How do you use your Auto Gen Start (AGS) and does it Auto-Stop?

[gordonsick]

I am frustrated that the Auto Gen Start on my Berk doesn’t perform particularly well, so I wonder if I am using it incorrectly, or whether my expectations are too high. I am making four postings on the subject:
1. This posting asks for your methods of using AGS and success/disappointments/failures.
2. The next posting will discuss my efforts to use AGS “by the book” and using emailed advice from Forest River.
3. Then, I will discuss my efforts to use AGS with the supplied Temperature Sensor but the AGS set to Temp=Ext On. This seems to be an undocumented but partially successful solution.
4. Finally, I will discuss an alternative using a Magnum Pig Tail 2 (PT2) remote cable and a Dometic-Magnum interaction module. I wonder if any others have gone this route, since it is a promising solution “by the book”, but it will cost money to install.

A common explanation of the use of the auto-start feature is to run the air conditioner while the RV is unattended but not on shore power. This is potentially valuable for protecting pets while in the RV. I am more interested in using it to run the A/C while I am driving, as way of augmenting the dashboard A/C that is powered by the engine.

So, I hope that people can answer the following simple questions for me:
• Do you use auto generator start (AGS) on your motorhome?
• For what purpose do you use the AGS?
• If you are successfully using the AGS, what settings are you using on your A/C system and Magnum (ME-RC or whatever) remote?
• If your AGS auto-starts the generator, does it also auto-stop it when the condition that requires the generator is removed? For example, if it auto-starts to run the A/C does it auto=stop (in a reasonable time) after the A/C turns off?

[gordonsick]

The manuals provided with my Berk are very sketchy in telling me how to use the AGS.
• The overall RV manual from Forest River doesn’t mention AGS at all.
• My RV came with a Magnum ME-RC remote control and a manual, which is also at http://www.magnum-dimensions.com/sit...-ME-RC_Web.pdf
• I had to download the documentation for the Auto Gen Start Network module (AGS-N) module that came with my RV: ME-AGS-N Owner's Manual | 64-0039 Rev B | Magnum Dimensions
• There is also an AGS-N Spec sheet at http://www.magnum-dimensions.com/sit...sheet_revc.pdf
• I had lengthy email discussions with the Magnum/Sensata tech department, representatives at the Forest River Diesel Division.

I have also had the local Magnum service rep swap in a new AGS-N unit and it performed the same as the one shipped with my RV.

My AGS-N came with a Remote Temperature Sensor Cable as per Section 2.4.1 of the AGS-N manual. The Forest River rep says that it is connected to a temperature sensor in the bedroom air conditioner. I assumed that the temperature sensor for the bedroom A/C is on the bedroom wall next to the bathroom, in a little round black button, but I may be wrong. It could be in the A/C unit.

Section 7.0 of the ME-RC model describes how to set up the run time and start conditions for the generator. It discusses two methods for starting the generator to run the A/C: either use a temperature setting on the AGS: -4 Start Temp F Menu, or an optional ME-PT1 or ME-PT2 pigtail adaptor. I don’t have the pigtail adaptor, so I will discuss it in a later post. I have set the run time to the shortest allowed: 0.5 hours

This leaves me to run the generator on the basis of the temperature read by the sensor wire. The big question is how to set this temperature relative to the temperature set in the A/C thermostat (a Dometic CCC 2 in my case). In a paragraph in Section 7.0 entitled “Where should I set Start Temp?” it says:
“the AGS: 04 Start Temp F setting should be slightly above the A/C unit’s thermostat “cool” temperature (usually around 70-72F). Once the temperature setting is reached, the generator will start providing power to the A/C unit. The reason the temperature is set above the A/C unit’s thermostat is to ensure the A/C unit will run when the generator starts.”
When I do that, the A/C attempts to start from the Magnum ME2012 inverter before the generator is on. Although the inverter claims to be able to produce 3100 watts of power for 5 minutes, it doesn’t have enough power to run the A/C. The A/C doesn’t run and gives an E7 fault code in the Dometic CCC LCD panel.

Perhaps this would work if I had a bigger set of batteries than the 4 golf cart batteries that I have. But, I’m not sure if the battery bay will handle the weight of bigger batteries, such as L16s that would weigh 500 lb vs 250 lbs for the golf cart batteries.

When I discussed this by email with Mike Bukowski at Forest River, he said that I need to set the temperature on the A/C to start after the generator starts, so it should be slightly lower than the temperature set for the A/C. This is opposite to the Magnum recommendation. There are three problems with this approach:
1. The ME-RC unit only allows 5 degree steps in the the temperature threshold, which is pretty coarse. For example, I could set the ME-RC to start at 75 degrees F, and the A/C to start at 76 F. But, I couldn’t get the AC to start at 73 F.
2. The generator could run for a very long time before the room temperature rises the extra degree to start the A/C. This is a waste of fuel.
3. On the downside, the A/C won’t get the room temperature low enough to auto-stop the generator when cooling is no longer needed. This is because the generator needs a temperature one degree lower to auto stop. Again, this is a waste of fuel.

As a positive note, I must say that if I am just auto-starting the generator based on temperature or voltage, and if I remove the temperature or voltage requirement in the ME-RC, then the generator does successfully auto-stop if it has run for my preset time of 0.5 hours.

I’d be very interested to hear if others successfully use this procedure “by the book” or some variation of it. And, does it auto-stop the generator when the A/C comes off?

[gordonsick]

This procedure seems to be undocumented, but comes from natural experimentation of the settings of the ME-RC control unit.

In the ME-RC, I set the AGS: 04 Start Temp F to Ext Input. According to Section 7.0 of the ME-RC manual, this requires the use of an external switch (such as a pigtail PT 1 or PT 2) connected to the AGS-N Remote port in place of the Remote Temp Sensor Cable. Remember that I have the Remote Temp Sensor Cable in this port, so it is not clear that this should work because the Remote Temp is an analog device, while the Ext Input requires a digital on or off signal.

Now, magically, this undocumented feature will let me auto-start the generator based on the Dometic CCC thermostat settings! That is, if I set the Dometic thermostat to request a temperature that turns the (front) A/C unit on, the generator first auto-starts, then the A/C fan comes on, and finally the A/C pump comes on and the A/C runs. I’m not sure why this works. I only found out about it before I found that the remote wire is connected to a temperature sensor rather than a switch. I asked Forest River if they have modified the Temp Sensor wire to also hook into the thermostat or A/C somehow. They say it isn’t modified.

Now, this magic would be wonderful if it could also auto-stop the generator when the A/C goes off. But it doesn’t. If I reset the thermostat so that the A/C goes off, the generator will not auto-stop, even if I let it run for over one hour (when the run time is set to 0.5 hours). When I monitor the AGS: 08 AGS Tech menu for Gen Run, I can see the Gen Run incrementing in tenths of an hour every 6 minutes. But, when it is supposed to step up from 0.4 to 0.5 hours, it resets to 0 hours and the generator keeps running. At this point, the AGS: 02 AGS Status reads “AGS: Start Temp” which seems to mean that the generator is running because it is still getting a Start Temp signal (which is Ext Input). The TECH button 01 Temperatures shows AGS: Ext On.

Note that I’ve had lengthy emails with the Sensata/Magnum tech reps and have had the local Magnum rep (Little “D” RV) look at this with me on my RV. We can’t find any documentation that makes sense of this.

Is anybody using this procedure? Can they modify it to auto-stop the generator?

[gordonsick]

Appendix 6.1.1 of the AGS-N manual discusses AGS Pigtail adaptors that work as switches to turn the generator on and off. They are also mentioned in Section 7.0 of the ME-RC manual, under the heading AGS: 04 Start Temp F Menu. The pigtail adaptors plug into the AGS-N Remote port, in place of the Remote Temp Sensor that I have.

I downloaded the manuals for the two adaptors, and it seems that the PT-1 works with Coleman and other air conditioners requiring one wire, and the PT-2 works with Dometic and other air conditioners requiring two wires. Here is the manual for the PT-2:
http://www.magnum-dimensions.com/sit...klet_Print.pdf

Figure 2 on Page 2 of the PT-2 manual has a discussion of a Dometic/Duo Therm kit 3109226.005 “to connect the t-stat output of the air conditioner directly to the AGS. This allows the AGS to start on demand from the a/c for either heat (heat pump only) or cool.”

That sounds exactly like the solution I need. I notice that that unit can be purchased from Amazon, but I’d be tempted to have it installed by my local Magnum rep Little “D” RV, since he is also an authorized Dometic dealer. BTW, he tells me that the Dometic thermostat is usually connected to the front A/C and that there is a communication cable between the front and rear A/C units to get the rear A/C to work. This sounds sensible, but is slightly different from the Forest River assertion that the AGS temp sensor cable goes to the rear A/C. Of course, these are different things, but it does suggest that Forest River thinks of the rear A/C as being in charge of things, so Forest River might have done things in reverse of the normal.

So, my question to forum members is whether they have installed a Pigtail PT2 adaptor, along with the Dometic/Duo Therm kit. If so, does it work as expected?

[padcarroll]

I can only add that the bedroom temp sensor in my Legacy is under the drivers side shirt cabinet in the bedroom.