Starting Softly - RV Enthusiast Magazine

Starting Softly

by | Dec 21, 2021 | Accessories, Gadgets, Technology

The use of a SoftStartRV unit can dramatically reduce the initial start surge of an RV air-conditioner, allowing for its use with a portable generator producing just 2,500 watts of power.

Reducing the power requirements for running a roof-top air-conditioner with a SoftStartRV device adds off-grid versatility by making it possible to employ smaller portable generators

Given the surging popularity of boondocking, it’s not surprising that sales of portable generators have likewise jumped of late. After all, camping off the grid doesn’t always mean camping without life’s comforts — especially air conditioning. Unfortunately, some RV enthusiasts have found themselves with a fairly expensive genset incapable of keeping things cool in the dog days of summer…through no fault of their own.

Picture this: You bought a new 2,500-watt generator for your RV travels that you believed should be able to provide enough power to operate an air-conditioner. After all, it provides 20 amps of current, and the A/C only requires 13 amps to run. Piece of cake, you think to yourself; “If I need the A/C I just won’t run anything else.”

Famous last words. You start the generator, hook up the RV, and all is good — until you turn on the A/C and the generator gives up the ghost.

What happened? Two words: Start surge — which is much higher than the generator’s run-power requirement. And that’s if absolutely everything else in the RV, which also tax the system, is turned off.

SoftStartRV chart
This chart from Mike Sokol shows the difference between a 15,000-Btu air-conditioner starting with its own capacitor versus with the SoftStartRV. The start surge is more than double without the SoftStartRV.
An air-conditioner has two or three electric motors, which are inductive loads. The electrical energy creates a magnetic field that converts the power to mechanical energy. There also is a refrigerant compressor and one or two fan motors in an RV rooftop air-conditioner. In order to start the motor, there has to be enough force to turn it over, as it is under some load (depending on pressure, weight, etc.). This is the start surge, which is momentary, but can be quite high. All air-conditioners have a rating on the compressor called locked rotor amps (LRA), which indicates the maximum amp draw the compressor requires if locked.

This surge literally lasts for only 1/6 of a second — but it’s enough to cause a generator to stall out. All single-phase air-conditioners, like those in RVs, have a start capacitor, which provides an inrush of amperage to kick-start the compressor, and a spike of power to recharge the capacitor. Unfortunately, this momentary inrush and recharge will cause an under-rated generator to stall or a borderline shorepower provision to trip a breaker.

the starter/junction box is removed and/or opened
Once the cover of the air-conditioner is lifted off, the starter/junction box is removed and/or opened, depending the brand and model of air-conditioner, and the soft start wires are routed into the box.
Does that mean the aforementioned 2,500-watt genset is relegated to running the coffee-maker while you sweat out the afternoon in a primitive campsite? Well, it used to. Fortunately, this is where SoftStartRV by Network RV comes into play. This relatively new technology substantially reduces the start surge — which allows an RV air-conditioner up to 15,000 Btu to start on as small as a 2,500-watt genset, or a couple of roof airs to run on a 30-amp shorepower connection.

The SoftStartRV electronically ramps up the compressor over a longer period of time (about 1/3 of a second), substantially reducing the current required. RV Enthusiast contributor Mike Sokol tested the SoftStartRV on a Dometic Penguin 15,000-Btu air-conditioner (https://www.youtube.com/watch?v=iJqijovoMW0&t=3s) and, with his recording equipment, was able to visually demonstrate how the technology works. In his example, the air-conditioner spiked at 58 amps stock — and just 24 amps after the SoftStartRV was installed. That’s 6,960 watts without, and 2,880 watts with the SoftStartRV.

We recently installed the SoftStartRV on a Furrion 14,500-Btu CHILL air-conditioner mounted on a Lance truck camper with a 2,500-watt LP-gas inverter-generator. In our practical test, we found the generator couldn’t start the new Furrion unit, whereas the legacy Carrier Air-V 13,500-Btu model could be started (although the generator would bog down substantially). After installation of the SoftStartRV, not only would the Furrion start on the genset, but the generator would barely bog. From fan only to starting the compressor was a smooth, quiet transition, unlike the clunking or rattling experienced with many air-conditioners. Not only will the SoftStartRV help prevent the annoying noises, but the lower starting requirement reduces strain on the compressor, which increases longevity, according to the company.

The installation is straightforward for any do-it-yourselfer — it only takes minutes to complete the job. SoftStartRV also offers videos and relatively clear instructions for all brands of RV A/Cs and can provide a live call with a technician to walk you through the installation. Installation kits have everything needed for the installation; you’ll need a screw gun with bits, wire strippers, a wire crimping tool and, for the Furrion, a long bit extension to remove the wiring box inside the A/C.

all the wiring
securing the box
The capacitor and wiring changes are made inside the box. Directions for each specific brand and model are available on the website, but some capacitor-top terminals will be changed and a couple of splices are made with solderless connectors. Once done, resecure the capacitor inside the box and the cover.
The SoftStartRV box is sealed from the factory. Three LEDs on the front indicate run, start and self-test modes. The unit can be mounted pretty much anywhere inside the air-conditioner where there is room and a way to secure it, out of the way of moving parts. We tucked it into a corner by the condenser fan and attached it to the foam fan shroud using the included VHB tape and screws.

Once installed, there is nothing further to do; just run the air-conditioner. The main unit is a one-size fits all design; install kits are available online if you want to move the device to another RV.

This technology has revolutionized RV air-conditioning and manufacturers are integrating these devices into some of their models, providing 65-70% startup power savings right from the factory. While the $329 Amazon price (https://amzn.to/3nT0zOn) isn’t anything to sneeze at (there is a 5% coupon bringing it down to $312.55 with Prime shipping), the ability to run a roof air-conditioner off a generator or inverter, as well as make the compressor last longer, is a huge benefit.

the starter box installed
The starter box is reinstalled in the pan, the wiring dressed and the SoftStartRV device mounted in a suitable location. Before replacing the shroud, we tested the air-conditioner and ran it through its paces.
SoftStartRV device fully attached
Here, device is secured to the foam shroud with VHB tape and screws in an out-of-the-way place that also allows users to see the status LEDs from outside the air-conditioner.
Sources:

SoftStart RV
(954) 606-6886
https://www.softstartrv.com/

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