Reviews
SoftStartRV Soft Start Kit Review
Researched from published standards and manufacturer specifications. Updated .
Quick answer
The SoftStartRV Soft Start Kit reduces the compressor inrush current a rooftop RV air conditioner draws on startup, which is what lets that air conditioner run on a smaller inverter generator or a modest inverter that would otherwise trip or stall under the surge. It is frequently cheaper than upgrading to a larger generator. Skip it if your rig's power problems are with resistive loads like heaters or lighting, since a soft starter changes nothing about a load that has no motor to start in the first place.
A rooftop RV air conditioner's compressor draws several times its running current for a fraction of a second at startup, and that surge, not the steady running wattage, is usually what trips a breaker, stalls a small inverter, or overloads a modest generator. A soft start kit installs inside the air conditioner's control box and limits that inrush current electronically, spreading the startup load over a longer window instead of drawing it all at once. The running wattage the compressor needs once it is up and spinning does not change; only the size of that opening spike does, which is exactly the number that decides whether a given generator or inverter can start the unit at all.
This review is researched from SoftStartRV's published specifications and from verified owner reviews on the listing, not from an installation tested in person for this site. The decision that matters most here is whether your actual power problem is a motor-starting surge, which this kit addresses directly, or something else entirely, which it does not touch.
Why does an air conditioner need a soft start at all?
A compressor motor draws locked-rotor current, several times its running amperage, for the brief moment it takes to spin up from a standstill, and that spike is what a generator's wattage rating or an inverter's surge capacity actually has to survive, not the appliance's steady-state draw. A rooftop RV air conditioner rated around 1,500 running watts can demand a startup surge well above that, which is why a generator that comfortably powers the air conditioner once it is running can still fail to start it in the first place. A soft start kit limits that inrush electronically, which is a different fix than simply buying a bigger generator to absorb the same surge.
What it does not include and what to check first
The kit does not include installation labor, and fitting it means opening the air conditioner's control box, which on most rooftop units means accessing it from inside the RV through the ceiling assembly rather than the roof itself. It also does not change the air conditioner's running wattage once started, so a generator or inverter still needs to comfortably cover that steady draw plus whatever else is running at the same time. Run your actual generator wattage against the air conditioner's running load, not just the startup surge, using a generator size calculator before assuming a soft start alone solves an undersized generator problem.
Soft start kits compared
All three of these address the same compressor inrush problem, but installation method and rated capacity differ enough to matter for a specific rig.
| Kit | Max BTU | Installation | Price |
|---|---|---|---|
| SoftStartRV Kit | Not published | Wired into control box | $295.00 |
| Spartan SpartanStart | 20,000 BTU | Wired into control box | $189.00 |
| SoftStartRV Plug and Play | Not published | Plug in | $595.00 |
Published standard Source: Manufacturer spec sheets on the product listings, current at time of writing..
What owners report
Owners consistently report that a soft start lets a standard rooftop air conditioner start reliably on a 2000 to 2200 watt class inverter generator that previously could not start it at all, which is the core use case this kit is built for. Several owner reviews describe the installation as straightforward once the control box is actually accessible, with the main time cost being reaching the control box through the interior ceiling assembly rather than the wiring itself. A smaller number of owner reports mention needing to confirm compressor compatibility before ordering, since not every soft start model covers every compressor type on the market, which is worth verifying against your specific air conditioner model before purchase.
Who should not buy a soft start kit
Skip this if your power problems have nothing to do with starting a motor load. A soft start changes only the startup surge of a compressor or similar motor; it does nothing for resistive loads like a space heater, incandescent lighting, or a hair dryer, which draw their full current the instant they are switched on with no meaningful inrush to smooth. It also does nothing to reduce the air conditioner's running wattage, so if your generator cannot sustain that steady draw once the unit is started, a soft start alone will not fix an undersized generator problem. In that case, sizing up the generator itself, not adding a soft start, is the correct fix.
Never run a generator, of any size, inside an enclosed space or right up against a closed window or vent. Carbon monoxide from a generator's exhaust is a fatal risk indoors or in a poorly ventilated generator bay, and a soft start kit that lets you run a smaller generator does not change that risk in any way. Keep any generator outdoors, well away from windows, vents, and doors, regardless of its size or how quietly it runs.
Alternatives to the SoftStartRV Kit
Spartan's soft start is the strong budget pick for a single standard-sized rooftop unit. If wiring inside the air conditioner's control box is not something you want to do yourself, the plug-and-play version or simply buying a larger generator are both honest alternatives, at different costs.
Spartan Power SpartanStart Soft Start Kit
$189.00About $106 less at $189.00, rated to 20,000 BTU which covers the common 13,500 and 15,000 BTU rooftop units most RVs run, a genuinely fine choice for a standard single air conditioner.
Best for: A standard rooftop unit up to 20,000 BTU.
Check price on Amazon
SoftStartUp Plug and Play RV A/C Soft Start
$595.00At $595.00, this plugs into the existing air conditioner circuit rather than being wired inside the unit's control box, worth the premium if you are unwilling or unable to open the rooftop unit yourself.
Best for: Anyone unwilling to open a rooftop air conditioner.
Check price on Amazon
WEN 6800W Dual Fuel RV-Ready Inverter Generator
$798.00At $798.00 with a built-in CO shutoff sensor, a generator sized to start the air conditioner outright is the other legitimate path if a soft start kit does not fully solve your setup for other reasons.
Best for: A large rig or two air conditioners.
Check price on AmazonFrequently asked questions
- Will a soft start kit let my RV air conditioner run on a smaller generator?
- In most cases, yes. The kit reduces the compressor's startup surge, which is usually the specific reason a smaller generator fails to start a rooftop air conditioner even though it could power the unit once running. It does not reduce the air conditioner's steady running wattage, so the generator still needs to comfortably cover that ongoing draw alongside anything else running at the same time.
- Does a soft start kit help with resistive loads like heaters?
- No. A soft start specifically addresses the inrush current a motor draws when starting, and a resistive load like a space heater or incandescent light has no meaningful startup surge to smooth in the first place. If your power problems come from resistive loads rather than a compressor starting, a soft start kit will not change anything.
- Is installation something I can do myself?
- Owners report the wiring itself is straightforward for someone comfortable working inside an electrical control box, but reaching the air conditioner's control box on most rooftop units means accessing it from inside the RV through the ceiling assembly, which is the more time-consuming part of the job. If you would rather avoid opening the unit at all, the plug-and-play version installs without touching the control box.
- How many air conditioners can one soft start kit support?
- A soft start kit is installed per air conditioner unit, so a rig with two rooftop units needs two separate kits, one per compressor. Confirm the specific kit's compatibility with your air conditioner's compressor type and BTU rating before ordering, since not every soft start model is rated for every unit on the market.
- Is a soft start kit cheaper than buying a bigger generator?
- Often, yes, particularly if the rest of your power setup, including an existing generator, already covers the air conditioner's running load and only the startup surge is the problem. A soft start kit in the $189 to $295 range is typically less expensive than stepping up an entire generator class, though if other loads also demand more running wattage than your current generator provides, a larger generator solves more problems than a soft start alone.
- Does a soft start kit reduce how much power the air conditioner uses overall?
- No. It only reduces the brief startup current spike; the compressor's steady running wattage while operating is unchanged. Any expected reduction in fuel use or generator load has to come from the startup surge no longer being the limiting factor, not from the air conditioner using less power once it is running.
- Does this void my air conditioner's warranty?
- Manufacturer warranty policies on aftermarket soft start kits vary by air conditioner brand, and SoftStartRV's own listing does not make a blanket warranty claim on this page, so check your specific air conditioner manufacturer's warranty terms before opening the control box. Some manufacturers explicitly permit soft start installation while others require it to be done by an authorized technician to preserve coverage.
Buy this if a compressor startup surge, not steady running wattage, is what is actually stopping your generator or inverter from running the air conditioner. It is frequently the cheaper fix compared with a full generator upgrade, but it solves one specific problem, and running any generator, soft start or not, in an enclosed space still carries a real carbon monoxide risk that has nothing to do with the unit's size.