3000 Watt Inverter vs. Makita MAC2400 Compressor

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Phishin

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I tried and I failed. LOL!! In my 2018 Silverado 3500, I have a dual battery set-up with a 3000W inverter in the truck. It comes in handy on the farm.

I specifically bought a Makita MAC2400 air compressor because it's advertised to draw a maximum 12.3 amps at max PSI (130). The owners manual even states that a minimum 15 amp circuit is recommended.

The air compressor pumps up from empty to 130 PSI no problem (cut-out pressure). But when the cut-in pressure is reached (100 PSI), my inverter is overwhelmed and the motor won't turn and my inverter starts beeping.

Watts = Amps x Volts
Watts = 15 Amps x 120 Volts = 1800 Watts

I'm not sure why my inverter isn't covering this demand. Any ideas?

mac2400__1_1000x1000.jpg
 
When a motor starts, it can draw over 5 times its rated current before it gets up to speed. Look at the manual for your inverter and it will probably say something about the largest motor loads it can handle.

Also, the current rating of 12.3 A doesn't match the 2.5 hp motor rating from the photo. A 2.5 hp motor will draw around 30 A at full load at 115 V. If it works on a 15 A circuit, they're probably just inflating the horsepower rating.
 
I have a similar twin lung Emglo compressor. It doesn't lie about it's HP rating and its 1.1HP 15A. The surge watts on it are anywhere from 3000 to 4000W depending on temperature. On one particular day I had to start it and run it on AC power until it got hot, then take it a few hundred feet away to the worksite to run on a Coleman 5000 something-or-other generator.

To answer your question simply, you are not accounting for the startup surge watts of a compressor. I can sympathize with your situation. I think its BS these things don't rate surge watts.
 
It's a special designed pump that claims to drastically reduce startup amp surges..... It's why I bought this specific compressor
 
I have a similar compressor. The magic starting thing is simply a compression release valve in the side of the head that lets pressure out for the first few strokes of the piston. Even with that, it is hard to start(*). The motor is probably PSC which is efficient when running but does not have a lot of starting torque.

(*) Keep indoors in cold weather or the oil will be too thick to start. Don't even think of using an extension cord.
 
3000watt inverter on the 12vdc side at full starting load pulls. Really have to check with the manufacturer for their specs there different efficiency of inverters 80-90%. When starting a air compressor from 0 psi verses 80-100 lbs can be 4-5 times starting loaded.
Full load 12 vdc 250 amps
120vac 24.25 amps
 
Phishin said:
It's a special designed pump that claims to drastically reduce startup amp surges..... It's why I bought this specific compressor
Click to expand...
Likely marketing jargon for an unloader valve which is industry standard. The reason these motors have high surge watts on start is not due to compression. It's due to the design of induction motors.

Motors have high current draw upon startup because if the rotor isn’t moving, then the only resistance in the circuit is the motor windings. The windings by themselves are low resistance electric heaters, if power is applied to them and the shaft isn’t moving then it’s going to draw high current. When the shaft is moving, there is more resistance in the form of magnetism, this is called inductive reactance.


Motors are inductive loads and have both physical resistance and magnetic resistance. Here’s more info-


https://hvacrschool.com/what-is-inductive-reactance/
Click to expand...
 
Ive had that same exact compressor for probably 15 years. I actually burned up the inverter board on a Robin Subaru generator running it (I needed site power and that was the generator I had).

It’s a lower speed 1750rpm motor. I don’t recall thst it has any special attributes relative to inrush, dynamic performance, or power quality…
 
Phishin said:
I tried and I failed. LOL!! In my 2018 Silverado 3500, I have a dual battery set-up with a 3000W inverter in the truck. It comes in handy on the farm.

I specifically bought a Makita MAC2400 air compressor because it's advertised to draw a maximum 12.3 amps at max PSI (130). The owners manual even states that a minimum 15 amp circuit is recommended.

The air compressor pumps up from empty to 130 PSI no problem (cut-out pressure). But when the cut-in pressure is reached (100 PSI), my inverter is overwhelmed and the motor won't turn and my inverter starts beeping.

Watts = Amps x Volts
Watts = 15 Amps x 120 Volts = 1800 Watts

I'm not sure why my inverter isn't covering this demand. Any ideas?

View attachment 204757
Click to expand...
Start up amps. Also, if the compressor is full at startup, then there will be more draw to get the compressor going at 90 psi than @ 0. I have a Senco single tank I use for testing pipes, and it works off of a 2000w schumacher, if started at 0 psi.
 
A couple of odd thoughts. One of which is “monetarily dangerous, bitog style.”

In the inverter/battery chain, it could be the inverter tapping out during the surge load. Or the inverter might be pulling enough amps that the batteries sag below its low voltage limit. I mean, 3000 watts is going to be something like 360 amps or more at 12V, which probably dips well into the sub-10V range. So - more batteries, thicker leads….

Or … you might try buying a soft-start module, such as for an RV AC compressor. Supposed to hookup easy, inline.
 
Marcozi said:
Hmmm, I thought inverters were not designed for motors.
Click to expand...
If the inverter is large enough, it can work, but inverters produce harmonics that cause additional heating in the motor compared to a clean sine wave, so it can reduce the life of the motor.
 
Marcozi said:
Hmmm, I thought inverters were not designed for motors.
Click to expand...
I guess not. That said, motors are driven by vfds all the time…
twX said:
If the inverter is large enough, it can work, but inverters produce harmonics that cause additional heating in the motor compared to a clean sine wave, so it can reduce the life of the motor.
Click to expand...
yeah. Ut this was the opposite. The motor caused some caps on the board inside the generator to burn up…
 
Hey if it’s a square wave, a soft start probably won’t work. It probably needs a sine wave to work
 
meep said:
Hey if it’s a square wave, a soft start probably won’t work. It probably needs a sine wave to work
Click to expand...
It's a pure sine wave supposedly..... should I go ahead and buy the soft start? It looks like they are about $300?

Screenshot_20240225-210351.jpg
 
So…. Man $300 is a fair amount of cake, it might work, it might not. If it does, you have pioneered something pretty cool. If it doesn’t work, you’re out $300 unless you can return it. $300 also approaches a small generator which could also run the compressor. I’ll throw out 50/50 odds that it works. What’s this solution vs another worth to you?
 
3000W @ 12V with a 6000W surge capability?

Off a car battery?................

Yeah right
 
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