Measuring electrical loads

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SailorGreg

SailorGreg

Senior Member
Joined
Jun 21, 2014
Messages
180
Location
US
Vessel Name
Privateer
Vessel Make
Kadey Krogen 52
I have been looking for a way to accurately measure the amp draw of my fridge and freezer. They are both AC units and I dont have access to the plug so a simple solution using a receptacle device would not work. And it is tricky to measure usage over time for devices that cycle on and off.
I found a device at EKM Metering that is, admittedly, overkill for this application but it works. Too long a story for posting here but if anyone is interested I posted the article on my blog, mvprivateer.com.
 
SailorGreg said:
I have been looking for a way to accurately measure the amp draw of my fridge and freezer. They are both AC units and I dont have access to the plug so a simple solution using a receptacle device would not work. And it is tricky to measure usage over time for devices that cycle on and off.
I found a device at EKM Metering that is, admittedly, overkill for this application but it works. Too long a story for posting here but if anyone is interested I posted the article on my blog, mvprivateer.com.
Click to expand...
If it is AC you can temporarily connect a simple house main kw meter. You can easily find cheap ones.

L
 
If you can't get at the plugs, you must be able to get to the wires leading to the plugs at some point, no?
Besides, the units should have a rating for energy consumption and average wattage.

Personally, I was more concerned about the average daily consumption of all the loads that were inverter or directly battery powered myself.
 
Easy with a clamp-on ammeter. Measure current at the wire off the circuit breaker. Just make sure it is the only thing on that breaker.
Measure the voltage with a DVM at the breaker as well. Volts times amps equals watts. Watts times time is watt-hours.
 
yep, but my goal was to capture 24 hrs worth of data
 
A Kill-A-Watt meter and a bunch of jumpers and extension cord. Where there is a will there's a way.
Less than $30.
 
Last edited:
Yep, that meter works well if you can get at the plug. I cant. at least not without lots of work
 
Ok, can you get to the back side of the breaker that feeds the refrigerator?
Are you ok with working with de-energized wiring?
If not, stop here.
If so, send me a PM an I'll tell you how to do this pretty easily.
 
Thanks, all done already. My initial post was just to a blog reference for the way I chose to do it. Was hoping to get some easier/cheaper approach out there and some of the replies help.
I should have been more informtive w my initial post. My goal was to capture a full 24 hrs of power consumption for compressors that run intermittently and have wiring that is inaccessable, at least at the unit. So plugging in a kill-o-wat meter or clamping on a multimeter won't work very well. That said, it looks like there are devices out there cheaper than i bought. The unit I bought does have some nice features as it talks to my pc and creates a data base for later analysis.
My fridge and freezer are separate units. They cycle on and off, and run for different lengths of time based on how often they are opened, and probably how hot it is outside. I will run the test agian in the Bahamas/FL to measure the impact of changes in ambient.
 
SailorGreg said:
Thanks, all done already. My initial post was just to a blog reference for the way I chose to do it. Was hoping to get some easier/cheaper approach out there and some of the replies help.
I should have been more informtive w my initial post. My goal was to capture a full 24 hrs of power consumption for compressors that run intermittently and have wiring that is inaccessable, at least at the unit. So plugging in a kill-o-wat meter or clamping on a multimeter won't work very well. That said, it looks like there are devices out there cheaper than i bought. The unit I bought does have some nice features as it talks to my pc and creates a data base for later analysis.
My fridge and freezer are separate units. They cycle on and off, and run for different lengths of time based on how often they are opened, and probably how hot it is outside. I will run the test agian in the Bahamas/FL to measure the impact of changes in ambient.
Click to expand...

We were able to gain access to the back of our fridge by cutting a 12"X12" hole in the back wall. On KK48's, this is behind a mirror in the guest stateroom. I realize KK52's are different, so you may not be able to do this. After that, cleaning the dust bunnies off the compressor coils and testing with our Kill-A-Watt was easy.

We noticed that there was considerable variation from day to day on power consumption, with days when we opened the door a lot or restocked the fridge using more power. We tested our fridge for four days, but on reflection should have tested it for a week. Except for A/C which we run only on shore power or generator, we found that our fridge was the biggest power consumer on the boat.

Tanglewood have tested their their power consumption too, with similar results.
 
"we found that our fridge was the biggest power consumer on the boat. "

Except for air cond it is the huge power consumer on most boats.

Our solution an RV propane reefer works great , about a month on a 20lb tank , silent and sure.

With no need for a noisemaker , we still enjoy seasons on board.
 
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