Author Topic: 12 volt circuits dead when on hookup... (Read 2611 times)

Bryan · « **on:** December 03, 2009, 02:22:28 PM »

Hi,

I have an R-Vision Trail-lite 2002 with a Parallax 7355 converter.

My rig is currently on mains hookup but none of the 12v circuits are working.

Using a multimeter I have discovered the following:

Removing both 30amp polarity fuses and testing between the converter input to the fuse board (blue wire) and the negative connection gives 13.6 volt.
Testing across the battery connections at the converter fuse board gives 13.6 volt
Replacing the polarity fuses and testing from any of the 12v circuits positve (just below fuse) and the battery negative connection on the fuse board gives 13.6v.

NO 12v circuit works.

Now, despite having a reading across the battery connections on the converter fuse board of 13.6 volt, the actual reading at the battery is 9 volt. Now I know that this means that the battery is no good, I can't understand why I get the differnce in readings.

Also, and perhaps crucially, if I connect an external battery charger to the battery then the 12v circuits in the coach come on...

And in case it helps, with the polarity fuses removed, the reading at the fuse board across the battery connections is the same as at the batteries.

I am really confused as all the information I can find says that the Parallax should be powering the lights etc even if there is no battery, and I do read 13.6 volt at the 12v circuit fuse bu tget no power anywhere.

I really hope you can help as we are due to go away for a couple of weeks real soon.

Bryan

Just Lou · « **Reply #1 on:** December 03, 2009, 03:32:11 PM »

What happens if you completely disconnect the battery?

If it requires a new battery, why not put it in? Now.......

Bryan · « **Reply #2 on:** December 03, 2009, 04:02:26 PM »

Thanks for the reply

Without a battery I still have no lights etc. But the Parallax 7355 converter should be powering the 12v stuff without a battery anyway.

Not concerned about the battery, that's an easy fix. But I do need to get the 12v stuff running off the hookup.

I've dug deeper and the converter is getting 110v from the hookup, and it is giving out 13.7 volts to the fuse board. And the fuse board is putting 13.7 volts through the fuses to the live wires for the circuits

I am sooooo confused

Fred G. · « **Reply #3 on:** December 03, 2009, 04:51:18 PM »

Have you checked the circuit brakers? I had a similar problem not too long ago where while connected to shore, the converter was not charging the batteries and I was getting low readings at the points you just mentioned. I removed all the fuses, cleaned the connections, also at the fuse board, then I replaced the adapter (30amp to 15amp) cause it looked melted on the hot wire. After done all that, I put back all the fuses (including the 30amp fuses), and my batteries charged up back to 12v and the readings were correct again. I don't know if it was the cleaning or the changing of the adapter but it worked. Also I heard on another forum that there is a possibility that the battery isolator switch may be at fault.

Just Lou · « **Reply #4 on:** December 03, 2009, 05:05:15 PM »

Quote from: Bryan on December 03, 2009, 02:22:28 PM

Also, and perhaps crucially, if I connect an external battery charger to the battery then the 12v circuits in the coach come on...

Don't you think a GOOD 12v battery hooked up as you have the battery charger would do the same thing?

Bryan · « **Reply #5 on:** December 03, 2009, 05:09:00 PM »

Quote from: aka Porky on December 03, 2009, 05:05:15 PM

Don't you think a GOOD 12v battery hooked up as you have the battery charger would do the same thing?

Possibly, but the parallax should power the 12v circuits even if a battery is not present.

Just Lou · « **Reply #6 on:** December 03, 2009, 05:10:46 PM »

Quote from: Bryan on December 03, 2009, 05:09:00 PM

Possibly, but the parallax should power the 12v circuits even if a battery is not present.

That's the third time you have said that. Is it doing it yet?

Bryan · « **Reply #7 on:** December 03, 2009, 05:18:04 PM »

Quote from: aka Porky on December 03, 2009, 05:10:46 PM

That's the third time you have said that. Is it doing it yet?

Sorry if I am repeating myself, but I am only doing so to clarify that the battery is not what is concerning me at the moment.

Quote from: Fred G. on December 03, 2009, 04:51:18 PM

Have you checked the circuit brakers? I had a similar problem not too long ago where while connected to shore, the converter was not charging the batteries and I was getting low readings at the points you just mentioned. I removed all the fuses, cleaned the connections, also at the fuse board, then I replaced the adapter (30amp to 15amp) cause it looked melted on the hot wire. After done all that, I put back all the fuses (including the 30amp fuses), and my batteries charged up back to 12v and the readings were correct again. I don't know if it was the cleaning or the changing of the adapter but it worked. Also I heard on another forum that there is a possibility that the battery isolator switch may be at fault.

Which circuit breakers?

I'm not too concerned about the battery charging, I'm sure that once the main issue is sorted the replacement battery will charge okay.

Which adapter did you replace?

Battery isolator is okay I think. When I have a battery connected the isolator switch just inside entry door does what it should.

There is something else a little odd...

Further diags - I have removed the front of the parallax; the converter is getting 110v, the fuseboard is getting 13.6v from the converter. I removed the positive lead from the fuseboard (that is connected to the battery, allegedly) and whilst the battery has a seperate charger attached , the wire reads 16-ish volts even though the battery that is at the other end reads 9 volts...

I mention this in case it is helpful - I repeat, I'm not too concerned about the battery, the parallax should power the 12v on it's own and that is what I need to fix first

Fred G. · « **Reply #8 on:** December 03, 2009, 09:52:02 PM »

Follow these troubleshooting procedures to determine if your converter is bad or not.
http://www.parallaxpower.com/7300/Flowchart7300.pdf
If everything check out OK, then you need to trace back the 12v circuit.

Gary RV Roamer · « **Reply #9 on:** December 03, 2009, 09:59:16 PM »

Does your rig perhaps have a battery disconnect switch that is off? Most motorhomes have them, but only some trailers do.

The battery disconnect switch is intended to isolate the RV's 12v electrical system from the battery and in some designs it also isolates it from the converter.

Bryan · « **Reply #10 on:** December 04, 2009, 01:33:47 AM »

Quote from: Fred G. on December 03, 2009, 09:52:02 PM

Follow these troubleshooting procedures to determine if your converter is bad or not.
http://www.parallaxpower.com/7300/Flowchart7300.pdf
If everything check out OK, then you need to trace back the 12v circuit.

Already done that

result is that cxonverter is working fine.

Trace which 12v circuit? The battery is not included remember and the 12v circuits in question are the lights etc...they can't allbe wrong and besides, if I bring the battery back into play it powers the lights etc.

Quote from: RV Roamer on December 03, 2009, 09:59:16 PM

Does your rig perhaps have a battery disconnect switch that is off? Most motorhomes have them, but only some trailers do.

The battery disconnect switch is intended to isolate the RV's 12v electrical system from the battery and in some designs it also isolates it from the converter.

Yes it does, and as it is 12volt powered from the battery it works as follows:
Battery connected - switch works fine, on/charge/use, everything fine - switch off/store all 12v disconnected (no lights etc.)
Battery disconnected - all 12v dead anyway as parallax not providing power to 12v circuits.

BTW Thanks for all the advice and help guys

Gary RV Roamer · « **Reply #11 on:** December 04, 2009, 08:04:05 AM »

This sure is a mystery. As I recall the 7355 wiring, it has only one 12v output that does both charging and provides house 12v power. Older Magnetec 63xx series had separate outputs for charging and house power, but I don't think the 73xx series is designed that way. I believe the 73xx 12v output goes to the 12v bus in the power center and then to both batteries and house 12v system. Perhaps you can verify that is how it is wired?

Given that, it would seem to be impossible for it to do what you describe, unless the converter simply shuts down when it finds no battery load. The bad house battery may be having some odd effect on the whole situation. I'd replace that and see how/if the symrtoms change.

Bryan · « **Reply #12 on:** December 04, 2009, 12:33:51 PM »

Quote from: RV Roamer on December 04, 2009, 08:04:05 AM

This sure is a mystery. As I recall the 7355 wiring, it has only one 12v output that does both charging and provides house 12v power. Older Magnetec 63xx series had separate outputs for charging and house power, but I don't think the 73xx series is designed that way. I believe the 73xx 12v output goes to the 12v bus in the power center and then to both batteries and house 12v system. Perhaps you can verify that is how it is wired?

Given that, it would seem to be impossible for it to do what you describe, unless the converter simply shuts down when it finds no battery load. The bad house battery may be having some odd effect on the whole situation. I'd replace that and see how/if the symrtoms change.

Spot on Gary. One 12v from converter to fuse board where the 12v loads are - the battery is seen as just another load. This is confirmed by the parallax website info.

Impossible? I know! That's why I am soooo confused

I have tried disconnecting the battery positive wire at the fuseboard but I will remove it completely and see if anything changes, and then add a good battery and see what happens.

One extra thing - it has been suggested to me that there may be a thermal cutout somewhere with a little reset button on it but it could be anywhere...Can any-one shed any light on this possible solution?

Fred G. · « **Reply #13 on:** December 04, 2009, 04:01:50 PM »

According to Parallax schematics, your converter should have two 12v outputs. The white wire goes to terminal C (I believe) which charges the batteries. The blue wire goes to terminal D (or viceversa) which supplies 12v to the coach for lights and everything else. If you say that when connected to shore power, you have 13.7v at the blue wire, then check for volatge after every 15amp fuse (I believe 5 or 6 depending on how many devices you have). If in fact you can read 12v after the fuses, then the next thing is to check for rats behind the converter panel. I doubt that they would chew every 12v wire available, but it is possible. They have eaten whole trunks of fiber optic cabling at my workplace. If you cannot read any voltage after the fuses, then you might have a loose contact between the blue wire terminal and the fuse terminals at the fuse board.

Just Lou · « **Reply #14 on:** December 04, 2009, 04:22:25 PM »

All the material I can find would indicate that Fred is correct. I would check every wire and every connection on the DC distribution side of that converter.

I'm not sure if Parallax uses the same method of isolating the regulated DC output from the charger output that the older Magnetek converters did, or not. Seems to me that that was a relay.

Bryan · « **Reply #15 on:** December 04, 2009, 05:18:09 PM »

Thanks Fred and Lou,

Yes there are a blue wire and a white wire coming from the converter to the fuse board. The blue is the +ve and the white (I am pretty sure) is the -ve. The blue is connected at the top of the board in the centre and the white is connected behind the board to the same post that the battery -ve connects to on the front.

I can read 13.6 volt after the fuses.

I don't think the wires are chewed. To support this, when I connect a battery to the board the 12v circuits work. Lights come on. BUT very dim and is is very obvious that the lights are being powerd form the battery, not the converted 12v.

After all your help and support I am starting to think that there may be something else messing it up. Maybe a relay, maybe a cutout. I would have thought that a cutout or relay fault would take out the converter and show no volts at the fuses but maybe not. I just don't know.

I'm still prety sure that there is not a seperate charger circuit and that the battery is just there as another 12v circuit/load attached to the converter.

Just Lou · « **Reply #16 on:** December 04, 2009, 08:29:47 PM »

Bryan, maybe these diagrams will help figure this out. They are of older Magnetek converters which were the ancesters of the Parallax converters.

here and here

They show you how Magnetek used a relay point to switch the loads from the converter to the battery. Hope they help

Gary RV Roamer · « **Reply #17 on:** December 05, 2009, 09:36:50 AM »

I believe both of those diagrams pertain to the 63xx series of converters, while Bryan has a 73xx. They MAY still be essentially correct for a 73xx, but we can't be sure.

Gary RV Roamer · « **Reply #18 on:** December 05, 2009, 09:55:24 AM »

I can find no reference to a reset switch in the 73xx operator manual, which is available here:

http://www.parallaxpower.com/7300/51092351-000%20rev%20G.pdf

The 73xx Installation manual shows the wiring, which may be instructive:

http://www.parallaxpower.com/7300%20Series%20Installation%20Guidelines%20rev%20A.pdf

It does show reverse polarity protection fuses, which might result in some strange readings if one or both are blown.

There is also a troubleshooting flowchart:

http://www.parallaxpower.com/7300/Flowchart7300.pdf

which shows the proper method for checking converter output power.

Just Lou · « **Reply #19 on:** December 05, 2009, 10:25:20 AM »

Quote from: RV Roamer on December 05, 2009, 09:36:50 AM

I believe both of those diagrams pertain to the 63xx series of converters, while Bryan has a 73xx. They MAY still be essentially correct for a 73xx, but we can't be sure.

I thought I made it clear that the diagrams I linked to were the older Magnetek converters. i.e.63XX or prior. (maybe not)

Quote from: RV Roamer on December 05, 2009, 09:55:24 AM

I can find no reference to a reset switch in the 73xx operator manual.....

Any reset "button" or "plunger" would probably be located on the circuit breaker (in the positive battery lead) shown on the last page of your diagram(s) link here

Gary RV Roamer · « **Reply #20 on:** December 05, 2009, 10:38:10 AM »

Yeah, and that breaker is an installer added device, so may not even be there. In any case, it would disconnect the battery from the house circuits if open and Bryan says he has 12v power from the battery, so I doubt if that is it.

Yes, Lou, you did say "older Magnetek converters". I was just cautioning not to place too much faith in them, since the 73xx uses a different converter technology than the 63xx.

From what i can see, only the blue wire is a 12v output from the converter and nothing goes direct to the battery from the converter itself.

Just Lou · « **Reply #21 on:** December 05, 2009, 11:34:47 AM »

Terminal "C" goes directly to the battery.

(edit)
OOOPS! Sorry, I guess that would be on the distribution/fuse panel and NOT what you were referring to as the "converter itself".

Bryan's symptoms are so strange that I'm now chasing myself in circles

Howard R · « **Reply #22 on:** December 05, 2009, 02:30:11 PM »

Quote from: Bryan on December 03, 2009, 05:09:00 PM

Possibly, but the parallax should power the 12v circuits even if a battery is not present.

I'm with Lou here ... I'd get a good battery, even a starter battery would do as long as it's charged up and see what happens when it is connected. You said it works ok with a battery charger connected.

Not at all familiar with your unit, but what if for instance there is a relay or solenoid somewhere in the circuit that gets it's power from the house batteries ... bad battery ... no power to pull in ... would do as you say.

Looking over the thread from the beginning, the post where you connected the battery charger (good 12V) was the only place where you symptoms changed ... aka ... system worked.

Just an idea ... but if it were me I would get that bad battery out of the picture, even if with a temporary good one ... that may be causing you to go in circles ... this is one of those, don't ask me how I know that deals!

Good luck,

Howard

Bryan · « **Reply #23 on:** December 06, 2009, 03:05:57 AM »

Quote from: Howard Rawley on December 05, 2009, 02:30:11 PM

You said it works ok with a battery charger connected.
Looking over the thread from the beginning, the post where you connected the battery charger (good 12V) was the only place where you symptoms changed ... aka ... system worked.
Just an idea ... but if it were me I would get that bad battery out of the picture, even if with a temporary good one ... that may be causing you to go in circles ... this is one of those, don't ask me how I know that deals!

Quote from: aka Porky on December 05, 2009, 11:34:47 AM

Bryan's symptoms are so strange that I'm now chasing myself in circles
Any reset "button" or "plunger" would probably be located on the circuit breaker (in the positive battery lead) shown on the last page of your diagram(s) link here

Quote from: RV Roamer on December 05, 2009, 09:55:24 AM

It does show reverse polarity protection fuses, which might result in some strange readings if one or both are blown.
There is also a troubleshooting flowchart:
http://www.parallaxpower.com/7300/Flowchart7300.pdf
which shows the proper method for checking converter output power.

Hi Howard,

Not quite correct, what happens when I connect the external battery charger (or connect the starter battery to the leisure battery via jump leads) is that the 12v circuits work, proving something, but they are not being powered by the parallax converter, they are being powered by the battery.
This is leading me to think that the wiring is fine, but there is somerhing blocking the converter output. This seems to be nonsense though as I can measure 13.6 volts all over the 12v fuse board...

Hi Lou,

You and me both

hmmm....On the last page of that pdf, is the curcuit breaker the thing near the battery with what looks like two terminals on it?

I *think* I may have one of those under the front of the coach near the starter (not leisure) battery...
Quite hard to get at but could that have a reset button/plunger that may be worth feeling for?

Hi Gary,

Polarity fuses okay and troubleshooting guide followed...It concludes converter is okay.

Tom · « **Reply #24 on:** December 06, 2009, 08:34:27 AM »

Quote

the starter (not leisure) battery

Translation from Britlish to Amlish:

the chassis (not house) battery

John From Detroit · « **Reply #25 on:** December 06, 2009, 11:18:13 AM »

Regarding Reset buttons or switches... Most converters use fuses. the reset button, if any, will be elsewhere.

For example the schematic for my battery control switches shows a pair of 30 amp post type (Push in to reset) breakers... What Damon gave me is something else (And way lower maintenance) but that's what the diagram shows.

On my rig the breaker (Which is a self-resetting type) is a good 35 or more feet from the converter.. (And the rig is only 37')

Just Lou · « **Reply #26 on:** December 06, 2009, 11:27:15 AM »

Quote from: John From Detroit on December 06, 2009, 11:18:13 AM

Regarding Reset buttons or switches... Most converters use fuses. the reset button, if any, will be elsewhere.

For example the schematic for my battery control switches shows a pair of 30 amp post type (Push in to reset) breakers... What Damon gave me is something else (And way lower maintenance) but that's what the diagram shows.

On my rig the breaker (Which is a self-resetting type) is a good 35 or more feet from the converter.. (And the rig is only 37')

John, the reason Damon did it this way was because the batteries were installed away from the BCC. They wanted a breaker located so that it would protect the long run of wire to the converter an loads. In my rig, the batteries are within two feet of the BCC, so the internal breakers are used.

Your schematic, provided by Intellitec, just shows what their option would be.

Bryan · « **Reply #27 on:** December 06, 2009, 12:04:14 PM »

Right, I'm now getting so confused I went out to my rig 10 minutes ago and met myself coming back!

I have now totally remove the house battery. The +ve lead is hanging in the air and the -ve had been connected to the chassis battery to preserve the integrity of the earth. (Tell me if I did wrong)

Now, the converter is still measuring the same voltages everywhere but still no lights.

Whilst playing with my meter and measuring everything that I could (the cat look very concerned at one point) I discovered the following which may help someone come up with a EUREKA! or may, as it did with me, just confuse the issue even more...

(Refer to this doc page 7) Paralax boardhttp://www.parallaxpower.com/7300%20Series%20Installation%20Guidelines%20rev%20A.pdf

When I connect my meter set to vdc I get 13.6v if I connect to number 4 on the fuse board (this is supposedley connected to the battery negative) to the negative earth bar...

But I get no reading if I connect the meter to the earth bar and the connection 1 where the 12v+ve from the converter is attached.

Unless I'm completely crazy this is totally wrong.

Do you agree?

Bryan · « **Reply #28 on:** December 06, 2009, 12:43:00 PM »

UPDATE:

Looks like I have an earth problem...I think :-)

I was starting to investigate the strange voltage reading between the battery neg connection on the fuseboard and the negative earth bar when I unscrewed the fuse board to pull it forward (don't ask why) and when I was putting it back the rear connection block (which has the converter white wire -ve attached) touched the metal frame of the converter housing...
The lights came on

So, I don't know what is wrong or how to find out but I think this points to an earth/short/wiring issue...

Gary RV Roamer · « **Reply #29 on:** December 06, 2009, 01:36:23 PM »

It appears your "earth bar" (or whatever set of termination points are attached to terminal 4) is grounded only if the battery (-) is present. That's not real bad - the battery negative should always be connected to the RV's chassis for grounding purposes - but if you have a bad (corroded) connection somewhere you can indeed get very strange results. Strange problems in an automotive-style 12v system are nearly always grounding problems.

Without seeing your actual wiring it is hard to tell if there should be an additional ground strap on your "earth bar", but that's one thing I would be looking at. The other is the condition of the battery (1) lead and the connection at both ends (battery and chassis).

News:

Author Topic: 12 volt circuits dead when on hookup... (Read 2611 times)