Odd Inverter Issue..

[Cubflyer]

Jim J,

>>>So in the future, if I have to bypass/remove the inverter how do I get the 12 volt circuits to work?<<<

My guess is to connect to the chassis the big black (negative side of the batteries) cable while the inverter is removed..... there is no other reason the other 12v items on the circuit would be inop other than the ground is missing.  Weird to me that the only connection of the house batteries to ground would be thru the inverter but if that is the only negative side of the batteries disconnecting it kills the circuit....

Ken

Edited August 22, 2021 by Cubflyer

[jacwjames]

You might be right, I crawled under the coach to see if I could find another ground and never found one although I didn't spend much time looking, I had bigger fish to fry. 

[Bob Jones]

I think Ken nailed it - good call! 

This does make me wonder though about your vehicles grounds. On my inverter there is a bare thin copper ground wire that runs to the rear of the inverter. If yours has the same perhaps it's only grounding through there? It might be something to keep in the back of your mind to look into when you have time as it *might* indicate you have a ground issue? I'm no expert, but it sticks out in my mind. 

13 hours ago, waterskier_1 said:

The plastic rivets are about $5, in the USA - not sure about CA.  Depending on size, you might get them at an auto parts store.  I buy mine in quantities on eBay.  

Yes, you'll need a charge source for the batteries if you plan on not reinstalling for an extended time, and don't have solar. 

Best of luck on the relay replacement fixing the problem. 

I'll try the auto parts store today although the rivets are a little odd. Not the normal push in button type but they seem to literally be a type of plastic rivet. Plan change! I've got the unit all back together. It's going to take a long time for the new relay to show up so what I did was take the relay contacts off (pretty simple, remove the spring and then the arm lifts off). Then I could see the contacts and cleaned them up with emery paper. 

I'll put it back in today and see what happens. I took lots of pics. Here's some. My ultrasonic cleaner was not large enough to do the whole board at once 😞

[Dr4Film]

4 hours ago, Cubflyer said:

Jim J,

>>>So in the future, if I have to bypass/remove the inverter how do I get the 12 volt circuits to work?<<<

My guess is to connect to the chassis the big black (negative side of the batteries) cable while the inverter is removed..... there is no other reason the other 12v items on the circuit would be inop other than the ground is missing.  Weird to me that the only connection of the house batteries to ground would be thru the inverter but if that is the only negative side of the batteries disconnecting it kills the circuit....

According to the wiring diagram below of the Trace/Xantrex RV2012 Inverter/Charger, once you remove the Inverter the ground is missing for the 12 VDC supply to power those devices in the coach.

When changing House Batteries the coach doesn't lose 12 VDC power as it is getting it from the Inverter/Charger. However, when you remove the Inverter there is no more ground. You would have to make a temporary ground for it to work correctly.

Trace RV-2012 Schematic.pdf

[waterskier_1]

Ken and Richard are correct.  The only way for the battery negative to get to chassis ground is through the inverter.  This is by design.  This way, ALL current flowing into/out of the battery MUST flow through the inverter, so it knows how much current is going into and out of the battery.  It uses this to show current flow, and also, if you have any sort of battery monitor, this is the input for it to gauge State Of Charge (SOC).  Since the inverter is removed, no inverter functions or readouts are available, so you can connect the negative battery cable to chassis ground.  Just remember what you did (and hopefully why you did it.).

[Bob Jones]

That makes perfect sense. But it also makes me wonder why mine is working. Perhaps it's wired differently. I even went out there and made sure the ground to the rear of my inverter was not touching ground - still works. 

[Dr4Film]

I believe the Legend Series is wired differently.

Here is a manual which closely matches your Inverter. I could not find one labeled exactly for the Legend 1500 Watt Inverter.

3178UX-L-TRevNew.pdf

[Bob Jones]

Thanks Richard - that is the one that I have (L model in 1500 watts). I'm just about to re-install so will be offline again. I'll know in short order whether I missed any connections inside or put them in the wrong place........or just generally screwed it up 🙂

I did take pictures of everything before dissasembly and checked and double-checked them during reassembly. I'm as sure as can be that it's correct. If cleaning the 'points' did the trick I should know soon! Likewise if I introduced a problem. One thing is sure though, I know more about how it works than I did before.

[Bob Jones]

So far...so good. It's back in and charging and I've tested the inverter operation several times so...the relay is working OK at this point. Time will tell if the intermittent issue is gone. But...what is interesting, is the buzzing noise the inverter used to make is much quieter and a higher pitch. Go figure. Fan works, charger works, relay works, it looks like I didn't introduce a problem and that's always a good thing. Plus, I learned a lot. If it packs it in, I can bypass it. I also realize that I can replace the relay without taking the entire thing apart. 

Here's some pics for anyone interested....that date code is correct, it's from 1999.....they made them a LOT better back then...

Edited August 22, 2021 by Bob Jones

[Bob Jones]

I'm going to declare victory on this one 🙂  The inverter has been working perfectly, the issue with it dropping the outlets has not come back (fingers crossed) but it's very clear that the inverter's operation has changed. In fact, it's changed a lot!

I know that the relay contacts are now clean but I have to say, I think the ultrasonic cleaning did a real number on it. There was a lot of dust and sand in there, no doubt from Palm Desert and the Sonoran (?) desert? My parents spent 3 months a year at FOY for many years (almost 20?) and the unit also spent time in Mexico somewhere, along with AZ and other places with sand and wind. There was also tiny particles in there that looked like magnetized iron filings stuck to things. Anyway...

I've noticed some changes, most of them seem to be with the charging circuit?

• Absorption stage now works. In the past, if it went into absorption it would only be for a few minutes. Often it skipped the stage entirely because the bulk charge voltage seemed to get the battery volts too high. This was deemed normal by others in the know when I last asked about it.
• The interior lights (all 12v) seem to be consistent in light output. They used to be dim at times and bright at others and it really bugged me. I suspect this also tracks back to the charge circuit keeping the batteries at a constant level.
• The bathroom fan used to speed up a great deal when I turned off the light in the bathroom or the lights at the vanity. Now it stays at the same speed.
• Once the batteries are fully charged the panel indicator lights no longer flicker all the time between charge and float (regardless of 12v load). They now spend 90% of their time locked on Float with the voltage locked as well. Ie, the voltage is stable. Really stable. 
• The inverter used to buzz a lot. Now, when the batteries are full and stabilized, it's silent. I put my ear right on the unit and still could not hear anything.

The ultrasonic cleaning removed all the dirt & debris and I know it cleans all the contacts and solder points. These are just my observations, nothing scientific, but from what I'm seeing, the operation has changed a lot. Stable and consistent are the words that come to mind. 

Almost forgot one. Because the voltage on the panel is now so stable I saw yesterday that it was at 13.0 volts and when the ambient temp got colder it went up to 13.50. You could never 'see' the battery temperature compensation work before because the lights indicating the voltage were so sporadic and all over the place.

Anyway, just wanted to give up an update after a few days. If the original complaint (dropping inverter outlets when there is shore power present) comes back, I'll post about it. Many thanks to all that helped! Knowing the contacts are clean on that relay makes me feel a lot better. They were pitted and they all had some level of arc burn on them. But when I look at the panel and see three green lights that are not flickering or moving around, I know it's operating like it used to back when Dad bought it nearly new all those years ago. 

Edited August 26, 2021 by Bob Jones

[StephenW]

Congrats on your success!  Thanks for all the valuable information you have posted.It's nice to see a plan come together!