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Converter replacement question
Yahoo Message Number: 97678
Hi, I have done a search but didn't find much that had to do with my situation. My 7345 in my 2005 LD began overheating and producing a bad odor so we shut it down and ordered a new one. Someone had mentioned to us that we could replace it with a 7355. We ordered the 7355 and I installed it. When I turned on the battery switch, both 30 amp fuses went kaput. I replaced the fuses (while the batteries were switched on) and all seemed well. The converter seemed to function properly and was charging the batteries as well. The next day we were leaving so we shut off the lights and turned on the outside light and heard a chirp from the converter box. I checked and both 30 amp fuses were toast again. I went outside and turned off the 120vac and the batteries, replaced the 30 amp fuses then turned on the 120 vac and then the batteries. As soon as i switched on the batteries the 30 amp fuses got fried. What is going on??? Was I supposed to change out the fuse board too? It looks exactly the same. help!!!
Re: Converter replacement question
Reply #1 –
Yahoo Message Number: 97679
Quote
Hi, I have done a search but didn't find much that had to do with my situation. My 7345 in my 2005 LD began overheating and producing a bad odor so we shut it down and ordered a new one. Someone had
mentioned to
 
Quote
us that we could replace it with a 7355. We ordered the 7355 and I installed it. When I turned on the battery switch, both 30 amp fuses went kaput. I replaced the fuses (while the batteries were switched
on)
 
Quote
and all seemed well. The converter seemed to function properly and was charging the batteries as well. The next day we were leaving so we shut off the lights and turned on the outside light and heard a chirp from the converter box. I checked and both 30 amp fuses were toast
again. I
 
Quote
went outside and turned off the 120vac and the batteries, replaced the 30 amp fuses then turned on the 120 vac and then the batteries. As soon as i switched on the batteries the 30 amp fuses got fried. What is going on??? Was I supposed to change out the fuse board too? It looks exactly the same. help!!!
Also, when I try to replace the 30 amp fuses with the batteries switched on, it sparks.
Re: Converter replacement question
Reply #2 –
Yahoo Message Number: 97686
Quote
Hi, I have done a search but didn't find much that had to do with my situation. My 7345 in my 2005 LD began overheating and producing a
**
 
Quote
us that we could replace it with a 7355. We ordered the 7355 and I installed it. When I turned on the battery switch, both 30 amp as i switched on the batteries the 30 amp fuses got fried. What is going on??? Was I supposed to change out the fuse board too? It looks exactly the same. help!!!
I would guess that something is causing a heavy current flow at 12V, and this is probably what cooked the first converter too. Was any work done with the batteries shortly before the first problem? Have you measured voltages or checked polarities?
 Note that the batteries are connected to the engine charging system as well as the converter. If there is a problem up front, this could be really overtaxing the converter.

Steve
2004 FL
2013 Honda Fit
Re: Converter replacement question
Reply #3 –
Yahoo Message Number: 97687
Sounds like a problem with either the wiring or the new converter. To troubleshoot, check the wiring carefully. If all looks well, disconnect the converter wiring. Then try replacing those fuses again. If they still blow, there's a short elsewhere and the converter is not the problem.

bumper
bumper
"Yonder" '05 MB
"WLDBLU" glider trailer
Re: Converter replacement question
Reply #5 –
Yahoo Message Number: 97698
I'll try that. I have another question. If I leave the battery switch off and replace the fuses, then connect the vac should the converter be able to function and supply 12v?
Re: Converter replacement question
Reply #6 –
Yahoo Message Number: 97699
The batteries will a little low on water so we filled them.
While waiting for the new converter we were using the engine to charge the house batteries. We only did this for about an hour for 2 days.
The cables on the batteries were not removed so I don't think it's a polarity issue. The wiring on the converter is correct also. I don't have any way to measure the voltages at the moment.
Could the batteries be causing this?
Re: Converter replacement question
Reply #8 –
Yahoo Message Number: 97702
"Could the batteries be causing this?"
 If you mean "Could a battery malfunction be causing this," the answer is no. when two 30-amp fuses blow, you have a *serious* problem--one that likely would cause a fire in short order, if those fuses were not protecting you. Since you just replaced your converter, the most likely culprit is incorrect wiring.
 Yes, I know you said you rechecked it, but it's easy to overlook one's own error, especially if the error was caused by misunderstanding the instructions. I would suggest that you get *somebody else* to check the installation and wiring--and resist the temptation to look over their shoulder and explain things while they're doing it. Let them work it out for themselves, and see whether they come to the same conclusions you did.
 The second possibility is a defective converter. That seems unlikely, since your converter appears to be functioning normally. But since it is a new item, you can't rule out some kind of defect there. I wish I had advice to offer on troubleshooting it, but that's one task I've never had to tackle. You may need to take it to an RV shop.

But I'm betting it's a wiring problem, so I suggest pursuing that avenue first. Get outside help--with luck, the friend who looks it over will spot an error that you overlooked.
 Just bear in mind that 30A is a LOT of current--enough to make wires or connections incandescent in seconds. If that were to happen, your rig could burn to the ground in five minutes or less. So make VERY sure that you have solved this problem permanently, and that you know exactly what was wrong, before you use the rig again. I don't want to lose any of our members to fire! :-)

Andy Baird http://www.andybaird.com/travels/
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"
Re: Converter replacement question
Reply #9 –
Yahoo Message Number: 97703
Hi Andy, thanks for replying. The new converter doesn't seem to be working any longer.

Recap: When I have the AC on and the batteries off, the fuses don't blow but the converter does not seem to power up.

When I switch on the batteries, both fuses blow.

When I disconnect the converter and replace the 30 amp fuses. The fuses do not blow when the batteries were turned on.

We have now removed the 30 amp fuses and disconnected power to the converter. We are now running 12v off the batteries. The AC is working fine also. Is this safe?

I took pictures of my wiring that I will post
Re: Converter replacement question
Reply #10 –
Yahoo Message Number: 97705
OK...I disconnected all the wiring for the converter, replaced the fuses and turned on the batteries and the fuses did not blow. Does that mean the converter is the problem?
Re: Converter replacement question
Reply #12 –
Yahoo Message Number: 97708
"We have now removed the 30 amp fuses and disconnected power to the converter. We are now running 12v off the batteries. The AC is working fine also. Is this safe?"

If I understand you correctly, it should be. Removing the fuses ensures that the circuit they were protecting can't be powered up, so there should be no risk.

"Does that mean the converter is the problem?"

Probably either the converter or the wiring to the converter.

"I sent the same pics to Randy at bestconverter.com since he keeps saying it's a reverse polarity issue."

Good idea! Hopefully he'll be able to diagnose from the pictures.

Andy Baird http://www.andybaird.com/travels/
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"
Re: Converter replacement question
Reply #13 –
Yahoo Message Number: 97711
Quote
Here are the pics.
http://tinyurl.com/6s42mp
Why is there still a blue wire connected? The instructions clearly say to disconnect and remove the old converter, which should take the blue wire out of the picture. Where does it go now? You should definitely use the new fuse block, too. Swapping over the wires from the old board it a quick and easy operation.

Steve
2004 FL
2013 Honda Fit
Re: Converter replacement question
Reply #14 –
Yahoo Message Number: 97712
Quote
Why is there still a blue wire connected? The instructions clearly say to disconnect and remove the old converter, which should take the blue wire out of the picture. Where does it go now?
Hi Steve, I think you are mistaken. The old converter was removed. The blue wire is from the new converter. The new converter had 1 blue wire and 1 white wire just like the old one did. What directions are you referring to?
Re: Converter replacement question
Reply #15 –
Yahoo Message Number: 97713
Quote
Hi Steve, I think you are mistaken. The old converter was removed. The blue wire is from the new converter. The new converter had 1 blue wire and 1 white wire just like the old one did. What directions are you referring to?
I thought you were replacing the Magnetek with the Best Converter 55A model - my mistake. The Parallax instructions do mention taking care there are no shorts when reattaching the blue wire, though, so you should double-check all connections there for misalignment or stray wires. I would trace all exposed wiring runs terminating at the batteries for shorts, etc, check the disconnect switch for problems, and check the battery isolator for shorted diodes.

Steve
2004 FL
2013 Honda Fit
Re: Converter replacement question
Reply #17 –
Yahoo Message Number: 97715
I figured you must have been thinking of a different installation :-) Could the battery disconnect switch be somehow causing a reverse polarity? How can I tell? If the fuse board was getting reversed polarity from the batteries what would be the indicator when the converter is disconnected?
Re: Converter replacement question
Reply #18 –
Yahoo Message Number: 97717
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I figured you must have been thinking of a different installation :-) Could the battery disconnect switch be somehow causing a reverse polarity? How can I tell? If the fuse board was getting reversed polarity from the batteries what would be the indicator when the converter is disconnected?
Despite what Best said, I would doubt if reverse polarity is the situation. I don't know what sort of battery switch you have - our '83 has none. What I have typically seen installed is a manual switch or a relay operated by a small switch, with the intent of preventing small phantom loads - such as the propane detector - from drawing down the batteries when the RV is not in use. Is this what you are referring to?

I am suspecting a short circuit, or at least a 'sometimes' short circuit. This occurs when some 12V device develops a very low resistance to ground, or where your 'hot' circuit wiring somewhere contacts ground. It is possible that the switch/relay is faulty this way, or that some connection has a stray wire, or an exposed terminal has something grounded touching it, or even a staple securing the wiring has penetrated the insulation and shorted together plus and minus.

I would start with the concern that your original converter started smelling bad and stopped working properly. I suspect that this is unusual. I believe most converters are replaced due to age-related deteriorating performance, which this doesn't sound like, or to upgrade performance to more modern standards. I would review any changes made to the RV shortly prior to the first converter failing, even if not electrical in nature, and carefully inspect the environment there.
 If this approach comes up empty, then a careful electrical diagnosis is called for, and this will require checking components out of circuit for shorts or intermittants, and tracing all wiring where accessible throughout your LD. You will need a digital voltmeter (DVM) to do much of this. If you disconnect your battery from the converter fuse panel (both ends, at fuse panel and at battery switch), replace the 30A fuses, and the converter is still no longer functioning, then you will need to exchange that to start. With a working converter reinstalled, check that the branch circuits are actually receiving correct polarity and voltage, and operate each 12V appliance to make certain no fuses blow. Then, the disconnected cables to the battery must be checked for shorts along their path with the ohmmeter function of the DVM. If all seems fine to this point, then you will need to check the battery switch, the battery isolator in the engine compartment, and all forward fused circuits. If you are uncertain about this stage, it would be a good idea to bring in outside assistance. Good luck!

Steve
2004 FL
2013 Honda Fit
Re: Converter replacement question
Reply #19 –
Yahoo Message Number: 97719
"Could the battery disconnect switch be somehow causing a reverse polarity? How can I tell?"

I'm with Steve. In particular, you can't troubleshoot electrical systems without a good multimeter--among other things, it will instantly tell you whether you have a reverse-polarity situation. In a pinch, almost any digital multimeter will do, but I recommend Radio Shack's #22-820. Quoting Eureka's article on how to use a meter,

"It has auto-ranging, auto-polarity, and automatic AC/DC detection—three features that will greatly simplify your life. It's small and rugged, which is what you want as an RVer. Its clamshell case closes up into a little palm-sized box with a non-slip exterior.
It's small enough to easily fit into your shirt pocket, and it's completely protected from damage while it's knocking around in your toolbox or drawer."

Perhaps equally important, it has just one four-position function switch, instead of the dozens of switch settings and multiple test-lead sockets of a $10 Harbor Freight cheapie. In short, it's simple, easy to use and un-confusing. Those are major virtues in my book--you don't want to be struggling to understand a needlessly complex multimeter while you're trying to troubleshoot a circuit. :-)

Andy Baird http://www.andybaird.com/travels/eureka
Andy Baird
2021 Ford Ranger towing 2019 Airstream 19CB
Previously: 1985 LD Twin/King "Gertie"; 2003 LD Midbath "Skylark"
Re: Converter replacement question
Reply #21 –
Yahoo Message Number: 97731
Quote
I would start with the concern that your original converter started smelling bad and stopped working properly. I suspect that this is unusual. I believe most converters are replaced due to age-related deteriorating performance, which this doesn't sound like, or to upgrade performance to more modern standards. I would review any changes made to the RV shortly prior to the first converter failing, even if not electrical in nature, and carefully inspect the environment there.
I just remembered that we did have someone out to do the dometic recall work on the fridge. This was about 3 months ago. I went and looked in the fridge compartment but I'm not seeing anything obvious.

Quote
to do much of this. If you disconnect your battery from the converter fuse panel (both ends, at fuse panel and at battery switch), replace the 30A fuses, and the converter is still no longer functioning, then you will need to exchange that to start. With a working converter reinstalled, check that the branch circuits are actually receiving correct polarity and voltage, and operate each 12V appliance to make certain no fuses blow.
Can you help me understand why the 12v power works fine from the batteries when the converter is disconnected? Why would a short only cause the problem with the converter connected?

1. Batteries switched on with converter disconnected = dc power  working, no blown fuses.

2. Batteries switched off with converter connected = no dc power, no  blown fuses.

3. Batteries switched on with converter connected = both 30 amp fuses
 blown.

Does this tell me anything at all about where the problem is occurring?
Re: Converter replacement question
Reply #22 –
Yahoo Message Number: 97744
Quote
1. Batteries switched on with converter disconnected = dc power working, no blown fuses.

2. Batteries switched off with converter connected = no dc power, no  blown fuses.

3. Batteries switched on with converter connected = both 30 amp fuses
 blown.

Does this tell me anything at all about where the problem is occurring?
With the converter connected to the fuseblock, battery switch off, and converter input connected to shorepower, measure the voltage at the fuseblock, from converter negative to positive. If you do not get 12V - 14V with the correct polarity, then your converter is likely bad. If this is the case, get a replacement converter and perform the procedures I posted previously.

Steve
2004 FL
2013 Honda Fit
Re: Converter replacement question
Reply #23 –
Yahoo Message Number: 97761
Quote
1. Batteries switched on with converter disconnected = dc power working, no blown fuses.

2. Batteries switched off with converter connected = no dc power, no  blown fuses.

3. Batteries switched on with converter connected = both 30 amp fuses
 blown.

Does this tell me anything at all about where the problem is occurring?
I think #2 gives a good indication of where the problem is.  If you had the converter connected to shore power at that time and the 30 amp fuses were in place there should have been DC power.
 The two 30 amp fuses are connected in parallel between the + output of the converter and the + wire from the batteries which is also connected to the line side of the 12V fuses on the distribution board.  This gives them a capacity somewhere in the vicinity of 60A.  They are not in the path for current coming from the batteries to any of your 12V load devices and their only function is to protect the converter from reverse polarity.  This suggests to me that either your converter is bad or it is hooked up wrong in spite of you having the blue and white wires at the correct points on the distribution board. JMO.

Monti

Monument, CO