Low voltage-A/C

[Dave-O]

When we went camping during spring break at a state park, I experienced a low voltage situation when the A/C kicked on in the middle of the afternoon. The voltage, as measured by an analog plug in meter in an interior outlet, dropped from 120+ to the 106-108 range when the compressor came on. The park was pretty full, but the temps were around 80, not overly hot.
My question is: Is this a campground issue or a trailer issue? Could the A/C be low on freon? Would this matter? This can't be good for my cooling unit. Thoughts and advice are appreciated.
-Dave

[Inland RV Center, In]

Dave.
Old campgrounds are famous for low voltage on warm or hot days.

DO NOT run your AC on low voltage. To do so can and will destroy the compressor.

Low freon level causes the AC to draw "less" current, not more.
Low voltage causes the compressor to draw "more" current."

Andy
inlandrv.com
airstreamparts.com
airstreamcandy.com

[Dave-O]

Thanks Andy,
I did turn it off when I noticed it, thanks to some earlier discussions about low voltage and its dangers (Pahaska, I think). It sounded different, that was my first clue. Voltage improved later on and I felt comfortable running the A/C, after feeling uncomfortable not running it
Good thing I recently put in a Fan-tastic Fan!

[Silvertwinkie]

Yea, this one went round and round a bit and Andy is right the old places are bad with voltages. It was most likely a campground issue and not your issue.

Too bad there isn't a good 30-50a smart ups like I use on network equipment. It not only protects against surges and total power failures, but it also augments the power if it get below 120v.

The problem is that most of these are the weight of a tank (100+ lbs for a good one).

Eric

[dtbw]

Something from my memory of A/Sing with my parents, that at the time, seemed everyone had, was an autotransformer. This is a device that monitors the incoming line voltage and if it drops below 115, starts increasing the voltage automatically to a max of 10% above the incoming. Of course this also reduces the available current from the park power, but higher voltage means less current needs anyway. In those days, all these devices did was to increase the voltage should it drop. They made A/C operation possible in many situation where otherwise their use would have been precluded.

Well, after some searching, I have found that they are still available. Camping World sells the original device that I remember, and it has been update to include surge and spike protection. Now these are NOT cheap or light weight, but as an electrical engineer, I can tell you that they DO work as the principal is well understood and used in many places. Camping World sells 2 models, but the smaller one is simply TOO small as it is limited to 3600watts. The larger unit is a 50amp/12000 watt unit. It can suppress just over 700 joules of surge per line (surges many time are on one side only of the incoming line...so this means that unit can actually handle over 1400 joules should the surge occur on both incoming lines). This compares to most whole house units that are installed on high electronic content homes. On the spike protection side, it can handle 4500 amps per line for a total of 9000 amps. Bottomline, this unit not only can boost the incoming line to protect against brownout conditions, it also protects your A/S against spikes and surges that are all too common in RV parks (this includes lightening during storms as well). To use the unit, it plugs into the park power box and then you plug your A/S into the autotransformer

If you want to order or just look at the device, goto Camping Worlds website and them browse to the
Systems>Electrical>Surge Protectors section
and you will find it. Again, I would recommend the larger unit as it provides better protection and the ability to handle just about any load the A/S could put against it (such as full A/C, converter at full output, and a few A/C appliances such as hair dryer, electric skillet, etc).

Now the bad news. All this protection is going to cost you about $500 and adds about 40 lbs to the weight load you are carrying in either the the A/S or your tow vehicle. The larger unit is 12"X8"X5" and has an integrated handle on the top. As these things are expensive I also recommend that you plan to chain the unit to something very substantial as they have been know to sprout legs...if you know what I mean. This is the next item on my have to have list.

David
02 Bambi LS

[femuse]

The voltage, as measured by an analog plug in meter in an interior outlet, dropped from 120+ to 106-108

Where do you find places like this? Lucky you

We are longing for the times when we can get 100, we have seen as low as 80 volts !!!!!

I wonder how many people in these conditions fried the whole electric system in their RV. A lot of very $$ MH and buses. All trying to run AC, microwave,... at once. We have seen transformers glow red, and sometimes burst into flames. Really nice at night.

We have seen the 150 & 200 W bulbs we use in our vending display "glow" as bright as a 25 watts. That's why we carry generators and use only portable fans for cooling down. Cheaper to replace.

[Dave-O]

Thanks for answering my question AND my follow up question before it was asked (possible solutions).
What about an adapter so I can use the 50 amp plug-in at cg's that have them. Would that alleviate low voltage for my trailer?
Or should I take my generator with me for those times when voltage is lacking?
One more question: At what point is the voltage too low to run an A/C safely?
Thanks again for sharing your experience.

[dtbw]

Anything below 100 volts is asking for trouble. It is a good idea to have a voltmeter among your A/S assets so as to check things (you can easily find a simple analog voltmeter that plugs into any outlet in the A/S and shows you the voltage at glance). As for using a 30-to-50 amp adapter, you should always have one of these just in case you run into the situation where all that is available is a 50 amp connection. As to whether plugging into the 50 amp service will help is very dependent on how that RV park is wired and how many people are using the 50 amp service service in the park. If the park is underwired from the electrical utility, then plugging into the the 50 amp service may not change anything. On the other hand, if the problem is that too many are using the 30 amp service, then switching to the 50 amp service can many times solve the problem (this assumes that the park is correctly wired such that the 50 amp service is totally separate from the 30 amp service all the way back to the electrical utility connection and that connection is not already overloaded.

David
'02 Bambi LS

[Inland RV Center, In]

DAVID-O

I would suggest that you leave the 50 amp service alone.

Generally speaking, if the voltage drops 10 percent, down to 110 VAC, the current demand will go up 15 to 20 percent. The reason being that the compressor will have to work, much harder, resulting in eventual burnout.

Andy
inlandrv.com
airstreamparts.com
airstreamcandy.com

[john hd]

pull the plug and go to a campground that has it's act together.

some people i know bought a campground after they sold the farm.(literally)

they spent over 80 grand improving the electrical service.

kinda a no brainer, empty campground with bad electrical service, or full 90% of the time with happy customers.

vote with your feet.

leave. don't wreck your equipment. and let them know why!

john

[RoadKingMoe]

I see no reason to buy the 50A Autoformer and only use one leg of it rated at 120V X 50A = 6,000W per leg, when all you'll draw is 120VAC X 30A = 3,600W off one of the two legs.

Using only one leg of it with a 30A trailer, you still only get 733 joule and 4500A on the leg you're using... same as the 30A model.

If you look at the two models, their size and the bolts that hold the internal components, it sure looks to me like you're just buying two autoformers and using only one. Wouldn't surprise me if the 30A guts is just one of the two 50A guts to save production costs.