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John___Angela's avatar
John___Angela
Explorer
Nov 07, 2017

Do Onan 12K's in Moho's have an easy access 240 cnction

Hi folks. I am helping someone setup their built in EVSE for their electric vehicle charging station on their motorhome. It has (I believe) a 12k onan genny. He would like to setup something like we have with ours but would like to use the full capability of his Juice Box 40 amp EVSE for his EV. (Either a BMWi3 Rex or a Chevy Bolt). We have only a 7.5K Onan in our Revolution so it is only 120 volt so it takes a lot longer to charge the car (like 6 times longer). Both of the cars he is looking at are 7.2 KW (I believe) chargers so the'll pull 32 amps. I will be looking for an easy point to wire in an additional Nema 14-50 on the front of the coach as he will use a front compartment to mount the EVSE something we have in our picture below. They do a little dry camping seasonally and this will give them options if there are no DCFC facilities close to where they are. So any body played with their Onan 12K lately?

Thanks in advance

John

Class A

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  • John___Angela's avatar
    John___Angela
    Explorer
    Nov 08, 2017
    gutfelt wrote:
    does a 12K unit have a 50 amp feed (4 wire) or 30 (3 wire)like a 8K?? if it has a 50 amp feed just like the shore power you could tap in to the system fairly easy
    if its the same as a 30amp 8K you wont get 240V nohow



    Thats the kind of thing I would like to find out BEFORE we start working on this. I have heard various versions of this. I need 240 volts to make it work the way he wants or he'll be stuck with essentially what I have (120) but at higher current. EVSE's will run fine on 120 but most have a 12 amp pilot signal to the car when running on 120. There are some that send a 32 amp pilot to the car on 120 but obviously it is still half the speed of 32 amps at 240. I need somebody to measure across the breakers on a coach with a 12K Onan. Takers??
  • gutfelt's avatar
    gutfelt
    Explorer
    Nov 08, 2017
    does a 12K unit have a 50 amp feed (4 wire) or 30 (3 wire)like a 8K?? if it has a 50 amp feed just like the shore power you could tap in to the system fairly easy
    if its the same as a 30amp 8K you wont get 240V nohow
  • Ivylog's avatar
    Ivylog
    Explorer III
    Nov 08, 2017
    I added one at my 10k junction box on the generator.
  • John___Angela's avatar
    John___Angela
    Explorer
    Nov 07, 2017
    enblethen wrote:
    Look for a junction box between the genset and the rig's wiring to transfer switch. This is commonly at the rig's end of the flexible conduit.
    You could tap at this location. You would need a circuit breaker to protect the receptacle then run to EVSE receptacle.
    This should be a 120/240 four wire circuit.


    I believe it is a Newmar something or other. I won't be able to crawl under it for a another few weeks so I'm trying to get my ducks in a row. We'll be working on it in the desert if this comes about. So would you think the junction box is right at the Onan end (ideal because this is where he wants to put the EVSE). I have a handle on the electrical work but am still trying to work out a weather proof solution which I can't really do till I see what I'm up against.

    What size is the breaker on the Genny.

    I'll probably use a 40 amp breaker pair.
  • enblethen's avatar
    enblethen
    Nomad
    Nov 07, 2017
    Look for a junction box between the genset and the rig's wiring to transfer switch. This is commonly at the rig's end of the flexible conduit.
    You could tap at this location. You would need a circuit breaker to protect the receptacle then run to EVSE receptacle.
    This should be a 120/240 four wire circuit.

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