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Old 08-25-2018, 11:10 AM   #1
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30 Pilot II 3.5 KW gen problems and solution

The Nextgen 3.5 KW generator, which came to me in 2015 in this 2005 boat, had a mere 135 hours on the hour meter, but from the get go, it was a difficult beast to start. I took its recalcitrance as a characteristic of a single cylinder diesel engine, but it also liked to smoke black anytime it had a load of more than the 12-13 Amps the rooftop air conditioner placed upon it. Nextgen says it should be normally loaded to 15-27 Amps to prevent ugly things happening to the cylinder walls. A long story made short is that this last March it failed to even turn over with a couple of charged batteries behind the starter button, and in frustration over not finding anybody in town who would even look at it, I removed it in June at 225 hours and sent it to the Nextgen factory. Once they got a look at it, Nextgen estimated around $4K to fix and return it, but offered a nice discount at $5.1K for a new one. Yesterday, after three sweaty days in the August heat, I finished the installation and testing of the new generator, and I am well pleased with the results. While waiting for the generator to be delivered I installed Micro-Air Easy Start microprocessors on both the 13.5KBtu rooftop air conditioner and the new DTU 10KBtu marine air conditioner; replaced the 1400W heating element in the water heater with a 1000W element; and installed an ammeter on the generator circuit. These measures were aimed at being able to run the generator with either AC unit and the water heater running or both air conditioners while not exceeding 27 Amps of draw on the generator. I am happy to report that all this works like a charm, and the generator starts instantly without even the need of pre-heat (in this heat, who would!). The new generator came with a small panel with a starting switch and hour meter and harness which I installed in the engine compartment to allow me to start the unit there or at the power panel in the cabin - this makes for a much easier freshwater rinse of the cooling system after the boat is lifted clear of the water at my pier. I should also mention that a couple of years back I replaced the crummy Jabsco 12-Volt cooling fan (which seized up and burnt the wiring harness to a crisp because the installer failed to add a fuse) with a 120-Volt inline fan with a 30-second delay timer for a much more reliable cooling fan.
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Old 08-26-2018, 09:50 AM   #2
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Rich,
Glad to hear things worked out so well for you. I have had some issues with my 3.5 nextgen in the past and every time I called for help and or advice the staff at nextgen have always been great. I am very interested in the micro air easy starts that you put in. I replaced my cabin ac with a new model and wish to install the older one in the Pilothouse so I would need to probably go the easy start route. Can you elaborate more on the fan you replaced? I have issues with the generator shutting down due what I believe is heat build up in the engine room and I wonder if a fan change might help.
Cheers, Kevin
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Old 08-26-2018, 10:14 AM   #3
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the NextGen 3.5 KW model uses the same generator end as their 5 KW model, so you may not need a soft start on your A/C. The high inrush current required to start the A/C motor only lasts less than a second and the flywheel should be able to carry it through that period as long as the generator end can keep up.


I am not aware of any trips due to overheating that can be solved with a fan. The engine is raw water cooled and for the most part doesn't care about engine room temps. The generator end is air cooled and excessive engine room temps usually causes the voltage regulator capacitor to fail, not a short term high temp trip.


I have (or had) a fan in my engine room that pulls air from the NextGen enclosure housing and exhausts it. This doesn't necessarily reduce engine room temps, but it does increase the air flow through the generator end which keeps it cooler. NextGen recommends running the fan when temps are high. I always ran mine when outside air temps were at 85 deg or better which usually meant an engine room of 100+ F.


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Old 08-26-2018, 10:17 AM   #4
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Nextgen says that an exhaust fan is necessary to pull heat from the electrical end of the generator. Do you have a sound shield on the Nextgen? I do, and it came with a 3-inch hole right over the air discharge of the electrical end of the generator. To that hole was attached a 3-inch plastic flex hose which lead over to the 12-volt exhaust fan mounted outboard of the generator and blowing out of a vent on starboard side of the hull. The crummy fan eventually seized up causing all sorts of other issues because there was no fuse in its power line - burned up the whole wiring harness. I used a brushless 120-volt inline fan (a Vents model VK 100) taking power from the AC circuit breaker on the Nextgen via a 30-second delay timer I installed to protect the fan from trashy startup voltage spikes as the generator starts up. Email me at richgano@gmail if you need more.
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Old 08-26-2018, 11:31 AM   #5
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David,
It was sad to hear when sold your Mainship but I am happy to see that you are still on the forum. I believe I have the same fan set up you did but I believe it runs once you start the Genset, no need to turn it on by a seperate switch. The generator motor does not overheat, the electric end would shut down. The capacitor was the culprit and finally had to be replaced. I am trying to be proactive by somehow changing the fan around to keep the temp down if possible.
Rich I have the sound shield and ducting coming off it to a fan and an exhaust vent as well. Do you think the new fan makes much of a difference?
Cheers, Kevin
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Old 08-26-2018, 06:03 PM   #6
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That was so on the old one, but this new 3.5 has a different electrical end and just may not have the added capacity. Even if it does, Nextgen told me the little Kubota might just stall out. Also there is a big fat 30-Amp circuit breaker sitting on the end of the generator. Anyways, boy, is this a sweet little set up.
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Old 08-26-2018, 07:15 PM   #7
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When I spoke to Nextgen about my proposed fan mod, they suggested using a fan of about the same CFM as the Jabsco 12-volt. My Vents VK 100 is a 162 CFM unit. If you are feeling a good flow of air out the vent, and you are having issues with generator shut -off (the electrical end quits and the diesel keeps going), I would look to the capacitor and/or the circuit breaker on the unit, both easily replaced. BTW, my Vents fan is a four-inch diameter hose fitting while the original hose was crappy plastic 3-inch which had deteriorated leaving holes which allowed the exhaust air to partially of mostly remain in the engine compartment. The ONLY way to handle this is to remove the 3-inch flange on the sound box which allows a 4-inch PVC slip joint fitting to be stuck into the hole and glued to a 4-inch metalized dryer hose. The Vents fan is hung by very robust bunch of large zip ties outboard and aft of the generator - yes the genny has to be pulled out of the engine compartment for this. I had to cut a four-inch circular access with a hole saw inboard of the vent fitting in the side of the hull so that I could kluge together a union between the dryer hose coming up from the Vents fan to the overboard port.
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Old 08-29-2018, 02:02 PM   #8
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Rich,
Did you have a 6K BTU unit down below before you put the 10K unit in?
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Old 08-29-2018, 02:50 PM   #9
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The one which came with the boat was 7KBtu and totally inadequate in summer heat in my red boat in FL. The 5.8-inch inlet/outlet hoses were capable of handling more flow for a bigger AC; so I upped the March pump which came with the boat to a CAL 900. This 10KBtu DTU unit is much better able to keep up in the summer.
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