I understand that I should exercise my generator at least 2 hours per month, and at least at 50% load. If I am hooked to 30-amp shore power and start up the generator to exercise it with AC on, is that sufficient / correct? In other words, is it okay to leave the RV hooked to shore power while exercising the generator? Or should I disconnect while exercising the generator? Thanks for your response! —John, 2018 Leisure Travel Van Unity TB
According to the specifications for your 2018 Leisure Travel Van, the generator options were a 3.2 KW Onan LP or 3.6 KW Onan Diesel.
What an Automatic Transfer Switch does
Since your Mercedes drive train is a diesel, most owners opt for the diesel generator so they can use the diesel fuel in the chassis fuel tank. What I do not see in the specifications is a listing for an Automatic Transfer Switch (ATS), which will sense when your shoreline power is connected to the campground source or running the generator.
If your rig has an ATS, the generator is wired directly to the relay as well as the shoreline cord. If the generator is running, the relay automatically switches to that source of power. So, yes, you can leave the shoreline cord plugged into the campground source while running it.
A “J” box is an outlet wired to the generator
If you do not have an ATS, then you have what is called a “J” box. That is an outlet wired back to the generator, and you need to plug your shoreline cord into the outlet to get power from your generator to the distribution center.
In this situation, you can still leave your shoreline cord plugged into the campground source while exercising the generator. The power will just go to the box and not to the distribution center.
Gasoline-powered generators are prone to varnish conditions if not exercised often. Owners should stay away from ethanol blends of more than 10%. However, diesel and propane generators do not have such issues. Onan recommends running once a month at 50% load for 2 hours. According to the service manual:
Exercising a generator set drives off moisture, relubricates the engine, replaces stale fuel in fuel lines, and removes oxides from electrical contacts and generator slip rings. The result is better starting, longer engine life, and greater reliability.
Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club.
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