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Topic: 120VAC or 240VAC ? (Read 1516 times) previous topic - next topic

120VAC or 240VAC ?

I am replacing the Freedom 20 Charger / Inverter and want to get the AC input and output voltages correct. The Freedom 20 manual specifications state that it runs on 180VAC to 260VAC. I studied the Foretravel schematics and they are vague when is comes to showing where the legs of 120VAC and 240VAC power are routed. My genny outputs 120VAC, per the name plate. A few questions:

1. Am I correct that the input is actually 120VAC? It charges the battery at this voltage from home power.

2. Does the Freedom 20 inverter receive only one leg of the 240VAC shore power? If so, what is the other leg used for?



1997 U270 34FT Build 5140 Cummins 8.3 Allison 3060R
Solar 1920Watts, 14KWH lithium. Orion BMS.

Re: 120VAC or 240VAC ?

Reply #1 –
Just buy a 120 volt inverter/charger and wire it in just like the one you are replacing. Foretravel wiring is set up for this, and you do not have to worry about changing anything.
Really doubt your present unit is wired for 180 to 240, unless big changes have been made.
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.

Re: 120VAC or 240VAC ?

Reply #2 –
RV's, when hooked up to a 50amp 240/120VAC plug, technically have 240VAC available, but it is not normally used.  Why? Because when you use that 30Amp (120VAC) plug, you won't have the 240VAC available.

Note, this is for USA/North America.
1998 U270 34'

Re: 120VAC or 240VAC ?

Reply #3 –
Tim, The other leg runs the A/C's
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: 120VAC or 240VAC ?

Reply #4 –
Now, myself I'm totally confused, so are some usa cg's wired with 2 hot legs, nuetral and ground at the 50 amp service plug. So how do the 30 amp and 20 amp adapter 120 vac plugs work, and how do they split that so the 120 v from the genset still work?
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: 120VAC or 240VAC ?

Reply #5 –
The ATS takes care of the power from the generator not going to the pedestal . As for the adaptors I believe they just take the one leg and hook it to both legs of the 50 amp plug. Of this I am not sure, but someone else will know.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: 120VAC or 240VAC ?

Reply #6 –
@ Tim,
1.  Yes the power to your inverter should be off 1 leg that feeds your coach thus ~120VAC.
2.  Various other loads that are not fed through the inverter.  Like your A/C unit & engine heater

If I remember correctly some of the '97- 36'-  270 usesdthe internal transfer switch in the inverter/converter and only one transfer switch under the bed.  Do you only have 1 A/C unit? If so it is on the leg not fed through the inverter because the Freedom 20's transfer switch won't handle the load of an A/C unit along with the other loads that it feeds like the microwave.

@ Opp

1. Yes campgrounds should be wired that way 2 hot legs- one from each phase along with a ground and neutral.  If you read phase to phase you get ~240 VAC  phase to ground ~120 VAC.  There are some campgrounds that have fed both legs of the plug on the pedestal off one phase (not the most ideal set up) and is referred to as false 50 amp. by some people. If you measure phase to phase you get ~0 VAC  and phase to ground you will get ~120VAC. 

2.  They take one phase of power and split it internal to share power to both legs. As on both 30 & 20 amp adapters use only one phase, a ground, and neutral.

3. Most Foretravel coaches of this era the generator has 2 phases just like shore power.  What they have done is internal in the generator, they have wired both phases together, which gives you both legs ~120 VAC "in phase" (yes this  seems like "false 50 amp" but totally different)  Why they do that is the generator has only one voltage regulator. If you were to split the generator taps (which you can do) so it's output is like shore power your voltage regulator would only see voltage on one phase.  If this was to happen  you could have low voltage one phase/leg while the other is high (depending on load) and it could also cause problems with your neutral wire getting overloaded.

Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: 120VAC or 240VAC ?

Reply #7 –
Thanks for your wise advice. Who would believe that in America, we have so many diverse power schemes. However, we are probably in better shape than Mexico or Europe.
1997 U270 34FT Build 5140 Cummins 8.3 Allison 3060R
Solar 1920Watts, 14KWH lithium. Orion BMS.

Re: 120VAC or 240VAC ?

Reply #8 –
Quote from: Pamela & Mike –
3.  ...  ... If this was to happen  you could have low voltage one phase/leg while the other is high (depending on load) and it could also cause problems with your neutral wire getting overloaded.

Pamela & Mike

I would like to make a clarification to the above about the neutral wire.  When you are feeding 110V items from 240V 4 wire systems the neutral wire handles only the imbalance.    Say one leg is seeing 40 amps and the other leg is seeing 15 amp, the neutral is only seeing 25 amps. 

When you have your RV plugged into an RV 30A 120v 3 wirie plug, the adapter is taking both hot legs of the RV and connecting them to the hot leg of the plug and just continuing the neutral and ground.  There is no problem with doing this since all of the wires are capable of handling 50 amps.

The problem comes in when you are on generator or if you are plugged into as stated above a false 50 amp outlet . The two hot wires are both able to handle 50 amps each along with the neutral being able to handle 50 amps.  In these situations you are able to use more power then the neutral wire is able to carry since everything is the same phase the loads from both hot legs are added together on the neutral wire. In using the example as above. One leg is seeing 40 amps and the other leg is seeing 15 amp, the neutral is now seeing  55 amps.  Since the neutral can only handle the load of 50 amps safety it will start to heat up.  If total load is above 50 amps very long it is possible for a fire. 

I hope I explained this where everyone can understand it.
 
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago

Re: 120VAC or 240VAC ?

Reply #9 –
Quote from: krush –
RV's, when hooked up to a 50amp 240/120VAC plug, technically have 240VAC available, but it is not normally used.  Why? Because when you use that 30Amp (120VAC) plug, you won't have the 240VAC available.

Note, this is for USA/North America.
To build on krush's post, even though (typically) we don't directly use 240 V, with Foretravel using 240 V 50 amp split phase shore power, the coach has 240 V X 50 amps = 12,000 watts of power available (6,000 watts per 120 V leg). A 30 amp coach only has 120 V X 30 amps = 3,600 watts of power available. Another example of Foretravel quality.
Peter and Tammy Fleming
1991 U300 GV 40 - Sold, owned for 4 years
Downsized to Roadtrek Popular 210 class B
 

Re: 120VAC or 240VAC ?

Reply #10 –
Wow would have never guessed such a system would have been devised without the forums great knowledge base. Would probably been scratching my head for hours on this one. And smoking a power cord while trying to make the adapter plugs, if not burning up appliances. So if you were attempting to run both a/c units on the 30 amp cord things could get warm.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake