Intellitec EMS 800 Load Management Issue

[dmastroluca]

I am working with Intellitec support on this issue, but I was just wondering if anyone else has experienced this issue.

The EMS 800 contol pane has 4 input LED's showing your current power source.

Gen Set
50 AMP
30 AMP
20 AMP

All the shore power inputs 50/30/20 light up fine when you apply the desinated power source, and the unit works. When running the generator, the EMS control panel will not light the "Gen Set" LED only the 30 AMP LED. This is preventing me from running both roof airs bacause the load is 32 amps.

I checked at the input/output of the transfer switch, and I have 120 volts on both legs of the generator. I checked the input to the EMS 800 load center and I have both 120 legs of the genny going into the main box.

[jacwjames]

I have the Intellitec 760 system (I upgraded from the previous version when it quit working).

The system has a 12 VDC line coming from the house batteries but also has a 12 VDC line coming when from the generator. It senses the generator running via this feed and gives priority to the generator

On my system there was a wiring harness that plugged into the circuit board that had both these wires.

My guess is that you aren't getting the 12 VDC from the generator so it senses you are on 30 amp.

You should be able to test this with a volt meter but you need to know which harness and terminal # to check.

[dmastroluca]

Jim, I checked the 12v from the battery and the 12v from the genny and they are both there. The 12v line from the genny goes to zero when it shuts off as it should. The only thing strange I found was the 3rd terminal that is supposed to be a ground, it is not grounded, but the unit works fine other than the gen set issue. Intellitec support is stumped too, but they want me to call them, on Friday morning and they are going to have me check test points on the board with my multi-meter. I have a feeling the board will have to be replaced.

Is this thing worth the effort and cost? The only circuits on mine are the two roof AC's the water heater, and a non-existent washer/dryer. Thinking of just bypassing the whole thing.

[ShapeShifter]

Originally Posted by dmastroluca

Jim, I checked the 12v from the battery and the 12v from the genny and they are both there. The 12v line from the genny goes to zero when it shuts off as it should. The only thing strange I found was the 3rd terminal that is supposed to be a ground, it is not grounded, but the unit works fine other than the gen set issue.

A missing ground can cause strange things. If it's supposed to be grounded, then maybe try grounding it?

Just to be clear, the 12 volt signal from the generator is the run status signal, right? It should be the same signal going to the generator status light: it's on when the generator is running, off when it's stopped, and flashes when the generator is starting. It sounds like this is what you're saying, but it doesn't hurt to make sure.

If that signal is making it to the controller board, and the system is not recognizing that the generator is running, then I agree it sounds like a problem with the control board.

One simple thing to try: I've had situations where the controller board seems to get "stuck" and not work properly. I've found if I shut off all AC and DC power going to the unit (unplug shore power, and pull the 12V fuse in the closet, and leave it disconnected for a bit (20 to 30 seconds) it resets things and often fixes itself when the power is brought back (12V fuse first, then AC power.) Doing this may not help you, but it's an easy step to try.

Is this thing worth the effort and cost? The only circuits on mine are the two roof AC's the water heater, and a non-existent washer/dryer. Thinking of just bypassing the whole thing.

I have the same setup, and while I do have the washer/dryer, we hardly ever use it. Still, I feel it's invaluable to have and wouldn't want to be without it.

However, if it's worth it for you depends on how you camp. Are you always hooked up to 50 amp power (or the generator)? If so, you don't need it. If you only have 30 amp power, but don't run the air conditioners, then you don't need it. But if you want to run both air conditioners on 30 amp power, or if you often are limited to 20 amp power, then it can be really helpful.

When we have limited power, and need to run the air conditioning, I can turn on both air conditioners and put the water heater on electric, and not worry about it. When the front A/C wants to run, it does, cutting off the back A/C if necessary. When the front is done, the back will run. And when the back is done, the water heater will start heating. And at any time through all of this, if we use the microwave, it will automatically cut off the other loads, even the front A/C.

If you often have limited power, the system can make dealing with it a lot simpler. If you always have 50 amp power, you probably will never need it.

[jacwjames]

dmastroluca
I assume since you are talking the tech support they had you go through and do a reset of the system by completely disconnecting it and letting everything off for a period of time. I also assume you checked the fuse.

Other then that I'm stumped, but am wondering why it isn't grounded. Hopefully you can get this fixed.

As to whether you should bypass it depends on how often you are hooked to a 30 amp circuit.

We rely on ours quite a bit, my wife goes to dog shows and they hardly ever have 50 amp hookups.

You can bypass easily by simply wire nutting each of the circuits that feed and individual relay on the EMS board. I did this when mine quit working, I did have to leave one circuit connected to power the load monitor which is controlled via the EMS board, I believe it was the washer/dryer circuit.

[dmastroluca]

Jim, I did not do a complete power down/up, but I figured when I used my coach and chassis battery disconnect that it would of reset it. I did check the fuse and it was ok. I believe the fuse is only for the remote monitor panel. I am going to pull the board before my next tech support session on Friday and check for any solder joints that may need to be touched up. I did notice terrible strain relief techniques on the cables going to terminals on the board.

[phranc]

I had a somewhat similiar issue when I had the breaker for the washer turned off. The coach was winterized and I did not want to use the washer. Flipping the washer breaker back on allowed the intellitec to reboot and all was OK once again .

[dmastroluca]

Adam, thanks for the operational information. That makes me understand how the system should work. I have not camped in it yet since we just purchased it, and it needs alot of TLC since the original owner let it sit for a long time. I rolled back to Vegas from Cali on 10 year old tires, an oil packed, overheating radiator and CAC, a sprung awning, and what I thought was a busted rear HVAC unit. I am not sure how we will manage our power yet, but since it is so hot here in Vegas right now, I just wanted to run both HVAC units off the generator. Glad I don't need a new HVAC as it was just this EMS issue.

[jacwjames]

dmastroluca
Sounds like you are technically inclined.

One option for you might be to wire the front or rear AC unit so that you can plug it into a separate 20 amp outlet bypassing the system in the RV.

The previous owner of my coach did this. Normally the AC units are wired into a junction box up in the filter vent area. What he did was simply put a standard outlet in the electrical box and an extension cord end on the AC unit and plugged it into the outlet. He must have brought an extension cord end in through the rear window as there is a couple of hangers mounted so he could get it up to the AC unit without hitting it all the time

When plugged into a 30 amp circuit the rear AC unit can be run and the EMS circuit thinks it's OK to run the front so both AC are running.

That or just bypass the EMS unit with the 2 AC's and let the rest be controlled as normal.

Good Luck, sounds like you have some things to do with the new to your coach.

[dmastroluca]

Originally Posted by jacwjames

Sounds like you are technically inclined.

Luckily yes, I am an engineer by trade, and an uber DIY guy. Drove my wife crazy in June when the POS coach we rented had a ton of problems on our 3 week vacation. I spent every day working on that thing. It was returned to the owner in better shape than when we left. LOL.

[jacwjames]

Great, I am an engineer by trade also and working in the mining industry for +30 years. As I progressed in my career I was heavily involved with maintenance and at one time maintenance manager for 3 mines and concentrator.

Problem is it still did not prepare me for owning a motorhome

[shiggs68]

If your EMS detects 240vac between the two hot leads (L1 and L2), it assumes a 50amp RV supply. If that voltage is zero but 120vac on both L1 and L2, then it assumes you are using a 30amp adapter. From the generator, if the 2 feeds are not out of phase, then it looks like 30amp.

Has anyone changed or reworked the wiring in the generator or transfer switch. One winding just needs reversed. Check in the transfer switch for 240vac across the two hots.


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[ShapeShifter]

Originally Posted by shiggs68

Has anyone changed or reworked the wiring in the generator or transfer switch. One winding just needs reversed. Check in the transfer switch for 240vac across the two hots.

That's not going to work: they have a common neutral, so you can't really swap the polarity on one leg (it's three wires, not four.) with the common neutral, any attempt to reverse the polarity of one leg will cause a direct short because you will be connecting one leg's neutral to the other leg's hot. This is true for the Onan generators that are under 10kW - they are actually DC generators that then run through an inverter to create the AC power. It is likely just one inverter controller driving two output stages, so they will always be in-phase. The larger Onans, starting at 10kW don't have inverters, they are straight AC generators, and they already have the desired 240 volt split phase output.

But it's a moot point if you are trying to fake 240 volts for the sake of the EMS: there is a 12 volt DC status line coming from the generator to tell the EMS that the generator is running. (This is what the OP is fighting.) When it sees this signal, it overrides the normal voltage detection scheme you mention, and goes into generator mode: in this mode, it displays the total current (which is not possible with 50 Amp 240 volt split phase power) and disables load shedding (because it's assumed that the generator is powerful enough.) So in effect, the generator is already using the 50 Amp power rules, with no need to fake out the EMS.

A note about the current display: Intellitec took the cheap way out, and they only use a single current sensor on the neutral line. This works when the two hot lines are in phase with each other and the neutral carries the sum of the two hot currents (with 20 amp, 30 amp, and generator sources.) but with 50 amp 240 volt split phase power, the neutral carries the difference between the two hot currents, so simply reading the neutral current doesn't give you an accurate picture of power consumption - and that's why the current display is blank when on 50 amp power.

[shiggs68]

ShapterShifter. I agree in theory. However, in reading the manual (page 3), it indicates exactly what I have stated above about sensing 240vac or 0 vac from L1 to L2 and the 12vdc generator signal.

With that said, you are probably correct in that Onan Generators have one tapped winding. However, the OP did not state what generator make/model. I'm only expressing what the EMS is looking for and possible causes not knowing the rest of the story.

It would seem relatively simply to validate what the EMS voltages are and working backwards from there.


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