Onan Generator Issues - RV-Dreams Community Forum

dmorse68 · RV-Dreams Community Member

Onan Generator Issues

Lynn and Ed · RV-Dreams Family Member

A couple things to check regarding the generator breaker tripping:

If you have a Magnum Inverter/Battery Charge (or another brand), look at the “shore power” setting – if that setting is set too high, it might cause too high of an initial power draw on the generator. If you don’t have the option to change the “shore power” setting and/or you would like to make certain the battery charger is not the problem-- you should be able to turn “off” the charging functionality before starting the generator and then turn it back “on” a few minutes after the generator is fully operating. Although, having the battery charger “on” has not caused us any complications (i.e., we have the same generator and a Magnum Inverter/Battery Charger), but I would suggest looking at the “shore power” setting and consider what power leg items such as your refrigerator and charger are wired--if your refrigerator and your battery charger are on the same power leg, you could easily be pulling 20 amps or more on that leg. For what it is worth, our particular charger pulls a maximum of 17-18 amps when bulk charging the batteries.

Another thing to check for is an unknown power draw; the simplest time to do this is when you are “plugged in” at a campground. One way to check for an unknown power draw is to perform an abbreviated energy audit – turning off all breakers, and then turn them individually “on” (and then back "off" again, once you look at the power draw) -- if everything is turned “off” inside the RV, you should not see a noticeable energy draw when the different breakers are turned "on", with the obvious exception of the refrigerator. What you are looking for is item(s) you did not realize were drawing power and particularly if something was wired incorrectly in your RV (i.e., a “switch” might be turned “off” but the item is still drawing a large amount of power—in other words the “switch” is not actually turning "off" the item). This should be a fairly straight forward way to identify an unknown power draw(s)--except for things such as a hot water heater, since the water in the heater has to be cool for this audit to catch if the heater/switch was not correctly wired. Other than taking a little time, this approach is a fairly easy activity if you have a hardwired Progressive Industry EMS system with a display that shows your power draw.

Hope that helps!

Lynn

P.S. No specific thoughts on the GFI breaker, but possible causes are a circuit overload, a short circuit and/or a ground fault.

-- Edited by Lynn and Ed on Monday 16th of October 2017 03:48:49 AM

Bill and Linda · RV-Dreams Family Member

dmorse68 wrote:
Hello All,
First of all thanks for reading this. My purpose for this post is to ask the community who have or used generators in their RVs in hopes I can narrow down and identify the issue I am having with mine system.
The Problem: I have a brand new Onan 5500 Genset and 50 Amp Mobile Suites 36rrsb3. When I fire up the genset so I can charge my four, 6v AGMs, The electrical part of the generator sometimes trips. But the generator continues to run. When this happens, 50% of the time the 20 amp breaker on the generator itself trips. The other 50% of the time, I get a "Bedroom/GFI Outlet" breaker trip off inside our Mobile Suites in the breaker box. It is important to note that the only things on in the RV at the time I fire off the Genset are the residential fridge and maybe a few LED lights. It's not like I am overloading the circuit.
Any insightful info on what might be my issue would be greatly appreciated.
David

-- Edited by dmorse68 on Sunday 15th of October 2017 10:10:22 PM

First thought - if that is a 5500 generator the breaker(s) - there are two - physically on the generator itself are 30, not 20 amp breakers. Assume that 20 amp comment is just a typo.

Actually, as Lynn commented, IF the "Shore Power" amp point is set above 20 amps, including the fridge -"depending" - you could well exceed the 30 amp generator internal breaker. They can trip at anything much above 25 amps. (Ask me how I know this.)

Unless one has a really big battery bank (600AH is not that big) and is connected to a 50 amp shore power service, there is no reason to have the shore power set above 20 amps. The odds are good the fridge and Magnum are on the same leg. With a depleted batter bank and the fridge coming on at the same time it would be pretty easy to trip the 30 amp generator breaker when the Magnum starts charging in the Bulk mode.

If setting the shore power to 20 doesn't solve the issue try 15. If the GRI keeps tripping at 15 then change that breaker. If that doesn't work I "suspect" - and that's all I'm doing - suspect, there is a ground wiring error in the rig to the generator which the GFI would detect and trip off. The grounding point is different when using a built in generator then when on shore power.

This may or may not be the problem, but for those reading along, OEMs, like DRV and others, sometimes just install the Magnum and other chargers at the factory (Magnum factory) default settings. 30 amps Shore power is the default.

(Related - again for information - those using small 2000 watt Honda type generators to charge batteries with the Magnums will want to set the shore power at 10 amps when using the generator and do not put the generator in the Econo mode. ("Ask some how they know this.") The little generators in the Econo mode just don't have enough capability to rev up from that idle speed when the AC amp draw hits it.)

Bill

Lynn and Ed · RV-Dreams Family Member

To Bill’s point about the breaker size on the Onan 5500 Genset, you may have two 30 amp breakers (we do) or possibly one 20 amp and one 30 amp breaker [at least a friend told us that was their set-up on their Onan 5500]. Regardless, you typically want the “shore power” set lower than the amp rating on your smallest generator breaker--particularly if you don't know which leg different power sources are pulling from.

For what it is worth, I adjust our “shore power” setting depending upon where we will be located (i.e., boondocking for a couple weeks, when we might run the generator; 30 amp campground; 50 amp campground). Although our battery bank is larger than yours (i.e., 1200 Amph), I find it helpful after a couple weeks of boondocking (i.e., think beautiful remote locations out west) to increase the “shore power” setting, when staying at a 50 amp campground, if I want to quickly charge the batteries back to 100%. If someone is regularly connected to 30/50 amp service or always boondocks, as Bill stated, you can probably set the “shore power” at 15 or 20 amps and just leave it at that setting.

Lynn

On edit: One of the reason that I feel comfortable "playing around" with our "shore power" settings is I know the power consumption of the different items in our RV and what power leg they are on (i.e. I sometimes have the "shore power" set at 40/50 amp when running the generator -- because I know that we will use less than 20/25 amps on either power leg and I don't want to minimize the charging of the batteries). If you have an interest in performing a full energy audit, Technomadia.com provided a nice outline on how to perform an audit related to solar planning, but it is helpful otherwise: http://www.technomadia.com/2014/12/solar-planning-conducting-an-rv-electrical-consumption-audit/

-- Edited by Lynn and Ed on Wednesday 18th of October 2017 10:38:50 AM

dmorse68 · RV-Dreams Community Member

Bill and Linda wrote:
First thought - if that is a 5500 generator the breaker(s) - there are two - physically on the generator itself are 30, not 20 amp breakers. Assume that 20 amp comment is just a typo.

Hi Bill,
Thank you for your help. 20 amp wasn't a typo. I double checked and I have one 30 amp and one 20 amp breaker on the actual Onan 5500w generator. You say there is suppose to have two 30 amps there? I wonder if the dealer I bought the rig from changed one 30 amp out for a 20 amp. One breaker is white (20 amp), and one is black (30 amp). Are yours both black by chance?

David

-- Edited by dmorse68 on Saturday 21st of October 2017 11:20:27 PM

dmorse68 · RV-Dreams Community Member

Hi Lynn,

Please forgive me for my nube questions. 2 questions for you:

1) How do I change the "shore power" option? Is that on the panel inside the RV? I will be getting shore power run to the rig in 2 weeks. It will be a 50 amp service.

2) 2nd question is: What is the danger or mal-effects if I set the shore power option to 50 amps instead of a lower amp setting?

Thank you in advance

David

-- Edited by dmorse68 on Saturday 21st of October 2017 11:36:44 PM

dmorse68 · RV-Dreams Community Member

Update:

Replaced the 20 amp GFI breaker inside my DRV. The GFI breaker no longer trips so I think I had a faulty GFI breaker. HOWEVER, I still have the issue of the generator electrical charging system tripping off 30 seconds after the "initial single phase delay" ends and the gen begins to provide juice to charge the batteries. Any thoughts?

Also found out today that I have a shower pan leak in my brand new rig as well as a faulty heater vent in the bedroom. I guess I am getting a crash course in fulltime RV owning now lol!

Thanks for all the help guys. Let me know what you think might be my gen/charge control issue?

David

bjoyce · RV-Dreams Family Member

The "shore power" setting is on the inverter/charger and only applies to what the inverter/charger sees, not the whole RV. If the inverter/charger is only wired for 30 AMPs, setting it to 50 AMPs has the potential to try to run more than 30 AMPs through the wiring. A breaker inside the RV should trip if that happens.

Lynn and Ed · RV-Dreams Family Member

dmorse68 wrote:
1) How do I change the "shore power" option? Is that on the panel inside the RV? I will be getting shore power run to the rig in 2 weeks. It will be a 50 amp service.

Best place to start is your inverter/charger manual. However, if you have a Magnum Inverter/Charger similar to ours -- look at the front of the control panel, you should see a small button toward the bottom labeled "Shore", press that button and then turn the "Select" knob to choose a shore power setting of "15 amps" -- which is what you should select given your 20 amp breaker on the generator.

As Bill Napier has shared in other threads, your breakers can trip when the power draw reaches about 80% of their amp rating.

2) 2nd question is: What is the danger or mal-effects if I set the shore power option to 50 amps instead of a lower amp setting?
What can happen is the generator breaker will trip--what you are currently experiencing. In other words, by reducing the "shore power" setting to 15 amps the battery charger will only pull a maximum of 15 amps (or less, if other items are running) to charge the batteries--helping you not trip the breaker on the generator.
Once your generator breaker is not tripping and you determine the power draw of the different items in your RV and what power leg they pull from--that is the best time to start playing around with the "shore power" setting. Alternatively, if you don't have an easy way to read your power draw -- you could gradually increase the "shore power" setting (when solely having "on" the refrigerator, a few lights and the battery charger) until the generator breaker trips and you will have identified the problematic "shore power" setting for running the generator.
The other issue with setting the "shore power" to 50 amps (and leaving it there) is when you are connected to a 30 amp outlet (where I typically set our "shore power" to 20 amps, but 25 amps or lower should work). With the setting at 50 amps, you will potentially trip the breaker on the outlet/campground pedestal--particularly if your batteries start bulk charging (i.e., the battery charger is potentially pulling 17-18 amps on top of anything else you are powering.) In other words, at the 50 amp setting, the inverter/charger is only looking to help manage how much power is pulled to charge the batteries when the total power pulled starts reaching 50 amps (and even then, solely the power draw that is visible to the inverter) ... not overly helpful when the total available power is managed by a single 30 amp breaker).
Hope adjusting the "shore power" setting addresses the issue!

on edit: updated with further information

-- Edited by Lynn and Ed on Tuesday 24th of October 2017 11:32:24 AM

Bill and Linda · RV-Dreams Family Member

dmorse68 wrote:
Bill and Linda wrote:
First thought - if that is a 5500 generator the breaker(s) - there are two - physically on the generator itself are 30, not 20 amp breakers. Assume that 20 amp comment is just a typo.

Hi Bill,
Thank you for your help. 20 amp wasn't a typo. I double checked and I have one 30 amp and one 20 amp breaker on the actual Onan 5500w generator. You say there is suppose to have two 30 amps there? I wonder if the dealer I bought the rig from changed one 30 amp out for a 20 amp. One breaker is white (20 amp), and one is black (30 amp). Are yours both black by chance?

David

David: Yes, mine are both black and no, 20 amps can't be correct. That is, it must be a 30 amp breaker or it is impossible for the generator to deliver 5,500 watts in the real world. It's just math.

On Edit: Well, it seems the "factory," not sure which one, has decided to use a 20 amp breaker on one side. Makes absolutely no sense to me based on a balanced load between the two legs. This sure seems, at best, strange for a lot of electrical engineer talk I won't go into. But I still bet it is very difficult to actually use those 5,500 watts in that configuration without a breaker popping.

Anyway, both those breakers should be 30 amps, IMO, unless the RV's wiring requires that 20 amp limitation - which also makes no sense to me. But hey, I've only been at this professionally for like 45 years. Maybe something changed since I retired. :) Always willing to learn.

Bill

-- Edited by Bill and Linda on Monday 23rd of October 2017 05:52:47 PM

heyjohnm · RV-Dreams Family Member

My Onan has one 30 amp and one 20 amp breakers just like David's. If my generator's voltage was 110 volts at 50 amps I would be producing 5500 watts. My generator's voltage is regulated to 117v so it only takes 47 amps to produce 5500 watts. On my set up, if the batteries are low (bulk charging) and I'm trying to run 2 a/c units, I can easily pop the 20 amp breaker.

Bill and Linda · RV-Dreams Family Member

heyjohnm wrote:
My Onan has one 30 amp and one 20 amp breakers just like David's. If my generator's voltage was 110 volts at 50 amps I would be producing 5500 watts. My generator's voltage is regulated to 117v so it only takes 47 amps to produce 5500 watts. On my set up, if the batteries are low (bulk charging) and I'm trying to run 2 a/c units, I can easily pop the 20 amp breaker.

John, where is that 117 volt regulator? In the generator or external? I agree with that math but as you mentioned, the 20 amp breaker trips and that is the issue. For a balanced load on the two legs of the generator one needs 1/2 the wattage from each side. So with a 20 amp breaker, which won't always hold 20 amps, don't know how the true watts of the generator are actually available, like for running two AC's and charging the batteries like we can.

My real question is: Why not two 30 amp breakers like we've seen in the 5500 watt Onans for a long time? Is this a RV OEM request to Onan / change or did the RV OEM factory change that breaker? Just weird, IMO. Always ready to learn.

Bill

heyjohnm · RV-Dreams Family Member

Bill,

The voltage is regulated at/by the generator. Spec sheet says it's a 120v single phase generator rated at 120v, 45.8a, 5500 w.

My generator nominally measures 117v at the EMS under load. The spec sheet also shows one 30a and one 20 amp breakers as previously noted by David. Other forums (IRV2 and Heartland Owners) have threads regarding the 20 amp breaker. As this is a single phase generator the breakers, in my guesstimation, are more for splitting the load over providing balancing and the generator breakers facilitate the l1 and l2 split at the transfer switch as set up by the coach manufacturer. So to answer your question, I have no idea how two 30 amp breakers are installed in some (but not all) Onan 5500 w generators. That would be a question that possibly could only be answered by Onan.

Here's the link I used to get Onan specs for the generator:

http://www.rvtechlibrary.com/generator/Onan5500specsheet.pdf

Bill and Linda · RV-Dreams Family Member

heyjohnm wrote:

Bill,
The voltage is regulated at/by the generator. Spec sheet says it's a 120v single phase generator rated at 120v, 45.8a, 5500 w.
My generator nominally measures 117v at the EMS under load. The spec sheet also shows one 30a and one 20 amp breakers as previously noted by David. Other forums (IRV2 and Heartland Owners) have threads regarding the 20 amp breaker. As this is a single phase generator the breakers, in my guesstimation, are more for splitting the load over providing balancing and the generator breakers facilitate the l1 and l2 split at the transfer switch as set up by the coach manufacturer. So to answer your question, I have no idea how two 30 amp breakers are installed in some (but not all) Onan 5500 w generators. That would be a question that possibly could only be answered by Onan.

Here's the link I used to get Onan specs for the generator:
http://www.rvtechlibrary.com/generator/Onan5500specsheet.pdf

Ah, you have the more expensive one.

https://powersuite.cummins.com/PS5/PS5Content/SiteContent/en/Binary_Asset/pdf/Consumer/specsheets/a-1425.pdf

Above lists an alternate 5500 watt unit with 2- 30 amp or now a 30 and a 20 amp breaker. I stand corrected. Onan offers it both ways. But still glad we have two 30 amp breakers on our HGJAB 5500 watt LP unit. More "user friendly," at least in our coach.

I do agree with your assessment that is is possible, with regulated power, to get 5500 out of a 30 and a 20, but its seems, from the reports, it is more difficult depending on how the trailer is wired load wise at the panel, especially without keeping an eye on an amp meter on L-1 and L-2 - which I do.

I notice on the spec sheet you referenced the "Gold" generator is only rated for one 13,500 BTU air conditioner or two, 11,000 BTU air conditioners at 500 feet elevation at 100 degrees F. With the second 20 amp breaker that doesn't surprise me - especially if considering the 80% breaker load "rule." Just noting what the spec sheet says. I have no personal experience with the "Gold" genset. My professional, and personal experience is not with the "Gold" version.

I'd like to better understand the why(?) of this configuration would be selected by the RV OEM in the more practical RV world as you have described how easy it is to trip the 20 amp breaker, which I would expect. 20 amps will "barely" run one AC - especially under adverse conditions as noted in their specs and that, by spec is not a 15,000 BTU. We run two 15,000 BTU units all the time plus other items up to about 23 amps per leg - per the amp meter. I don't think you really have an answer to that question as the same generator, in our case the HGJAB, can be ordered by the RV OEM either way. Just don't understand the why of a 30 and a 20 on a large coach that most likely would have two, 15,000 BTU AC's.

Learn something everyday, thanks.

Bill