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Do You Really Need a Soft Start for Your AC?

Have you thought about a soft start for your AC? Perhaps you’re ready to hit the road and chase warmer temperatures, but how will you stay cool in your RV with no shore power? Whether boondocking in the wild or moochdocking at a family member’s house, running the AC may not be an option because it requires so much energy; even being plugged into a typical 110V household outlet won’t always cut it. 

This is where AC soft starts come in. For many RVers, soft starts make it possible to run their AC when they’re either plugged into a household outlet or running off battery power. But how do soft starts work? And do you really need one? Let’s talk about that. 

What Is a Soft Start for an AC? 

A soft start is a device you hook up to your RV’s air conditioner. It limits the initial current of electricity when the compressor first kicks on. This reduces the strain on the motor and decreases the spike in amps that occurs when the AC starts up. It even reduces wear on its internal circuits, thus extending the lifespan of your unit. 

Soft Start your RV Air Conditioner

Do You Really Need a Soft Start for Your AC?

Is it really worth investing time and money installing a soft start for your AC? This depends on the type of RVing you’ll do and your existing electrical setup. If you plan to stay at RV parks with access to full hookups, you won’t need a soft start for your AC. This is because most RV and campground electrical hookups can handle the initial spike in current when your AC first starts. 

Another obvious reason you may not need one is if you plan on camping in cool climates. You’ll focus on heating your RV, not cooling it down. 

However, suppose you plan on boondocking or plugging into a friend or family member’s outlet for the occasional rest. In that case, you’ll probably benefit from a soft start. Let’s take a look at how they work. 

Pro Tip: In addition to using a soft start for your AC while boondocking, use these 40 RV Boondocking Tips To Make Your Off-Grid Camping Better!

RVs parked on beach for boondocking.
Keep cool while camping in a hot climate by installing a soft start for your RV air conditioner.

How Does Soft Start for RV AC Work?

Air conditioners guzzle energy — especially when they first turn on. When the compressor first kicks in, the current will briefly jump up past 30 amps (roughly 34-35 amps). This is called a surge current. After that, the amperage hovers around 11-14 amps. Therefore, the problem isn’t the running current at all, just that initial spike.

A soft start for an RV AC works by gradually building up the initial voltage instead of allowing a huge spike in amps when it first starts. It causes the compressor to take longer to start, but the amperage doesn’t jump up as high. Rather than jumping up to 30 amps, it will stay under 20. 

Therefore, instead of being a sudden energy spike, the amperage increase has a slow curve. In fact, good soft starts like SoftStartRV can reduce the initial current by up to 70%. This allows RVers to start their ACs in various circumstances. 

These situations include starting an AC unit on a smaller generator, being plugged into a 15 amp shore circuit or even starting an AC from an inverter.

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Soft starts are easy to install in your RV.
www.softstartrv.com

Can I Run My RV AC Off My Batteries?

This question ultimately depends on the type of batteries you have, your AC, and various other factors. For example, you can’t usually run your air conditioner on lead-acid batteries. They’re less energy-dense than lithium, and they can only handle a 50% discharge. 

However, if you have enough amp hours of lithium-ion batteries (270 Ah+), a large enough inverter (at least 3,000W to 5,000W), and a soft start, you can use your AC for a few hours during the hottest times of the day. The key is the soft start and the upgrade to lithium

How Do You Install a Soft Start on an Air Conditioner? 

It’s relatively easy to install a soft start on an AC. You’ll need your soft start, a wire stripper, wire terminals, and tools to remove your cover. You’ll install your soft start into the run capacitor of your AC to influence the amperage of that first current surge.

Start by attaching end terminals to the wires of your soft start. This will make it easy to connect to your AC when on the roof. Then, once you’ve taken off the cover, identify the wires that attach to its run capacitor. 

You’ll need to disconnect these, attach them to the soft start, and then attach the soft start wires back to the run capacitor. Basically, the soft start will intervene before the current gets to the run capacitor. For an amazingly detailed tutorial, take a look at this video.

Pro Tip: Unsure about the ins and outs of your air conditioner unit? We put together The Complete Guide to RV Air Conditioners to make it easy to understand!

Couple eating breakfast in their RV.
RVing in high heat can get toasty quick! Keep cool on the go!

How Much Does a Soft Start Cost? 

Soft Starts aren’t necessarily cheap, but if they mean the difference between dealing with sweltering heat and staying cool in your RV, they’re probably worth it. In general, they hover around the $300 range regardless of the brand you choose. Popular models include the MicroAir EasyStart for $299 and the SoftStartRV for $319. 

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RV parked by lake in sunset
If your access to electricity is limited, a soft start for your RV air conditioner can be a great investment.

How Long Do Soft Starts for ACs Last?

According to SoftStartRV’s website, it has over 45,000 operation hours. And while we don’t have the operation hours for the MicroAir EasyStart, you can expect any model to last approximately 10 years with normal use. 

What Goes Into an Off-Grid Power System? Overland RV Solar Power System With 12V Air Conditioning

Do You Really Need A Soft Start?

So, is it worth buying a $300 soft start for your RV to limit the number of amps your AC gobbles up? That depends. If your access to electricity is limited, it’s probably worth it. This is especially true if you’ll travel in the summer or in winter hotspots like Florida and Arizona.

If you want to start your AC on generators, weak shore circuits or inverters a soft start is a great idea. It will not only allow you to get it started, but also help reduce stress on the AC components and the equipment running it.

Like we said before, the running current of your AC is not the problem—it’s the initial start-up. Therefore, a soft start could easily make the difference between having AC and not having it at all. 

Do you think a soft start is worth it? Let us know in the comments below.

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About Tom Morton

Tom, a Pacific Northwest native, is our technical genius. Born in Washington and raised in Alaska before settling in Michigan. He's the man who keeps our operation running, both figuratively and literally.

With a background in Electrical Engineering, Tom specializes in RV solar systems and lithium batteries. He made history as the first documented individual to use a Tesla battery module as an RV battery. Tom has personally assisted countless RVers with system installations and has educated thousands more through his videos and articles.

Cinematography is another of Tom's passions, showcased in his work on the Go North series. You can see his camera skills on display in The RVers TV show on Discovery Channel and PBS where he also stars as a co-host.

Tom's mechanical expertise extends beyond RVs to boats, planes, and all things mechanical. He's renowned for taking on maintenance and repair projects single-handedly and is often spotted underneath RVs, making him the technical backbone of our endeavors.

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Gavin F

Sunday 9th of July 2023

Fantastic article thankyou. Particularly to the editor who made it so easy to read! Can I just ask, I only have a small AC(4.2amps at 240v) and soft starts just aren't a big thing in Australia camping circles so I have to do it myself, is there anything special about soft starts advertised specifically for ac's versus ones that day they can run just about anything with an electric motor? Is it just about sizing it up correctly? Cheers Gavin

Mortons on the Move

Saturday 15th of July 2023

No there is not much different. They work by reducing voltage to lower current, this however can screw with electronics sometimes so having one directly inline with the motor (a dedicated AC soft start unit) might not screw with electronics as much.

Michael Prue

Saturday 2nd of July 2022

I’ve been researching these on and off for a couple of years now. In my mind, the ability to extend an AC units life AND provide the ability to run off of 20 amp house circuits if needed is a win win for me. I think we will be investing the time and money. Anyone know which one of these is the best to purchase ???

Raymond J Ramirez

Friday 10th of June 2022

I need a soft start for my portable Sharp air conditioner. It must be a simple plug in device brcause ir is a 120 VAC unit and I don't want to open it up. The surge current is over 12 A and Iit runs later at 5 A. Where can I buy such a plug in device?

Mortons on the Move

Sunday 22nd of January 2023

These guys make a 30 amp model that can be used in line. https://softstartup.com/

JEFF CONLEE

Tuesday 12th of April 2022

OK, my logical mind is asking if this is such a cool deal then why AC manufacturers don't have them installed anyway? Then this goes against why we use surge protectors that help when we have low current also? Isn't this this same because aren't you damaging the circuits because of low current? Just not convinced for that price it is worth it. We should be requiring the manufacturers to build them that way.

Wes Duncan

Tuesday 14th of June 2022

Like any manufacturer, the companies that make these air conditioners focus on the bottom dollar. They engineer them to do what they're advertised to do, and strip out anything that isn't necessary. They want to offer a unit as cheap as possible so that they win the lowest bid. If they have extra bells and whistles that not everyone needs, the price goes up and profits go down.

J

Monday 11th of April 2022

I put softstart rv soft starters on both my roof a/c's. My 6500 watt genny caught fire and I opted not to replace it for a variety of reasons so now when I am boondocking and it gets entirely too hot I plug my honda eu2000 into the coach on the breaker box connection (no ext. cords as they add just enough resistance to overload my little inv/gen but the softstart rv allows me to run one or the other A/C but it is ALL the 2000 watt can handle I can't run anything else while I'm cooling down the coach interior