-
HELP!! First trip no charging off House Alternator
-
Keep in mind that Techlink screen is for DC voltage.
Engine not running..
-
Yep, where the white zero is I had what seemed to be a pretty high *green* number as I was monitoring it before it failed!
-
Hey guys, not much time to mess with this today, will troubleshoot more thurs/fri when I am back at the bus.
I do have 2 alternators, the big 50DN for the house and the smaller delco one for the chassis.
We just looked at the relay that the big wire off the alternator connects to: This is an SDLA 150, when we measure this for resiatnace/continuity it is open…so looks like no power passing through it. Googled that relay and it is suppoded to be automatic reset but seems like it is blown….but why? Just old and failed?
This is a shot looking from the curbside engine door, note both alternators and big red wire coming off house 50DN:
-
The main red wire coming off house goes to the SLA fuse/relay mounted on the roof of engine compartment
I have not checked the red wire closely where it meets this fuse, it kinda looks like it has got hot, but it is more like some grunge build up…
Close up of the relay that tests open:
Finally against the back wall is another relay that as Jon points out is probably for the Marathon installed option to “jump start” the chassis batteries if they are dead off the coach house bank. This one tests open too, which makes sense as the “jump start” button is not selected on the dash panel.
-
Since the problem is the house and the 50DN is the house battery alternator, once it is determined the alternator is putting out voltage it is a simple matter of following the flow of current.
I’m not familiar with the specifics of the Marathon system so maybe some who are more conversant with the system can jump in here. But you obviously do not need an isolator or have problems with one as long as each set of batteries has its dedicated alternaor.
-
Okay, G-man, let’s see if we can make some since of what you have or at least some observations. Unfortunately, you have a coach converted by one of the few that doesn’t supply even the most basic electrical drawings, or so I’ve been told. This means you will be doing a lot of tracing of wires and measuring voltage.
You said the red wire is coming from the house bank. It is connected to 300A of circuit breaker protection. Just an observation, that cable doesn’t look rated to handle 300A. From the other side of the twin 150A breakers there are 2 wires. One that goes to teh solenoid and one elsewhere.
Let’s apply some logic to the solenoid and try to determine why it’s there. I can think of only two reasons for it being there and only one that has any merit. Some coaches have a solenoid that prevents the alternator from providing charge current when the generator is running. They claim that the battery charger and alternator will fight one another if both attempting to charge at the same time. That’s BS, so let’s rule that function out; at least I hope so. The more logical function would be to parallel the house and chassis batteries, given they are both 24V. This one is easy to test. Get someone to engage the boost switch at the dash and list for the solenoid to engage. For better proof or to prove the solenoid is faulty, use your voltmeter to read voltage on each side of the solenoid. One side should have chassis battery voltage and the other should have house bank voltage. This is easiest to see when the house charger is on and the engine is not running. If this proves true, then have someone engage the boost switch. With the boost switch engaged the voltage on both sides of the relay should be the same proving the relay has engaged. If you don’t hear the solenoid engage and the voltages on each side don’t become equal them it’s time to test the solenoid. Take the 2 small wire leads off the solenoid and measure voltage between them. It should be zero. Now have someone engage the boost switch. It should be 12V or 24V, depending on configuration. If it is, then the solenoid is not functioning properly.
Okay, if we have now proven the solenoid is for battery boost, then you have to look elsewhere for the problem you’re having with the alternator not charging. I can’t remember, did you test the alternator? I seem to recall you getting crazy high voltages.
-
Wrong Gil, I have good wiring diagrams and drawings, Marathon did a good job proving information and every wire is numbered and easily traced.
-
Gman. Those relays shown in photo with red and blue wires from our experience with Marathon Coach 740, 12 years ago, are called “Clixon” breakers. When ours went south, we had no house charging and the red idiot light came on. They fluttered before things went south. Replaced them, house batteries got juice from the 50 DN. Red idiot light went dark. My two cents.
-
Tom, get it right. I was misinformed. You should know better. You did read that I said, “or so I’ve been told”.
-
I got it right. If you don’t have actual experience or known facts, don’t make comments about something that is heresay. You’re the one that should know better and be more accurate when trying to help someone with a problem. That person doesn’t care about what you’ve heard, he’s looking for accuracy. Just like the Guest charger, you saw one that was fried, but didn’t know what caused it, so you discourage folks about Guest without the facts to back it up. Your beloved Marine Industry buy’s a lot of Guest Chargers, so they can’t be bad…
-
Gman- corrected myself above about the Clixon “BREAKERS”, not relays. Also they’re not resettable
-
Just so there’s no confusion, these are automatically resettable thermal breakers. Don’t read into this that they trip because of heat in the environment, although that can contribute to the trip point. They trip due to heat generated from the current passing through them. It’s best if you think of them as just circuit breakers.
Tom, here’s the reference for the subject thermal breakers: http://www.sensata.com/download/klixon-circuit-breaker-thermal-S.pdf
They are not typically damaged due to over current (temperature) conditions. Like all breakers, repeated over current setting or resetting will eventually lead to contact failure.
BTW, most breakers are designed to trip based on heat (my past expertise in the field, no reference provided).
-
Well Colorado Bus, same symptom I had and you turned out to be correct! Thank you!! (will send you an email soon!)
Replaced the breakers, expensive lil guys, and got charging back straight away on the Tech link and a healthy 28 volts out of the 50DN, but still had red light on dash.
Replaced the relay in the drivers side door for 12v battery relay 33 and that solved the dash light!
Thanks Gil, Jon, Tom and CO bus and all who offered advice. Got the generator cooling hoses sorted today and gen bay all cleaned up, gen running for a few hours to get batteries topped up and test it all out!
I replaced my roached Vanner monitor with a used one but now get a “hi/lo” light on dash so gotta test equalizer and see whats going on with chassis side or if the used monitor I got is funky!
Tom, Marathon told me they do not provide wiring diagrams, and the Marathon tech guy half jokingly said because most people would not be able to read/follow them anyways and that they are all different. My gut tells me if I pressed them I could get one for my coach…would like to have it!
-
Test the 12 and 24 voltages at the Vanner monitor first. I have never had an equalizer go bad, but I have replaced monitors. They have been one of the unreliable components of our coaches.
-
Glad you fixed up G-Man… My drawings are in the large Marathon book binder.
Log in to reply.