BAC Forum
General Boards => Technical Support => Topic started by: Dan n Lisa Lund on October 07, 2014, 11:22:04 PM
-
[face=Times][size=14]Hello :) My name is Dan Lund and I am a new member. Already I have a tech question! Our new to us 03 Marquis shows chassis voltage pulsing between 13 and 14 volts when rolling down the road. At night I can see the gauge lighting brighten and dim respectively. Has anyone encountered this before?
Thanks, Dan Lund
2003 Marquis
C12[/size][/face]
-
Dan,
I have never had the problem that you are referring to. There are several things that could be causing the condition. The most common one would be an alternator voltage regulator. However, there are several other things that could cause the same issue. A loose or poor connection in a 12 volt supply circuit could also be the problem.
There are a few things that can narrow down your search. First is the inverter on when this happens, if so, turn it off and see if it stops. Watch the inverter output to see if something is cycling on the A/C side of the coach. If not I would check the alternator output to determine if the output is steady. Also are you watch this voltage fluctuation on the dash gauge or on the Aladdin?
Gerald
-
Gerald,
Thanks for the reply. I don't know if the inverter was on or not at the time. I will check that. I am watching this on the dash gauge as well as the intensity of the dash lighting fluctuates too. I will start first by looking at the inverter status.
Thanks,
Dan
-
We had the same issue on our Beaver. I traced it to a bad connection of the voltage sense wire at the alternator. Repaired the connector and the pulsing stopped.
Dan
-
[size=14]Dan,
Ah HA! another possibility. I was looking at the alternator today and the wires going to it didn't look quite right. I think we may have a winner here. I will go look more closely at it. Plus I read up on the inverter operation as well so between getting me educated and a possible wiring problem maybe we can get this solved. Thank you sir :)
Dan[/size]
-
As mentioned by Gerald and as often as this happens with cars and boats, a less than optimum major wire connection is a common cause of your symptom, especially a ground connection. Corrosion at the chassis battery ground posts is simple to look for. The alternator would be one of the first places I'd check as Dan suggests also. You might also look at the solenoid under the main buss in the 12v. electrical bay (below the driver's seat) as it has been known to be problematic, though not my main suspect in this case. In all places you are looking for looseness or corrosion, both of which can restrict adequate electron flow.
Joel
-
I had an issue with wandering regulation of the alternator voltage while on the road and it turned out through vibration that all but a couple of strands of the ground wire from the alternator had broken at the place that it goes into the crimp connector. It was hard to spot given it was covered by some shrink tubing, had to flex it to tell. The ground wire point going to the engine block from the alternator is a area to check for sure. if you have the problem there and replace it create a coil of three or four turns of wire in a circle about an inch in diameter (like the coils of a spring). That will dampen the vibrations that cause fatigue at the crimp connector point.
Later Ed
-
[size=14][face=Arial]Thanks for all the suggestions and ideas guys. I appreciate it and will check all of the above.
Dan[/face][/size]
-
[size=14]UPDATE: Turns out that I ended up replacing the alternator. The regulator seemed to be working as designed so I believe that something internally was going wrong with the alternator. All is good now and no more pulsating. All the wiring seemed to be good as well. I am just happy that it is fixed. It was driving me nuts. Thanks again for all the suggestions.
Dan[/size][/b]
-
Dan, be aware that one of the most common cause of alternator failure on coaches is inexperienced owners not charging their battery banks back up with the generator before departing after a period of dry camping. Our alternators aren't designed to take on the load of rebuilding deeply discharged batteries. As a new owner, you couldn't know whether the previous owner had followed the best practice, which is using the genset to bring the system up at least past the Bulk Charge phase before starting the engine after dry camping.
Joel
-
[size=14]That is a possibility Joel, although the house batteries were new when I picked up the coach they may not have been fully charged. The alternator only charges house batteries when the "connect" switch is on though.....am I right? Either way I am sure that the house batteries were quite low. Thanks for the info. [/size]
-
Connect switch? What and where is this switch?
-
Like David, I'm not sure what you mean by "Connect switch". To my knowledge, the alternator will get the chassis bank up to snuff first, which shouldn't usually take long, then move to the house bank. The genset or park power (inverter sourced) will do the house set to something above 13v. then charge the chassis, as will solar. I welcome others more astute to correct me there, as different coaches can have different configurations, some a bit unlike my BIRD system.
If you mean by "Connect switch" the Coach Power at the entry door, aka. Salesman's Switch, that should not affect your charging scenario. You should not mess with that switch, by the way. It was not designed to be regularly turned on and off by owners, but rather for relatively brief dealers' convenience on sales lots. It and its solenoid have been known to wear inside and fail, and perhaps leave you in a spot sometime - been there done that, but was lucky I was in the BCS parking lot and the crew hadn't quite all left for the weekend. I was advised to leave that Coach Power switch in the "On" position 24/7/365, period. If you are storing the rig for awhile, turn its batteries off with the Main Switches in the battery bay, and never use the Coach Power switch. Mine get a constant solar input during storage (even with Mains off), but some people that store inside will disconnect battery ground cables to remove all parasitic drains including those from the electronic control modules not affected by the Main switches.
Regardless, once the alternator has your chassis bank up, perhaps within seconds, it will begin work on the coach bank. If you've been parked for long unplugged, the alternator will stress itself trying to boost 4 or more deeply depleted house batteries; the time involved at high charge rates can overheat it, deteriorating its components, and make for the most common cause of alternator failure. These commonly 160 amp diesel alternators aren't cheap, as you probably just discovered. The charger in your inverter, and in some cases one in the genset, are designed to do what the alternator isn't - deal with deep cycle house battery banks. Use the genset to recharge after dry camping or stored away from AC power - whether using its own built-in charger or feeding AC through the inverter's charger, your generator is more capable than your alternator. Plan ahead though; it can take quite awhile to get charged up before you dare start the engine to pull out on the road with minimal alternator stress.
On my rig I monitor the Magnum remote panel. After it has left the Bulk charge state, and gets into the Absorption phase where it begins topping things off and the batteries are around 90% charged, I like to see the charging voltage down to around 14.2 volts or less. That is the charging voltage, not necessarily the charge on the batteries, so as their state of charge comes up then the voltage required to pump current in should drop over time. Thus the charging voltage you see on your panel will slowly head down from maybe 14.6v to around 13.5v. The actual charge state of the batteries will be creeping up. Not long into the Absorption phase or Absorb Cycle is when I usually judge it relatively safe to start the engine and get underway. But as I said, it can take quite a long while to get to that point - maybe well over an hour - so plan your departure and start the genset accordingly.
Joel
-
I actually was thinking Mr. Lund meant the Battery Boost switch on the dash. And I suppose the Battery Boost could be used for a charging circuit, but it's probably not a good idea... perhaps in an emergency?
-
[size=14]I am familiar with the battery boost switch. It is the momentary switch that will allow you to 'jump' or assist the chassis batteries for engine start. Feel free to correct me if I am wrong. The switch I am referring to as the 'connect' switch is right next to the boost switch with a picture of a battery on it. It is not 'momentary'. I am not sure what it does. I do not see any increase in charge amperage with it on or off. So I can't tell what it does. I haven't looked it up in the manual yet. I assumed that it tied the alternator into the house bank, but I haven't messed with it much since I am not sure what it does.[/size]
-
[size=14]I may have just figured out what that switch is that I am talking about! HAHA.... I think it is the mirror heat switch! HOW embarrassing..... ! Well it looks like a battery picture on it but I bet it is a picture of a heated mirror!!! ??) I still have a lot to learn. [/size]
-
My coach has 5 toggle switches in a horizontal row beneath the Kenwood on the left dash. They are, in order, left to right: 1) Driving Lights, 2) Dock Lights, 3) Start Boost, 4) Gen Start, and 5) ATC. None of the switches in my coach have pictures, only words in a white plastic plate imbedded within each switch.
I wonder if your "Connect" switch is the same as my ATC switch? ATC - Automatic Traction Control, wasn't it?
Hmmmm... my mirror heat switches are on the left wall horizontal plate (left of the driver's arm rest) aft of the transmission shift pad.
Hey - this is fun... like looking for Easter eggs.
-
[size=14]Yeah, thats it! The left wall horizontal plate is where this switch is that I now know as the mirror heat switch. I don't think I have an automatic traction control switch. But who knows? Like I said, I have a lot to learn. So with all this information, I think what Joel said is probably what happened to my alternator. I believe that when we picked up the coach that the new house batteries were not fully charged. That is something that the dealer should have caught and informed me about. Thank you guys.[/size]
-
It's a $400 to $500 lesson we all must learn, I guess. I learned it in July 2013. You can either buy diesel to run the generator, or pay for shore power, or replace the alternator every now and then if you don't charge up the batteries before hitting the road.