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In what way could an inverter fail that would cause it to fry motors without going overvoltage?

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Checkthisout

Solar Wizard
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Nov 14, 2021
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1) Microwave transformer burned up. Thought it had just suffered under voltage.

2) Noticed when I was using my shop vac, the motor speed all of a sudden drops and it makes a burning smell, then after about 20 seconds it speeds back up to normal and burning smell goes away. Thus happens repeatedly. Light output on lights running off inverter don't fluctuate and voltage on panel doesn’t change.

This is an Aims 3kw PSW unit.

I have a victron MP ready to swap in to replace the existing inverter but I'm just curious.

Thanks.
 
Ok.

So I changed out my original inverter for a victron multiplus, upgraded battery etc and vacuum works fine now.

Get this though. Vacuum works great off multiplus.

But, the inverter in my inverter generator is starting to go bad. The vacuum loses substantial speed when the generator is on and the MP is on. (Not power assisting, just allowing pass-through and battery charging).

So, while I haven't verified via scope, I think my Aims inverter is a turd that is unable to sustain a consistent sign wave. Voltage is fine.

New microwave sounds very different when it's running off MP without generator on and different than when it was running off the aims.

I was watching a couple videos. It looks like a failing inverter can run resistive load fine but struggles with motors.
 
Checkthisout said:
So, while I haven't verified via scope, I think my Aims inverter is a turd that is unable to sustain a consistent sign wave. Voltage is fine.

New microwave sounds very different when it's running off MP without generator on and different than when it was running off the aims.

I was watching a couple videos. It looks like a failing inverter can run resistive load fine but struggles with motors.
Click to expand...
Well I often think of turd when I think of my aims inverter :)
 
Checkthisout said:
But, the inverter in my inverter generator is starting to go bad. The vacuum loses substantial speed when the generator is on and the MP is on. (Not power assisting, just allowing pass-through and battery charging).
Click to expand...
Depending on how much power is being used for charging you might be pulling too much from the generator if you don't have power assist on?
 
Brucey said:
Depending on how much power is being used for charging you might be pulling too much from the generator if you don't have power assist on?
Click to expand...

Don't wanna tap it all out on a phone but no.

The inverter in the 13 year old Yamaha is going bad.
 
Something else for giggles.

With the Aims and same generator, I got a faint glow from my LED fixtures when off.

With the multiplus inverting, no glow but when generator turns on I get a faint glow.
 
Do you have a good Multimeter?
You say the voltage is fine but when this problem is happening did you switch the meter to DC volts and see if there is a DC component to the output. Secondly most meters can measure the frequency. See if it is Changing under the load.
An oscilloscope would clear this mystery Within minutes but multimeter can pickup on the root cause of the issue.
 
robby said:
Do you have a good Multimeter?
You say the voltage is fine but when this problem is happening did you switch the meter to DC volts and see if there is a DC component to the output. Secondly most meters can measure the frequency. See if it is Changing under the load.
An oscilloscope would clear this mystery Within minutes but multimeter can pickup on the root cause of the issue.
Click to expand...

So, no. Didn't bother (or even think or even know) doing that.

This is at my cabin, 190 miles, 3.5 hours from my house so it was a turn and burn.

Another fun tidbit. I had the neutral ground bonded on my inverter gen for the last 2 years (800 hours of operation) to help with an interference issue. The generator quit producing power so I went out and picked it up and brought it home. Machine would let out a loud chirp noise then overload light would come on right after starting. I removed the neutral ground bond and the issue stopped.

When I reinstalled the generator, the multiplus would not charge at more than 50 amps. I had to disable the "enabled weak a/c setting" and it ramped right up.

That's how, among other things, I know the inverter in the inverter generator is going bad.

I have the Aims home now. When I get time I'll grab a scope and see what it does under higher loads and maybe do the same to inverter gen next time I go to the cabin.

I have a feeling the inverter is going to fully retire soon. Hopefully not.
 
At any rate, my apologies for not being able to provide full satisfaction in regards to cause.

Nothing more than a matter of not having a scope ready and the distance time involved in going out there.

I'll update thread again when I have meaningful data.
 
Checkthisout said:
So, no. Didn't bother (or even think or even know) doing that.

This is at my cabin, 190 miles, 3.5 hours from my house so it was a turn and burn.

Another fun tidbit. I had the neutral ground bonded on my inverter gen for the last 2 years (800 hours of operation) to help with an interference issue. The generator quit producing power so I went out and picked it up and brought it home. Machine would let out a loud chirp noise then overload light would come on right after starting. I removed the neutral ground bond and the issue stopped.

When I reinstalled the generator, the multiplus would not charge at more than 50 amps. I had to disable the "enabled weak a/c setting" and it ramped right up.

That's how, among other things, I know the inverter in the inverter generator is going bad.

I have the Aims home now. When I get time I'll grab a scope and see what it does under higher loads and maybe do the same to inverter gen next time I go to the cabin.

I have a feeling the inverter is going to fully retire soon. Hopefully not.
Click to expand...
When charging at 50A you must be close to or beyond the max output of your Yamaha?
 
What doesn't make sense to me is to why all of a sudden the neutral ground bond in the generator started causing it to trip into overload and quit producing power.

And, why my led lights to produce dim light even though they are off when the generator is running.

Odd failure mode.
 
Sounds like your ground is not grounded properly. The light switch only disconnects the hot lead. The Neutral is still connected at all times.
It could be that you have voltage on the neutral.
I don’t know what kind of light you have but it may have ground connection. Possibly exists that power circuitry in the light could be aiding the led to complete it’s own neutral ground .
LEDs will light up dimly when these problems happen.
 
robby said:
Sounds like your ground is not grounded properly. The light switch only disconnects the hot lead. The Neutral is still connected at all times.
It could be that you have voltage on the neutral.
I don’t know what kind of light you have but it may have ground connection. Possibly exists that power circuitry in the light could be aiding the led to complete it’s own neutral ground .
LEDs will light up dimly when these problems happen.
Click to expand...

Yeah but why doesn't it light up when the Multiplus is providing the juice in invert mode?

I think the MP provides the n/g bond under that condition.
 
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