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Ask Hank F. Your Own Question
Hank F.
Hank F., RV tech - emphasis on gensets
Category: RV
Satisfied Customers: 15006
Experience:  RV tech since the beginning of the millenium.
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We have a Generac 7500 diesel in our 2004 Alfa RV. When you

Customer Question

We have a Generac 7500 diesel in our 2004 Alfa RV. When you start the generator, and the power kicks on, it's stays on for only a few seconds and kicks out. It will keep coming on and kicking back off. I also plugged the shore cord into a generator and it kicks the breaker out of the generator. If we plug into shore power, it works like it's supposed to. We have tested with no load, main breakers shut off, and it still does this.
Submitted: 1 year ago.
Category: RV
Expert:  Hank F. replied 1 year ago.

Hello, thanks for requesting me.

Let start with the model and serial number of the genset, so I know which one you have.

When you say you have plugge the shore cord into a generator, are you referring to a different genset than the Generac?

When you are losing power, exactly what method are you using to deterine this, and where are yo9u checking at?

Remember, I can not see or hear what is going on, so I only know as much - or as little - as you tell me.

Customer: replied 1 year ago.
We plugged the shore plug into a Troy Built portable generator when the Generac quit powering. The rv powered off the Troy built generator for a few hours and then started tripping the breaker on it. Now the only way we can get power to it is by plugging in shore power to a plug at our house. It will stay on and everything works just fine.It is now reading that the AC voltage input is low. Would low batteries be causing the generator to not kick over power?Just clearing up, the 120v power will not work on generator. It only works when plugged into a shore power at homeSerial number 3485-330
Make: generac 7500 diesel
Customer: replied 1 year ago.
We are checking this at the power station on the rv where it shows the voltage levels. We also checked it at the transfer switch with a meter. Sorry I did not answer that question in my prior response
Expert:  Hank F. replied 1 year ago.

Low batteries will not cause low voltage output from the genset.

If you have good voltage coming in to the transfer switch on genset power, but nothing coming in to the coach, there is an issue with the transfer switch.

You need to monitor the input and output at the transfer switch while the unit is acting up.

If it is tripping breakers on both gensets, you need to have a running amp test done on the coach. You may have a bad appliance in the coach.

Customer: replied 1 year ago.
The only issue with it being a bad appliance is that it does this without any load. We can turn off all breaker and it still does this. Does that make you lean heavily on the transfer switch, even if it still works on shore power?
Expert:  Hank F. replied 1 year ago.

Yes. When on shore power, the TS is deactivated. But when on genset, it is activated. A problem in the TS usually shows up on genset power - not shore power

Customer: replied 1 year ago.
really the only way to know for sure is to replace the switch? We were leaning this way but the shore power working and the fact that it tripped a portable generator had us confused!
Expert:  Hank F. replied 1 year ago.

No, test the switch.

Monitor both the input and outputs while the unit is acting up.

Customer: replied 1 year ago.
Will do. I will let you know the results. It will be tomorrow though. Thanks
Customer: replied 1 year ago.
We tested the voltage.... It was receiving 63 volts until the generator kicked in then it went to the correct 240v across.... About 10 seconds later it kicks out and back down to 63 volts.... It keeps repeating the process... And we measured voltage on the legs of where the generator power enters the transfer switch. I will attach info on the transfer switch
Expert:  Hank F. replied 1 year ago.

I am not sure what you mean when you say "until the generator kicked in ". As long as the genset is running, it should be producing 120V.

if it is only producing 63V, this is the problem.

You still have not provided me with the model number of the genset, and the serial number you provided is not a valid serial number.