Low voltage Issues on N/L Generator

Thank you for letting us be a part of your group.
It was recommended by our DeFever Group to contact the Trawler Forum for help.
Our issue is we have a DF40 with a Northern Lights M643 generator that is going to low voltage in a Bulk state charge on our new Mastervolt Plus charger which was replaced once after it damaged $2200 of on board equipment.
Mastervolt have been very good to us by getting the replacement to us in a timely manor since we live on our boat in the North Channel here in Canada.
The replacement was a new version of the Plus with 10 dip switches instead of 8.
The M/V Plus replaced an aging Xantrex Freedom 2000 combo charger/inverter (the Link 1000 was acting up).
We have not had any issues with the N/L M643 generator with only a 1000 hrs on it.
The M/V charger works great on shore power and also works great on our backup Honda 2000e but goes to a low of 90.2 volts when using the N/L generator during the “bulk” charge state.
Note; if the hot water heater kicks in the voltage does go back up to its normal 122.3 volts…go figure
We can “baby sit” the monitor on the charger(EasyView 5)and change the current load setting form the factory setting of 16A to 8A to maintain the 122volts but amps in bulk charge goes to58 amps instead of the 75 amp rating that we payed for but the most important part of this is the damage and potentially a fire that good be created by this problem.
No wiring changes have been made other than the direct replacement of the Xantrex to the M/V.
The N/L folks have stated Since your generator set is wired for straight 120 VAC the issue can’t be due to imbalanced loads and is more than likely due to the excessive non-linear load of you charger. When your water heater energizes with purely resistive load it helps to mitigate the negative effects of the charger. I do not believe that it is caused by any problem with the generator but can’t say with a 100% assurance since your generator is older and I do not know the condition of the windings.
I have read that there are isolation transformers on the mart that are specifically designed to filter the effects of non-linear loads but I have not seen any in operation.

If anyone has experienced this problem we would love to find a resolution.
With thanks Paul

What is the generator engine RPM at 122 VAC, and what is it at 90.2 VAC?

I don’t have a rpm gauge but the generator doesn’t seem to change in sound compared to adding a different load to the gen set such as coffee maker or microwave.

Welcome aboard. You can get a photo tach on Amazon for less than $50 if you do need to check the RPMs.

This does indeed have all the hallmarks of excessive non-linear loads. The fact that the problem goes away when you add a good resistive load is the big clue.


Here is some more info, and some pointers to filtering transformers.


https://eepower.com/technical-articles/ways-to-reduce-harmonics/#


If you find a transformer and it solves the problem, I'm sure the folks at NL would appreciate hearing about it.

It should be running at 1800 RPM for 120VAC @ 60Hrz. When the electrical load increases the RPM should stay the same, but the engine governor should open to hold the RPM. At the same time you should be able to hear the engine loading increase to maintain the RPM.

What is the frequency when the generator loads up? Your dvm should have a frequency function. There is a specification for frequency and voltage. At higher loads the frequency maybe lower but shouldn’t be below 58Hz and at zero load no more than about 62Hz. These are approximate.

1- Buy a Kill-A-Watts energy monitor and plug it into any onboard receptacle. It will monitor generator output voltage and frequency.
2- Buy a simple cube heater used at a thrift shop or <$20 new at Dollar General. Turn it on Low or High setting with an extension cord to outside to put a resistive load on the genny. Your gen will handle the extra load, plus it is good for the gen to run loaded anyway. Your batt charger is only using about 1200 watts on full charge. It drops fast after you reach Acceptance charge rates. Thats a long way from a healthy load.
BTW, Welcome Aboard.

Thank you

twistedtree said:

This does indeed have all the hallmarks of excessive non-linear loads. The fact that the problem goes away when you add a good resistive load is the big clue.


Here is some more info, and some pointers to filtering transformers.


https://eepower.com/technical-articles/ways-to-reduce-harmonics/#


If you find a transformer and it solves the problem, I'm sure the folks at NL would appreciate hearing about it.

Click to expand...

thank you

High Wire said:

1- Buy a Kill-A-Watts energy monitor and plug it into any onboard receptacle. It will monitor generator output voltage and frequency.
2- Buy a simple cube heater used at a thrift shop or <$20 new at Dollar General. Turn it on Low or High setting with an extension cord to outside to put a resistive load on the genny. Your gen will handle the extra load, plus it is good for the gen to run loaded anyway. Your batt charger is only using about 1200 watts on full charge. It drops fast after you reach Acceptance charge rates. Thats a long way from a healthy load.
BTW, Welcome Aboard.

Click to expand...

We’re you having the same issues and did this clear it and thanks for you input.

Not exactly. I bought the Kill A Watt monitor for my old generator as an easier way to monitor frequency/rpm than using a digital photo tach.
Since my old gen died from chronic under loading I have been very sensitive to monitor loading. On my boat after an hour, I can’t even hold 20% load. The battery charger tapers off and the water heater is hot and the AC units are cycling. I had two cube heaters to break in the new generator with both air conditioning units on heating mode with the doors and windows wide open. It’s the only way to reach 8 Kw on my boat.
As far as low voltage goes, there have been at least two similar threads within the last year where the cause was low frequency.

High Wire said:

Not exactly. I bought the Kill A Watt monitor for my old generator as an easier way to monitor frequency/rpm than using a digital photo tach.
Since my old gen died from chronic under loading I have been very sensitive to monitor loading. On my boat after an hour, I can’t even hold 20% load. The battery charger tapers off and the water heater is hot and the AC units are cycling. I had two cube heaters to break in the new generator with both air conditioning units on heating mode with the doors and windows wide open. It’s the only way to reach 8 Kw on my boat.
As far as low voltage goes, there have been at least two similar threads within the last year where the cause was low frequency.

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Thanks Archie

Thank you everyone for some good advice and I will follow up with the ideas and get back to the group.
Thanks again, Paul

The folks that are recommending that you check the RPM are dead on correct.

I have seen this same problem many times with clients land based backup generators. They are a bit too high in frequency at low loading levels.

Add some load and the natural droop of the mechanical governor slows down the engine enough for the voltage regulator on the generator to stabilize the voltage.

One gauge you really want on your electrical panel is a frequency meter. That and make sure your onboard handheld DVM will also read frequency.

With no load you should have 61.5-62 hertz out of any mechanically governored generator. This will produce a fully loaded frequency of about 58HZ

ksanders said:

The folks that are recommending that you check the RPM are dead on correct.

I have seen this same problem many times with clients land based backup generators. They are a bit too high in frequency at low loading levels.

Add some load and the natural droop of the mechanical governor slows down the engine enough for the voltage regulator on the generator to stabilize the voltage.

One gauge you really want on your electrical panel is a frequency meter. That and make sure your onboard handheld DVM will also read frequency.

With no load you should have 61.5-62 hertz out of any mechanically governored generator. This will produce a fully loaded frequency of about 58HZ

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Thank you, would a Fluke117 be good replacement for my old meter( doesn’t read Htz) or could you recommend a affordable meter. Thanks

Small Change said:

Thank you, would a Fluke117 be good replacement for my old meter( doesn’t read Htz) or could you recommend a affordable meter. Thanks

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Yes that one would work since it measures frequency.

Actually though I thought that I read that the 117 auto selects AC or DC automatically. I did not read up on it to verify but I would greatly prefer a DMM that you choose AC or DC over one that auto selects. That way for example you could look at a AC component on a DC signal.

It is not an RPM issue. The charger is a highly non-linear load. It distorts the voltage/current waveforms. Your gauge will not read correctly (unless it is a true RMS meter). Adding meaningful resistive load fixes it.

So you saying if I add a resistance load like the small micro heater(which was recommended by another boater) when starting the charger in the bulk stage, this will settle out the generator, much like the hot water system did to maintain the 122 volts?

Have carefully read all posts on this thread and agree with both schools of thought 1) Most common low voltage on the single phase 120V generators is caused by low rpms as the machine is loaded. I had this problem and adjusting rpms up solved. 2) That it is likely a non-linear load problem. Suspect so since you can’t audibly detect generator speed changes and goes away with addition of resistance load. Suspect shore power is immune due to robust nature of the power and Honda gen immune because it is actually inverter type output. That said, My thought is that your beef is with Master Volt and not Northern Lights. Think an isolation transformer as a remedy would cost more than scrapping the Master Volt. And big and heavy. And when at anchor, turning on resistance load doesn’t make sense. I have had very good luck with Iota chargers. Not ignition protected, but fine for diesel powered boats. You do need a separate battery monitoring system.

Thanks for all your advice and it does make sense.
It is a shame that when we had the folks from M/V spec out the charging system that they would of recommended a charger that was compatible with our M643 generator.
I guess I could find something with a residive load to run that is better then a micro heater during charging since the generator runs great on all other demands on the vessel.
Thanks again for all your help.

Following

Am I correct, your M643 is a 5kw machine? Don’t know if you have a single 30A 120V distribution or a double (one or two shore power cords). In either case when at anchor, depending on what loads you attempt to run at the same time, you may find that you reach capacity of a 30A circuit, or if you have two, the generator capacity. On my boat, I have two 30A circuits, but one is dedicated to air conditioning. So everything else is on the other. If we attempt to charge batteries in the morning, power the water heater, and turn on the coffee maker all at the same time, we trip the 30A breaker. And if we were to attempt to run air conditioning (or reverse cycle heat perhaps in your location), we would likely trip your generator output breaker. Our generator is 8.5kw, so we’re not generator limited, but we do have to manage how we load the one 30A circuit.

Depending on how you intend to use the boat, turning on a small heater or the water heater when charging the batteries may work ok.

By the way, we should have let you know that most thing that do not have a motor is a resistance load (ok, the small heaters have fan motors, but a small percentage of the load). Thus, the water heater. Or space heater. Or coffee maker. Or incandescent lights.

I have same genset.

Before buying anything try turning voltage up on voltage regulator in control box.

It may do nothing, but I raised ours from 110 to 130. Still within electrical spec.

All my problems went away. Might also check brushes while there.

If you decide to add an isolation transformer, only put it in front of the charger, not the whole boat. It will be much smaller and cheaper. You are not changing voltages, just making a magnetic choke to smooth the effect of the charger.

The charger does not pull current smoothly, but only as the capacitors need it, This is hard on that model NL.

I used to work with guys that could explain what it was doing, but that takes longer than fixing it.

Good advice above, however call a NL technician and have it fixed right before you cause more damage, meaning more $$$$

gsholz said:

It is not an RPM issue. The charger is a highly non-linear load. It distorts the voltage/current waveforms. Your gauge will not read correctly (unless it is a true RMS meter). Adding meaningful resistive load fixes it.

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Then why does everybody else's NL generator work just fine with their inverter/charger?

I am willing to bet that he is not the only person on the planet with a NL generator and whatever brand of inverter/charger he has.

So how are these things wired? And where are you measuring the 90Vac? And what are you measuring it with?

If all your ac to panel is fed through the inverter, could it be an inverter problem? With output at 90V, go check the voltage right at gennie output. Is it 90V or 120V?

Also some cheapo voltmeters get fooled by harmonics coming out of inverter equipment. Try a different (better) meter like a Fluke. It might not be 90V at all.

The NL 643 has a very simple revolving brush type field and a simple four pole stator. It does have an electronic voltage regulator feeding the field, but tends to be quite reliable. Should be pretty close to clean sinusoid power. It is possible for that VR to be getting fooled by some harmonics from the inverter on the output.

That is why it is important to check volts right at gennie output when boat is reading 90V. With a good meter.

I had a NL tech boost my voltage output and change brushes.

Also, the glass Japanese fuses are very expensive unobtanium.

A company in Houston called Fuseco got me a box (10) of exact equals for about $40-50.00.

Troubleshooting mine we used all the spares in the unit. So now I have plenty. Suggest you buy a box.

Not any old fuse will do on the genset....

The highly inductive load of the inverter charging at high amps causes distortion of the generator waveform, and this has the effect of chopping off of the peak voltage. Turning on non inductive loads such as a heater stabilizes the waveform. Capacitor regulated generators have the worst waveform stability. If yours is one of these, it is pretty low cost to see if a new capacitor improves the situation. Otherwise, I would suggest using the settings available to reduce the bulk charge rate to where it doesn't fault out. It is normal that inverter chargers, due to their double duty design, are sensitive to waveform and do not put out as much on a generator as on shore power. Another possible solution for you, depending on how much charging capacity you need, is separate charger(s) with power factor correction such as the Pro-Nautic series from Pro Mariner. I'm not a fan of PM products, but this is a good one. I have seen some glitches with MV products, not a fan of those. I don't see any reason this issue would have been the cause of a power board failure. The kind of issue that would also would zap other 120V digital appliances like TVs, etc.

...BUT, don't overlook integrity of all devices and wiring between your source of power and the inverter input, that's first.

EngNate said:

The highly inductive load of the inverter charging at high amps causes distortion of the generator waveform, and this has the effect of chopping off of the peak voltage. Turning on non inductive loads such as a heater stabilizes the waveform. Capacitor regulated generators have the worst waveform stability. If yours is one of these, it is pretty low cost to see if a new capacitor improves the situation. Otherwise, I would suggest using the settings available to reduce the bulk charge rate to where it doesn't fault out. It is normal that inverter chargers, due to their double duty design, are sensitive to waveform and do not put out as much on a generator as on shore power. Another possible solution for you, depending on how much charging capacity you need, is separate charger(s) with power factor correction such as the Pro-Nautic series from Pro Mariner. I'm not a fan of PM products, but this is a good one. I have seen some glitches with MV products, not a fan of those. I don't see any reason this issue would have been the cause of a power board failure. The kind of issue that would also would zap other 120V digital appliances like TVs, etc.



...BUT, don't overlook integrity of all devices and wiring between your source of power and the inverter input, that's first.

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I guess I am lucky. My boat came to me with a 12kw Kohler and a 7.7kw Westerbeke. I installed a Magnum 2812 inverter-charger that charges at 125 amps. Both generators and shore power bulk charge at 125-130 amps, never anything less. Both generators charge at 59Hz - 61Hz after I tweaked the RPM settings.