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Voltage Regulator and Geny Battery Isolator
Happy New Year everyone!
taking the bus for a quick trip the week before last I discovered I had two issues that were not found during the PDI and my testing..
First one is spent the night on inverters and had auto gen turned on… batteries got low… auto gen engaged and tried to start the geny but it wouldn’t turn over…. started the bus and it started right up.
PDI had local techs test the isolator diode and it tested low/bad so they sent me a new isolator and I was going to either try to swap it out myself or seller said he would cover the expense.
Second problem was voltage regulator crapped out and wasn’t charging the 24V side of the house got a warning light called marathon and took it to my normal service place on the way home…. as we were trying to trouble shoot it the regulator cracked and basically started to smoke/fire…. we killed everything and disconnected it and they sent me a new one of those as well
I am not very mechanically inclined so not sure if it makes sense for me to try to swap these out myself or leave it to the pros….all kinds of warning labels about the proper disconnect order for disconnecting the batteries and I am assuming that they need to be disconnected before swapping either of these units out.
I was able to remove the curb side vender this morning and access the battery area… so is the extent of me getting my hands dirtyt on this one but I have only had it for a week or two…
Thanks
Bill
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18 Replies
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Bill,
Not sure the isolator has any effect on your batteries going down while camping, I’m sure Jon or one of the Marathon guys will jump in here. As for the regulator, unless it’s complex, it’s not that big of deal. Tape or isolate the connectors and be sure to replace the wires in the correct location. If there is a jumper, be sure not to miss that, you can see it on mine.
Mine is pretty simple (12v 300 amp alternator) yours being 24v is most likely different.
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Thanks Tom…. I went ahead and changed out the battery isolator tonight after talking with the Tech that helped me with the PDI and coach training…. I then turned off shore power and loaded up the house to deplete the batteries and test if the auto gen would start. Auto gen was turned on on invertor #1 and I got the low battery before the auto gen even tried to start this time…Last time it tried to start but gen wouldn’t turn over…
So as soon as the low battery lights and beeper went off.. I tried to manually start the geny and it wouldn’t turn over….
I tested the voltage of the geny battery and it was 12.89….(which is normal right) so I am no expert but it appears the isolator did it job as the other batteries were well below that…. so perhaps my problem isn’t/ wasn’t the isolator after all…
Any suggestions on what to check/test next… I am kicking myself that I didn’t do a test of this during my overnight on the PDI…. when I was where someone could trouble shoot and fix it…
Thanks in advance for any help anyone can provide.
Bill
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with 12.89 volts in the gen battery, it should fire right up. Does
it attempt to turn over or are you getting nothing? I’m not familiar
with the gen setup on your vintage. If there is no attempt to even
turn over, then you have an electrical glitch somewhere. I assume the
start function at the gen is on and ready for action. Boater Al has a
Marathon and his setup may be the same, even though it’s an XL2.The LBCO, low battery cut-off should not be happening if the
auto-start parameters are set correctly and the gen is functioning.If the gen won’t start manually, none of this matters. You’ll have
to get the gen running manually before you can make any anto-start
adjustments.Not knowing what inverters you have, most are adjustable for
either percentage of discharge or a specific voltage such a12v to
start the auto-start. Marathon may have a default setting that can’t
be changed, usually too low in my opinion and the LBCO will be lower
than that value. -
Good morning Bill,
Check the connector (white ) behind the control panel on the generator. As you look at the big black box it would be on your upper right corner. It needs to be pushed in tight.
Hope that’s it
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Al,
Thanks for that suggestion… I pulled the geny out and I think I see the white wires there seems to be a bunch of them the connection seems good to me.
I went into the coach and it starts right up this morning from the cockpit or at the geny…. The problem seems to be when the house is drain or the bus isn’t running….
Tom said the 12.89 last night on the geny battery should have been enough to fire it up… Anything else I can check? or test?
When I was in KC the other week the auto gen engaged and at least tried to start the geny last night it didn’t even do that…. To Tom’s question when I manually tried to start it…. I just heard a clicking noise like it was trying to start…. as soon as I restored shore power and let it sit for about 5 minutes it fired right up….
There is a 12V disconnect in the Geny bay… it was on which I assumed was the correct postion… when I turned it to the off position the LED on the Geny control box hour meter etc… when dark
Thanks for the help!
Bill
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Bill,
That wire “gang” into geny (white connector ) is the mother line for all gen functions.
Making sure that connector contacts and connection is 100 %…. it’s worth a extra look see.
AL
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Al,
I Just checked it again and it appears secure…. I tried to remove it and reconnect it but I couldn’t get it to come off and didn’t want to damage anything.
Do you or does anyone know if there is more than one path for the 12V to the geny… I clearly am a newbie to all this Prevost stuff but what I can’t figure out is this:
1) geny starts perfectly when house batteries are at our near full charge
2) geny starts perfectly when drive engine is running even if house are depleatedEven when house batteries were depleated last night… Isolated Geny Battery tested 12.89
I need to give Marathon a call in the morning to confirm the connections on the replacement Voltage regulator I need to install…. so perhaps they can shed some light on the Geny Auto Start / start issue as well.
I was hoping my first minor Prevost Repair was going to be uneventful….. Oh well I did get the vender off 🙂
Thanks for the suggestions everyone… Happy New Year!
Bill
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So, if I read this correctly, if house batts are good, gen starts. If main engine is running gen starts, but if neither is good then gen is a no go?
If so, the gen battery (or connections) must be bad even though it has voltage, it may not be anything but surface voltage. I assume that you have a way to tie into the house batts as well as the starting batt for gen set? It would appear that is the case as it will start with the above listed requirements. You must have a switch that is allowing the house to power generator starting circuit. When main engine is running, it is flowing volts to house, so that is probably why gen will start.
On my Legendary, I can tie into house circuit for starting as well as dedicated generator batt.
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Bill
I’am not at the bus.
There are two (2) switches on the left side of the gen black box. Memory recall …… both must be in up position.
These are sort of out of the way and can be unknownly tripped while working in the generator compartment.
AL
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If you throw the house batteries disconnect what happens to the LED gen control box light? Probably goes out. Sounds like you may have bad gen batt (if you have one) and bad house batteries, since you need shore power or engine power to start the generator.
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Greg,
Great Idea…. I just tried that I killed both the 12v and 24v main disconnects as well as the emergency 12v constant disconnect and the geny LED panel remained on and the geny fired right up from the switch on the generator.
I do have a isolated geny battery and all house batteries and I believe the geny batter were replaced in August by Marathon in FL…
So now I am really confused 🙂
Perhaps it’s not a battery issue but something with the setup of the auto gen… but the crazy thing is when the house batteries are in a deplated state to test the auto gen… the generator would not start manaully from the Geny control panel…
Bill
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Bill in the house battery compartment do you have a master switch for the House batteries? If so you need to switch that one off and see if the LED light goes out. I am thinking that the your generator battery is connected to the house batteries and when they get depleted so does the generator battery. If this is the case maybe you should find and disconnect that link or at least put a switch between the two battery systems.
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I have seen three set ups for generator start batteries. The first was no dedicated battery, but a connection to the house batteries, with a means to tie the chassis batteries into the system if thehouse batteries were depleted. The second was a single battery, charged by the generator alternator and isolated from all other coach batteries. The third was a dedicated generator battery tied into the house battery system but with an isolator in the line between the house and generator batteries so low voltage house batteries did not draw down the generator battery.
I have never seen a generator batery set up so it could be depleted by weak house batteries. There has always been an isolator or automatic disconnect bwetween the two.
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Jon,
I have option three… a dedicated battery for the geny that is isolated from the house batteries… I removed the battery and took it to two places to have it tested and it tested “bad” in both places eventhough the voltage was 13.10 and 100% charged…
We tested the remote start from the invertor #1 panel and it controlled the geny perfectly so my guess is the battery isn’t good… although it’s a lifeline that was just put in service in August by Marathon according to the markings in the battery bay…
Bill
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Guys,
a bit of an update on the never ending saga here… In the process of trying to get a replacement battery… I had another shop test it and they said the battery was fine… the testers at the typical autoparts place aren’t setup to test glass mat batteries apparently…
It was suggested to me to test the voltage at both sides of the 12V geny disconnect as well as the starter to eliminate the disconnect as a potential problem. I did that and the voltage is consistent at all three places…
The gen battery is showing 12.91V at the battery… at the disconnect if the shore power is disconnected it shows 12.67 which will not turn the geny over… if I plug in shore power I can visually see the voltage increase to 12.76 or higher and it starts right up.
So as best as I can tell somehow I am having a drop in voltage from the geny battery to the geny…
Bill
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