GR "Scott" Cundiff Posted August 23, 2020 Report Share Posted August 23, 2020 (edited) Please bear with me, I'm not an electrician by any means. Our motorhome is 50 amp. We also travel with a Ford C-Max Energi - a plugin Hybrid. It charges on 110. Usually I plug the motorhome in to the power pedestal 50 amp outlet. I then plug the car into the 30 amp outlet. It has always worked okay till now. Today the motorhome surgeguard reports low voltage (103v) on L2 when the car is charging. Otherwise, with the car unplugged it is about the same as L1 - around 113v. I normally don't charge the car during the day, knowing it is better to charge it when the temps aren't so high. Today, I rolled the windows down and went ahead and charged it (never mind the reason). So, I'm guessing the 30 amp receptacle is wired off of L2 and the car charging is pulling the voltage down. 1. Is that likely the reason for the low voltage on L2 when the car is plugged in? 2. Is it normal for the 30 amp plug on the pedestal to be connected to one side of the 50 amp? I doubt there will be many times when I want to charge the car on a hot afternoon - so it really isn't a big deal. Still, I'd like to understand what was happening a bit better. Thanks. Edited August 23, 2020 by GR "Scott" Cundiff Quote Our "Here and There" Blog 2005 Safari Cheetah Motorhome Link to comment Share on other sites More sharing options...
Darryl&Rita Posted August 24, 2020 Report Share Posted August 24, 2020 1 hour ago, GR "Scott" Cundiff said: So, I'm guessing the 30 amp receptacle is wired off of L2 and the car charging is pulling the voltage down. 1. Is that likely the reason for the low voltage on L2 when the car is plugged in? 2. Is it normal for the 30 amp plug on the pedestal to be connected to one side of the 50 amp? 1. Yes. ish. If this is on your own property, I'd be checking connections all the way back to the breaker feeding the receptacle. At the very least, confirming wire size and run length. If it's an RV park, you might be stuck suffering through it until the next park. 2. Yes. In a properly designed park, the 30 amp receptacles will alternate between the 2 main feeds to try and keep the loads balanced. Sometimes, it even almost works. Quote I have been wrong before, I'll probably be wrong again. 2000 Kenworth T 2000 w/N-14 and 10 speed Gen1 Autoshift, deck built by Star Fabrication 2006 smart fourtwo cdi cabriolet 2007 32.5' Fleetwood QuantumPlease e-mail us here. Link to comment Share on other sites More sharing options...
mptjelgin Posted August 24, 2020 Report Share Posted August 24, 2020 1 hour ago, GR "Scott" Cundiff said: 2. Is it normal for the 30 amp plug on the pedestal to be connected to one side of the 50 amp? Absolutely. There are only two hot legs available in most areas, and the 50 amp circuit uses both of them. So the 30 amp circuit must be "piggy-backed" onto one of the legs, and if the box has a third, 15/20 amp plug it is generally on the other leg. Quote Mark & Teri 2021 Grand Designs Imagine 2500RL, 2019 Ford F-350 Mark & Teri's Travels Link to comment Share on other sites More sharing options...
GR "Scott" Cundiff Posted August 24, 2020 Author Report Share Posted August 24, 2020 Thanks folks! Our last night here, finished charging the car after dark, and ready to go tomorrow. I appreciate the helpful replies. Quote Our "Here and There" Blog 2005 Safari Cheetah Motorhome Link to comment Share on other sites More sharing options...
GlennWest Posted August 24, 2020 Report Share Posted August 24, 2020 Why not put a 30 amp plug on rv. Quote 2003 Teton Grand Freedom towed with 2006 Freightliner Century 120 across the beautiful USA welding pipe.https://photos.app.goo.gl/O32ZjgzSzgK7LAyt1 Link to comment Share on other sites More sharing options...
durangodon Posted August 24, 2020 Report Share Posted August 24, 2020 8 hours ago, GlennWest said: Why not put a 30 amp plug on rv. Wouldn't the result be the same? Quote Link to comment Share on other sites More sharing options...
Darryl&Rita Posted August 24, 2020 Report Share Posted August 24, 2020 7 minutes ago, durangodon said: Wouldn't the result be the same? Potentially worse, with the extra connections. KISS. Quote I have been wrong before, I'll probably be wrong again. 2000 Kenworth T 2000 w/N-14 and 10 speed Gen1 Autoshift, deck built by Star Fabrication 2006 smart fourtwo cdi cabriolet 2007 32.5' Fleetwood QuantumPlease e-mail us here. Link to comment Share on other sites More sharing options...
lappir Posted August 24, 2020 Report Share Posted August 24, 2020 5 minutes ago, durangodon said: Wouldn't the result be the same? Good question. Is there room in the RV panel for it and would it overload or unbalance the panel? Quote White 2000/2010Volvo VNL 770 with 7' Drom box with opposing doors, JOST slider hitch. 600 HP Cummins Signature 18 Speed three pedal auto shift. 1999 Isuzu VehiCross retired to a sticks and bricks garage. Brought out of storage the summer of 2022 2022 Jeep Wrangler Sport S Two door hard top. 2007 Honda GL 1800 2013 Space Craft Mfg S420 Custom built Toyhauler The Gold Volvo is still running and being emptied in July. Link to comment Share on other sites More sharing options...
durangodon Posted August 24, 2020 Report Share Posted August 24, 2020 1 hour ago, lappir said: Good question. Is there room in the RV panel for it and would it overload or unbalance the panel? If the car charger was drawing the voltage down on one leg at the pedestal, it'll do the same thing in the coach, since the coach is using the pedestal for power. He'd be just moving the problem from the pedestal to the coach's breaker box. Adding a 30 amp outlet on the coach is not going to magically produce more current. The only way this could help is if he installed the new 30 amp outlet on the side of the coach breaker box with the lightest load, or refrained from using things on that leg while charging the car. However, I think most breaker boxes will be fairly well balanced. Quote Link to comment Share on other sites More sharing options...
Kirk W Posted August 24, 2020 Report Share Posted August 24, 2020 There are only 2 supply sources in any 120/240 V power system, even if you go all of the way back to the transformer that supplies the RV park. While I'm not sure what current lever the supply into the park is unless they have their own transformer and distribution equipment, it is just a larger version of what you would have in a stick house. The typical house has 200A service with two supply leads, L1 & L2. At the distribution box it is then broken down to be circuits of 120V and a few with both supplies that result in 240V. When using both L1 & L2 the effect is that of +120V one one side of the load and -120V on the other with causes the load to see a total of 240V. In the RV park there are usually several circuits to various parts of the park, each with it's own set of circuit breakers which send both L1 & L2 to the various power pedestals. Typical pedestals will have a double 120V/15A outlet, a single 120V/30A outlet, and a single 120/240V-50A outlet. If wired properly the 30A outlets are half to L1 and half to L2 with most cases they alternate from site to site, much as Mark stated. 35 minutes ago, durangodon said: He'd be just moving the problem from the pedestal to the coach's breaker box. Adding a 30 amp outlet on the coach is not going to magically produce more current. Exactly! Quote Good travelin !...............KirkFull-time 11+ years...... Now seasonal travelers.Kirk & Pam's Great RV Adventure Link to comment Share on other sites More sharing options...
GlennWest Posted August 24, 2020 Report Share Posted August 24, 2020 2 hours ago, lappir said: Good question. Is there room in the RV panel for it and would it overload or unbalance the panel? Well, without spealing it out, my thughts were you are in control deciding which L1 or L2 you pull that power from. You never know with the parks. You could arrange your panel to accomade it. Be a little work. It would still be easy to pull more than 50 amps but at least you would decide which leg to pull from. Quote 2003 Teton Grand Freedom towed with 2006 Freightliner Century 120 across the beautiful USA welding pipe.https://photos.app.goo.gl/O32ZjgzSzgK7LAyt1 Link to comment Share on other sites More sharing options...
TXiceman Posted August 24, 2020 Report Share Posted August 24, 2020 http://www.rvparksupplies.com/p/503020AMPSMPOWER/ Here is a post showing the wiring for a typical RV pedestal. The 30 amp is usually taken from one side of the 50 amp legs. Ig a park is wired properly, they will alternate which side carries the 30 amp plug to help balance the laod. Ken Quote Amateur radio operator, 2023 Cougar 22MLS, 2022 F150 Lariat 4x4 Off Road, Sport trim <br />Travel with 1 miniature schnauzer, 1 standard schnauzer and one African Gray parrot Link to comment Share on other sites More sharing options...
Kirk W Posted August 24, 2020 Report Share Posted August 24, 2020 23 minutes ago, TXiceman said: The 30 amp is usually taken from one side of the 50 amp legs. There isn't any other place to get power. Quote Good travelin !...............KirkFull-time 11+ years...... Now seasonal travelers.Kirk & Pam's Great RV Adventure Link to comment Share on other sites More sharing options...
Bill Joyce Posted August 24, 2020 Report Share Posted August 24, 2020 It sounds like you are using a Level 2 charging cable on the 30AMP. Have you tried the Level 1 cable under the door, to do the charging? With a friend's C-Max the Level 2 would do a full charge in under 2 hours, but took 6 hours on Level 1. You have the time. Quote 2004 40' Newmar Dutch Star DP towing an AWD 2020 Ford Escape Hybrid, Fulltimer July 2003 to October 2018, Parttimer now. Travels through much of 2013 - http://www.sacnoth.com - Bill, Diane and Evita (the cat) Link to comment Share on other sites More sharing options...
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