Autoformers Good or Bad

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.

butchiiii

Well-known member
Joined
Sep 8, 2014
Posts
347
Location
Los Angeles
Hi folks,
Have been reading about autoformers this weekend. Does anyone here use one or have experience with using.
what are the good points and bad points. What is everyone's overall opinion or impression of this device.
Thanks
 

docj

Well-known member
Joined
Oct 16, 2010
Posts
1,766
Autoformers are useful if you are at a park with chronically low voltage.  We were at one such park for a summer and ended up buying one to keep our appliances from being damaged.  They get a bad rap because people without an understanding of electricity think they somehow "steal power" from other campers.  In fact, the current through your pedestal is limited by the 30A or 50A breaker on the pedestal.  No device after the breaker can change that.  All the autoformer does is make sure that the voltage on your side is in the range it should be.
 

lynnmor

Well-known member
Joined
May 14, 2013
Posts
1,585
I use one, it can save the air conditioner and the trip.  There are no downsides other than the initial cost.
 

docj

Well-known member
Joined
Oct 16, 2010
Posts
1,766
Just remember that autoformers aren't a substitute for a good EMS system such as those made by Progressive.  An EMS will protect you from a whole host of issues that an autoformer won't. 
 

butchiiii

Well-known member
Joined
Sep 8, 2014
Posts
347
Location
Los Angeles
Yes I have the progressive EMS already and that is what prompted my question about autoformers. I occasionally
noticed the power drop to 105-106 during a high power demand time of day. So someone mentioned autoformers
and was wondering if they are worth the investment. Also if I do get one is it plugged into the power pedestal 1st
and then the EMS is plugged into it?

 

John From Detroit

Well-known member
Joined
Apr 12, 2005
Posts
24,798
Location
Davison Michigan
Both I and the man camped beside me use them... I recall a few years back backing into a site in this park very close to where I am now my Wife said "You won't be happy with the power here this other camper says her voltmeter is always in the red.. Mine was green.  (Autoformer hidden in RV fixed it)

I have seen voltages below 90 volts at the pedestal here. but GREEN in my RV.

So the Up-side is a park with weak power.. It may bring the voltage up. BUT what is the downside.

For many devices the phrase Watts=volts Times Current applies (Fridge (RV type) Water heater. Resistive cooking appliances like a coffee pot.  Space heaters) so if you have to boost voltage say 10%, well then the amount of current at the "plug" (Shore plug) also goes up 10 percent so your 30 amps is now 27.    But with Resistive things.. Lower voltage = LOWER CURRENT. (And fewer watts)

WIth Inductive loads (Like Air Conditioners.. Residential Fridges, Fans) the formula is much more complex.  Watts now = Volts Times Amps Times POWER FACTOR. and as the voltage changes at first the power factor changes. then you start to loose power. . I won;t even try to calculate how say 105 volts v/s 110 or 115 or 120 will affect an Air Conditioner because without testing it is impossible to predict and two different serial numbers (same make and model) may well have different "Sweet Spots".

Used to be a device you could by called a "Green Plug" or some such that would adjust the voltage (Pulse Width Modulation) to get a better power factor. You can also change it in other ways.

I used to have one..

But basically with the Auto-Former you are more likely to have power "in range" inside the RV even if it is "Low" outside (With one make it will buck if you are High as well)

But it may or may not put a heavier load on the park which is bad for your neighbors.

And some parks will ask you to leave if you use one or so sayeth the rules (One of the reasons mine is hidden)
The other reasons.. That sucker is HEAVY and by "installing" it I don't have to heft it manually less I need to access what is behind it..
I never forget it
It won't grow legs and walk off
and it's out of the way... completely.


 

Optimistic Paranoid

Well-known member
Joined
Jan 19, 2013
Posts
355
butchiiii said:
Also if I do get one is it plugged into the power pedestal 1st and then the EMS is plugged into it?

Well, let's think about this.  The Progressive EMS considers anything below 104 volts to be too low and shuts off the power to your rig.  So if you plug in EMS to Autoformer and the power drops below 104 volts, your power will go off.  If you plug in Autoformer to EMS, the Autoformer will boost the voltage 10% when it goes that low, so at 103 volts at the pedestal, the EMS will still see 110 volts thanks to the Autoformer.  The Pedestal voltage would have to drop to around 9o to 95 volts or so before the EMS would see a low enough voltage to kill your power.
 

lynnmor

Well-known member
Joined
May 14, 2013
Posts
1,585
Optimistic Paranoid said:
Well, let's think about this.  The Progressive EMS considers anything below 104 volts to be too low and shuts off the power to your rig.  So if you plug in EMS to Autoformer and the power drops below 104 volts, your power will go off.  If you plug in Autoformer to EMS, the Autoformer will boost the voltage 10% when it goes that low, so at 103 volts at the pedestal, the EMS will still see 110 volts thanks to the Autoformer.  The Pedestal voltage would have to drop to around 9o to 95 volts or so before the EMS would see a low enough voltage to kill your power.

You kind of said it backwards, but we know what you meant.
 

butchiiii

Well-known member
Joined
Sep 8, 2014
Posts
347
Location
Los Angeles
Optimistic Paranoid said:
Well, let's think about this.  The Progressive EMS considers anything below 104 volts to be too low and shuts off the power to your rig.  So if you plug in EMS to Autoformer and the power drops below 104 volts, your power will go off.  If you plug in Autoformer to EMS, the Autoformer will boost the voltage 10% when it goes that low, so at 103 volts at the pedestal, the EMS will still see 110 volts thanks to the Autoformer.  The Pedestal voltage would have to drop to around 9o to 95 volts or so before the EMS would see a low enough voltage to kill your power.

And that's why I asked as I know nothing about autoformers. the 1st I heard of them was last week. Thank you for the benefit of your wisdom
 

blw2

Well-known member
Joined
Aug 9, 2012
Posts
3,325
Location
Saint Johns, FL
John From Detroit said:
......The other reasons.. That sucker is HEAVY .....
I don't have one, although I wish I did....but after $, that's the "bad point" that I was thinking.... heavy.

I think I'd install it inside like John, if I had one.  That weight thing though...with my rig I have to keep an eye on that.
 

docj

Well-known member
Joined
Oct 16, 2010
Posts
1,766
blw2 said:
I don't have one, although I wish I did....but after $, that's the "bad point" that I was thinking.... heavy.

I bought a 30A one even though our MH uses 50A.  There were two reasons for this--weight and $$.  Our experience is that voltage problems are more common at older, smaller parks which are more likely to have 30A service.
 

lynnmor

Well-known member
Joined
May 14, 2013
Posts
1,585
blw2 said:
I don't have one, although I wish I did....but after $, that's the "bad point" that I was thinking.... heavy.

I think I'd install it inside like John, if I had one.  That weight thing though...with my rig I have to keep an eye on that.

The 30 amp is 21 lb and the 50 amp is 35 lb, and they do have a handle.
 

Back2PA

Well-known member
Joined
Jul 26, 2015
Posts
5,766
docj said:
I bought a 30A one even though our MH uses 50A.  There were two reasons for this--weight and $$.  Our experience is that voltage problems are more common at older, smaller parks which are more likely to have 30A service.


Very good point. An autoformer has been on my wish list for some time but it keeps sliding down the list because $$. I?d always assumed it would be silly to get a 30A w a 50 RV, but now that I think about it I don?t think I?ve ever had voltage problems when on 50A service.
 

motoxbob

Well-known member
Joined
Jun 20, 2011
Posts
120
I used a Surge Guard 30 amp autoformer for a couple of summers at a low voltage park and it worked fine. I don't need it anymore and it just sits in my garage so if the OP or anybody else wants it come over and pick it up! (That is if you are near Stockton, Calif LOL) 
 

Isaac-1

Well-known member
Joined
Dec 3, 2016
Posts
4,579
Location
SW Louisiana
Are you sure about that, the two big names in Autoformers are Hughes, and Frank's though the Frank's unit is no longer produced.  To my knowledge Surge Guard only builds EMS uints that will disconnect on low voltage, not boost low voltage.
 

zulu

Well-known member
Joined
Dec 13, 2011
Posts
180

motoxbob

Well-known member
Joined
Jun 20, 2011
Posts
120
Yes the yellow one is the one I have. It is labeled Surge Guard. I got it from Camping World about 5 years ago. It has been sitting in my garage for 3 years.
 

John From Detroit

Well-known member
Joined
Apr 12, 2005
Posts
24,798
Location
Davison Michigan
Years ago I put a 50 amp Hughes Autoformer in this rv (RV and autoformer are both 2005 models).

IN a few hours I pack up and haul to a different park than the one I'm in now. Last time I was there the site they had me on had LESS THAN 100 VOLTS at the pedestal.. As you can imagine  I had good power. Not enough (First time I"ve tripped a 30 amp breaker in over a year) but I had good power. So did my next door neighbor and for almost the same reason (My Autoformer is hidden inside the RV and fully "INstalled" (ok so it is plugged in) his was on the ground next to the power pole).

NOT the first time I've visited that park. not the last. but often I have good power when neighbors do not. Because of tat big HEAVY box that's hiding in the auto-transfer-switch compartment.
 

Back2PA

Well-known member
Joined
Jul 26, 2015
Posts
5,766
John From Detroit said:
Because of tat big HEAVY box that's hiding in the auto-transfer-switch compartment.


John, how hot does the autoformer get? Is air circulation/ventilation in a small compartment an issue?
 

John From Detroit

Well-known member
Joined
Apr 12, 2005
Posts
24,798
Location
Davison Michigan
I greatly increased the air circulation in that compartment so it does not overheat.  Cut several Slots like 2" wide in the doors and removed a panel. All in the name of keeping my cool.. USed the panel elsewhere too. Never any sign of overheat.

A couple feet above it sits my main Ham Radio .. a Kenwood TS-2000.. For 12 years I've had an antenna that is an "Antenna of last resort" is is a 1/2 inch copper pipe runs about 30 feet along the edge of the roof like a goat rail then hangs a corner and turns into a fiberglass CB "Whip" (Sprial wound effetive length about 11 feet but shorter)

FOr the first time tonight.. I actually talked to someone on it.. (Normally I use a longer wire 50-90 feet)
 
Top Bottom