Mobile split air conditioner overloads 2 x 5kW inverters

[SenileOldGit]

Hi, I have an AIRFORCE 16,000BTU SPLIT mobile air conditioner, and sometimes my 2 x 5kW Voltacon Conversol v7 inverters overload when (I think) the compressor in the air conditioner is starting up, or maybe turning off. (I can't be sure because I only notice it happening when the air conditioner suddenly turns off and my computer turns off!)
I have ordered a UPS for my computer so that I won't lose any unsaved work, but is there a simple (i.e. cheap) way to prevent the air conditioner from overloading my inverters? It's plugged into a standard 240V mains socket. I presume that changing to two 10kW inverters would probably fix the problem, but I can't afford that amount of money, and it only overloads the inverters when I have maybe 2kW or more of other loads already turned on.

 

[timselectric]

Micro-air easy start.
Put one on it, and your problems will be solved.

 

[Zwy]

Hi, I have an AIRFORCE 16,000BTU SPLIT mobile air conditioner, and sometimes my 2 x 5kW Voltacon Conversol v7 inverters overload when (I think) the compressor in the air conditioner is starting up, or maybe turning off. (I can't be sure because I only notice it happening when the air conditioner suddenly turns off and my computer turns off!)
I have ordered a UPS for my computer so that I won't lose any unsaved work, but is there a simple (i.e. cheap) way to prevent the air conditioner from overloading my inverters? It's plugged into a standard 240V mains socket. I presume that changing to two 10kW inverters would probably fix the problem, but I can't afford that amount of money, and it only overloads the inverters when I have maybe 2kW or more of other loads already turned on.

Have you ever cleaned the condensing coil?

 

[SenileOldGit]

Zwy, how do I clean the coil? I am very open to DIY so technical stuff doesn't bother me, I just don't know much about the insides of the air conditioner.

Timselectric - many thanks, that's exactly what I was looking for! I didn't want to have to buy yet more inverters just to fix a minor problem like this. I've been running the air conditioner all day today, no overloads all day, but I will definitely have a good look at the Easy Start.

 

[Zwy]

Zwy, how do I clean the coil? I am very open to DIY so technical stuff doesn't bother me, I just don't know much about the insides of the air conditioner.

Timselectric - many thanks, that's exactly what I was looking for! I didn't want to have to buy yet more inverters just to fix a minor problem like this. I've been running the air conditioner all day today, no overloads all day, but I will definitely have a good look at the Easy Start.

It would depend on accessibility. This is a unit with a condenser outside and indoor unit connected by hoses thru a window, correct? If so, water and compressed air should get the job done.

What occurs is airflow is reduced resulting in poor heat transfer to the exhaust air. This causes increased starting load as the pressure on the condensing side will be higher as the compressor cycles on/off.

 

[SenileOldGit]

timseletric - I've bought a MicroAir EasyStart - it's arriving on Monday - impressive service from MicroAir, two day delivery from the USA to the U.K. It cost me about £350 (so far - there may be import duties to pay).
Zwy, thanks for the info., I will give the outside unit a clean, the case is easy to take apart thankfully.

 

[Vigo]

Newer inverter-driven compressor types of split ACs dont really have startup surge and i believe they all actually monitor system pressures to avoid silly things like attempting a compressor restart before the high side pressure has equalized, etc. the easy-start should fix this issue on an older compressor that only overloads the inverter during unusually high loads.

But even though i suspect it will fix this particular issue, its generally a good idea to diagnose things a little further before choosing your solution. For example, many inverters will give codes or log files that will help make clear what actually happened during a fault. For example, I assume there are plenty of 10kw+ inverter banks hooked up battery banks which cant do 10k without serious voltage sag, or through wiring which will introduce serious voltage drop trying to flow the 200+a it will take to make 10kw. So you COULD have perfectly fine inverters hitting low voltage shutdown because of wiring or battery issues that don’t appear at lower loads, and the same inverters hooked through larger wiring or to an enlarged or healthier battery bank would not fault out starting the same compressor loads. In cases like those installing an easy start on an ac unit would just be a bandaid over a specific symptom but would not address root causes. It would be tragic to add another inverter to a system like that, because while youd think you were going up to 15k of inverting power, youd really just be adding a very expensive capacitor bank to an inverter system that could only sustain 5kw (or whatever) because it was limited by its battery input side, not by the actual inverting hardware. It would be like swapping a bigger engine into a car that had a clogged fuel filter and couldnt even feed the engine it already had.

 

[SenileOldGit]

Hi Vigo, I have three Pylontech US5000 batteries, and I have charged them at 80A per inverter for hours at a time (I have reduced it to 40A because the sun is out so much that I don't have to grab every bit of charging power when it's available), with no problems, so I don't think there is a problem supplying 8kW or more. My girlfriend uses a 4.5kW shower with a 1.5kW fan heater, while I use a 1.5kW fan heater in my second bathroom, and never have a problem, and that's normally all coming from the batteries at night.
I will see if I can find a log file from the inverters though.

 

[Vigo]

Sounds like you are definitely not experiencing those nasty theoreticals i put out there. I just tend to want to get enough out there that someone else reading later doesnt latch onto a really case specific thing and go ‘thats what i need!’ if they werent even aware of other possibilities. Due diligence blah blah blah. ?