Soft Start Install on Dometic ECD 10K Air Conditioner

 We added a Soft Start to our Dometic AC System on board our Catalina 34 Sailboat

We have had our Dometic ECD 10K AC unit since 2016 and we would power it at Anchor with our Honda eu2000i Generator, they worked well together.

Then I upgraded the electrical system on our boat to a Victron System which is really clever, even too clever!  When we run the generator and turn on the AC, the Victron would detect that the generator output was insufficient during the AC Startup and it would then start powering the AC from our LiFePo4 Batteries. That's great, until the battery power is too low and then we're without DC power. But we could run the Multiplus in Charge only mode and recharge the batteries, but that process is a pain.

Researching pro electrician 'Google', it seemed that a Soft Start would solve the issue.

I contacted Dometic and they confirmed that a soft start would help but when I contacted a local dealer, I found that the recommended Soft Start device would cost $700 !!!!! Wow!  Searching the web, I found several vendors that sold similar devices at over $300 but then I found SpartanStart for $180, a significant difference from the local dealer $700 for the Dometic device. I called Spartan and they recommended the SpartanStart - Softstart and advised that if I had any issues with the install I could call them and they would walk me through the process.

Here's a link to the product: https://spartanpower.com/product/spartan-power-spartanstart/

Installation was easy! The AC unit is beneath our V-Berth, so we removed all of the bedding, mattress and locker covers from the V-Berth

Step 1: Connect Shore Power and turn on the AC - Just to make sure it's working normally.

Step 2: Disconnect Shore power

Step 3:  Remove the Cap on the top of the compressor that covers the electrical wiring that connects the electronics box to the AC unit. There's a single screw that also secures the Ground terminal to the Compressor. 

Underneath that cap are the connectors to the compressor, there's 3. Run, Start and Common. Colors are as shown in the pic below.

Now that I knew which color was what, I replaced the cap.

Step 4: The individual wires are inside a plastic, split, conduit. I separated the conduit about midway from the top of the Compressor and the Electronics unit, and pulled the three wires needed out of the conduit.

Step 5: I cut the wires one at a time and crimped them to the correct wire as shown in the diagram above.  That's 6 crimps. 

Step 6: Time to test;

First I reconnected shore power and turned on the AC unit, after it's typical delay it turned on and started to pump out cold air.  Looking good so far.

Next I disconnected shore power and connected it to our Honda eu2000i generator and switched it to, what I call is 'Turtle' mode - it's a power saving option. The generator runs at minimum power and adjusts the power on demand.  Time to test the AC on the Generator. 

Turning on the AC system, it had it's usual delay, not noticeably different from when the AC starts up on Shore power.  The AC ran and the generator barely changed it's output.

The AC unit pulls about 900Watts when running.

At this point, the AC was running and the Victron system was showing that all power was coming from the Generator ( shore power ) and that no power was coming from the Battery.

We left the AC running and tested it running on the inverter powered by the batteries. I simply switched off the master shore power switch. The AC didn't even blink, it continued running but now pulling the 900Watts from the Battery ( 12.8v x 100a *3 = 3840 Watts ) 

With the AC running off the batteries, I turned the master shore power switch back on and after the normal delay the Victron Multiplus turned on and started powering the AC system, there was plenty of  power available from the generator, so the Victron Multiplus started to recharge the batteries.

With everything working correctly, time for a bit of wire management, and a few zip ties pulled it all together.

This was a major step towards our cruising plans. With the current heatwave that is being experienced all over the East coast of the USA, we believe we'll need the ability to run the AC from the Honda Generator.

See  you on the water and if we're running our generator at Anchor, then it'll probably be for the AC unit and it will probably be running in turtle mode.