I'll be outside a friend's in a residential neighborhood tomorrow. We can plug into his standard household outlet if needed (outdoor 15A outlet on a separate breaker - no other loads). With solar - us plugging in is normally not necessary. But I need to work a normal 9-5 in the coach, and high temp tomorrow is 97 degrees. It's a pretty crowded neighborhood - running the generator to run A/C isn't really a great option... But....
Our front A/C is wired through the inverter and the battery. I can run it for maybe an hour, but not all day. The A/C on high uses about 150 DC amps (~125 medium, ~90 low). I was thinking of trying to start the A/C on battery power to get past the compressor kick, and then plugging in to the 15A outlet while the A/C is running, which would switch the load over the shore power. Maybe running the A/C on low or medium to make sure I'm not flirting with the max power of the outlet?
If I made sure to keep everything else in the coach pretty much completely off, could I get away with doing something like this? Is my math wrong? Sure don't want to fry anything.
You would have to turn off the charging through the inverter to keep the amps down.
Yes, and set thermostat low, so ac does not cycle and have to restart compressor. Hard to believe 60 amp difference between hi and low fan speeds. Most fans only take 60 0r 70 watts even on high.
James, the 115 should start the AC if the inverter starts it. Soft starter starts AC every time no matter what the source of input current is. Have you tried to start inverter on 115v?
The high reading is correct, but med/low I am functioning of memory - could easily be wrong. I do remember when cycling between them to test, that the difference in speeds was far far greater than I expected, however.
Tim, I'm not sure I follow this question.
Great point - hadn't thought of that. Will do.
How long of a cord and how heavy of cord will you be using? You will have to monitor the adapter that plugs into the receptacle to not melt it.
Dometic Duo Therm Brisk Air Conditioner 13500 BTU RV Camper Trail.. (http://www.adventurerv.net/dometic-duo-therm-brisk-air-conditioner-13500-btu-camper-trailer-p-130.html)
James,
Turn everything off, including the inv/battery charger. Put the fridg on propane and turn on the air conditioner.
You won't hurt anything, make sure you have access to the CB in the house incase you trip it so you can reset!
Hope you have a good heavy extension cord. You might go out and feel it to be sure it isn't getting hot after it runs for a while.
We have plugged into my sisters 20 amp outlet with mixed results. You should also be aware of what is connected to that circuit at your friend's house as that will directly impact your amp usage.
We tripped my sister's breaker a number of times. During our last visit I asked and was allowed to add one 30 amp circuit to the house breaker box. Parts were less than $50.00 - I opted to pay a local electrician to get the job done. Took him about 30 mins. No more problems.
Use a large short cord , run the AC on low cool . Monitor the volts. My bus stays cool and the volts read over 107 on a good cord.
I can run one air conditioner on a dedicated 15 amp plug with a 50 foot extension cord here.
That being said switching your power source with that much load operating is very hard on your switching mechanisms. A transfer switch will fry the contacts as they close.
I have both a 12 gauge rigid 100' extension cord and a 10 gauge rigid 100'.
As was stated better to use as much big cabling as possible to lessen the voltage drop.
James,
If it were me I would turn off all of the 120V loads possible, including the inverter/charger, and run the AC on low and see if the 15 amp breaker will hold. Using your 30 or 50 amp power supply cord with the 15amp adapter, the voltage drop wont be a problem. Don't use a small 14 gauge drop cord. As mentioned above dont over heat the adapter (and it probably won't). I have done this before and the breaker didn't trip with the AC on low speed.
Justin
RLA of 12.1.
I agree to this. Better to use a 10g cord and as has been written, check your connections to make sure they do not get too hot.
I have a 100 ft. 10/3 cord. There are no other loads on this circuit - it's a dedicated outdoor circuit for workshop saws / power tools etc. I do have access to the breaker. I'll try to remove all other loads and give it a go starting directly off the 15 Amp - sounds like that is a better idea than trying to transfer power under a significant load.
Thanks all for the help!
Is my understanding that the inverter/battery/solar will be able to help if you are drawing too much for a short time correct? If that is the case you should be good with the 10g cord, I have used 10g cord at my father-in-laws house, with an electric space heater with no problem. AC is about the same as space heater load.
Only if he has a "hybrid" inverter designed to do that. Only Victron, Magnum and maybe a couple of other brands do.
If the breaker throws too much and the panel is older a possible replacement of the individual breaker might add some reserve capacity. Testing is the only way to know for sure.
I have one and have seen "Cheater cords" that allow two separate circuits on the source of power to be combined.
Not two plugins on the same outlet. Two separate circuits. You would need two hd extension cords
May or may not be possible. Or available...or two separate source circuits available?
I purchased this but have not used it. Yet.
Progressive Industries ADT-230 Cheater Box.
You would have two 15 amp capacity circuits into the coach as far as I know
The reverse is available
Also I have a Conntek RV Y Adatper Cord with 50 Amp Male Plug To (2) 30 Amp RV Female Connector (3-Feet
With the cheater box and if the a/c's are on separate coach breakers you might be able to run two airs
That's why I have two 100' rigid extension cords.
Maybe two different houses?
I'd ask the neighbors for permission to run the generator rather than take all those other risks.
X2.....I don't even carry a "15 amp cheater cord" any more. ^.^d Even with our EMS, it would freak me out!
I frequently run one AC on a 15 amp circuit. You have to be careful of other loads (letting your solar charge the batteries is a good idea) and not running much else on AC power and youll be fine, no need to start the AC on inverter, as the AC supply will handle the transient surge much better than your inverter, especially with your soft start. I can even run one dometic AC unit off my honda EU2000 if very careful, but it is not ideal.
As said, 10 or 12 gauge extension cord and running only the AC unit and youll be just fine. Many of us do this regularly.
James,
Do you all have one of the new Hybrid style inverter/converters you? If so it might work. If not I wouldn't try it based upon our hit or miss experience with 15 amps and air conditioners on Sprinter based RVs and trailers.
If you do have a new hybrid inverter/converter then this would be an interesting experiment on how solar and the hybrid unit works with 15 amps.
In theory... if more power is needed then the hybrid inverter/converter should be able to pull from the batteries to supplement power. Which would mean the system should be able to handle a hard start and buffer the 15 amp draw if it began to get near the limit.
Early adopters get to be the guinea pigs that tell the rest of us if the new technology allows us to change our old ways.
Chris
agree on the 15Amp circuit - start with soft start should be no problem, run at 13.1 amps should be no problem, just make sure battery charger is off and nothing else in the coach or on that circuit is drawing any amps.
One air will work fine - question is, how do you do anything in coach other than a PC etc. since shore power is connected, Invertor will be in standby on all the circuits, correct? So cool inside, but not much else.
Tim Fiedler
Sure Start Soft Start (http://www.gen-pro.biz)
TCER Direct (http://www.tcerdirect.com) generator-gas-prod (http://www.generatorgasproducts.com) 630 240-9139
Gen-Pro
You'd probably want to run the single AC that is NOT on inverter power and switch off the breaker feeding your inverter so you can run your house power circuits off your solar via the inverter. That would give you full functionality of any AC powered equipment you need for work without running more amps thru your extension cord. If your batteries run down, no worries as you can simply charge them off the 15 amp circuit at night once the need for AC has ended.
One issue that hasn't been discussed is under voltage from the house during hot weather due to the house air conditioning unit coming on. This will be dependent on how a particular house is wired. This is why our experience with 15 amps was hit or miss over the years.
It wasn't only a matter of starting the RV (coach/trailer) air conditioner. The coach air conditioner was being added to the load on the house, and the house supply had to also start the house AC.
Depending on how the house is wired things like house AC units can cause the lights to dim while the house unit is starting up. If the coach unit is starting at the same time that might cause issues.
When our house AC is running I've noticed that the voltage available to the coach is reduced. The coach is plugged into a dedicated 30 amp circuit wired with appropriate sized wire for the length of the run from the breaker to the 30 amp outlet. Still the voltage available at the coach is reduced when the house AC is running.
With a 15 amp circuit it could be hit or miss and there were several times our Progressive Industries EMS would cut power to the coach because of under voltage when the house AC came on.
With a 30 amp circuit it's never been a problem even if the voltage drops a little.
Chris
I would have both our EMS and autoformer on the setup.
Actually on the dual input cheater cord if two circuits are available
Just installed a 220VAC 50 Amp service after suffering with overloaded extension cords. I was tired of:
- 20 volt drop from my 15 Amp outlet.
- Three heavy-duty extension cords, all of which got warm. Even a short cord had a 10 volt drop.
- Worrying about an electrical fire. Extension cords are TEMPORARY: not designed for full-time use. The two little contacts on a 115VAC extension cord get HOT.
It is totally worth installing a 220 Volt system, where both ACs can run and share the cooling load.
Just to clarify, what Tim (hopefully) installed was an RV 120/240 VAC outlet with this wiring:
Outer straight #1 hot from L1
Outer straight #2 hot from L2
Center straight neutral
Center round ground
I use a cheater usually a 30 and 20a, it will usually run both airs. However the 2 outlets you plug the cheater into have got to be on different legs. If not it will trip the breakers for the outlets.
Cheater cords that connect two different outlets into one 50-amp connection are useful. The two male ends can be 30 or 15 amp plugs and can be used in any non-gfci outlets. Each leg of coach outlets and loads must not exceed the breaker rating of the individual campground outlet it is plugged into. There is no need for the campground outlets to be on separate legs. Knowing what coach outlets and loads are on each of the 50-amp legs, and managing coach loads is the secret to using these gadgets.
What is original LRA (AC) of the roof air?
Two years ago we "boondocked" in the yard of some friends. We only had a 20A outlet available, so we used that overnight and in the morning - no a/c. When it got warm enough to need the a/c I unplugged from the outlet and the coach and ran the generator. This was at a rural church (our friend was the pastor) so running the generator during the day didn't bother anyone.
Whoops I missed this before. Yes this appears to be true - I was giving you Magnum display reading of the battery draw when run on battery power, which apparently includes the ~20-30% loss due to inverter.
No, no hybrid. I actually originally ordered a hybrid unit, but was concerned about some of the failure rates we were reading about, and went with the tried-and-true MS2812 instead.
James,
Well... How did plugging into 15 amp service work for you?
Chris
You know.... we ended up not needing to... Unexpected cold front moved in, thunderstorms during the late night . Instead of a high of 97, the next day was a high of 82. I can deal with 82 using the Kool-matic and a fan or two...
But I will post back eventually - I'm sure the need to try it will arise eventually.
You'd be surprised how tiny of a power draw the PC is. Daylight, so no lights needed. Fridge (and hot water if needed) on propane. A high powered laptop is 5-6 DC amps, monitor is another 2-3, Mobley might as well be 0. Works out to be negligible.
I have rewired the main AC power panel and added a second neutral #8 wire from the power panel to the service bay. Installed two 30 amp twist lock receptacles in the service bay. I split the neutral bar in the power panel into two neutral bars, one for the red hot circuits and one for the black hot circuits. With separate red & black neutral wires from the power panel to the service bay 30 amp receptacles, I can plug in two 30 amp extension cords, one for red hot and one for black hot even if the campground plugs are ground fault protected. You cannot do that with a 50amp / two 30amp cheater.
I can still use the 50 amp service bay receptacle but not when a 30 amp cord is plugged in.
Tried starting a single ac on a 15 amp circuit with everything else off. Transfer switch chatters like crazy but won't start. Contacts shot? Todd engineering PS-250, with a warning if a malfunction blow out terminals with compressed air due to dust. Junk it or tear it apart to attempt clean/repair? Thanks
Are you letting the transfer switch lock on before turning on the air?
Yes, let it lock, check for good voltage, switch fan on and recheck voltage, and then enable the compressor. Same circuit I run a 14" steel chop saw on. A/c units have hard start cap.
Likely this 15 amp is not enough to consistently start such a load. Voltage may be dropping too low to keep transfer switch coil energized. Also if voltage drops too low roof air compressor and fan motor can be damaged. Low voltage is always problematic to motors. And chattering transfer switch points may be arcing and damaging points. Many roof air conditioners draw more than 15 amps to start.
Without some more facts, we are speculating here.
If you do have 15 amps AT 120 VAC (not 108, 102, etc) and nothing else is running, you are fine to run one roof A/C.
Please do post what voltage is before you turn on the A/C and after. Very likely your shore side wiring is not sufficient to provide the 15 amps at 120 VAC.
As said, you can do a lot of damage to electrical equipment running on sub-par voltage.
Are you using the coach power cord or an extension cord? If you use an extension cord it must be 12 ga. or better