BAC Forum
General Boards => Technical Support => Topic started by: Roger Rempe on July 27, 2017, 08:29:03 PM
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I've had my rig sitting unplugged in a storage lot for the past three weeks. This morning I started the engine and after running for a minute or so, I noticed smoke coming through the dash radio. I then shut down the engine and noticed more smoke coming from the Multiplex control master box back in the electric breaker closet. I started the engine again and noticed that the dash volt meter was pegged out beyond 20 volts. It starts out at about 13.8 and then will climb.
At one point the Magnum control panel was showing a fault and indicating battery overload with the engine running. Engine off, I set the shore input to 15 amps and plugged into 120v. The control then read searching and the charge button doesn't light up when pressed.
With the engine off, the chassis batteries read 12.7 and the house 13.2 (unplugged). All of the Multiplex light control switches in the rig are lit up and inoperable. Also, can't get the HWH leveling pad to light up and level to travel mode. And the generator won't click to start.
Any ideas on where I should begin? I'm afraid that I'm looking at a faulty alternator AND fried house electric.
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Roger,
Sure sounds like the alternator has gone west. Not clear why the generator won't start unless you've got a bad battery. Try resetting everything by disconnecting from shore power and also removing the ground battery cables for a few minutes. That should reset the multiplex and inverter (unless your inverter has a reset button. Then press it after power is restored). If the multiplex and magnum look normal on shore power, see if the generator will turn over. If no joy, check the high amperage fuses near the battery bay. The geni start line runs through a 125A fuse.
Steve
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Thanks Steve...that gives me some good leads. Right now I'm lining up a tow to a Cat shop for the a.m.
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Roger,
You may want to check it out yourself first. If bad, the alternator can be rebuilt for a lot less than a replacement. In any case, Good Luck.
Steve
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I've noticed that, if my batteries are not fully charged, when starting the engine after storage, the alternator will be asked to charge the chassis and house batteries "all at once" and the Aladdin will show 100a or more current going to the batteries. I've heard that subjecting the alternator to this max charge load can overheat the alternator. Any truth to this rumor?
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10-4. TRUE. I had to replace my alternator after the first year I owned it.
Run your generator for 30 to 60 minutes BEFORE starting the coach engine. Let the generator and inverter charge up at least the coach batteries before starting the coach's engine.
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After dry camping, I always make sure the genset has built up battery banks enough that my Magnum panel has reached at very least the Absorb Charge reading before cranking the engine, and ideally but not mandatorially bouncing off the Float Charge point. Since my rig in storage is charged either via solar or 30 amp outlet, storage is not the alternator concern for me as it may be for you, Bill.
Joel
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I was under the impression that my solar panel would keep the batteries charged as long as I had all of the breakers off along with the chassis and coach battery switches? After my incident, I took volt reads and they all read fully charged. However, Joel makes a good point about the dry camping.
Still waiting to hear back from the Cat shop and what they found.
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Roger, I don't think you need to flip breakers off. Turning the main 12v switches off prevents parasitic drain, esp. at night when the solar unit is passive.
Usually when an alternator is overtaxed and fails its symptom is no or inadequate output. Yours seems to be the less common overcharging case, obviously. Wish I could remember all I once learned when decades ago I rebuilt alternators on our farm and the 350 Chev on my boat. The precise causal mechanics behind failed output regulating that I'd otherwise know eludes me, but others here probably can refresh my memory, and enlighten you and others.
Joel
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If memory serves, then I think someone said over taxing an alternator makes it get hot and causes failure of one or more diodes. So the precaution is to not over tax the alternator. In other words, don't ask the engine's alternator to charge six or eight batteries at one time. BEFORE starting the big engine, first charge the battery banks up to a medium to upper charge level using the generator/inverter-charger. You can do this easily without wasting time by running the generator while packing up, putting in the slides (unless you dumped the air), hooking up the toad, having breakfast, putting down the satellite dish, etc.
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Turns out that the alternator was bad and it got replaced last week. However, I just got back from the RV repair shop. It appears that my Magna invertor had a major failure during the engine startup and fried pretty much all of the 12v system's motherboards. HWH leveling, multiplex controller, etc. Stairs and keyless pad don't work. Not sure of the generator's status. They haven't gotten to that yet.
I guess that you could say that this repair is gonna be the "mother of all repairs" that I've faced!
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An update and question for the forum on my meltdown. The repair shop is making progress on replacing the electric components. However, no one seems to have a solid reason for the incident's cause. The tech thinks it may be caused by a faulty Magnum inverter/charger. I talked to Ken at BCS and he thought that would be unlikely as well as the alternator being the cause.
Now I'm concerned that I could have a repeat if the real culprit isn't addressed. Does anyone have a plausible explanation?
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Im not familiar with the tech specs of your coach, and am just learning mine, but I was an electronics technician in the military of 20 years on some advanced gear and can offer some general observations that may help.
Always start with most common failures and denomenators, don't assume multiple independent and simultaneous system failures without having evidevnce of a catastrophic event. It's much more likely to be a sequence of failures as a result of a common/shared system or component, ie. what do all these systems have in common?
It's pretty clear you had power regulation issues that has allowed some pretty high current to overheat your wiring/fry modules. Most alternators have internal regulators now. If those fail it could send high current due to unregulated voltage down the line to a fuse block/ breaker box/ invertor if hardwired direct. Not sure where the Power transfer switch fits in this sequence, but seems it would have at least a collateral relationship as it has to switch between the Alternator and generator as power sources. The dash radio should have been protected by a fuse preventing the wires from ever getting close enough to overheat/smoke so that's a collateral issue that will need to addressed to prevent future problems. The leveling system, etc. should also have been protected by fuses. If they weren't already, I'd install some ASAP. Visually inspect your dash radio wiring to see whether it was in fact smoking, or the smoke just exited the dash there. Do the same for each INOP piece of equipt. Look for potentially shorted and burned wires near each piece you remove. Pay careful attention to nearby harnesses that may have chaffed against the chassis at some point.
You stated the coach was stored without power, does that incude solar? Solar controllers could cause similar probs if they fail.
Assuming the coach was working fine when you parked it, you then also should consider the possibility of other environmental causes. Namely, rodents. It wouldn't be the first time a mouse has snacked on a wire bundle. Most of this is basic visual inspection stuff. Without schrmatics and a through understanding of your coach's systems and components it's all I can offer. Good luck.
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I like your analytical thinking Jeff. Rodents did enter my mind as the possible gremlins. I had 'em make off with my "anti-pack rat rope light deterrence system" in AZ. I tracked it to their den... So much for that and deer whistles!
I think that the dash smoke was mainly from the underlying genset board. However, the tech said the radio works but, the volume is low. Electricity is a funny thing, I guess.
"Not sure where the Power transfer switch fits in this sequence, but seems it would have at least a collateral relationship as it has to switch between the Alternator and generator as power sources." ...Me neither but, a dual breakdown in components could explain the rarity of this happening...from what I've been told multiple times. I'll pass along to the tech to check the solar controller.
One of the bad multiplex gang switches ended up real bad. Fried the chipset too and now I have to take the entire rig to Ohio for "remapping". It's the closest place from here in Iowa.
Thanks for the input...it gives me something to "chew on"...pun intended.