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treadlite asked

Onan generator not staying connected with ESS on multiplus

I have a 24/3000 multiplus and a Onan 5500 generator. While running ESS I can see the generator connected and the multiplus starts pulling power. I then increase load and all looks good, but whenever there is a spike in load, the generator disconnects from the multiplus.

I look at my Venus controller and the Active AC In put shows my generator has an input, 120v or so, and 60-62hz, but "Active AC Input" says Disconnected. After some time it will try to reconnect again, but then disconnect.

I have Incoming current limit set to 50 amps, I have turned UPS mode off and weak AC turn on in configuration app, but nothing seems to work. I even read up on some stuff with a ground relay but again, nothing has worked.

If I use the geneterator assistant instead of ESS, I can get the generator to run with passthrough, but even that sometimes has problems with the generator disconnecting.

Anyone else having issues with an Onan 5500. the model number is HGJAB


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1 Answer
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treadlite answered ·

Turns out, the control unit on my generator was failing. I had some other symptoms with the ignition system failing, and after tons of troubleshooting and part replacements, I replaced the control board with an aftermarket one from

Not only did it fix my ignition system, I guess it is also the voltage regulator.

The generator connects to the Multiplus just fine. It still seems it disconnects on heavy loads, but then the Muliplus re-connects shortly after.

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Thanks for reporting back.

You may wish to adjust the AC input current limit down on the Multi to see if that helps with the disconnection under load situation.

Failing that, there are also some other settings adjustments available -

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