Onan for exterior work?

Crank · 10-10-2014, 04:34 PM

It just occurred to me that I am driving my '95 Roadtrek around carrying a useful portable generator. (I am planning on upgrading the charging system to a modern charger/inverter, which might have a bearing on the answer I seek.

Can anyone advise me if the 2800W Onan generator mounted on a '95 Roadtrek can be disconnected and safely employed to operate power tools within its rated capacity? (I understand the rating of power tools and the additional start-up draw). It does not activate the van's 110v receptacles like shore power, does it (that would require converting the 110v output to 12v and then back again)? How would one disconnect the Onan and connect to its 110v output: make a special harness and wire a 110v receptacle into it? Would the Onan need any special overload protection?

(This question arises from considering sale of my 1850W Coleman along with my old RV.) I need to make that decision by noon Saturday (tomorow). If the Roadtrek generator can put out more power, I don't need the Coleman!

(It seems odd that the Onan starter is powered by the very battery it is supposed to charge. If the house battery is too low to start the generator, is this problem usually remedied by running the vehicle engine?)

Thanks!

peteco · 10-10-2014, 05:23 PM

I have used my Roadtrek Onan to run power tools from the external receptacle. Works great.

Pete
2006 RT210P

skiMore · 10-10-2014, 06:05 PM

Does it use the main vehicle gas tank? If yes, where would it get gas from if you removed it from the van?

stanw909 · 10-10-2014, 06:50 PM

If you removed your $3000 Onan from your van to use elsewhere you would need a gas . Tank and a battery to start it. Why not go to Harbor freight and buy an inexpensive self contained generator?

markopolo · 10-10-2014, 11:01 PM

A 2800 watt Onan will power any tools that normally plug into a standard 120v 15a outlet. An Onan 2800 is 23A at 120V. It is more powerful than the Coleman at 120V.

It should provide power to your van outlets. If it doesn't then something is not right. Maybe the automatic transfer switch isn't working.

Yes, you can start the van to boost the coach battery so you can start the generator.

Your Onan produces 120V AC current.

stanw909 · 10-11-2014, 12:58 AM

I had to reread the OP again.I though he wanted to take the generator out to use on job sites. Sorry. The Onan, like any generator IS shore power(110).Nothing has to be converted.If your house outlets don't work check your breakers .If they are ok then check the breaker on the generator itself right on the control panel below the start button on the generator not the start button inside the rig. If the house battery gets too low then starting the vehicle will send power from the alternator to power up the generator. Generator will charge house battery from the built in power (110 to 12volt) converter/charger. With the right length of power cord (thicker the better), I see no reason why a 2800 watt generator will not equal or surpass your 1800 watt gen.

Crank · 10-11-2014, 03:19 AM

Thank you for the prompt and helpful replies. That's great news, the Onan will be better than the Coleman with its extra power. I didn't realize it powers the 110 receptacles directly.

Something is not right because the house battery does not charge up when driving. I have not had time to explore the problem. The 110 receptacles are live when plugged into shore power, but I have not checked them when the generator is working instead - thanks for the diagnostic tips and other helpful info which confirms I should sell the Coleman.

peteco · 10-11-2014, 02:06 PM

I have jump started the vehicle using jumper cables from the house batteries to the vehicle battery. I suppose you could jump start the Onan using cables from the vehicle battery to the house batteries.

Lou · 10-18-2014, 04:46 AM

Our generator (onan) needed a workout and our hedge needed trimming so my husband spent the afternoon with a large electric hedge trimmer plugged into the van. The hedge is higher than the first story of our house and half the length of the lot ( a big job). He pruned both sides and the top. It is my understanding that although the generator takes gas from the gas tank it won't take anymore once the gas tank dips down to 1/4 full.

peteco · 10-18-2014, 12:46 PM

I use the Roadtrek generator for yard work also. Trimming bushes and trees that are far away from the house. I try to time the work so it fits the generator exercise schedule. My favorite tool is an electric pole chainsaw.

Pete
2006 Roadtrek 210P

Crank · 10-18-2014, 03:54 PM

Good ideas: make that exercise time pay for itself!

Mike · 10-19-2014, 01:26 PM

Quote:

Originally Posted by Crank

Thank you for the prompt and helpful replies. That's great news, the Onan will be better than the Coleman with its extra power. I didn't realize it powers the 110 receptacles directly.

Something is not right because the house battery does not charge up when driving. I have not had time to explore the problem. The 110 receptacles are live when plugged into shore power, but I have not checked them when the generator is working instead - thanks for the diagnostic tips and other helpful info which confirms I should sell the Coleman.

The chassis charging system should be routed through a (multiple) battery isolator, which will probably be mounted somewhere in the engine compartment or below it on the van's frame as it is on my '02. It handles directional current flow from the van's charging system via internal diodes. If your house battery isn't charging from the chassis system, it's probably the place to start for troubleshooting. There's also a high capacity fuse or breaker along the wiring from the isolator to the house battery that might be bad. It could also be a loose or corroded wire somewhere along the normal house battery charging route. There will be high voltage/amperage involved, so if you're not an electrician, be extremely careful or seek qualified assistance.
A few years back i had charging system problems and the battery isolator was the culprit. I replaced it.
If yours is an HDPSI (Hehr power systems) which was the Roadtrek OEM model, they have simple testing procedures on their website. You'll need a multimeter with diode test settings on it.

Crank · 10-19-2014, 02:56 PM

Thanks Mike, for picking up on this somewhat throwaway remark, and for the detailed suggestions. I am considering upgrading the charger/converter to a modern system with better battery charging control, and so decided to wait and see if that would eliminate the problem. If it doesn't, the isolator and the line to the battery certainly become suspect.

If I can't solve this problem myself, I will start a separate thread, in order not to confuse the bathroom conversion discussion.

Thanks again, the responses to this Roadtrek newbie's several inquiries have been so warm, prompt and helpful: I have been surprised and gratified to receive replies and advice from some of the most experienced and busiest members: what a great forum!

Mike · 10-19-2014, 04:12 PM

No problem. It's what we do.

Here's a link to the HDPSI website...
www.hdpsi.com
Their website isn't as user friendly as some but it has the info.
They're also pretty good at answering email queries. At least they were.
I know Roadtrek has gone from isolators to separators in recent years, but I'm guessing yours has an isolator unless a previous owner changed it out.
Good luck with it.

JohnnyFry · 11-16-2014, 09:54 PM

If the engine alternator is not charging the house battery you may have:
1. A faulty isolator in the engine compartment which splits the charging to charge both engine and house batteries
2. Faulty circuit break between the isolator and the house battery. Usually there are 2 of them, one at each end of the cable from the front to the house battery since a short on this line could start a fire from either battery.

On the 120 volts, it could be:
1. Circuit breaker on the Onan itself or in the inside 120 volt panel
2. Faulty AC voltage regulator on the Onan
3. Heavily tarnished slip rings on the Onan
4. Faulty automatic transfer relay in the coach. This transfers the 120 V circuits from the shore power cord to the generator.

Good luck.

Crank · 02-07-2015, 11:54 PM

I haven't been working on the van lately, so just read your informative comment, Johnny Fry: thanks.

Back to the OT - using the generator for power tools.

I just checked, and all the circuits are only 15 amp (12 gage wire & 15 amp breakers). So that puts a limit on the size power tools that can be used, even though the Onan is rated at over 2800w.

Anyone know if a 20 amp circuit could be wired in somehow? It could be an exterior receptacle and an even more useful generator. Maybe all I need to do is add a 20a breaker and wiring to match.

markopolo · 02-08-2015, 01:55 PM

12 gauge should be OK for a 20 amp 120v AC circuit.

14 gauge - 15 amp
12 gauge - 20 amp
10 gauge - 30 amp

You'd have to know that all of the wire in the circuit is at least 12 gauge before just putting in a larger breaker.

Crank · 02-09-2015, 10:15 PM

Thanks Marco: I just discovered my Onan 2800 has its own 25 amp breaker, so I wonder if one could wire directly into that. if all other breakers were OFF, using 10 Ga wire.

It is also worth noting generator output at different altitudes - I live at 5500'.

Elev. above sea Level Max genset power (Watts)*

Up to 500' 2500-2800

2500' 2325-2600

5500' 2060-2310

Above 5500 2060-2310 - 87w for each additional 1000 feet

So I, at my elevation, can't even get the rated capacity: no use looking for more amps.

*Data from Onan Manual

mlts22 · 02-12-2015, 09:04 PM

A few weeks ago, I posted a question almost identical this onto rv.net. Mainly because there is a property I'm interested in that has a cabin that is completely off-grid. The current owner has a class "C", and powers the cabin from the generator on his rig. Since the cabin is small, its biggest load is either the microwave or the 10,000 BTU A/C. Unless both are run at the same time, a 15-20 amp extension cord easily handles this.

I plan to buy the property, and use the Onan from the "B" to keep the cabin powered and the A/C on. This is doable, and won't damage anything, although it is wise to change the oil and do other upkeep on the Onan. It also is wise to be 100% sure that the generator will cut off at 1/4 tank, so you can drive to a gas station if the generator quits.

There are a few mods to make life easy though:

One of them is to have a dedicated outlet with a 20 ampere, SWD (switch rated) circuit breaker in the box. This way, you can go in the van, flip the CB off, hook up the cord, flip it on, to minimize arcing. Basically the same thing one does at a power pedestal, except the RV is producing, not consuming power.

Another modification is to have a 3000 or 4000 watt Magnum Energy hybrid inverter coupled with their generator controller. What this does is allow the batteries to power the cabin... and if the batteries get below 12.2 volts, the generator automatically fires up to recharge the RV's batteries as well as provide power for the cabin. This way, if one is using the cabin in the wintertime, one has power, but no generator noise... and the batteries will have protection against being run dangerously low.

Of course, I could just get a portable generator to run the cabin... but if the "B" has a generator, it should see some use. Plus, why waste the space for a generator when there is one built in.

Mike · 02-12-2015, 10:31 PM

How many solar/wind amps and deep cycle batteries could you get for the same price I wonder? I might think in those terms. Rather than tether your van to the cabin to recharge your battery bank. I guess if you've got another ride you could leave the van parked at the cabin.
Just got back from a recon mission down that way mostly along the I 10 corridor. It was fairly sunny for the 3 days we were in the area, and it was breezy. Two good sources of energy to keep a cabin sized battery bank topped up?

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