generartor switching question

[cj99]

like the title says, I have a question on the switching of my gen-set
I have a 2012 road warrior by heartland ( toyhauler ) with a Onan 5kw gen set. the question is I know when you are plug into shore power there is a auto switch so that if you start you gen set it either runs on generator or shore power but wont let them connect to each other and damage gen set. So which is the default side ? meaning if the power goes out and we start the gen set and the power comes back on while we are asleep ( as we have done with no issues ) what power are you on ? the shore power or gen set ?

[pianotuna]

For small loads such as the entertainment system I'd set up a dedicated inverter and simply use that 100% of the time.

If you want to do large loads then a hybrid inverter/charger from Victron or Magnum will do a great job. Both of them have load support which will ease the burden of surge when heavy items cut in while running the generator.

My Magnum lets me run my Yamaha 3000 Sieb in eco mode and starts the roof air without serious voltage drop.

Another nice thing about the Magnum is the built in transfer switch is rated at 60 amps. I'm in a 30 amp RV so I expect long life from that switch. I'm still careful to disconnect loads when I have shore power before I plug in.

I just completed one night at 4 C (40 f) without running the generator at all. I simply used an inverter to power my laptop and a heating pad to keep my cosy and warm. The bedroom got to 14 c (58 f).

[MEXICOWANDERER]

c99,

The only company that I have experience with that had an inverter that would successfully survive conflict was TRACE. They warned against it, but old dummy me managed a dozen or more connections. The inverter shrugged it off.

You know you do not HAVE to utilize your rigs transfer switch or risk the transfer switch inside the inverter. Make your own diverter using a relay and a touch button wall timer. I just purchased a 2-5-10-30 min 1-2-4 hour switch that fits a duplex box. Has nifty LED pilot lights beside each button. 1,825 watt capacity.

[wa8yxm]

The answer depends on what you call default so i will just skip that word and use Priority instead

The Generator has priority

That means if the generator is running, THAT is the power source.. If the generator is NOT running, then Shore power is selected on a two source switch,

On a 3 source switch, Generator has priority, then shore power, and the last to be chosen (if no other source present) is Inverter.

NOTE: Shut down A/Cs for 3 minutes when transferring, shut down all big loads, and if possible all loads, before transferring.

(The 3 minutes, shut down, transfer and when 3 minutes is gone by re-start). Other loads Shut down transfer restore. (no need to wait)

[DrewE]

I would not suggest hooking up the inverter to the main power input for the RV, simply because there are too many things to remember to turn off when you're using the inverter that you want to have on when you're using shore power. This includes the converter, the fridge AC element, the water heater AC element, and most any other electric heater.

It's not that it can't be done or doesn't work, it's just a good bit of hassle and a rather rapidly discharged battery bank if you forget something.

A better approach is to have only selected circuits switched to the inverter, or dedicated to inverter power. If you don't have a large power draw on the inverter circuits, leaving them dedicated isn't a big problem when you're on shore or generator power because the converter will supply sufficient power to the inverter to prevent the batteries from being discharged. This has the nice side effect of not causing the TV or DVD player reset itself when you switch power sources.

[cj99]

I was already thinking about killing the breaker to the 12 volt converter during dry camping as the solar should take care of them ( 2 x 185 watt panels ) and don't plan on running the gen set long enough for charging and to eliminate a loop ( running inverter and inverter trying to run converter to charge battery's ,etc endless loop ) but it would be nice to not have to run a cord to shore power from inverter and just hard wire the inverter in. maybe I can find a inverter that can auto shut down if it see another AC line coming in. the problem is a lot of those type inverters have what's called as a pass through. but I did not want to start a rewiring job with the gen set or shore power , etc And auto switchs are not cheap for on that can handle full shore power loads

[westend]

I just looked at an Onan 5.0 with a transfer switch. It was set to default to shore power. Yours may be similar. You have the correct experimental solution in mind with the AC.

The most elegant situation would be having the ability to turn your inverter off when using the genset. Some do have a remote switch. There is no reason to drag on the batteries or have that undesirable power loop happening between converter and inverter. Maybe you can't be bothered if it is just brewing a pot of coffee but I would definitely look into a switch to control the inverter.

An alternative would be to have another transfer switch between your inverter and the other power supplies. That would be wired into the main load supply, eliminating the path of plugging shore power cord into the inverter. Lots of ways to make fur out of felines.

[Bobbo]

DrewE wrote:
If it's just a transfer switch (and not some more sophisticated electrical management system), the most common setup is for the generator to have priority over the shore power when both are energized. I suspect that, like many details of RV design, this is not universally true.

This ^^^^^^^^^^^^^^ is the norm, but is not universal.

[cj99]

I guess to test to see which is the default side, I can hook up shore power and the gen set and fire up the AC unit to see if the generator loads up or not, if not then it is on shore power and if I hear the gen set load up I know its defaulted to gen set power ?

[cj99]

The reason I ask is , I do stay in my RV for long periods when working out of town, and on the off season I take the family camping for long weekends , sometimes for 2 to 3 weeks in the mountains ,etc.
And I have a Solar set up for off grid / dry camping . I am going to go ahead and install a inverter for regular loads like TV , etc but for the short periods when we want to run the coffee pot , etc I will just fire up the gen set. So what I was thinking about doing is connection the inverter output to the shore power line ( probably using a plug into the side of the RV so it can not be connected when I really do have shore power ) and If the gen set is the default then all I have to do is fire it up for 5 mins or so then when done kill it and power should jump back over to shore power which will be the inverter. unless someone has a better Idea.at first I was going to connect the inverter to a plug in the side box but don't want to have to worry about killing a breaker or unplugging it every time we fire up the gen set and I am sure the wife wont think about it either and do not want to burn up the inverter with the gen set..

[MrWizard]

30amp or 50amp
they function slightly differently, although the end result is the same

30amp will have a set of normally closed contacts and a set of normally open
usually shore power is the default "closed set of contacts"
and the genset power has a slight time delay 20~60 seconds and switches over
opens the shore side closing the generator side
and will stay that way until you turn off the generator, no matter if shore power returns

50amp will have usually have (2) contractors with open contacts
neither will be energized unless there is power, and that locks out the other side, again generator takes precedence over shore power

[randy328]

On my current KZ and my last one the generator has precedence. If I am on shore and start the genny it takes over. I can then unplug shore. If I replug the shore in, nothing happens until I disconnect the genny.

[DrewE]

If it's just a transfer switch (and not some more sophisticated electrical management system), the most common setup is for the generator to have priority over the shore power when both are energized. I suspect that, like many details of RV design, this is not universally true.

[darsben]

On m old class A the autotransfer switch would be pulled to the shore power side.
The genny would then shut down