When Smarter is not always better..

My coach has a Precision Circuits Power Control System; it is a very sophisticated, smart, system.  This system routs and monitors power throughout the RV regardless of source, generator or shore.  It works with the Magnum Inverter to reduce battery charge rate prior to shedding loads.  It will shed non-critical loads during high peak loading.  Here is one of its self proclaimed features, ?Monitor and Manage total RV current (amps) to avoid nuisance circuit breaker tripping?.  This is where the system becomes too smart.

We camped at a camp ground that had only 30amp service available, not a problem I thought, it was hot outside, but I have run 2 A/C units on 30amps, on a previous coach, without a smart Power Control System.  Just monitor your amps, stay at or slightly under 30 amps and you are good to go.  If I drew too much current the trusty circuit breaker on the shore power pole would let me know.  It has been my experience you can run a bit over 30 amps and still not trip the breaker, less that 30amps is preferred, but a slight bit over 30amps for short periods of time will not trip the breaker.

With a smart power control system running the show, this being loose with an amp or 2 is not an option, the instant the smart system detects 30 amps, it sheds the second A/C unit.  2 A/C units can run on less than 30 amps, after initial start up, but if the smart system detects a battery system in need of charging, which is a higher priority than my 2nd A/C unit, the A/C unit is ?shed?.  Of course the big new RR is always drawing its 6 amps which compounds the problem.

We love our Tour with 100 available amps, with exactly 30 amps, it is a hot box.

My first load to shed is the electric hot water element. #2 AC compressor is next.  Do you have a electric hot water element you can shut off?

We have an AquaHot system, the electric heaing element was off..  Next time I run into this problem, I am going to try turning the RR off for a few hours.

One of our friends in our Winnie club has a brand new Journey with a really different energy management system.  I was helping him try to figure it out one night at about 9 PM at the GNR.  If the load temporarily exceeds 30 amps (I have no idea what the algorithm is) the inverter will supply the difference.  I think he was also having a problem with the second roof air not running on 30 amps.

Circuit breakers are specified to carry 80% of their rated amperage continuously.  Exceed that and they will eventually trip, so a 30A breaker should only be loaded to 24A continuous.

John Canfield said:

One of our friends in our Winnie club has a brand new Journey with a really different energy management system.  I was helping him try to figure it out one night at about 9 PM at the GNR.  If the load temporarily exceeds 30 amps (I have no idea what the algorithm is) the inverter will supply the difference.  I think he was also having a problem with the second roof air not running on 30 amps.

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That's what this system is suppose to do, I don't know how to tell if it really works as advertised- when 30 amps was reached the system shed an A/C unit.  I wonder if there is a way to test wheather or not the inverted  is indeed supplying extra juice to the system?

If the load temporarily exceeds 30 amps (I have no idea what the algorithm is) the inverter will supply the difference.

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That's the Onan Hybrid Quiet Diesel system, in which the generator and inverter are integrated with power management. If you have a temporary power shortage the inverter is used to assist; if sustained or more than the inverter can handle, the generator comes online. It is programmable for things like quiet time and demand thresholds. It's a slick system. Glad to hear Winnie is installing it.

http://autopowerinverter.blogspot.com/2012/03/cummins-onan-rv-products-hybrid-quiet.html

Ned said:

Circuit breakers are specified to carry 80% of their rated amperage continuously.  Exceed that and they will eventually trip, so a 30A breaker should only be loaded to 24A continuous.

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...and this is tempered further by the number of times the breaker has been blown. The higher the number of times, the more sensitive it is and the more likely it is to blow at a lower amperage than expected.

tomnnva said:

We camped at a camp ground that had only 30amp service available, not a problem I thought, it was hot outside, but I have run 2 A/C units on 30amps, on a previous coach, without a smart Power Control System.  Just monitor your amps, stay at or slightly under 30 amps and you are good to go.  If I drew too much current the trusty circuit breaker on the shore power pole would let me know.  It has been my experience you can run a bit over 30 amps and still not trip the breaker, less that 30amps is preferred, but a slight bit over 30amps for short periods of time will not trip the breaker.

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I think smarter is better. I don't think it is a good idea to rely on circuit breakers tripping like you are doing. If the circuit breaker fails you could end up burning up your motorhome. Just because you could run two A/Cs with your last unit does not mean it is a good idea.

Our coach with basement air, two compressors, and a high/low blower speed controlled by the energy management system makes camping on 30 amp power basically a non-issue.  It's not a real smart system like the new Winnie's have, but it's very effective and reliable.

Once the 42 footers came out with three roof airs, energy management on 30 amp shore power became much more problematic and difficult.  Winnie ditched the Dimensions charger/inverter and the old EMS system for something else - not sure if it is based on the Onan system or not.  Maybe Tom (tommnva) can shed some light on the system and the vendors.

Smarter is not always better.

The Power Control System is manufactured by Precision Circuits Inc.  Here are the features right out of the manual;

1) Monitor and manage total RV current to avoid nuisance circuit breaker tripping.
2) Manage power no matter what the source: 50amp Service, Generator,  30amp service, 20amp service. (20amps, they have got to be kidding)
3) Provide Inverter-Assit (their word), additional power from battery bank to smooth out high peak demands. (I would like to know how to test this feature, 30amp threshold seems to trump everything.)
4) Shed non-critical loads during high peak loads. (My second A/C)
5) Remote panel displays Service Type, Load Status, and RV Current and Voltage.
6) Generator Soft Start.

I would like to be able to change the ?critical load? sequence, i.e. make my 2nd A/C a higher priority device than my RR.  The manual says this cannot be done by ?dealer or owner?. 

Has anybody ever tried to change the critical load sequence on one of these devices?

John Canfield said:

Smarter is not always better.

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It sure beats the hell out of dumber.

tomnnva said:

...Has anybody ever tried to change the critical load sequence on one of these devices?

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Thanks for that overview Tom.  It sounds like that feature was not coded into the program.  My Xantrex is highly configurable, but that was a design criteria of the RS2000 and the AGS.  Chances are Winnie worked with Precision Circuits to get the necessary features built in at a cost they could live with.

Hmm - is there a way to make some changes at the breaker panel?  Swap the 2nd AC for the fridge?

The Intelletec version of an EMS can be configured to any priority order for load shedding, but you need the installation( or service) manual to do it. There are jumpers and possibly physical wiring to change (in the case of an a/c). Probably the Precision Circuits unit is similar.  Generally speaking, the unit has to be configured for the load-shedding sequence when it is installed, since not all RVs have the same equipment.  If you can get an installation manual from Precision or Winnie, I'll bet you could do it yourself with little difficulty.  Upon further study, I see that the shed order is digitally controlled and a "dongle" and a Windows program are needed to alter it.

This is not a Winnie-specific product, though it may have their logo on it when installed in a Winnie or Itasca. Precision offers their system with any Magnum Energy inverter system and Tiffin uses it too.

Here is a link to the PCS Installation manual:
http://www.precisioncircuitsinc.com/Documents/PDF%20Documents/PCSInstallationInstructions.pdf

Hi Tom, hope all is going well except this issue...I see you have made progress in your great adventure since we saw you in south Dakota! I picked up on of these adapter boxes http://www.campingworld.com/shopping/item/50-amp-rv-box-adapter/25774 in case of a situation like yours...as you know I need 50 amps!

According the attached diagram the residential refrigerator IS turned off before the air conditioners are turned off.

DennisGraham said:

According the attached diagram the residential refrigerator IS turned off before the air conditioners are turned off.

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My system does not have a display that looks like the one you have pictured.  It does, however, list the items to be shed in order of least importance;
engine heater, water heater(AquaHot), Front A/C, Rear A/C, Middle A/C, Dryer, Washer.  It does not even list the RR.  I'll be on the phone with Precision Industries Monday to sort things out and report back.

DITTO said:

Hi Tom, hope all is going well except this issue...I see you have made progress in your great adventure since we saw you in south Dakota! I picked up on of these adapter boxes http://www.campingworld.com/shopping/item/50-amp-rv-box-adapter/25774 in case of a situation like yours...as you know I need 50 amps!

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Joe - thanks for that tip, it is my next purchase, 50amps we could live with.  We are now in Salt Lake City and will be here for about 10 days.  Jane has to fly back home to the OBX, when she returns its off to Zion and Brice.

Tom,
  A couple of items.  First, with the "cheater" you will not have 50 amps.  You will actually have two separate lines with 30amp each.  Or, stated another way, with 50 amp you have Line1 with 50 amps or 6,000 watts AND you have Line2 with the same for a total of 12,000 watts.  With the "cheater" you will have Line1 with 30 amps, or 3,600 watts AND you will Line2 with the same for a total of 7,200 watts.  Not the same but certainly better but remember, a "cheater" will not work on a post with a GFI connection.
  The second item, is I think I know the problem you are haviing when your second ac is being shed by the power control monitor from precision circuits.  If you call them tomorrow tell them they may not be aware of the fact that RV Products (the makers of the air conditioners) changed their thermostat to 3 zones, each with a demand from the ac's of 14 amp.  Previously they only had two zones one with a 28 amp demand and the other with 14 amp.  If you set it to the one with 28 amp then you had two ac's working on 30 amps but with three separate zones their control module is not allowing the second ac to operate.  I don't know a solution but I think this is the reason for the problem.  I doubt if RVP ever told precision circuits about the change.  (Mabye I can send them an email too.) 
  I need to know myself as I pick up my new Meridian 43E in October and will be facing the same problem when we connect to 30 amp service.
Let us know what you find out.

DennisGraham said:

Tom,
  A couple of items.  First, with the "cheater" you will not have 50 amps.  You will actually have two separate lines with 30amp each.  Or, stated another way, with 50 amp you have Line1 with 50 amps or 6,000 watts AND you have Line2 with the same for a total of 12,000 watts.  With the "cheater" you will have Line1 with 30 amps, or 3,600 watts AND you will Line2 with the same for a total of 7,200 watts.  Not the same but certainly better but remember, a "cheater" will not work on a post with a GFI connection.
  The second item, is I think I know the problem you are haviing when your second ac is being shed by the power control monitor from precision circuits.  If you call them tomorrow tell them they may not be aware of the fact that RV Products (the makers of the air conditioners) changed their thermostat to 3 zones, each with a demand from the ac's of 14 amp.  Previously they only had two zones one with a 28 amp demand and the other with 14 amp.  If you set it to the one with 28 amp then you had two ac's working on 30 amps but with three separate zones their control module is not allowing the second ac to operate.  I don't know a solution but I think this is the reason for the problem.  I doubt if RVP ever told precision circuits about the change.  (Mabye I can send them an email too.) 
  I need to know myself as I pick up my new Meridian 43E in October and will be facing the same problem when we connect to 30 amp service.
Let us know what you find out.

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You may be on to something, the thermostat that came with this RV had 2 zones; zone one controlled 2 a/c units, center and forward while zone 2 controlled only the rear unit.  While attending the Grand National Rally in Forest City, I had Winnebago upgrade my coach to a 3 zone thermostat, hoping to gain better amp management.  I am wondering now how the PCS reacts to this new configuration without being reprogrammed or is it strictly looking at current flow regardless of zone configuration?  I will ask that question.  Thanks for the tip, Dennis.