roof airs, convection oven it increases… you might also check the connections of the voltage regulator on mine its passenger side near the chassis batteries.
Hope that helps and you get it figured out.
Bill
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