MOD Micro-Air EasyStart for RV air conditioners

[Neal]

In the summer of 2018 I decided to configure my Class A Motorhome guided by @Chuggs to be able to run the front AC on solar. With 1800W of solar on the roof and a 100A Victron 150/100 tr solar charge controller already installed I was ready to be the guinea pig for one of Charlie's next inventions. I installed a 3 position switch near the circuit breaker panel that allows the power for the front AC breaker to source either off of shore power or the inverter. The inverter being powered by alternator + batteries with solar providing the current for the batteries (charging while use). One item required to make this happen was the installation of the Micro-Air EasyStart. First off, installation does not void or affect the Dometic warranty. Per the Micro-Air web site I found an installer not far from me that did the work. It wasn't that expensive to have installed but did take some time for various reasons (he bumped some dip switches which took a call to Dometic to sort out) but also a learning cycle you have to put it through which is 5 cycles of a 2 minute AC run followed by a 5 minute off interval. The placement wasn't ideal by the installer but it worked, Charlie installed on his and found a much better way to do so and maybe if he remembers how to install this he can reply with the instructions for others to follow as I sure don't remember. I followed Charlie's instructions and installed on my 2nd roof air conditioner and it went very smooth, took about 30 minutes and wasn't hard at all.

Prior to using the Micro-Air EasyStart such as if being powered by your gen you would hear your gen load up with the AC spikes with the startup load. With the EasyStart you don't get that startup spike of around 120 amps so the gen doesn't even load up and for this reason you won't hit low battery cutoff (LBCO) in a solar powered AC scenario. They are amazing and when your 50A coach is connected to a 30A shore power setup you most likely will not load shed. I was able to run both AC's just fine on 30A among the other items in the coach.

Check it out. Great thing to install for your AC's for various scenarios.

EasyStart Breeze RV AC Soft Starter for RV Air Conditioners

EasyStart Breeze technology reduces RV AC startup current by up to 75%, enabling RV owners to run their AC using a portable generator.

www.microair.net

 

[J&JD]

Seriously thinking about doing this mod. It just makes sense to me.

 

[Chuggs]

Here’s a wiring diagram for our Dometic Rooftop AC units...

 

[Chuggs]

If you install it yourself...the instructions are pretty easy to follow.

I would recommend the installation kit add-on to keep from having to run to the parts store.

wire stripper, screwdriver, cutters, crimper...


I found the plastic molded shrouding wasn’t fitted together properly...so having some duct tape to properly seal the gap is nice. You also have to route the wiring harness thru a shroud...some duct seal (grey silly putty looking stuff) is handy for sealing the wiring routing thru the shroud.

Takes no time at all to install...It takes some time to go thru the programming...turning the A/C on/off Thur a series of cycles...

 

[texskeet]

I am getting code E 7 which is low voltage when my ac tries to turn on. Please help.

Thanks

 

[Chuggs]

E7 on mine usually means I left the Dometic units on when switching or removing power.

Go from one end to the other... Power Pole Breaker or Generator Breaker...PI surge protector clamping due to a fault...Main distribution panel...A/C 1,2 &3 20A breakers, too high a load causing the Precision Circuits to cut A/C (I don’t think this will cause an E7 since it’s a command to the Dometic control box...not an actual AC power cut out. Loose connections, bad capacitor, and if you have a Micro Easy start there is a way to reset and reprogram it to relearn your compressor starting loads.

Can’t think Of much else...

 

[texskeet]

I am a failure at telling my story. Every thing off but frig and back ground stuff . power for front ac switched to inverter . Turn on front ac only. Get E7 want run.

 

[Neal]

power for front ac switched to inverter

So you have your front AC wired up like @Chuggs and I to run the front AC off of solar? It sounds then like your inverter breaker has tripped. Are you getting power to other inverter outlets in the coach?

 

[texskeet]

Yes It is running the frig and micro .

 

[Chuggs]

Does the A/C work when switched to Line power vs inverter?

 

[texskeet]

Yes just fine. Both shore and generator .

 

[Chuggs]

Yes just fine. Both shore and generator .

Seems you've isolated the problem.

I would check the wiring between the breaker and the switch. Specifically the inverter breaker and selector switch for selcting Inverter v Main AC.

If this is good...then something is happening, and probably too quickly to catch.

Loads? Neutral?

If you have the Precision Circuits panel...with the Inverter sub bus...I would leave the Inverter 30A on...and the Air Conditioner 20A on...and flip the rest of the breakers. You're just checking to see if the Inverter can power the A/C when it's the only thing. If it runs...you may be getting the drop out on the A/C because the inverter sees itself as overloaded.

Would be nice to measure amps on the 12v Inverter feed...and the 120v air conditioner Inverter powered LINE. Also check Inverter settings...maybe something is misconfigured.

The last item I can think of is something we avoided...so I haven't witnessed it. Did you use a double poled switch? I worried the Inverter might misbehave IF the Netral Line isn't switched along with the HOT. The distribution panel has two buses for A/C Line distribuition... One for main AC and one for Inverter. Each have thier own specific HOT rail and Neutral Rail. There is a combined ground bus. The neutrals aren't joined...nor should they be.

For your AC to complete a circuit...if you let the Neutral stay on the main AC neutral rail, it can't complete the loop without coming from the AC in supply side of the inverter. I don't think the Inverter likes this. Kinda acting as a ground fault...but on the Neutral line. If yours is wired with just the 120V LINE (hot) being switched...I would try wiring it with the LINE (hot) and Neutral both being switched...so each source to air conditioner maintains continuity... Main AC or Inverter...but not half and half.

That's all I can think of now...

 

[texskeet]

I will check all of that and see Thanks

 

[Golfer Guy]

The previous owner had the soft start wired to the middle AC so it will run off the batteries. Last summer in the heat it was a very nice addition to keep the coach comfy when boondocking.

 

[Chuggs]

The previous owner had the soft start wired to the middle AC so it will run off the batteries. Last summer in the heat it was a very nice addition to keep the coach comfy when boondocking.

I'm interested...I realize temperature, sun exposure, and battery capacity all factor in...but how long could you run the A/C without hitting 50% SOC?

 

[Golfer Guy]

Good question Charlie, I really don't know. I will have to take a look at that as things warm up. I watch the battery levels in the coach closely and don't remember a time where the AC was bringing the batteries down to a critical level. With the 1200 amp hours of lithium batteries it was never an issue. Usually if its that hot there is also plenty of solar for me to use. I suppose the dometic has a chart that shows how much draw it pulls when cooling but not sure where to find that.

 

[Chuggs]

Good question Charlie, I really don't know. I will have to take a look at that as things warm up. I watch the battery levels in the coach closely and don't remember a time where the AC was bringing the batteries down to a critical level. With the 1200 amp hours of lithium batteries it was never an issue. Usually if its that hot there is also plenty of solar for me to use. I suppose the dometic has a chart that shows how much draw it pulls when cooling but not sure where to find that.

Yep...1200aH of LiFePO4 is sweet!... You don't waste as many aH to resistance at high amp draw and have more useable aH by a massive margin.