What Else is Drawing Power From Your Generator?

The most common issue customers run into when they have trouble operating on generator is the unknown auxiliary loads in their trailer that are drawing power in addition to the air conditioner.

The average generator may demand upwards to 1750W or even 1900W in extreme heat.
This means there is very little headroom left in a 2000W generator for other loads in an RV or Marine environment. 

Seeing The BIG Picture

The best way to understand what's really happening is to use a clamp-on ammeter that you place around one of the power conductors as it exits the generator. That way you can see the ENTIRE load the generator is supporting.

As a best practice, customers should:

  • Ensure that refrigerators (4A) are manually switched to propane
  • The hot water heater is manually switched to propane, and
  • Any converter (battery charger) is breakered off or verified to be in float (trickle charge) mode.

2000W is 16.7A, and typically we have found that no more than 3-4A can be getting drawn by other loads before the typical A/C attempts to start.

Any more auxiliary load than that, and your generator may overload when the startup takes place - even with the EasyStart™ soft starter.

Examples of Customers Having Auxiliary Loads That Hindered Start-Up

Below you'll find some of the questions we received from customers having start-up issues, and the answers our engineers provided them.


Q:
I just finished installing my new EasyStart 364 and I'm a little disappointed!
I followed the install instructions, cycled 5 times then tried to run my Dometic 15000 BTU AC with my Honda eu2000i generator only to have the AC compressor keep shutting off!  
The AC works perfect on shore power.
Do you suppose something is not wired correctly?
The main reason I purchased the EasyStart was to use the AC with generator power and according to many reviews I read, it should do just that.
Any suggestions would be greatly appreciated.

A:
Thank you for your inquiry and for your previous purchase.
 
Please don't give up hope yet.  There has to be an explanation.  We own a 15kBTU Dometic Penguin II and a Honda EU2000i generator at Micro-Air, and with EasyStart installed, we can start and run this A/C on our Honda, even at 103°F, with about 150 watts to spare.  We would never claim that it would work unless we were certain.  Hundreds of other customers as you know have also succeeded with similar setups and Honda EU2000i generators.
 
I have a few questions for you to begin the troubleshooting:
 
1) Which model of the Dometic 15k do you have?  Is it a Penguin, Penguin II, Brisk, or Brisk II?  If you have a complete model number, I can look it up.
 
2) What exactly do you mean by "shutting off".  Are you stating that the A/C's compressor starts up and runs on generator, but then shuts off unexpectedly a short time later?  Or, does the A/C compressor never start up at all?
 
3) Is the generator lighting its Overload LED and completely turning off its AC output power?
 
4) Given a 15k BTU A/C will draw upwards to 1800W of power and sometimes higher in hot weather, there will not be much headroom left on your 2000W generator to run other auxiliary loads, some of which you may not even realize are turned on.  Specifically, you must make sure your hot water heater and refrigerator are manually switched to propane.  Next, you must determine if your converter/battery charger is operating or not.  Converter/battery chargers are typically the most elusive auxiliary load since you may not even know where its circuit breaker is located.  They can draw upwards to 1000W (!) in rapid charge mode, and also when you have a lot of 12V loads (e.g. lights, fans, etc.) turned on inside the trailer since the converter will attempt to power these loads by converting the available AC power to DC power to avoid discharging the batteries.  Therefore, a good test would be to find and turn off the circuit breaker for the converter to make sure it is not the cause.
 
5) If you have a clamp-on ammeter, then I highly recommend you rig up a special plug as shown in the attached photo and connect it between the cord you have plugged into the generator and the generator itself.  This setup will allow you to measure the exact amount of current the generator is sourcing at all times, even before the A/C is turned on.  That way you can more precisely determine if any of the auxiliary loads are causing you the issues.
 
I'll do my best to assist you.  Thank you for your patience.

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Q:
I'm looking for a little followup advice on the Easy Start cap.
I completed the wiring instructions successfully and as you instructed, also completely removed the existing start cap wires and those in the #1 and 2 position on the relay.
5 startups for the learning phase, all under regular 30 amp shore power.
After the sixth start, I disconnected shore power to power up with the Honda eu2000i.
At power up, my thermostat/LED panel came on and the blower started blowing, so I assumed all was well.
This all occurred dockside, so the next evening at anchor, I tried again and  the blower came on but only warm air.

I checked the compressor and it wasn't running.
At restart, I could here a click sound at the compressor, but it failed to start up.
I tried again at dockside a couple of days later and the compressor came right on blowing cool air.

What's happening?
I started the Honda on full power at startup and then switched to Eco and the compressor ran just fine.
I had been running the AC on shore power prior to the successful start on the Honda, so maybe the compressor was hot and started easier?
Any suggestions or help would be appreciated.

A:
In the sequence you described in your first and second paragraph, it would seem that after 6 successful starts on shore power, a 7th on the Honda EU2000i may or may not of have worked.
A day later (following evening), a start attempt on shore power did not work.
A couple days after that, another start attempt on shore power did work successfully.

In your third paragraph, I gather some time or days after the last test described above, you successfully started the A/C on the Honda with ECO mode off, then again on the Honda with ECO mode, both times successfully, proper to which the A/C had been running on shore power?
 
If so, then you've demonstrated opposite cases.
The first where the Honda did not work immediately after multiple shore power runs, the second where the Honda DID work immediately after multiple shore power runs.
This doesn't seem to point to any particular cause.
 
You may have an issue with auxiliary loads on your boat that are loading your Honda when you don't realize it.
Battery chargers, refrigerators, and refrigeration equipment are the most elusive, so you may have to dig deeper.
Use a clamp-on ammeter and a special line cord extension as shown in the attached to be able to tap into and measure the power output from your generator feeding the entire boat.
That way you'll know what is going on prior to starts that work, and prior to starts that do not.

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Q:
Sorry for the confusion.
To be clear, start up on shore power was always successful.
Only one out of three attempts on the Honda was successful.
I have a dedicated outlet for only the AC on my boat, so all the power supplied by the Honda goes to the AC.
Also the compressor started up when the eco was off and then I switched it to on while still running just to make sure it would run in the eco mode and it did.
Would a hot compressor draw fewer LRA's at start up with the Honda?

A:
Thanks for the clarification.
Your Marine Air CSD should toggle the reversing valve prior to the startup if the off time is short, so there should be little difference between a hot start and a cold start.
If I were to hazard a guess, a cold start might be lower amps because of the totally balanced refrigerant pressures, but a hot start might be lower amps because of the oil migration.  It may be awash.
I would still use a clamp-on ammeter to measure the total current being fed by the Honda.
When the startups "fail", does the Honda light its overload LED?
If yes, then taking amp measurements just prior to and during startup will be necessary to what is going on.
The SW pump will be presenting its load first as well as the fan (or fans if there is more than one evaporator).
If the Honda does not light its overload LED during the startup, then something else is going on that may be related to the Honda only.