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EG4 18K - Air Conditioning won’t run without grid

AW1511

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Aug 8, 2021
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I have run almost 1MWh through the 18k+ 2x PowerPro (400A, 20kW peak) Batteries + 18kw panels and it’s been working great (mainly off grid). Now that we are hitting a couple hot days in Texas I have tried to use my 4ton lennox xp21-048-230-04. It will not run while I have the inverter disconnected from the grid. I have purchased a soft start and will go into details.

The units RLA=21A(5kW) and LRA=104A(25kW). After installing the soft start I read ~41A(10kW) peak startup while on grid power (By grid power I mean grid connected through 18k to the load) and everything runs fine. This is within the capability of the inverter so that’s expected.

After this testing I turned off my grid disconnect(running on batteries and solar) and the air conditioning will not startup and run. I thought this was odd so I re-connected the grid and the ac started up fine. I let it run for a few minutes and the data shows that ~5kW is being pulled from the batteries as expected with no grid power being used. Now I turn off my grid disconnect and the air conditioning shuts down. I can’t figure out why the 18k can’t keep the air conditioning running while it is in its 5kw steady state or why it is not capable of starting it with the soft start.

My 2-ton unit runs on the 18k perfectly fine with grid power turned off.

My dad is working through the troubleshooting process with signature solar, but wanted to see if anyone here could help.

Firmware version is fAAB-1717
 
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Whilst this is not your problem, just note that my Easy Start will disconnect the compressor if the inverter switches modes, you then will have to wait for the protection timeout.
Can you list/dump your settings for the EG4 18k.
 
I'm watching this with interest because this has always been my question with all of these newer hi frequency inverters. Starting large inductive loads consistently, time and again, for several years.

Perhaps it has nothing to do with the load, but it will be interesting how this thread plays out.
 
I have run almost 1MWh through the 18k+ 2x PP Batteries + 18kw panels and it’s been working great (mainly off grid). Now that we are hitting a couple hot days in Texas I have tried to use my 4ton lennox xp21-048-230-04. It will not run while I have the inverter disconnected from the grid. I have purchased a soft start and will go into details.

The units RLA=21A(5kW) and LRA=104A(25kW). After installing the soft start I read ~41A(10kW) peak startup while on grid power (By grid power I mean grid connected through 18k to the load) and everything runs fine. This is within the capability of the inverter so that’s expected.

After this testing I turned off my grid disconnect(running on batteries and solar) and the air conditioning will not startup and run. I thought this was odd so I re-connected the grid and the ac started up fine. I let it run for a few minutes and the data shows that ~5kW is being pulled from the batteries as expected with no grid power being used. Now I turn off my grid disconnect and the air conditioning shuts down. I can’t figure out why the 18k can’t keep the air conditioning running while it is in its 5kw steady state or why it is not capable of starting it with the soft start.

My 2-ton unit runs on the 18k perfectly fine with grid power turned off.

My dad is working through the troubleshooting process with signature solar, but wanted to see if anyone here could help.

Firmware version is fAAB-1717

If you could DM your inverters serial number, I can take a look at this.
 
Could the Soft Start be bad,(incompatible) because the grid would not need it to run?
 
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I have run almost 1MWh through the 18k+ 2x PP Batteries + 18kw panels and it’s been working great (mainly off grid). Now that we are hitting a couple hot days in Texas I have tried to use my 4ton lennox xp21-048-230-04. It will not run while I have the inverter disconnected from the grid. I have purchased a soft start and will go into details.

The units RLA=21A(5kW) and LRA=104A(25kW). After installing the soft start I read ~41A(10kW) peak startup while on grid power (By grid power I mean grid connected through 18k to the load) and everything runs fine. This is within the capability of the inverter so that’s expected.

After this testing I turned off my grid disconnect(running on batteries and solar) and the air conditioning will not startup and run. I thought this was odd so I re-connected the grid and the ac started up fine. I let it run for a few minutes and the data shows that ~5kW is being pulled from the batteries as expected with no grid power being used. Now I turn off my grid disconnect and the air conditioning shuts down. I can’t figure out why the 18k can’t keep the air conditioning running while it is in its 5kw steady state or why it is not capable of starting it with the soft start.

My 2-ton unit runs on the 18k perfectly fine with grid power turned off.

My dad is working through the troubleshooting process with signature solar, but wanted to see if anyone here could help.

Firmware version is fAAB-1717
What is a PP battery?

Ability to start loads depends on available power. How much are the panels producing and how much can be pulled from batteries? I think you need more battery power than just a pair of 48V batteries even if the panels are producing.

The 18Kpv is not an 18Kw inverter. It is 12Kw when on battery power and claimed to be 15Kw with PV. Your LRA surge even with soft start could be higher than 15Kw.
 
What is a PP battery?

Ability to start loads depends on available power. How much are the panels producing and how much can be pulled from batteries? I think you need more battery power than just a pair of 48V batteries even if the panels are producing.

The 18Kpv is not an 18Kw inverter. It is 12Kw when on battery power and claimed to be 15Kw with PV. Your LRA surge even with soft start could be higher than 15Kw.
The eg4 power pro battery. 2x of these have a peak discharge capability of 400A or ~20kW.

The panels at the time of testing were putting out >5kW

I thought it may be the startup current issue even with the soft start and that is why I tried starting with the grid and then turning off the disconnect. This indicates to me it’s not just a startup problem, but a running problem. Although the running shutdown may be due to a mode switching that happens when the grid is disconnected. Understand it’s a 12kW AC output, but should run this steady state just fine. And with a soft start and 15kW peak it should be able to start it with the soft start
 
Whilst this is not your problem, just note that my Easy Start will disconnect the compressor if the inverter switches modes, you then will have to wait for the protection timeout.
Can you list/dump your settings for the EG4 18k.
Can you explain this one in more detail? How long does it take to bring the compressor back?

Best way to dump setting here?
 
The eg4 power pro battery. 2x of these have a peak discharge capability of 400A or ~20kW.
Power Pro- thank you.

You most likely need more battery as has been mentioned.

The panels at the time of testing were putting out >5kW

I thought it may be the startup current issue even with the soft start and that is why I tried starting with the grid and then turning off the disconnect. This indicates to me it’s not just a startup problem, but a running problem. Although the running shutdown may be due to a mode switching that happens when the grid is disconnected. Understand it’s a 12kW AC output, but should run this steady state just fine. And with a soft start and 15kW peak it should be able to start it with the soft start
How are you measuring peak LRA?
 
Do you know what Power Factor is?

Maybe your unit is recognizing bad power factor as the compressor starts and it's refusing to run.

Wattage is based on a power factor of 1. As soon as you power a heavy motor like a compressor the power factor goes off and you start to draw inductive power. This is typically measured in VA (Volt Amps). If you see something measured in Volt Amps it's not reliant on a power factor of 1. I'm thinking you can draw 12k of resistive power at a PF of 1 but you likely can't draw 12k of inductive power at a PF of say 45 degrees.

You can google power factor yourself but as a general indication, pulling the power factor off by 45 degrees with a motor will reduce your power from 12k to about 8500. (Cos 45 = .707, 12000 * .707 = 8484.).

Drawing the PF off from 1 is also really hard on the MOSFETS that are used to make inverter power, the commutator diodes work really hard and it gets noisy in there. I've worked on dozens of blown inverters that were hooked up to air conditioners, the two just don't get along very well. The software in yours may be saying NO just to save the circuitry.

In the end, not having AC when the power goes out is definitely a first world problem so my advice would be to consider how much time and money you want to spend solving this 'problem'.

Then again my unsolicited advice is worth exactly what you paid for it!
 
Can you explain this one in more detail? How long does it take to bring the compressor back?

Best way to dump setting here?
This timeout depends on which soft start you have and any possible delay the compressor itself may have, 2 to 5 mins is typical.
Seems like Jared is going to help you out with it, please let us know what happens.
 
EG4 PowerPro battery, 14.3kW 280Ah, 200A max discharge, 306lbs !!!! x2 should be plenty

It's the surge LRA that is the problem, I don't think there is enough battery to handle the surge. PV can help but with a large surge it has losses.

I don't believe in running things to the max, it is hard on equipment. That in itself would make me install a pair of 18Kpv's and probably 4 batteries.

Any other loads on the system with a grid down situation and the 18Kpv with the 2 Power Pro's won't probably work.

Reading this article, one could use 2.5 x 5000W running and see surge at 15Kw. https://eepower.com/technical-artic...rical-load-for-stand-alone-pv-system-sizing/#

I don't know where or how you got to this
There are conversion losses also and that affects output.
 
Do you have all 4 battery terminals on the 18Kpv occupied with Battery cable? If not, this could starve the 18Kpv.
 
You should get a MicroAir Easy Start. It makes a huge difference. I'm with Zwy, I think it's the batteries falling over with the surge. A normal 4T A/C can pull as much as 28000 watts during startup, meaning your battery has to produce 500+ amps for a moment... If your battery voltage drops too low it's going to cause resets.

I'm running a pair of 18KPV's with 60KWH of batteries. It always started my 4T, when I only had 30KW of battery (600A) but it seriously caused light flickering, UPS clicking, etc. It actually flicks the lights slightly when on grid if you are paying attention.

With the "Magic Start" the UPS's stopped clicking, and I don't really notice most of the time even in the hottest part of the summer on battery. It will likely let you get away with not buying more battery. In the summer peak my 4T can pull just under 5KW continuous (4.87). In milder cimates you will probably get away with something less.
 
Needs to be micro air 368-72

I tried the one SS sells and it wouldn't start when I was getting higher start amps.

I'm usually around 33 amps now with 4t. They also changed my firmware. I was on 1717 before what I have now. I also have no grid input at all
 
Copied from another thread.

So, we were having the same issue. I noticed the yellow arrows were feeding power to the EPS rather than standard consumption. I'm not sure what the EPS stands for but by reading what I did it was meant to be hooked up to a critical loads aka backup panel. Following the flow charts in the manual gets it set up this way.

What we did to fix it was turn OFF off grid mode. This moved the arrows to consumption mode rather than EPS. I don't know why EG4 labeled it the way it did, but EPS mode does not like very high inrush current. By switching this, we went from an 18kpv that wouldn't even start a 2 ton ac to one that would not only start the two ton, but start a 4 ton on an easy start with the 2 ton running and about 2k worth of normal loads.

I'm not sure how it'll work without grid connection but I would think it would do the same.

In brief, if your 18kpv won't start ac even with micro air soft start, turn OFF off grid mode.
 
While he did not say what brand, he did say he has a soft start.
A normal "soft-start" is an extra capacitor that is connected to the motor to provide more current to the start winding in the motor during the initial start, that is removed once the unit starts to keep from burning up the winding. Staring current is only reduced nominally. MicroAir actually limits current flow.

I did the same thing with a thermistor, actually worked pretty well, but during the summer would not stay off long enough to cool down. I was going to build something with a thermistor and a bypass contactor on a delay, but for $300-odd the MicroAir just seems to work. Their tech support was great as well.
 
A normal "soft-start" is an extra capacitor that is connected to the motor to provide more current to the start winding in the motor during the initial start,

You are referring to a hard-start. The OPe'r can clarify, but I'm pretty sure he has a soft start based on his LRA measurements after installing it.
 
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