Nextgen generators

[a64pilot]

Any opinions? Especially the newer ones? I called and asked about them not
working well with inverter chargers and not having a clean wave form power wise
and was told that's not longer an issue, they have a different generator head now?
Also I've heard the exhaust mixer may be an issue, but that the newer ones are fixed?
I have a boat that has a single 30 amp shore power plug, and can live with that
which means of course the 3.5 is all I can use, but should I buy the 5.5 anyway?
Northern Lights are way heavier and more expensive, I just don't want that much
weight in my stern if I don't have to.

[colemj]

Unless they have something newer than shown on their website and posted owner's manuals, there has not been any changes in their generators for several years.

They offer them either as capacitor-excitated or with AVR regulators. The AVR ones regulate the voltage a bit tighter, but the waveform problem is due to the 2-pole nature of the generator head on these types of light gensets.

These types of generators are a tradeoff, and NextGen makes the best of the tradeoffs possible. For a small generator, they run at 2800rpm instead of 3600, but that means they use a lighter duty, belt-driven generator head (Markon).

The dirty waveform means that it takes ~20% more power to run high draw stuff, or that something like a HO battery charger may have ~20% less output.

The exhaust elbow is stainless, but it isn't very high quality. I heard from many people who had these units before we bought ours (2010) that said their elbow rusted and got holes within a year or so. Ours is now 4yrs old and has considerable rust around the welds and maybe a slight leakage, but still holding in there. Maybe ours is a "newer" design. I had a better SS one made a couple years ago to swap in when this one goes The design is dead simple, and cheap to make.

As for which model to get, remember that the continuous rating is lower than the model rating. For the 5.5kW model, the continuous rating is 5kW, and you need to shave another 10-20% off due to waveform distortion. So you would need to understand what the largest power draw you will need from it - the 3.5kW model will probably routinely give you 20-22A continuous.

In deciding on gensets, one begins by partitioning them into 4-pole, low speed sets and 2-pole high speed sets. Always go for the 4-pole low speed if space and weight are not issues, and particularly if you plan to run it a lot.

In the other category, I think NextGen makes about the best there is, with the most reasonable tradeoffs. Phasor is just as good (and very similar). NextGen support and service has been exceptional for us. These are light-duty gensets and really not meant to be powering the air conditioning 24/7. They are more for occasional use - which means up to an hour or two per day, or all day once a month, etc.

Mark

[a64pilot]

Mark, which one do you have and how much does it vibrate?
I assume you can quieten one down, but if it's imparting a vibration into the hull, then that is pretty much perceived as noise.
Are you happy with it? Would you do it again or buy theNorthern lights?
Right now with both the 16k and the 5k running I'm drawing 21 amps, I can't turn on the water heater or I'm over 30. Only thing I can foresee adding that will draw significant AC power is a water maker and for that I could cut off an AC unit.
So you think the 3.5 is happy making 21 amps continously? Or should I go for the 5.5, the additional weight and expense to include upgrading the boat to twin 30 amp shorepower?

Intended use is occasional, only if it's hot or the bugs are out and to make water, charge batteries if they get low etc., Some people crank them up before they leave the dock, I do not plan on that

[Cuttyhunk]

I have a 2001 3.5k nexgen. When I bought the boat 2 years ago, the mixing elbow was leaking. We got the new design elbow, and it does appear to be constructed differently in such a way that it won't fail where the other one did (probably will fail in a different place!). In the picture, the new one is at the top with the red covering, the old one is at the bottom. I took the pics as it was tricky to install the new one and I corresponded with NexGen to be sure I had gotten the right part (I had). NexGen has been quite responsive to my questions and quick to send me the parts I ordered.

The generator is, I guess, "dirty" but it runs the microwave and the battery charger just fine. I haven't tried running the AC with it yet. We have a separate inverter and charger. It is quiet, but it is far forward in our port hull and has soundproofing in the compartment, and below the waterline exhaust. So I don't know how it would be installed in your boat.

I can say that the thing was not working very well when we bought the boat, due to hardly any use in the previous 12 years (150 hours or so on it). But it is dead simple and you can get parts. We replaced some hose, the water pump (will rebuild the old one), the mixing elbow, and the belt. The water strainer lid had cracked due to the previous owner not winterizing it properly. Nonetheless, we got it running and putting out 125 v (a little high for my taste, but it works). Currently we have to push in the solenoid to get it to start, but we have that part, as well and will replace it in the spring. Basically it is a simple little engine and I am delighted to have a diesel generator that is all wired and plumbed and works as advertised. Yes, we will keep spares on hand when we head south.

[a64pilot]

My understanding is the old style mixing elbow could develop a leak and due to the way the engine's cylinder is laid on it's side, salt water would get into the cylinder when the engine wasn't running if it's the 3.5 anyway.
I assume yours is the 3.5?
Does it vibrate the hull? I keep asking this as it's a single cylinder and I can see where a single cylinder could vibrate more than a multi.
I'm assuming vibration might could be dealt with by double isolating the thing, with additional silent mounts

[Rick R]

Originally Posted by a64pilot

I have a boat that has a single 30 amp shore power plug, and can live with that
which means of course the 3.5 is all I can use, but should I buy the 5.5 anyway?
Northern Lights are way heavier and more expensive, I just don't want that much
weight in my stern if I don't have to.

The 5.5Kw model is the appropriate size. 5.5Kw is 45.8Amps. It is usually recommended that a generator not be operated continuously at more than 70% power, which is 32Amps.

[colemj]

Originally Posted by a64pilot

Mark, which one do you have and how much does it vibrate?
I assume you can quieten one down, but if it's imparting a vibration into the hull, then that is pretty much perceived as noise.
Are you happy with it? Would you do it again or buy theNorthern lights?
Right now with both the 16k and the 5k running I'm drawing 21 amps, I can't turn on the water heater or I'm over 30. Only thing I can foresee adding that will draw significant AC power is a water maker and for that I could cut off an AC unit.
So you think the 3.5 is happy making 21 amps continously? Or should I go for the 5.5, the additional weight and expense to include upgrading the boat to twin 30 amp shorepower?

We have the 5.5kW. It doesn't vibrate much at all - not really perceivable unless you are standing right next to it. Ours is mounted on double mounts - an aluminum plate is mounted on engine mounts, and the Nextgen (with its own mounts) is mounted on this. That is the way our old generator was mounted, so I just kept the plate and mounted the Nextgen on it also.

Compared to a 1800rpm genset, though, you do know it is running at higher rpm's.

We are happy with it for our usage. We considered every generator and would have really liked a Northern Lights. However, our generator is mounted in a bow locker on a catamaran (about the worse place possible), and the extra size and 150lbs of the NL ruled it out.

Our usage is occasional, like you describe yours would be. It rarely runs for more than an hour or two at a time. The only time we run our AC is on windless, humid, hellish hot nights with bugs, when we run it for an hour or two during cooking/dinner and it cools down the boat and dries things up before going to bed. We have the occasion to do this maybe 3 nights/yr - mostly, it never gets that bad in the Caribe. Other than that, it gets run for 3/4-1hr every other day or two for making water and boost charging our batteries so the solar can take them full up to float.

Most likely, you would not be running both AC units at once in normal cruising usage. I assume the 16k is the main boat AC and the 5k is the sleeping cabin AC? If so, you might run like us on hot windless nights - the 16k for an hour while cooking/eating and then the 5k for an hour before bedtime to cool off the sleeping cabin.

And when the conditions are such that you are running the AC, you will not need to worry about the water heater!

Neither of the exhaust elbows in the posted picture look like ours. The elbow on the 5.5kW is a very simple bend with a water injection pipe welded into it. The SS is very thin and cheap, but ours has held up for 4yrs with rust and possible small seepage around the injection pipe weld. Like I said earlier, I have a more robust one ready to swap in. The new 3.5kW elbow looks like it will last a lifetime because they moved the injection point to a lower, and flanged, part. At most, you will just need to replace that flanged part once in a while.

Mark

[Arthur Garfield]

colemj -I am trying to understand this -

" The dirty waveform means that it takes ~20% more power to run high draw stuff, or that something like a HO battery charger may have ~20% less output."
Please explain.


All the Best

[colemj]

The waveform doesn't have a clean sine wave shape to it. As a result, it doesn't produce peak voltage expected from a clean AC power source and the RMS voltage is a bit lower as a result. Approximately 20% in our case. So anything that relies on peak voltage will run a bit less efficiently.

See this thread for examples of the waveform: http://www.cruisersforum.com/forums/...ut-126997.html

A real life example is that our air conditioner draws 14A when on clean shorepower, but draws 16-17A when running on the generator. Likewise, the battery charger will put out 120A on clean shorepower, but only 105-108A on the generator.

Mark

[Cuttyhunk]

Originally Posted by a64pilot

My understanding is the old style mixing elbow could develop a leak and due to the way the engine's cylinder is laid on it's side, salt water would get into the cylinder when the engine wasn't running if it's the 3.5 anyway.
I assume yours is the 3.5?
Does it vibrate the hull? I keep asking this as it's a single cylinder and I can see where a single cylinder could vibrate more than a multi.
I'm assuming vibration might could be dealt with by double isolating the thing, with additional silent mounts

Mine is the 3.5. It does not vibrate the hull. It is not bad at all, much quieter than running an engine. Of course, it is forward in the starboard hull (I said port hull above, must have been thinking backwards!), in a sound-insulated box with a door between it and the shower stall, then the head, then the living area. So most of the time we run it, we have two doors shut.

[a64pilot]

Thanks guys

Mark on the two pole thing, I'm assuming generator RPM is 3600? If so isn't a two pole turning at 3600, the same as a 4 pole turning at 1800?
That's a couple of back to back assumptions there, one that the NexGen is geared to run the generator head at 3600 RPM to get 60 CPS, and that the four pole Norther Lights isn't geared, but direct drive at 1800 to get 60 CPS

[Rick R]

Mark is correct. His scope readouts generally agree with the Victron test results. Marine Generator Test - Victron Energy

Victron did not test Nextgen generators, but they did test several other brands that use the same technology (Synchronous capacitor alternator). They found that these generators had a harder time starting electric motors than other generator types. This is because "Capacitor alternators are self limiting. Therefore, their output voltage will drop when overloaded".

There was no significant difference between generator types on resistive loads.

Richard

[a64pilot]

Not doubting his results, I've seen the post of the O scope pictures, hard to argue with that.
So it's not a two pole vs 4 pole thing, it's the Capacitor?

What is AVR regulation? does it help much? Maybe they are all AVR now? I called and asked specifically about using one with a inverter / charger and was told "that's no longer a problem, we changed the generator head the caution on the website is old and no longer valid"

[Rick R]

Originally Posted by a64pilot

Not doubting his results, I've seen the post of the O scope pictures, hard to argue with that.
So it's not a two pole vs 4 pole thing, it's the Capacitor?

What is AVR regulation? does it help much? Maybe they are all AVR now? I called and asked specifically about using one with a inverter / charger and was told "that's no longer a problem, we changed the generator head the caution on the website is old and no longer valid"

Yes, the number of poles only dictates the RPM required for 60 (or 50) cycles. For 60 cycles, a 2 pole generator must run at 3600RPM, and a 4 pole at 1800. For 50 cycles, the speeds are 3000 and 1500RPM.

AVR is a different regulation technology, and is much better at starting electric motors, and other loads that require a high startup current. But it is also more expensive. If your loads are mostly resistive like incandescent lights, toaster, coffee maker, elec heater, then it doesn't matter which kind of generator regulation you have. But if you would like to start a large elec motor, eg: a 16000BTU air conditioner (with a 5.5Kw generator), then you should go with AVR regulation.

There are several other wrinkles in this story. Fischer Panda and Honda use asynchronous regulation which allows the engine RPM to decrease under light load, but that is a whole other discussion.

And Victron Multiplus and Quattro inverter/chargers use "power assist" which draws power from the batteries to supplement power from a generator or shore when total load would otherwise exceed their capacity. This means that a smaller generator, or a Synchr cap generator can be used in a situation where it would otherwise not be suitable.

Richard

[a64pilot]

I just got off the phone with NextGen, apparently the 3.5 KW now uses a Syncro generator and AVR is not available for this set.
The 5.5 KW uses the Markon head still, AVR is available, but according to NextGen the Syncro is still a cleaner wave form, the are recommending me to go with the smaller gen.

I'd rather not have the weight, price between the two isn't enough to be the major concern, I may end up with the smaller Gen, plan is for occasional use anyway, not to become addicted to the thing, just every few days, make water, wash clothes, charge the batteries etc.
It will replace the two Honda's I have and can run in parallel that has less than 10 hrs on them, I may have them or one anyway up for sale soon.