Community Forums

jwmaustin · 03-14-2016, 10:34 PM

Thanks folks. This got going what I wanted: a current discussion of the low site voltage problems. Looks like I have managed to avoid some problems sites so far. Another factor that seems to play in is how long someone is staying at a site. I don't stay more than one to two weeks so I maybe don't feel the pain enough.

The comments on the power situation are good. I can't see how how an individual RV can impact the rest of the CG too much. What an RV "appears as" is a load and adding more inductance to the whole CG with a transformer would not seem to me to be that much of a problem. It's still a case of drawing so much power. It may be that CG owners just run scared of anything different.

If you assume the power company has done it's job, the limiting factor on the power draw is the current available coming through whatever size wire is used (or misused) at a CG. As the voltage at the post drops then some equipment will start to draw more current...any motors and some other equipment can also enter a lock mode where the starting current will really spike. For the CG, Ohms law plays a factor but Watts law of volts x amps = watts is sometimes more useful I think.

This is just my remembrance. It's been 40 years since I was in school and I kind of ignored the power courses!

As usual this site is great to get info passed around!

milasman · 03-14-2016, 10:52 PM

Ohms law says that power equals current times voltage. P=IE If you change one of the variables, one of the others has to change. So the Autoformer boosts voltage. If it increases voltage, then current has to decrease. That is the trade off.

flaggship1 · 03-14-2016, 10:58 PM

Quote:

Originally Posted by milasman

Ohms law says that power equals current times voltage. P=IE If you change one of the variables, one of the others has to change. So the Autoformer boosts voltage. If it increases voltage, then current has to decrease. That is the trade off.

And presumably, no harm no foul. And, my heat pumps, convection oven etc. Live long happy lives.

nothermark · 03-15-2016, 01:30 AM

The big issue is the deliberate undersizing of the power feed to the park. Most folks use less than full power most of the time. The power companies know that and adjust up and down the line including the power feed. Then we get a hot afternoon with every A/C available on line so a lot of current thus a lot of line drop thus problems like we are talking about.

Brian W · 03-15-2016, 09:47 AM

Quote:

Originally Posted by jwmaustin

Thanks folks. This got going what I wanted: a current discussion of the low site voltage problems. Looks like I have managed to avoid some problems sites so far. Another factor that seems to play in is how long someone is staying at a site. I don't stay more than one to two weeks so I maybe don't feel the pain enough.

The comments on the power situation are good. I can't see how how an individual RV can impact the rest of the CG too much. What an RV "appears as" is a load and adding more inductance to the whole CG with a transformer would not seem to me to be that much of a problem. It's still a case of drawing so much power. It may be that CG owners just run scared of anything different.

If you assume the power company has done it's job, the limiting factor on the power draw is the current available coming through whatever size wire is used (or misused) at a CG. As the voltage at the post drops then some equipment will start to draw more current...any motors and some other equipment can also enter a lock mode where the starting current will really spike. For the CG, Ohms law plays a factor but Watts law of volts x amps = watts is sometimes more useful I think.

This is just my remembrance. It's been 40 years since I was in school and I kind of ignored the power courses!

As usual this site is great to get info passed around!

Bill,
If you recall I had problems at the campground down the street from your house, as did others. The common denominator was 50 amp coaches. We were also towards the back of the campground, which might have been another cause. As coaches get more "stuff" added to them I wonder how campgrounds will be able to keep up, especially the older ones.

flaggship1 · 03-15-2016, 10:41 AM

Quote:

Originally Posted by Brian W

Bill,
If you recall I had problems at the campground down the street from your house, as did others. The common denominator was 50 amp coaches. We were also towards the back of the campground, which might have been another cause. As coaches get more "stuff" added to them I wonder how campgrounds will be able to keep up, especially the older ones.

They're still at 50 amp and on board energy management is shedding things to keep the load in line. With LED lights and low voltage and or high efficiency appliances, supplemental solar etc, I don't think the coaches are or will be the issue. It's throttled power and old and undersized lines and lack of maintenance that's the real culprit. I have seen RVers pull their volt meters and testing posts in front of park management and they deny it's their post???

Dutch Star Don · 03-15-2016, 11:48 AM

I'm a gadget guy and will buy anything that I think will help my coach perform better. With that said, I never saw the need to buy an autoformer, but I think "Bluepill" brings up a good point. If you routinely stay at a campground with low voltage, an autoformer may be a good choice. In simple language, autoformers increase low voltage by reducing amps to increase volts. Unless you need every amp available, the autoformer could work for you.

In 40 years of RVing, I've seen my SurgeGuard (previous coach) and Progressives Industries in my current coach only shut down on a couple of occasions due to low voltage. If I'm at a park with chronic low voltage, I either move to another site, not stay there again or run off my inverter until I leave (obviously a short stay).

Dr4Film · 03-15-2016, 12:09 PM

I see a lot of good information on this thread and also some bad WRT Autoformers and Voltage Boosters.

I have a Power Master Voltage Booster FIRST in line with the shore power supply followed with the Progressive Industries EMS-HW-50C second.

For those that have stayed in campgrounds where everyone has two to three A/C's running and your pedestal is supplying you with voltage down around 102 VAC or lower

, that's about where the EMS-HW-50C will cut your power off. So now you are sitting there with no A/C's at all in the sweltering heat.

With an Autoformer or Voltage Booster you would still be cool with all of your A/C's running. In fact you probably would have lots of visitors coming over to get cool.

For those that don't use the EMS-HW-50C, well you still have power BUT you are slowing killing your A/C's with the low voltage.

If you never stay in parks that are subjected to these power situations then I wouldn't worry about it.

Dr4Film ----- Richard

jwmaustin · 03-15-2016, 11:19 PM

Brian you are correct, the old campground has problems. As do other old CGs which several point out. I'm not sure how we get those all fixed...maybe just let capitalism solve it. BTW if you buy and Entegra you will still come past my house in Indiana on the way to the factory!

Richard, I think I agree with what you wrote. Your experience is similar to mine. I don't stay long at any CG. If others do and see an ongoing problem they might want an autoformer or something similar.

Milasman, what you say is useful for people to understand. That's kind of the basic problem. (although the law you quote isn't Ohm's).

Old-Biscuit · 03-15-2016, 11:48 PM

Standard is 120V AC +/- 10% (108V to 132V)

Surge Gard & Progressive Industries power protection devices shut off at 102V (TRC) & 104V (PI) or 132V

Damage is being done to inductive loads at voltage below 108V

Ignore....
Monitor and shut down....
Boost.....

Simple choices

Mr_D · 03-16-2016, 12:27 AM

Stayed at a friends house in Fresno. My power setup wouldn't let power in from the 20 amp plug so I tried another one a few feet away and it worked. Later I noticed that our EMS was going from shore to battery power. Turns out that the circuit I used also ran his shop. He runs a business out of his house and he had some orders to fill. Everything he turned on his saw the voltage went low and our EMS shut it off and switched to battery. The change over was so quick the TV's never knew and all we got was a slight flicker of the lights.

Dr4Film · 03-16-2016, 06:15 AM

Quote:

Originally Posted by Mr_D

Every time he turned on his saw the voltage went low and our EMS shut it off and switched to battery. The change over was so quick the TV's never knew and all we got was a slight flicker of the lights.

That used to happen to me often at different places where I was hooked to shore power except the switch-over is seamless. I don't even get a light flicker.

One time in San Antonio TX, the power was off for several hours during the night due to a winter storm and we were not aware of what had happened until the generator started up after the batteries reached the 50% SOC set point.

Later I purchased an alarm that is plugged into a non-inverter powered outlet. Now when the shore power is interrupted the alarm lets me know.

Dr4Film ----- Richard

TLGPE · 03-16-2016, 07:55 AM

Milesman, what you said is, of course accurate, but the conclusions need some interpretation. Please understand, I'm not criticizing you, just looking at the overall picture.

If the park had a good distribution system and could supply all the amperage needed for the loads of the park but the power company was giving them low voltage, then boosting the volts to your unit would have no effect on anyone else. That's true.

Unfortunately, the problem is, as others have observed, that the parks usually have undersized wires and connections. This means that when people start using their equipment, the voltage drops, often to unsafe levels. Another point of Ohm's law is that E=IR. "E" is voltage, "I" is amperes, and "R" is resistance. The tricky part is what's called "IR drop". This means that if a lot of current is going through a wire, the voltage drops at the far end. If you are at that far end, your pedestal will suffer.

Adding a transformer to boost your own coach's voltage will require even more amps on that wire so that the voltage drops even more. That's the effect of IR drop. You will be fine but the others along the line will suffer even more. Too bad. If you have the AT unit, use it. If enough people complain, the park will fix the problem or people will just stay away. Either way, the problem is solved.

I don't mean to get too pedantic, but this stuff is tricky. My answer is that you can't help the basic problem with the park, so use what you have to satisfy your own particular needs. You will not be creating a problem for others; their problem already exists.

Tom

Old Scout · 03-16-2016, 08:07 AM

Tom--well stated, my pea-sized brain doesnt allow for great articulation on most matters of substance but I was fairly sure you can't raise voltage caused by line resistance [eg poor CG infrastructure] and not create an impact somewhere else. If you could it would be a wonderful machine--kind of like "cold fusion."