Onan Generator Control Problem - RC as solution?

Technical Electrical
1

I know this is a different thread, but the forum seems kind of quiet and I have a problem and would love some input.

On our boat, we have a 2001 9kW Onan Marine Genset Generator that is not running. I’ve narrowed the problem to be a faulty Voltage Regulator. To my understanding of the owner’s manual and a short troubleshooting guide from some RV people, the Voltage Regulator does not regulate anything, but actually just shuts the generator down if it has too much current being pulled or of the voltage is too high or too low.

If I force the generator to run (yea… probably a bad idea) the voltage output is 220V, which is what the generator is supposed to output and we have a step down transformer in the engine room. So… the voltage regulator is faulty because the voltage output is correct, and there is not an over current condition.

I looked up voltage regulators online and could not find any marine ones, and the regular RV ones were around $350. Ouch! There is no one to service the generator around anymore since Katrina wiped out most of the marine service places and we are now resorting to an RV place in any help we can get (which is just replacement parts, etc).

I would just plop a new voltage regulator in, but it is hard to get out, and the part that looks to be fried is a diode (which would not catastrophically fail like it did for no reason). So, I don’t want to pay $400+ for a new voltage regulator and have it immediately fry again.

The generator model number (or letters in this case) are MKDAL.

Now to the robot controller solution. The generator has horrible ways of indicating what is wrong. The only way I figured what was wrong was by driving 30 miles to the RV place, they gave me some troubleshooting papers, and I found that the reset breaker that kept on tripping to be for an over current condition. It also linked me to the AVR (Which I guess means automatic voltage regulator). There are no large wires going to the AVR, but there are some pretty massive capacitors and what looks to be some transistors attached to a large heat sink buried in the generator.

Now, I had an idea to use a 2005 IFI Robot Controller stuck in autonomous mode to control everything. Then with the program port, send back generator info through the COM port to a linked computer if needed. I would also add some indicator lights to detect low coolant, oil pressure, exhaust temperature, and coolant temperature.

What route would you go? Keep in mind that this generator is buried in the engine room of a boat with two large diesel engines that leave me hardly any room to access the generator, so taking out large parts is a large undertaken (as we would have to pull out the floor).

Thanks for any info regarding what could be wrong with the generator, and I hope to put some more info up later once I get some of the papers off the boat.

2

The idea is excellent but not so sure about the IFI controller. Your boat with 2 diesel engines sounds like an valuable asset. One that I would be inclined to use more industrial proven technology. I’m in the process control department for a very large steel producer. Our demands would be something like what you would be expecting. I’m sure the IFI can be configured to handle the task, but To be user friendly the complete package may get very intense. If this was an shop test set or a less valuable asset I would support the IFI unit. It would be fun and challenging to see these old units have new life. There are tons of “off the shelf” controllers with any number of I/O options starting at a few hundred dollars. There small, 4 x 4 x 4, with an LCD display. They can be programmed very easy with an laptop. Then you can mount the controller in the wheel house and just use multi-conductor cable to connect to the engine room. Honeywell, Precision Digital, Moore are just a few that come to mind. Oh… BTW… Please don’t force the generator!! It sounds like you just have some control issues. Doing that may result in a real tug-of-war replacing the generator in the engine room. Or a quick call to your friendly guys at the fire station.

3

I pretty much threw out the idea of using a RC to control it.

I’m pretty sure the voltage regulator is fried. Right now the generator is outputting 300VAC! This thing is starting to be more of a pain that I thought it would be.

This is what I have found in the troubleshooting guide:

“Check Generator” Faults: Fault breaker CB5 trips if generator quadrature winding current is too high.

I talked with an electrical engineer over the phone and he said that it meant that the generator has too much of a load on it. I know this cannot be right since there is no load at all.

It also has this in another troubleshooting area:

“Check Generator” Fault -
Corrective Action:
a. Reset “Check Generator” fault breaker CB5.
b. Run with fewer loads, especially when low power factor loads are connected or large motor loads are cycling on and off.

Winding current leads me to think that the actual generator has a shorted winding. I really hope this is not the case and maybe someone has a little more insight on this, as I’m not a generator expert by any means, but am quickly becoming one. :smiley:

Yesterday, all I did was try to get the water pump working. It took a lot more time than I thought because I could never get the water pump to get a prime. It took 3 hours just to get it primed!

Anyway, 300V is quite high, enough to fry everything in the boat.

4

I’ve heard of others having trouble with the Onan controls as well. Marine applications (similar to dewatering in some cases) are pretty tough on electronics, espeically ones without good cases.

If you’re pretty sure your generator is running fine on it’s own and you don’t really care about monitoring the generator’s output, you could just get yourself an engine control unit to autostart the engine and monitor that part, then just watch the generator’s output with a seperate meter.

I’m thinking you don’t mind not knowing the generator’s output though, since you were ready to run your engine with the IFI RC. I also don’t feel the IFI controller would hold up to the saltwater environment… you’d get contact corrosion on the board (not sealed) in just a few years.

I highly reccommend an engine autostart controller from ECU. They’ve been around for many years and have controllers running in environments ranging from oil rigs in the gulf to the ice roads up in alaska (saw that in diesel progress). They’re fully encapsulated and built like a brick, simple to wire, designed and built in the USA. They’ll cost you a couple hundred bucks… but compared to the cost of your generator set or even the cost of an IFI RC, not a bad deal.

Let me know if you have any questions, hope that helps,

Q

p.s. I am a human being inside this geekie exterior… what kind of boat is this? How big? What’s it for? :]

5

This is a 1985 45’ Hatteras Convertible yacht. Has 2 500HP Detroit Diesels and a 9kW Onan Marine Genset generator.

Really, I would love to let the engine run a little while since it has not been run really since Katrina. The little time I had it running yesterday it was blowing out a lot of black and nasty water. The owner before us obviously didn’t care for it much. The oil is black, the impeller for the saltwater pump was basically just a rubber wheel after running dry for a while, and it doesn’t run!

I think the engine runs great, but I hate forcing it on. I want to disconnect everything from the generator output and would like to let the generator run for a good 10 minutes or so. I’m also not even sure of the voltage output it is supposed to have. The boat can handle either 120V or 240V, as it has shore power connectors for both. I’m assuming the generator is supposed to output 240V, but everyone knows where assuming gets you.

I would look it up in the manual, but the owner before us took all the paperwork out of the boat before Katrina and put it in his home. Needless to say, the boat survived, the house did not.

Looking up this on Google has been impossible. There is little information for our model of generator, and I’ve been going off of info from like generators.

I love the boat, and getting this boat allows me to go back to the harbor, which I loved to do before the storm.

Before Katrina, we had a 33’ Chris Craft with 2 gasoline, saltwater cooled Chryslers, which is a recipe for disaster. It went MIA during Katrina, and probably sunk somewhere in the Gulf of Mexico, or could be in the woods somewhere. Who knows…

Anyway, any info is welcomed. I’ve pretty much gotten off the idea of controlling the generator with the IFI controller. I know it’s not weather proof, but the whole engine room is dry. Unfortunately, like any boat, it relies on small electric pumps to keep water out, and they like to fail often. We almost lost the Chris Craft like that when the stern bilge pump failed to automatically turn on.

I’d really like to get this thing running right. I hear of people talking about how great Onan generators are, and I saw some really old ones on YouTube. They’re designed to last, unfortunately, our has had its life cut short.

Another thing I want to add. I cannot believe how the engineers behind this generator used cheap bolts for the water pump. They were all rusty, and one broke when we tried to get it out! What a horrible design! I quickly replaced them with nice stainless steel ones.

6

Ok… so we now have more pieces of the puzzle. Was the engine room filled with water… at least over the generator for a long period of time? You could test the windings with an high voltage impedance tester. This will induce a very large voltage,10 - 25k, into the windings and report any voltage leaks to ground. This is a very safe way of troubleshooting motor windings in industry. I’ll almost bet water contaminates are breaking down the insulation. Since the boat is something that’s worth doing right and has been through H%*#, it might be worth a complete overhall of the engine room. Who knows what other surprises will turn up in the most inapproiate time. Good Luck

7

I really doubt the engine room has ever been submerged under water. It survived Katrina right by my uncle’s boat, so I know it survived because it was still floating when we went to check up on my uncle’s boat.

I can try looking at the the windings, but it’s a very cramped area that I would need a lot of time to take it apart and service it.

Luckily, I think we found an RV place that volunteers to work on boats as well right by Fusion’s HQ.

I still think it’s the AVR. It has a dark spot under all the silicon that appears to be a burnt diode, but I cannot really tell.

8

Ryan,
The voltage regulator supplies current to the field windings of the alternator. Increasing the current increases the output voltage. Since the regulator is fried, it likely is supplying max current to the field windings, and therefor is tripping that breaker. (also the high output voltage is a good indication of max field current. I am betting that water (could have been rain) entered the system at some point and took out the regulator. I know that $350 is a lot to part with, but I would recommend replacing the regulator rather than try to find an individual part. Once a board has been stressed, other failures are likely.
This is a spec sheet on your genset…http://www.cumminsonan.com/www/pdf/specsheets/a-1351.pdf

9

My dad is going to call in the experts. We talked to some people and they were recommending a place neither my dad nor I had ever heard of. It’s a family owned business, but they are highly respected by my dad’s friends, so he’s going to talk to them on Friday.

I did get the engine running a little Thursday. I disconnected the voltage regulator to prevent further damage if it is possible, and the generator was disconnected from the rest of the boat’s electrical system. No one would ever believe how hard it was to get the water pump primed… It took about 5 hours just to get the water flowing.

I hope none of the windings shorted out. It’s a relatively young generator compared to other generators that last much longer and has had only 400 hours.

I know it’s hard to see much of the generator in the picture, but it is pretty clean and rust free:

http://photos-a.ll.facebook.com/photos-ll-snc1/v420/83/59/1289760161/n1289760161_30039864_1502.jpg

If the picture doesn’t show up, try this link: http://www.facebook.com/photo.php?pid=30039864&l=5472b&id=1289760161