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Watt Warden

Sizing

Soft Starter vs a Bigger Generator

One of these costs a few hundred dollars and fixes the surge. The other costs thousands and fixes everything. Work out which problem you have before spending either.

By Sawyer V.Updated Published How we work this out
An air conditioner condenser unit mounted outside a building.

Watt & Warden earns a commission on qualifying purchases made through links on this page, at no extra cost to you. It never changes a ranking, and our picks include products we tell you to skip. Full disclosure.

Quick picks

#ProductBest forPrice
1
Micro-Air EasyStart Breeze soft starter

The cheap fix

Micro-Air EasyStart Breeze soft starter

Ramps the compressor up instead of slamming it on, with an in-rush reduction of up to 75% published by Micro-Air.

An air conditioner that trips the machine you own
$355.00 · Check price on Amazon

#ad how this is funded · price as of October 20, 2026

2
Champion 4500W dual fuel inverter generator

The machine a soft starter can rescue

Champion 4500W dual fuel inverter generator

4,500 starting / 3,500 running watts of dual-fuel inverter power with electric start.

An RV air conditioner after the surge is reduced
$988.62 · Check price on Amazon

#ad how this is funded · price as of October 20, 2026

3
Westinghouse WGen9500DF

The bigger-machine answer

Westinghouse WGen9500DF

9,500 running watts, dual fuel, with an L14-30R and a 50A 14-50R.

Central air plus the rest of the house
$999.00 · Check price on Amazon

#ad how this is funded · price as of October 20, 2026

4
DuroMax XP13000EH

When the list is genuinely large

DuroMax XP13000EH

13,000 running watts from a 500cc engine with a 50A transfer-switch outlet.

Central air, a well pump and a range together
$1,299.00 · Check price on Amazon

#ad how this is funded · price as of October 20, 2026 · $1,499.00 13% off

Prices come from the retailer at page-build time and change constantly. Where no live price is available the button reads “Check price” rather than showing a number we cannot stand behind.

Diagnose the problem first

These two purchases fix different failures, and buying the wrong one is expensive.

What happensWhat it meansThe fix
Generator trips the moment the AC kicks inStarting surge exceeds the machineSoft starter
AC starts, then the machine bogs when the fridge cyclesRunning watts exceed the machineBigger generator, or shed loads
Everything runs but the machine is at its limit all nightNo headroom for anything elseBigger generator
Nothing starts, including small loadsA fault, not a sizing problemNeither — troubleshoot the machine

Starting watts and running watts are different specifications and the distinction decides this whole page — here is how they differ.

What a soft starter does, precisely

An air conditioner compressor drawing a few thousand running watts can demand several times that for a fraction of a second as it starts. A soft starter ramps the motor up over a short sequence instead, and Micro-Air publishes an in-rush current reduction of up to 75% for its EasyStart Breeze.

What it does not do is reduce the running load. Once the compressor is turning, it draws exactly what it always drew — the air conditioner page has the figures.

The arithmetic, on a typical RV air conditioner

Without a soft starterWith one
Running drawUnchangedUnchanged
Starting demandSeveral times the running figureReduced by up to 75%, per Micro-Air
Generator that copesA significantly larger machineOften the one you already own
CostThe price difference between machinesThe starter plus fitting

The reduction figure is Micro-Air's published specification for its own product. Actual starting demand varies by compressor; your air conditioner's locked-rotor amperage is on its data plate.

When a soft starter is not the answer

  • Your running total already exceeds the machine. No amount of gentler starting fixes that.
  • The appliance is a fridge, a pump or a compressor you cannot modify. Soft starters are an air-conditioning product.
  • You want the whole house, not one appliance. That is a machine-size problem — work out the number before spending.
  • You are running from a battery. A soft starter helps there too, but capacity, not surge, is usually the binding constraint — the power station page covers it.

The order to spend in

  1. Measure or look up your loads. Running watts first, starting watts second.
  2. If one appliance is the blocker, fix that appliance. A soft starter is the cheapest useful upgrade in this whole category.
  3. If the total is the blocker, buy the machine. Once, with headroom, rather than twice.
  4. Spend what is left on the connection. A transfer switch does more for usability than extra watts do.

The short version

  • Soft starter = starting problem. Bigger generator = running problem.
  • Up to 75% less in-rush is Micro-Air's published figure, and it is often the difference between trip and run.
  • Soft starters do nothing for running watts.
  • Diagnose before buying. The symptoms are easy to tell apart.

The picks in full

01 — The cheap fix

Micro-Air EasyStart Breeze soft starter

Ramps the compressor up instead of slamming it on, with an in-rush reduction of up to 75% published by Micro-Air.

A soft starter attacks the surge directly, which is the specific reason most generators refuse an air conditioner. It costs a fraction of a larger machine.

It fits to the air conditioner, not to the generator, so it keeps working whatever you plug the house into afterwards.

The honest catch: it is wired into the air conditioner, which is professional work for most owners, and it does nothing for the running load.

Skip it ifthe problem is running watts rather than starting watts. This changes only the start.

Micro-Air EasyStart Breeze soft starter
$355.00 · Check price on Amazon

#ad how this is funded · price as of October 20, 2026

Published specifications for the Micro-Air EasyStart Breeze soft starter
SpecificationPublished figure
In-rush reductionUp to 75%, per Micro-Air
Made forRV and marine air conditioner compressors
Fitted toThe air conditioner, not the generator
InstallWired into the air conditioner — professional fitting for most owners

Source: Micro-Air — EasyStart Breeze soft starter. These are the manufacturer's published figures, not ours — we have not tested this unit.

02 — The machine a soft starter can rescue

Champion 4500W dual fuel inverter generator

4,500 starting / 3,500 running watts of dual-fuel inverter power with electric start.

This is the classic pairing: a mid-size inverter machine that cannot start a 13,500 BTU RV air conditioner on its own, and can once the compressor ramps instead of slamming.

Inverter output also suits the air conditioner's electronics.

The honest catch: 3,500 running watts leaves little spare once the air conditioner is running steadily.

Skip it ifyou need to run a house rather than a camper.

Champion 4500W dual fuel inverter generator
$988.62 · Check price on Amazon

#ad how this is funded · price as of October 20, 2026

Published specifications for the Champion 4500W dual fuel inverter generator
SpecificationPublished figure
Output4,500 starting W / 3,500 running W (gasoline)
TypeInverter, RV ready
FuelGasoline or propane (dual fuel)
StartingElectric start
RV outlet120 V TT-30R, 30 A
Warranty3-year limited with free lifetime technical support

Source: Champion Power Equipment — 4500-watt dual fuel inverter specifications. These are the manufacturer's published figures, not ours — we have not tested this unit.

03 — The bigger-machine answer

Westinghouse WGen9500DF

9,500 running watts, dual fuel, with an L14-30R and a 50A 14-50R.

Buying headroom solves starting and running in one purchase, and it covers the well pump and the range as well.

If your critical list was always going to outgrow a small machine, this is the honest route.

The honest catch: several times the cost of a soft starter, plus more fuel, more noise and more machine to store.

Skip it ifthe air conditioner is the only load you cannot start. Then fix the surge instead.

Westinghouse WGen9500DF
$999.00 · Check price on Amazon

#ad how this is funded · price as of October 20, 2026

Published specifications for the Westinghouse WGen9500DF
SpecificationPublished figure
Output (gasoline)9,500 running W / 12,500 peak W
FuelGasoline or propane (dual fuel)
Engine457cc 4-stroke OHV, cast iron sleeve
Tank6.6 gal (25 L)
Run timeup to 12 h on a full tank
Transfer-switch outlet120/240 V L14-30R, 30 A
RV outlet120/240 V 14-50R, 50 A
StartingPush-button electric with remote key fob
Warranty3-year limited

Source: Westinghouse — WGen9500DF product specifications. These are the manufacturer's published figures, not ours — we have not tested this unit.

04 — When the list is genuinely large

DuroMax XP13000EH

13,000 running watts from a 500cc engine with a 50A transfer-switch outlet.

A 3-ton compressor can demand up to 12,000W at the instant it starts without a soft starter, and this is the class of machine that absorbs that without complaint.

It also runs everything else at the same time, which is what whole-house backup actually means.

The honest catch: fuel burn and noise scale with the engine, and most households never need this much.

Skip it ifone appliance is the problem. This is an expensive way to solve that.

DuroMax XP13000EH
$1,299.00 · Check price on Amazon

#ad how this is funded · price as of October 20, 2026 · $1,499.00 13% off

Published specifications for the DuroMax XP13000EH
SpecificationPublished figure
Output13,000 running W / 16,000 peak W
FuelGasoline or propane (dual fuel)
Engine500cc OHV DuroMax
Transfer-switch outlet50 A
FrameAll-metal, no plastic panels
SafetyLow-oil shutoff; 5 ft propane hose with ACME connector

Source: DuroMax — XP13000EH product specifications. These are the manufacturer's published figures, not ours — we have not tested this unit.

How these were chosen

We did not test these. Nobody at Watt & Warden has plugged one in. What we did instead: read the manufacturer's published specifications, compile them into a table where the figures line up, and compute the numbers manufacturers leave out — runtime against a real appliance load, and what an hour of running actually costs.

Anything that could not be sourced was left out rather than estimated, and every pick names the buyer who should skip it. The full method is here, including where it is weaker than a publisher with a test bench.

Questions people actually ask

Will a soft starter let my generator run an air conditioner?

Often, yes -- if the failure is at the moment of starting. Micro-Air publishes an in-rush current reduction of up to 75% for its EasyStart Breeze, which is frequently the difference between a generator tripping and the compressor spinning up. It does nothing if the generator cannot carry the running load.

Is a soft starter cheaper than a bigger generator?

Considerably. A soft starter plus fitting is a fraction of the price difference between a mid-size generator and one large enough to absorb an unassisted compressor start, and it keeps working whatever machine you own later.

How do I tell whether I have a starting or a running problem?

Watch what happens. If the generator trips the instant the compressor kicks in, that is a starting problem and a soft starter is the fix. If the air conditioner starts fine but the machine bogs down when another appliance cycles on, that is a running-watts problem and only a bigger generator or fewer loads solves it.

Can I fit a soft starter myself?

It wires into the air conditioner rather than the generator, and for most owners that is professional work -- particularly on a home system. RV installations are a common retrofit and better documented, but the safe answer is still an installer unless you are qualified.

Do soft starters help with power stations too?

Yes, for the same reason: they shrink the inrush a battery's inverter has to absorb. The difference is that with a battery, capacity usually runs out before output does -- an air conditioner at 3,500W running drains even a large portable in about an hour.

Sources

Every figure on this page comes from a published source. We have not tested this equipment, so the specifications are the manufacturer's and the statistics are the dataset's — the arithmetic on top of them is ours, and it is shown in full so you can check it. How we work this out.

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