Need Generator recommendation

[AU92]

I have a 1989 Onan MDKD 8.0 kW 1800 rpm generator on my 1989 Carver Californian. I have rebuilt and nursed this generator for the last 10 years and I’m approaching my end of patience. I only run it under minimal load now (refrigerator, misc electrical outlets with wine cooler, iPad chargers etc) and the damn thing dies randomly. I’ll be doing a fuel filter change and oil change tonight to see if that helps.

BUT, I’m really looking for recommendations for a modern generator that would be sufficient. I have three Marine Air ACs that will need to be run once we move south. Currently we are on the Great Lakes so AC while underway is not essential. But if we do the loop, we will need them.

The only catch is that the hatch to my engine room is 22” wide by 33” tall. I don’t know if I can get a new generator through there. I had to disassemble the block of this one to take it out for rebuild. I’m pretty sure I could open up a floor hatch in the salon over the generator if absolutely need be. Just haven’t had to do it yet.

So, does anyone have any recommendations? If there is any info that I need to provide please let me know and I will do do. Thanks in advance - Michael

[ItDepends]

If you absolutely NEED to run 3 A/C units at the same time, your generator needs to be able to supply AT LEAST enough power to start one while the other two are running. Since the startup load can be three times the running load, that's a LOT. You do not mention the size of your ac units, or other loads, but I am guessing that 8kW is marginal...

You can bypass this by getting an inverter/charger that has "power assist," in other words it can draw energy from the batteries to make up short term loads that would knock the generator offline. I know Victron's do this, I assume others do now as well. It can let you significantly downsize the generator so it only has to supply the AVERAGE load instead of the PEAK load. That smaller sized genset might fit into a place something else will not. The cost of the Inverter/charger might easily be covered by the lower purchase price of a smaller genset.

With a setup like that you might be able to go with a 6kW or even a 5kW instead of the 8

On your Onan, it is EXTREMELY unlikly that a random shutdown has anything to do with the engine side of things. Diesel engines just don't die that way (except maybe from a fuel supply problem). The actual issue is actually almost certainly in the control circuits, some sensor is not happy... Oil pressure, Cooling water temperature, exhaust temperature, and a host of electrical faults will all shut down the system.

[AU92]

Thank you for the informative reply. I did not know the boost inverters were a thing. I will have to look more into that.

I agree with you about diesels and what may be causing it to conk out. Here’s some observations that don’t make sense. On three long trips (7 hrs in May and 15 hours last Friday, plus one 7 hr trip last fall..) the generator ran just fine. No shutdowns at all. Then today it started this random stuff. It’s done this before but I thought that it was solved bc I had three long trips with no problems.

It’s always been temperamental and what makes me think it is electrical is that it was struggling the other day with one of the ACs on. So, I just shut them all down on these long trips bc the lake is cool and air temps are nice. I figured that I still have something that is kicking on that kills the gen. That’s why I’m getting frustrated with it and considering a new.

We will be traveling again in a few days for 5 hrs and I will take some time to watch it and see if I can figure out why it is not happy.

Again, thanks for the info on the inverters. It would be great to save some cash on a smaller generator.

[mvweebles]

Consider soft starts on your AC units. They are about $300/per AC but manage the surge very well.

https://www.microair.net/collections...-soft-starters

Previous post is referencing "hybrid" inverters that have the ability to combine input sources. Fairly common these days. But there's no free lunch - undersize the generator and you'll deplete your battery in no time.

Northern Lights is, by far, the most frequently cited "best" generator on the marine market. Even with soft starts, your AC units will take close to 15-anps (120vac) each, plus another 2-amps for circulation pump. Plus anything else you're running onboard. You need to side your generator for that load. As far as fitting it in, if your generator is in the engine room, one engine can be temporarily stacked on the other two make room to pass the generator in. Somewhat surprising, it's not as difficult as it seems.

[Ded reckoner]

We have a Northern Lights, M673D.3, 4.5KW generator and it has been very reliable and is easy to service. I would highly recommend it. The specs indicate it's H/W/L is 20.25in/17.1/27.1 . I don't know the dimensions of the larger model you would be interested in. Otherwise, I think Panda generators have small dimensions. My limited experience with one was fine, but a friend had some problems with his brand new one.

[skipperpete]

Add me to the list of Northern Lights fans, very reliable and quiet genset. Compared to its nearest rivals, Kohler and Onan Cummins it’s streets ahead. Kohler have taken over Lombardini as a diesel end and Onan Cummins are no longer the quality product that served the marine industry so well for so long. Of the 2 pole compact units, none really stand out as reliable continuous use power supplies.

[Manateeman]

Northern Lights.

[NYSail]

I am installing a “next Gen” as we speak….. . Florida based company….. unit is built with limited electronics making it very serviceable.
Good luck!

Greg

[Madehn]

before you go to the major expense of replacing the entire generator - which sounds like it is going to be a beast to do, i would replace the high temp sensors, oil pressure sensor, exhaust temp sensor etc-- it sounds like a sensor failure and they are not normally that expensive or that hard to replace. i would gamble the $500 bucks or so that all new sensors are going to cost you along with a day to replace them all. i would also install a small automotive style electric fuel pump inline. All told that should cover most of the potential issues and i suspect will be FAR easier than replacing the entire generatorwith a high probability of fixing the issue. i just installed a generator in my boat 10kw westerbeke and it took a solid week of effort to get it right- it would run and produce power then quit after 5 to 10 minutes- finally found three things wrong- run solenoid was going out, oil pressure sensor was defective and finally the water pump">raw water pump had lost vanes in the initial startup. (last was fixed by putting a 110 volt pump in place of the mechanically driven raw water pump-- it is powered off the generator so it can only run when the genny is running and producing power. Anyway all of that took a week to run down- if i had just put new sensors on to begin with i could have had it done in a day.- too soon old- to late wise.

[sy_gilana]

Before you junk it, check the exhaust elbow for reduced size. Can solve a lot of problems.

[redneckrob]

Originally Posted by NYSail

I am installing a “next Gen” as we speak….. . Florida based company….. unit is built with limited electronics making it very serviceable.
Good luck!

Greg

I have had a NexGen 3.5 for several years and it is a very simple and thus reliable unit. It is pretty loud though compared to a Northern Lights, for example, even with the sound enclosure and isolation mounts. The bigger units with more cylinders might be smoother/quieter. I'll also say that it's not terribly happy putting out anything close to the rated 3500 watts continuously with the sound enclosure on; the generator portion gets extremely hot. I had to install two blower motors taking in and exhausting outside air and it still gets very hot even at 2500 watts continuous. If I had it to do over I would have gotten the 5.5 kW even though I would never use more than 3.5.

[mvweebles]

Good thread on Next-gen. Severalcautions for fulltime use such as running AC all day long.

https://www.cruisersforum.com/forums...ew-155713.html

[Turtle Blues]

My 2c worth answer to your question is you got 30 plus years out of the original Onan and the 7/9 kw fits your dimensions and needs. It is driven by a Kubota and is a first class piece of equipment. The next 3 posts will likely tout the Northern lights packages all with excellent usage histories.

I am terrible on load management. I want to cook with multiple ac's running and the hot water tank supplying the Admiral's shower.
Second the suggestion of real marine soft start packages on the ac's. they make a world of difference in smoothing out starting loads.
You rebuilt the existing so are no stranger to tools. Post #9 has a good list of things to check. I would add the frame, grounding and wire termination fittings as possible culprits for intermittent shutdown issues.