AC Amp Meter For Genset

It seems that my genset (NextGen Power) wants to overheat if I load it to near capacity. It's only a 3.5KW and I need it to last (i.e. I can't afford a new one right now). I have looked at most of the usual suspects for overheating issues short of pulling off the heat exchanger.

I want to put an amp meter on the generator to monitor the load we put on it. I'd like to have a 2" round gauge to go next to my new battery monitor. Any suggestions?

Tom-

Like this:

AC Digital Meters - PN - Blue Sea Systems

Anyone use this? It looks perfect. Fits in a 2" hole and has high/low alarms. Although, at $250, maybe it doesn't need to be "marine grade" for this internal application.

One on eBay.......Blue Sea 8238 AC Digital Ammeter Gauge 0 to 150 Amps Amperage Display 80 - 270 V | eBay

There's any number of cheap analog ammeters out there Tom. I bought one last winter and put it on the hot line after the gen/shore power switch. I have it for the opposite reason - my gennie will make more power than I can use but we routinely overload the shoreline. Mine's about as handy a location as hip pockets in long underwear but it was quick and easy to install and it didn't cost anywhere near $250 - $40 if memory serves and that was in a chandlery so I could likely have done better.

IF you watch a meter would be fine.

But a cheaper system is known as load shedding .

This is done with a simple relay that prioritizes your loads .

EG the air cond comes on , the HW heater goes off.

In the archives.

FF

GonzoF1 said:

I want to put an amp meter on the generator to monitor the load we put on it. I'd like to have a 2" round gauge to go next to my new battery monitor. Any suggestions?

Click to expand...

Try this: PANEL AC AMMETER 400 Hz 0-50 amp - MODEL 10909 | eBay

With this: 1pc CT Current Transformer Coil YAL-1 AC50A 50/5A 15VA Acc=1% Size=

There may be a slight error because this is a 400Hz meter but it should be insignificant. If you need lab quality readings you may be hard pressed to find a 2 inch round analog meter you can afford.

if you like the blue seas one and you don't like square off to the side...you could swap around the other round instruments to put it next to the square panel to the right...may look a bit more natural...

me...
I know what AC loads are on and usually pretty easy to calculate...always factor in around 5 amps for the misc/momentary stuff like electronics chargers, table lamps, etc.

Like FF posted...unless you look at the meter constantly to guess when the water heater kicks on or whatever...then just knowing the system loads will be enough and manage them from overlapping.

I'm sure you know all this or have thought about it....just reinforcing one side to a less than perfect situation for many of us with greater electric demands than supply sources.

bobofthenorth said:

.................... we routinely overload the shoreline. ............

Click to expand...

When I do that, my main circuit breaker trips. Or the one on the dock pedestal.

I agree with the thought of automatic load shedding, but it wouldn't be a simple project. Fixing the genset might be a better plan in the long run.

The easiest is to put the high amp items on a timer so you know when the come on/off. the first thing I did was put a time on the water heater, and the electric heaters. If you install a AC amp/volt meter wire it in for shore and the gen set.

A major reason engine get rebuilt is the raw water/exhaust muffle exchange is plugged and/or a hole in the exchange which back fills the engine. The outer tubes of most exchanges become plug so only the middle one are open thus restricting water. I would have the exchange pulled and looked at just for peace of mind.

Gonzo

Have you used an IR gun to be certain your genset is indeed overheating? Is it tripping out on high temperature? Are the ususal suspects for overheating OK such as RW pump, impeller and HX?

On many/most setups the amp meter is hooked into the same circuitry as shore power via a directional switch using the same amp meter and breakers as shore power.

Inverter/chargers in the 3000 watt range will easily pull 18 + amps then automatically cutback as the batteries are filled - thus consuming most of a small genset's capacity. Do you have a separate low amp charger you can use in place of the inverter's charger?

sunchaser said:

Have you used an IR gun to be certain your genset is indeed overheating? Is it tripping out on high temperature? Are the ususal suspects for overheating OK such as RW pump, impeller and HX?

Click to expand...

Yes. Part of why it overheated last time (A think) is my neglect in managing the load and leaving the hot water heater on. We (the diesle mechanic and myself) have indeed checked all the usual suspects.

sunchaser said:

On many/most setups the amp meter is hooked into the same circuitry as shore power via a directional switch using the same amp meter and breakers as shore power.

Click to expand...

I believe I will try RickB's inexpensive solution. I saw that Simpson meter at Grainger, but didn't find the coil. For $30, it might be worth a try.

sunchaser said:

Inverter/chargers in the 3000 watt range will easily pull 18 + amps then automatically cutback as the batteries are filled - thus consuming most of a small genset's capacity. Do you have a separate low amp charger you can use in place of the inverter's charger?

Click to expand...

My inverter and charger are already separate devices (Don't you pay attention around here? ) . With an accurate meter, I can easily work on learning what I can and cannot use when running the generator. While not 100%, it's far better than what I am doing now.


On another topic, during the repair process, I am sure I adjusted the full-throttle setting, something the factory indicates is the adjustment for the power frequency (in hertz). Is there a way to easily measure without bumming an o-scope from someone?

**EDIT** Look like I can use a multimeter if mine has the ability. Thought I'd need a scope for sure.

Tom-

GonzoF1 said:

... With an accurate meter, I can easily work on learning what I can and cannot use when running the generator. While not 100%, it's far better than what I am doing now...

Click to expand...

The amp gauge will also help manage your shore power demands as Sunchaser has said. It's a good tool when your at different marinas and only have 30 amps available.

If I have 2 30A 125V shore power cables, if I put the current transformer on neutral, I'll read total current on both legs, correct? Or should I get two for each hot leg and rig a selector switch?

GonzoF1 said:

.... With an accurate meter, I can easily work on learning what I can and cannot use when running the generator. While not 100%, it's far better than what I am doing now.

Click to expand...

It would be just as simple and less expensive to just write down the current draw from the appliance labels. 15 amps for the water heater, 18 amps for the AC, 3 amps for the refrigerator, etc. (I'm pulling these figures out of the blue, you need the real ones for your appliances).

Remember that many appliances, including the examples I listed, are controlled by thermostats so their consumption is intermittent. Many also have a larger current draw each time they start than they do once they are running.

If the genset output is not protected by a circuit breaker to prevent overload, installing one would be a great idea. Draw too much power and the breaker trips rather than the genset being damaged.

.............. On another topic, during the repair process, I am sure I adjusted the full-throttle setting, something the factory indicates is the adjustment for the power frequency (in hertz). Is there a way to easily measure without bumming an o-scope from someone? -

Click to expand...

An old fashioned electric (synchronous motor, not quartz) clock keeps time by the frequency of the input power. If the clock runs fast or slow, your genset frequency is off.

Installing an amp meter is a good idea in its own right...but it seems like an odd response to an overheat-under-load problem. The NextGen is quality gear and should be comfortable running at 85-90% load near-continuous. Is it a problem to re-circulate Rydlyme or BarnacleBuster or diluted pool acid through the HX, if you have checked everything else in the raw water circuit?

GonzoF1 said:

If I have 2 30A 125V shore power cables, if I put the current transformer on neutral, I'll read total current on both legs, correct? Or should I get two for each hot leg and rig a selector switch?

Click to expand...

Tom: You only need one. The generator, inverter (if you have one) and both AC hots, not neutrals, are wired through the coil.

Aquabelle said:

Installing an amp meter is a good idea in its own right...but it seems like an odd response to an overheat-under-load problem.

Click to expand...

Yes. It is attempting to treat the symptoms, not the problem.

Aquabelle said:

Installing an amp meter is a good idea in its own right...but it seems like an odd response to an overheat-under-load problem. The NextGen is quality gear and should be comfortable running at 85-90% load near-continuous. Is it a problem to re-circulate Rydlyme or BarnacleBuster or diluted pool acid through the HX, if you have checked everything else in the raw water circuit?

Click to expand...

After discussing my problem with NextGeneration yesterday, I will be doing this very thing. As well as making sure the freshwater coolant is correct. We are suspecting there might be some blockage in the exchanger. Maybe some growth or perhaps impeller scraps. Either way, this is supposed to be a very robust genset. The generator side is the same hardware as the one with twice the KW rating with only a smaller motor. As it was explained to me, as the load nears max, the engine will slow, the voltage will drop (which, of course, cause amperage to sky rocket), and the motor will tank itself and shut off before it overheats. Adding also that this little motor can take temps as high as 250 degrees quite easily and that they set the thermostat at 225 to tip you off that there might be a problem needing attention.

Whatever happens, I still am sure an ammeter on the A/C side of my panel is a good idea for all the reason you guys have mentioned. Most especially because it's a pretty easy project that will pay dividends down the road.

"I still am sure an ammeter on the A/C side of my panel is a good idea for all the reason you guys have mentioned. Most especially because it's a pretty easy project that will pay dividends down the road."

Who is going to spend their cruising time observing this?

FF said:

Who is going to spend their cruising time observing this?

Click to expand...

Why is this any different than an oil pressure gauge or a tach or a temperature gauge?

FF said:

"I still am sure an ammeter on the A/C side of my panel is a good idea for all the reason you guys have mentioned. Most especially because it's a pretty easy project that will pay dividends down the road."

Who is going to spend their cruising time observing this?

Click to expand...

Being able to determine the current draw (and voltage) of both the AC and DC circuits on a boat would be pretty valuable if you're not one of the "turn the key and drive until it breaks" kind of people.

And as RickB pointed out, a lot like engine temperature and oil pressure gauges.

OK guys, here's a little money saving trick...

The doughnut thing is called a Current Transformer, or CT.
Every CT will put out 5 amps at full load. For Example if its a 100 amp CT then 100 amps flowing through a wire going through the doughnut will equal 5 amps on the leads of the CT.
Every amp meter is really a 5 amp meter.

So, To save money...

Find a CT on ebay in the range you're looking for,IE 50 or 100 or even 200 amps.
Find an ammeter on Ebay. the amperage is irrevelant.
Make up a new ammeter "face" using whatever software you want, or buy one. Make the face match the CT you bought and space the numbers out evenly, and you're there.

ksanders said:

OK guys, here's a little money saving trick...

Click to expand...

I'd rather spend the $31 for a 50A meter and CT and skip the hassle of taking the meter apart and kludging a homemade scale onto it.

But if you do find a dirt cheap 100:5 CT (if $6 isn't cheap enough) just run the hot lead through it twice and it becomes a 50A CT.

It's not like you are going to save $1000.

I'm thinking if you can't afford a proper ammeter, you probably can't afford the electricity you're planning on measuring.

And if you try to cobble one up from spare parts, you're going to have to buy or borrow a "real" one just to make sure your cobbled meter is accurate.

Wasn't the first successful airplane built from bicycle parts???

The forum is about sharing ideas...while some may not use all of them....some people do enjoy the budget ideas that are brought up here...

Not everyone stops by West Marine for coffee and parts every day....

Its funny because when you order an ammeter, someone pops the plastic face off and inserts the "scale" with the numbers on it, then ships it out.

Its not using spare parts, non standard stuff, thats just how ammeters work.

An ammeter is a very simple device and what someone linked to is "proper". What BlueSea has done is make something simple, complex and pricey. The $250 device I was looking at had voltage readings, high and low alarms for voltage and amperage, big LED display, and measured Hertz. I just don't need all that. I thought I did at first, but now I see it's just fluff. I am happy with $40 off eBay or $80 off Grainger.

"a lot like engine temperature and oil pressure gauges. "

These are easily available with adjustable settings to trigger an alarm , so the watch stander does not need a great scan. Murphygauge.

My point is with automatic load shedding there is NO monitoring.

Usually its only the HW heater that is the problem , so a single relay and a single control wire from the Air cond makes the noisemaker load regulation automatic.

Works great at a dock with crap power.

GonzoF1 said:

It seems that my genset (NextGen Power) wants to overheat if I load it to near capacity. It's only a 3.5KW and I need it to last (i.e. I can't afford a new one right now). I have looked at most of the usual suspects for overheating issues short of pulling off the heat exchanger.

I want to put an amp meter on the generator to monitor the load we put on it. I'd like to have a 2" round gauge to go next to my new battery monitor. Any suggestions?

Tom-

Click to expand...

Can you access or see your house AC breaker panel from where you want to locate the amp gauge? Ours is within visual distance from our circuit breakers. If we're monitoring loads, it's when we're at anchor or at the dock and with breakers close by, I can see what I want or don't want to run.

An other source for gauges is: Manufacturer of Quality Electrical Control Panels and Assemblies

GonzoF1 said:

An ammeter is a very simple device and what someone linked to is "proper". What BlueSea has done is make something simple, complex and pricey. The $250 device I was looking at had voltage readings, high and low alarms for voltage and amperage, big LED display, and measured Hertz. I just don't need all that. I thought I did at first, but now I see it's just fluff. I am happy with $40 off eBay or $80 off Grainger.

Click to expand...

It's not "fluff" just because you don't need the other information. Other people may well make use of the other measurements and warnings.

If you want/need a simple ammeter, yes, buy just that, a simple ammeter. Figure your total possible current draw (in amps) and buy a meter with a range as close (but above) to that as possible.