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Start up 2 RV a/c with 30 amp

riverroyal

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Its only compressor that sucks all the instant power.

Would have loved to try one at black meadow
 

RiverDave

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Weirdly I have a 50 amp rv.. we went on a three week rv trip and some of the parks only had 30 amp. I went inside and set the magnum electric screen thing to 30 amp as its max input.. we ran both AC’s everywhere we went?
 

MrHooly

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Weirdly I have a 50 amp rv.. we went on a three week rv trip and some of the parks only had 30 amp. I went inside and set the magnum electric screen thing to 30 amp as its max input.. we ran both AC’s everywhere we went?
230-ADTP30-2.jpg

I just use this thing if I can
 

stingray11

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Pretty impressive for boondocking with a small generator , might just have to pick one of these up.
 

Uncle Dave

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Weirdly I have a 50 amp rv.. we went on a three week rv trip and some of the parks only had 30 amp. I went inside and set the magnum electric screen thing to 30 amp as its max input.. we ran both AC’s everywhere we went?

30 amps from the wall/grid is "typically" going to be fine and not the problem this addresses.

The problem is when you ask for ask for 30 amps from a small(ish) genset during compressor startup - the voltage sags and the compressors wont kick over.

This is a big giant capacitor that gives you a short " kick" to get the compressors started.

Once you get the compressors started you are fine.

Prior to this thing a way to solve compressors stall was to add a bigger hard start capacitor to your AC unit by climbing on the roof pulling the small old one and wiring a bigger one. SUPCO is a popular brand that works well. The other way was the external dometic hard start kit.
This mod allows you to run a 13.5 off a honda 2K.
 

Singleton

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Seems too simple to actually work. Doesn’t look right. I’m no electrician but I drove by a Holiday Inn Express last week
New product they just released. I am buying the softstarts that install within the AC itself.
Only reason I am doing that, is I already have an EMS (progressive industries EMS-surge protector) that stops and starts power to the trailer when the RV park is experiencing power issues.
 

Taboma

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30 amps from the wall/grid is "typically" going to be fine and not the problem this addresses.

The problem is when you ask for ask for 30 amps from a small(ish) genset during compressor startup - the voltage sags and the compressors wont kick over.

This is a big giant capacitor that gives you a short " kick" to get the compressors started.

Once you get the compressors started you are fine.

Prior to this thing a way to solve compressors stall was to add a bigger hard start capacitor to your AC unit by climbing on the roof pulling the small old one and wiring a bigger one. SUPCO is a popular brand that works well. The other way was the external dometic hard start kit.
This mod allows you to run a 13.5 off a honda 2K.
I trust you really don't want to encourage members into thinking the solution to minimizing start up load is installing a really big cap that can hold a really big charge and give your motor a really big kick in the ass ?
I know that you know it's far more complicated than that rather ridiculous exaggeration I just typed. ;) 😁
Using another over simplification, we know the start cap's function is to cause an initial current-voltage phase shift, creating a momentary poly phase sine wave to provide direction and increased torque.
The capacitor sizing isn't a random 'The bigger the better' formula but based on specific calculations to provide the best efficiency and performance for each motor's particular ratings and characteristics.
Hence, when I read of these types of 'Cure all' with one magic pill solutions, the skeptical me (Vs the gullible, " I want to believe" one 😁) just begs to pull back the curtain and know just what it's actually accomplishing and how.
What does it look like on a scope as compared to this ---

AC motor speed torque curve-1.jpg

Effects of capacitance on speed torque curve.jpg


Single phase voltage sine wave

Without start capacitor.png


Single phase voltage-current sine wave with starting capacitor

With start cap.png


The SoftStartUp manufacturer has graphs depicting massively reduced start up amperage peaks, how ? Are we reducing these starting load peaks by stretching the start up time ? Is this device providing an immediate and drastic power factor correction ? Are their engineers wholly smarter than those who calculated the OEM capacitor requirements ?
Just what the hell is in this $ 600 box anyway ? :oops:;)😁

PS: I don't own an RV, but I've got a small Honda genny I dream could run my home's AC unit 👍
 

Uncle Dave

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I trust you really don't want to encourage members into thinking the solution to minimizing start up load is installing a really big cap that can hold a really big charge and give your motor a really big kick in the ass ?

No I do not. One size does not fit all.

I do recommend that one follows the guide that the manufacturers of such products lay out like Supco and or the manufacturer themselves.

Many questions arise from this - why isnt the OEM one good enough?
Why do the manufacturers themselves sell these kits vs just build in the capability?

The answer typically comes down to trying to manufacture to price point.
"Good enough" is where they typically build to.
Devices like capacitors tend to weaken over time if not crap out completely.

FWIW to those just dipping in here - a hard start kit and a soft start kit are the same thing.

 
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MrHooly

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I was saying it just worked without anything else?
It's useful for places like like BML where the "30 amp" service is considerably less during peak weekends. I've seen the breaker trip while pulling 21. It works great until the management comes by and tells me I need to pay for the adjacent spot if I want to use both outlets 🙄 really need to find a new spot
 

Cdog

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expensive!! You can do two soft starts for around $500
 

Uncle Dave

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You’re my hero!! How do I wire it up?
Most are two or three wire.

Pretty easy stuff toughest part is getting the plastic cover off the AC unit without cracking it.

Make sure get the right unit. THS SPP6 is what worked on my Coleman 13.5K btu units.

While your up top get some DDD coil cleaner and clean the coil out.
 
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Cdog

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Most are two or three wire.

Pretty easy stuff toughest part is getting the plastic cover off the AC unit without cracking it.

Make sure get the right unit. THS SPP6 is what worked on my Coleman 13.5K btu units.

While your up top get some DDD coil cleaner and clean the coil out.
I believe all 3 of my Colemans are 15k. Same cap?

I do mine on my home heat pumps but it's easier when you're just replacing them. Is the 2 wire set up is just a pass through?
 

Uncle Dave

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I believe all 3 of my Colemans are 15k. Same cap?

I do mine on my home heat pumps but it's easier when you're just replacing them. Is the 2 wire set up is just a pass through?
Is it a mach? I think so.

Im not sure what you mean by pass through, the couple times I did them they were a direct replacement.

Supco used to have a fitment guide I dont see anymore, but I'll dig around a bit and see what I can find.
 

Cdog

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Is it a mach? I think so.

Im not sure what you mean by pass through, the couple times I did them they were a direct replacement.

Supco used to have a fitment guide I dont see anymore, but I'll dig around a bit and see what I can find.
Gotcha, the units have caps already. These are bigger?

Pardon my ignorance. I’ve never opened one up before
 

Uncle Dave

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Gotcha, the units have caps already. These are bigger?

Pardon my ignorance. I’ve never opened one up before

Typically the OEM units are smaller in capacity and tend to get weak over time.

I'm not an HVAC guy or an electrician, but have had solid results using these mostly with Coleman 13.5's so I could run them off 2K's.

I have done 2 dometic 15K's with different supcos and they worked well.

Where thy really shine and you can tell big difference is in the hot compressor restart this is typically where you get the highest locked rotor amp load.
 

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Weirdly I have a 50 amp rv.. we went on a three week rv trip and some of the parks only had 30 amp. I went inside and set the magnum electric screen thing to 30 amp as its max input.. we ran both AC’s everywhere we went?
Load surge on land power is a lot different than load surge on generator power. Land power is clean and generator power is dirty. Typically figure you need a generator with 3 times the power output of what ever its powering in order to get whatever is plugged into it to start spinning. Sometimes you only really need double the power.
 

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How many starts do you get an hour with this soft start? I know a soft start on a 15hp electric motor you get 7 starts an hour before it overheats or something.
 

Cdog

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Okay I found this video from the mfg. so this has a relay & cap in one. It connects to the existing cap spades and acts as a larger cap on demand.



Some other folks online are selling hard start kits that are a lot more expensive.

Example. $250-$300 on average


 

Cdog

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This is the one recommended by everyone I have spoke to. So what does it do better?

Hutch Mountain Microair Easystart 364 + Free Install kit - RV Camper air Conditioner Soft Start Easy Start https://a.co/d/71VbI9z
 

Uncle Dave

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How many starts do you get an hour with this soft start? I know a soft start on a 15hp electric motor you get 7 starts an hour before it overheats or something.
Dont know - never saw or felt a limit on them. Great question though.

It seemed to me that as long as you had enough time between starts to recharge them there wasnt a limit - but what the time is I couldnt tell you.
 

stephenkatsea

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It's useful for places like like BML where the "30 amp" service is considerably less during peak weekends. I've seen the breaker trip while pulling 21. It works great until the management comes by and tells me I need to pay for the adjacent spot if I want to use both outlets 🙄 really need to find a new spot
We were only plugged into one outlet. I’m sure George would have charged us had we been using 2 outlets. But, our electric consumption was metered and billed accordingly. So, if we were to have also used the adjacent site outlet, he could have billed us per that meter reading and we would have expected that. But, we didn’t need to use it, so not an issue. When it came to BML and George, we just tried to stay below the radar. That worked for us. Plus, George and his wife really liked our dog, so that helped.
 

Uncle Dave

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This is the one recommended by everyone I have spoke to. So what does it do better?

Hutch Mountain Microair Easystart 364 + Free Install kit - RV Camper air Conditioner Soft Start Easy Start https://a.co/d/71VbI9z

Before this dogbone unit that started the thread - there seem to be 2 categories of these

Fairly inexpensive " internal" replacements of the stock units like the supco units.
Higher priced "external" boxes that seem to be more powerful and reduce start up amperage even further.

I know the dometic branded external box does quite a good job at reducing start up amperage, but its several hundred dollars.
 

Singleton

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This is the one recommended by everyone I have spoke to. So what does it do better?

Hutch Mountain Microair Easystart 364 + Free Install kit - RV Camper air Conditioner Soft Start Easy Start https://a.co/d/71VbI9z
SoftStart and EasyStart seem do the same thing. EasyStart is better, but takes multiple restarts to get programmed. SoftStart is plug and play.
 

Cdog

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Before this dogbone unit that started the thread - there seem to be 2 categories of these

Fairly inexpensive " internal" replacements of the stock units like the supco units.
Higher priced "external" boxes that seem to be more powerful and reduce start up amperage even further.

I know the dometic branded external box does quite a good job at reducing start up amperage, but its several hundred dollars.
I have 30 amp at home by my Rv pad. The main AC works great on the house 30 amp. But when it’s hot & I need the 2nd ac it will pop the breaker.

My 4500 Westinghouse Gen would pop at Prescott altitude when the second was started too. I need to do something.

3 ac’s will cool this trailer into an ice box though.
 

Cdog

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SoftStart and EasyStart seem do the same thing. EasyStart is better, but takes multiple restarts to get programmed. SoftStart is plug and play.
So the easy start is better than the suppco cap/relay?

It actually does more for the extra $270?
 

Singleton

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So the easy start is better than the suppco cap/relay?

It actually does more for the extra $270?
Not sure about that. I just did the research between EasyStart and SoftStart that install inside the AC and ES got the better reviews, but had a longer install and setup time.
 

Cdog

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Not sure about that. I just did the research between EasyStart and SoftStart that install inside the AC and ES got the better reviews, but had a longer install and setup time.
Yeah!

I’m wondering if these aren’t the same thing with a pretty plastic box around for $270 more?
 

Uncle Dave

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Yeah!

I’m wondering if these aren’t the same thing with a pretty plastic box around for $270 more?

At its base yes

They (the boxes) are typically a little more effective and reduce start amperage even further.

What I heard from one spiel at a tradehow demo of the domestic unit - was the boxes have both the start and the run capacitor buffered vs just the start cap, but Im not sure that isnt bullshit.
 

Bowtiepower00

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Typically the OEM units are smaller in capacity and tend to get weak over time.

I'm not an HVAC guy or an electrician, but have had solid results using these mostly with Coleman 13.5's so I could run them off 2K's.

I have done 2 dometic 15K's with different supcos and they worked well.

Where thy really shine and you can tell big difference is in the hot compressor restart this is typically where you get the highest locked rotor amp load.
What did you use on the 15k?

Thanks..
 

Uncle Dave

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What did you use on the 15k?

Thanks..

One was a Supco -might have been a diff model than SPP6 (7?) - the other a brand I'd never heard of. (I think the brand was kickstart)

The 15K's were on dog grooming vans running off gen sets and shore power.

The 13'5's were all SUpco spp6's on my toyhaulers (s) and motorhome.
 
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SoCalDave

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I recently installed the softstart on our 13,500 A/C on our TT and I'm a believer of the system.

SoftStartRV Air Conditioning Soft Start Kit - RV A/C Starter Unit - Start an Air Conditioner & Appliances on RV Power, Even with a Small Generator - Trailer, Camper, & Motor Home HVAC - NetworkRV https://a.co/d/4q2Ze59
 

Cdog

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Maybe the soft start is just a packaged 5-2-1 kit?

 

Flying_Lavey

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So.... these are actually called Hard Start Kits (at least the normal ones that go inside the A/C). They are quiet beneficial on RV A/C's as there are almost never any installed from the factory. ALL single phase compressors have a run capacitor, these are starting capacitors that essentially get wired in parallel to the run cap.

@RiverDave your coach has the hardware and software to ensure both compressors don't start at the same time, thus allowing the use of 30 amp service. Essentially it monitors the thermostats and makes sure both Y wires do not energize simultaneously.
 
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TPC

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My advise and it's worth what you paid for it is turn the t stats to full cooling so you're not getting restarts (or as many) that can over heat the compressor winding and result in burnouts.
Jus' sayin'.
 

Ultra...Good

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My advise and it's worth what you paid for it is turn the t stats to full cooling so you're not getting restarts (or as many) that can over heat the compressor winding and result in burnouts.
Jus' sayin'.

That would depend on the duty cycle of the motor. I have a shallow well pump that is 100% cycle meaning it is better to keep it running then to keep restarting it. I have an old arc welder that is a 10% cycle, recomended to run for a minute and let it cool for 9.

What is the cycle for a/c comprssors? I don't know.
 
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TPC

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That would depend on the duty cycle of the motor. I have a shallow well pump that is 100% cycle meaning it is better to keep it running then to keep restarting it. I have an old arc welder that is a 10% cycle, recomended to run for a minute and let it cool for 9.

What is the cycle for a/c comprssors? I don't know.
The A/C compressor winding on an RV is hermetically sealed and sitting in oil. They rely on the refrigerant to stay cool. They get MFSOB hot on restarts and lots of cycling will kill them. They can't cool themselves fast enough and the winding burns out, especially in a starving for amps brownout situation like running 2 on 30 amps.. Less cycling is less heat soak. Yeah their is thermal protection but still running in the river heat that's not enough. A burnout is a mess to clean up. Best to junk the unit if you got the money.

3-s2.0-B9780081006474000048-f04-13-9780081006474.jpg

Back when I was a single paycheck-single parent and hanging at the river and dunes with other single parents I collected compressors outta of bone yard window units to cheap fix all our RVs ACs. Got good at it. Free fix for us broke-ass single parents. Small Cap tube systems are really hard to fix after a burn out. The oil turns into wax and clogs everything in the refrigerant system. Their are tricks to find the clog points and fix them, but that is really a lot of work, tricky high temp soldering on those tiny cap tubes and ya gotta be good at it. You'll get good at it.

I used a jewelers mini-gas torch and the oil from my fingers rubbed on the cap tube tip to control the flow of Silfloss. Add a shaky hand from a night of drinking Rum at RD's,,,
images
 

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