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Medusa Power Analyzer Pro Review

John Warren shares some of the many capabilities of the Power Analyzer Pro and demonstrates a small fraction of the tests this new unit has the ability to conduct.

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Introduction to Medusa Research, Inc.

Everything in the Deluxe Package.
Everything in the Deluxe Package.
Power Analyzer Pro - Basic:$99.95
Power Analyzer Pro - Standard:$126.95
Power Analyzer Pro - Deluxe w/ US adapter:$186.95
Power Analyzer Pro - Deluxe w/ UK adapter:$193.45
Power Analyzer Pro - Deluxe w/ Australian adapter:$193.45
Power Analyzer Pro - Deluxe w/ European adapter:$193.45
RPM Sensor:$26.95
Temperature Sensor:$7.95
Data Recording Module:$27.95
Manufactured and available from:Medusa Research

Medusa Research is an engineering company that has over 75 years of advanced engineering expertise and several of the staff at Medusa are RC enthusiasts as well. Jeff Little, one of the Medusa owners, told me, "We saw a need for quality engineered products in the RC market so we started designing and developing products with the outstanding results as you see to date".

Medusa Research, Inc., was started by Jeff Little and a partner in 1994. Medusa was incorporated as an engineering/software-consulting firm and began their entrance into the RC market with brushed ESC’s, BEC’s and the Power Analyzer line. This company has also ventured into designing their own brushless motors and has come out with a line of brushless 28mm and 12mm motors called Afterburner's. There are a line of 36mm motors scheduled out sometime around April 2006 and as well as a line of 50mm motors slated to be released shortly after.

"With the Power Analyzer we were the first to introduce an interface to your computer from the meter so that you could record and graph your data. Since then we have changed the serial interface to USB and have introduced the Power Analyzer Pro, which, has additional sensor inputs and ESC control for repetitive testing.

A few years ago we realized that the electric RC market was about to expand. With Europe having 80% electric and 20% fuel and the US have 20% electric and 80% fuel and with the new batteries that were coming out then we saw a market ready to grow. From what we saw in the market for electric products, at the time, there was a real need for well-designed and well-engineered products. There was a need for products that not only worked, but also worked well and to specifications. So being the engineers that we are we set out developing products," says Little.

The Power Analyzer Pro testing system is complex and has the ability to measure many aspects of a power system. I will attempt, within the scope and limited size of this review, to reveal to you as much as possible about the Power Analyzer Pro system and its capabilities.

Introduction to the Power Analyzer Pro

The Medusa Power Analyzer Pro is one of the best units I've seen for accurately measuring data on electrical RC components. With the Medusa Research Power Analyzer Pro (PAP) there is no more guessing as to the performance of your electrical power setup.

The PAP system measures nine different parameters in real-time, including:

  • voltage,
  • current,
  • power,
  • amp-hours,
  • watt-hours,
  • RPM,
  • two different temperatures,
  • thrust

It also has the capability to control your ESC. The analyzer is more than just a wattmeter. It is a highly accurate capture device and the brain of the entire system. The PAP unit can transfer all the information it gathers to a computer through the USB cable and can be saved by the PAP software for later viewing.

The PowerPROview software, through the USB interface to the PAP unit, allows you to display and view plots as well as real time data through user configurable gauges. Using the PAP system to control your ESC, you can program a test sequence to automatically measure thrust or monitor any of its measured parameters at different throttle settings. Its broad measurement range and high resolution make it just as useful on your park flier as on your hotliner.

The PRO unit can also be updated easily and can stay up-to-date with the latest innovations from Medusa. Medusa Research will offer new versions of the PowerPROview software for the PC, FREE, when new features are added. In addition to the free PC software upgrades, the PAP system has the ability to upgrade the software inside the Power Analyzer itself. This is accomplished without having to send the Power Analyzer back to Medusa Research for reprogramming. Instead, the user can perform the upgrade in their own home by downloading the updates from the Medusa's website and reprogramming the PRO unit though its USB connection. Medusa refers to this feature as "ISP", for In System Programming. ISP allows the Power Analyzer PRO unit to be compatible with new PRO accessories and features that Medusa develops and releases in the future.

In addition to the free PC software upgrades, the PAP system has the ability to upgrade the software inside the Power Analyzer itself.

Contents of the Deluxe Package

Medusa Research offers the PAP system in mix and match packages to suit your particular needs.

I opted to purchase the Deluxe system, which included:

  • the PAP unit,
  • the USB cable,
  • the RPM Sensor,
  • the Thrust Cell,
  • the power adapter,
  • two temperature probes.

AN ADVANCE GLANCE AT THE DATA RECORDING MODULE

The PAP system also will soon have, as one of it's upcoming accessories, an in flight Data Recording Module (sold separately). The Recording Module will be released by Medusa in the very near future and is presently undergoing the final testing phase. This accessory is scheduled for review at a later time.

The Data Recording Module will increase the versatility of the Power Analyzer Pro. By mounting the Power Analyzer Pro with the Data Recording Module in your model, you will be able to monitor the in flight performance of your propulsion system, such as: Measure the difference in current and power when the model is stationary or moving. Record how hot your motor, esc or battery is getting when installed within your craft. You get the idea. The Data Recording Module stores 3-20 minutes of data depending on the amount of data being acquired and the amount of data readings taken per second. You will be able to download and display this data to your PC using the PowerProView and Power Analyzer Pro at a later time. This unit will sell for $27.95.

POWERING THE PRO UNIT

The Power Analyzer PRO can be powered 3 different ways:

  • through the USB port,
  • by the battery connected to the SOURCE side*,
  • through the PWR/EXT port on the SOURCE side of the case.

Having multiple ways to power the PAP is a nice feature -- it allowed me to measure small amounts of power without the power draw of the PAP unit itself.

The battery connected to the SOURCE side needs at least 6 volts to properly power the Power Analyzer PRO. A NiCd or NiMH pack will need at least 5 cells to do this, a Lithium pack will need 2 cells. If the battery connected to the SOURCE side has fewer cells or the measured voltage is lower than 6 volts, connect an external power supply to the EXT/PWR port. The EXT/PWR port was designed to accommodate the connector from a standard flight pack.

POWER-UP SCREEN

Upon applying power, the Power Analyzer PRO will boot up, briefly showing the Medusa research logo, then its PRO software version, plus the PowerPROview software can add a customized 16-letter string above the version to personalize your PRO.

MEASUREMENTS ON THE DISPLAY

The Power Analyzer PRO is able to display 9 separate measurements but because of limited space on the display, only 4 measurements are shown simultaneously. The PRO can change the measurements shown on the display at a user-defined interval; the Screen Configuration section gives details on how to make these changes to the PAP screen display. Each measurement may occupy 1 position on each screen.

The 9 different measurements are:

  • Voltage - 0 to 60 Volts
  • Current - 30 to 100 Amps
  • Thrust - 0 to 5000g or other Aux port input - 0.1 to 2.6V analog input
  • Temperature 1 - 0°C to 130°C
  • Temperature 2 - 0°C to 130°C
  • Power - 1800 to 6000 watts
  • Amp-Hours - +/- 999.999
  • Watt-Hours - +/- 9999.9
  • RPM - 60,000 for 2 to 7 blades

Measurements are obtained from devices connected to the input ports on the side of the PAP.

RPM SENSOR

The RPM sensor accessory is an advanced reflective type of sensor. Instead of relying on ambient light or a flashlight, the sensor has both an infrared emitter to bounce light off of the propeller or fan blades and an infrared filtered sensor detects the reflected light. This allows the sensor to be used under normal room lighting without the kind of interference from fluorescent light sources that plague other tachometers. The threaded holes on the sensor use 4-40 thread screws so it can be mounted close to spinning blades safely.

The RPM sensor should be mounted to a test stand no more than 7/8 of an inch away from the propeller of the system under test. Some experimentation may be necessary to determine the best distance and position before permanently mounting the sensor. I found it best to have the RPM sensor mounted with a flexible mount to make positioning the sensor easier.

The sensor can be affected by the color of the propeller or fan because it is a reflective type sensor. If there is a poor reading from the RPM sensor and the target propeller is a dark color, try either painting white stripes on the target area, or backlighting the sensor as described below.

On a narrow propeller target, the sensor can also be sensitive to how it is oriented in relation to the propeller. For best results, when the prop blade crosses the path of the IR sensor (shown above) it should cross the path of both the emitter and receiver at the same time. The sensor should also be mounted at the same angle as the propeller blade, otherwise the IR light beam will not return to the sensor as effectively and bounce away. A 90-degree angle to the face of the blade eliminates this problem. By paying attention to how the sensor is aligned to the face of the blade, I have not found a blade that could not be tested; even the orange GWS props test fine.

TEMPERATURE PROBE

The temperature probe accessory allows the user to monitor the temperature of vital parts during testing. A ring type mount was provided on the sensor end for bolting to motors or other surfaces. Alternatively, it is also possible to secure the sensor with tape for measuring ESCs, batteries or other devices. I found this to be a better method especially for motors. By placing the probe directly against the can of the motor, I was able to eliminate the possibility of the wood firewall (on front mounts) acting as a heat sink. For best results, the sensor should be shielded from heavy airflow (such as that from the propeller wash in airplane power setups). Thermal grease compound will improve sensor accuracy.

AUX PORT

The Aux port can be used in two modes. It will either function as a generic analog input for a user-defined sensor, or as a communications port for the Medusa Research Thrust Cell. The Power Analyzer was shipped from the factory in Thrust Cell mode.

AUX PORT AS AN ANALOG INPUT

If the AUX port is not used for the Thrust Cell, it can be configured as a generic analog input, with a linear input range of 0.1V to 2.6V. This port will be useful to those who have the know how to connect other devices electronically to the PAP unit. Using the PowerPROview software, the user can configure gain and offset factors to apply to the reading shown on the display and what is transmitted through the USB connection to the PC. The port will accept a standard 3-pin female inline connector with 0.100" pin spacing. A standard 3-wire servo cable will fit into the port as well. The Pin-out specs are listed in the users manual.

AUX PORT AS A THRUST CELL INPUT

The Thrust cell is a tabletop style scale similar to the Pelouse or other brand of postage scale. This scale has been given an interface to connect to the PAP unit electronically. The thrust cell pictured below is Medusa's example of how the thrust cell can be setup to conduct tests. Medusa recommends for accuracy that the stand be tall enough that the moving air dose not generate a significant pressure difference between the top and bottom of the stand. This could cause a false measurement by the thrust cell. Conducting tests with this method would require the reversing of the motor spin and mounting the prop for a pusher configuration.

ESC PORT

The Power Analyzer PRO allows you to control your ESC for automated testing through the ESC port. There is an ESC section in the PowerPROview software, where the user can manually control the ESC through the PC, or even create custom throttle profiles to make perfectly repeatable tests for comparing different setups. This is a very cool feature of the PAP system and takes the safety level to a new height. No more fumbling with the throttle on the transmitter. Throttle settings can be set to specific percentages in step values, full on / full off sequences, as well as other default tests that come enabled with the software.

Minimum System Requirements

Medusa recommends the following:

  • 400mHz Pentium II or equivalent,
  • 128mb RAM,
  • 50 mb free disc space,
  • 800x600 minimum graphics resolution,
  • USB v1.1 compatible port
  • Operating systems supported: 98SE, 2000, or XP

BEFORE CONNECTING THE POWER ANALYZER PRO TO YOUR COMPUTER: Download and install the latest Power Analyzer PRO compatible software from Medusa's site.

The computer I have setup for the PowerPROview software is my Toshiba Satellite Pro laptop, 350mhz Pentium II, 64mb RAM and 640x640 display. I have had no problems running the software on this computer.

MY TEST RIG

I wanted to have a way of easily changing motors and have the ability to eliminate any possibilities for any outside force to effect measurements when I designed my test rig. Medusa's example of a test rig (pictured above), I imagine, is OK for those who test small motors. But, I wanted to have a setup that would accept large as well as small motors effectively and not be too large to store away or have a need for a dedicated section in my hanger to operate.

Basically, I came up with a test platform which is fairly compact with interchangeable motor mounts and sturdy enough to handle the swinging of large props. I opted to have the motor orientation the same as it would be in a plane. My idea was to have a mock firewall front on a horizontal plane without the worry of gravitational pull effecting thrust tests. This firewall front would be mounted to a piece of plywood and would need to have the ability to slide without any drag. To accomplish this I found a set of side mount drawer slides (# KV 8400) with a 100-pound rating, they are manufactured by the Knape & Vogt manufacturing company and fit the bill nicely. All the motor mounts are interchangeable and attach to the plywood slide with bolts and blind nuts.

The drawer slides, slide very easily! When I mounted the slides to a piece of board, I placed 15 pounds of books on them and used a digital hanging scale to measure the force it would take to pull the books. One gram of pull force was needed to pull the 15 lbs. of books. I felt confident the slides would not impose resistance in a sliding apparatus to mount the mock firewalls to and the resistance it did impose would be very minuscule.

When a motor is run for testing, it slides forward, and pulls against a rocker arm, to transfer the force of thrust to the thrust cell. The rocker arm was balanced with a prop balancer then a pull test was done to make sure 1 pound of pull = 1 pound of thrust on the Medusa thrust cell. I used my digital hanging scale to pull the rocker arm against the thrust cell. A pattern of holes was drilled into the front lower section of the rocker arm and used a piece of piano wire in each hole until I found the correct point that transferred the correct amount of thrust to the thrust cell. By switching both scales to kilograms, I was able to further refine the transfer. The rocker arm is connected with a ball bearing on a piece of piano wire for a drag free pivot.

More information about thrust rigs and conducting tests can be found in the following threads: The Power Analyzer Pro
How do YOU measure thrust?

A TEST RUN

Once I had built a test rig, I chose a setup to run. I ran several tests on the AXI 2820/10 brushless motor using a 3 cell, 11.1V Kokam 3200mAH LiPo, with an 11x7 folding Aero-naut CAM prop. The test runs in the video's below are with this setup.

I wanted to conduct tests on this power system because I was considering using it in a Skimmer. The skimmer kit was purchased from Hobby Lobby and the build can be found in the "skimmer 600" thread.

Before I purchased the PAP, testing a power setup was quite laborious. Glancing back and forth at the scale, then the digital thermo, then the watt meter, was very tedious. By the time I had a measurement written down and glanced back at a different meter things had changed a bit. Very difficult to do this in a safe manner as well, since most of the metering devices where so close to the spinning prop.

Now with the PAP system, I hook everything up and move back to a safe distance and monitor everything from my laptop computer. The ability to control the motor through the ESC, from the laptop, is a real cool feature of the PAP system. Step tests can be run from the waveforms section of the PAP program or control the ESC manually.

MANY DIFFERENT TESTS CAN BE RUN

VIDEOS

Downloads

Conclusion

I am personally blown away by this device! It's like hitting the lottery when it comes to the different tests that can be run with this product. The tests that I have shown in this review are a small part of the tests that can be run using the PAP. Even though the unit is very complex and has many capabilities, I found it very easy to use. Any questions I did have about the unit where answered by the help files within the PAP software.

Since a young child, I have always wanted to know how things work and the Power Analyzer Pro has definitely become a highly prized tool to enhance my technological curiosity! The product appears to have been well thought out in the aspect of a beginner’s tool as well. As a start-up option, you can buy the PAP unit by itself and add accessories to it later. As new accessories from Medusa become available, like the Data Recording Module, any upgrades or enhancements to the PAP system can be downloaded from the Medusa web site and loaded up via your computer. I like the capability of upgrades and knowing that the PAP will keep up, when new accessories become available.

My first wattmeter was an AstroFlight and it was a great tool for knowing what you need to know about what was going on with the electrical system. But, the Power Analyzer Pro system really takes power testing to a new, safer, level, with its capabilities of storing and recalling the data at a later time.

One other thing I was impressed with, was the AUX port on the PAP unit. Not only is this the port used for the thrust cell, but also this port is configurable for the end user to use devices by other manufacturers. Medusa was not stingy with the information on how to use it either. I was really impressed by their willingness to release the details of how to configure this port so other devices could access it and even more impressed by the help that I witnessed them give to other owners of the PAP and how to use it, when they had questions. You can find the pin out information for this port listed in the users manual. Other technical information about using the AUX port can be found in the "Power Analyzer Pro" thread located in the Medusa forum, here on RC Groups.

This is a very nice product! I will recommend it to anyone that may be looking for a lot more than a simple wattmeter. However, if a simple wattmeter is all you're looking for, it will do that too. Like other wattmeters on the market, the Power Analyzer Pro will fit in your flight box ready for the field. The PAP unit can operate as a stand-alone device, it's not necessary for the PAP to be connected to a computer to work.

Discussion

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Old Feb 02, 2006, 12:05 PM
When I'm not flying......
toni.b-r's Avatar
Emsworth, UK
Joined Jan 2004
103 Posts
I have been involved with running some tests on various MP Jet motors recently, and had the use of a PowerAnalyserPro with RPM sensor and Temp sensor. I concur with everything in this article, and add that playing with the data in Excel to display EXACTLY what is required is the most fun I've had in a long time (sad person!). I use a thrust rig with manual scale - I haven't had the time to take it to pieces to see if I can find an output I could tap into for the AUX port - later, perhaps.
The Temp sensor I just screw onto the firewall mount - It may not be precise, but it gives a good indication of how the motor is warming up or cooling down, and is easy to change with the motor.
I used masking tape on the back of the props to ensure good RPM readings.
The ability of the software to manage the ESC is great - repeatable throttle settings for each motor with each of five props on each of two batteries gives total comparison capability.
I did have a problem programming the ESC (Castle Creations Phoenix 10) for LiPo and NiCd, but an email to them sorted that fairly quickly. There were also a couple of occasions where I had to connect USB, battery and motor in the correct order to get everything to work properly, but I now have a sequence worked out that is repeatable.
All in all, it is a really good piece of kit.
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Old Feb 02, 2006, 01:40 PM
Just one more plane!
JWarren's Avatar
Port Saint Lucie, Florida, United States
Joined Aug 2004
2,537 Posts
Hi Toni,

Thanks for taking the time to post your experiences with the PAP!

Nice thrust rig you have there! You could try checking the voltage to the digital readout on your scale and trace backwards. I'm sure eventually you will come across the variable voltage that will fall in the input range of the AUX port of the PAP. A resistor may be needed to bring the voltage down to the range required once you find it. I'm not not much of a electronics technician, so I really couldn't tell you exactly where to look. But maybe that will help out anyway.

I am going to make a dongle of test leads with probes and clips so I can use the PAP as an electronics test meter as well. Then I will be able to clip on to the negative trace on the PC board and use a probe to search the board. I could even graph the search process and put labels of each component on the graph where the reading occurred. Since the PAP can be powered by an external power supply, it has the ability to measure small currents.

Thanks again for posting!

John Warren
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Old Feb 03, 2006, 11:02 AM
Fly a LiL' Lower Will Ya!
mrm1's Avatar
North Central Florida
Joined Sep 2004
4,811 Posts
Very nicely written John. Med has always been on the top of my list and I will be watching for the release of that in flight recorder. That may very well be the deal clencher (althought at the moment I am broke anyway so I am not getting any RC stuff for a while)

But good info. Thanks for your effort.

Mike
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Old Feb 03, 2006, 11:44 AM
Just one more plane!
JWarren's Avatar
Port Saint Lucie, Florida, United States
Joined Aug 2004
2,537 Posts
Thanks Mike
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Old Feb 07, 2006, 05:13 PM
Registered User
Breuillet, France
Joined Aug 2005
167 Posts
I am thinking about buying a power analyser plus. When avalable I would like to use the data recording module in small planes or electro-gliders (less than 1 kg. I understood that I will have to put in the plane the power analyser and the data recording module. Does everybody knows how much the power analyser weights, because it could be a problem for me ?

Thanks

Hal1
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Old Feb 07, 2006, 10:54 PM
Just one more plane!
JWarren's Avatar
Port Saint Lucie, Florida, United States
Joined Aug 2004
2,537 Posts
Hi Hal,

I'm not sure if the recording module can be used with the Plus system or not. You might check with Medusa before you purchase just to be safe.

The Pro unit weights:
4.3 oz. / 122 grams

Hope that helps!

John
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Old Feb 09, 2006, 05:08 PM
Registered User
Breuillet, France
Joined Aug 2005
167 Posts
Thanks John,

122 grams, it is too much to put it in a small plane, I hope it is possible to take only the recording module in the plane and to store the datas in it without taking the Plus system in the plane. I will ask to Medusa.

Hal1
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Old Feb 09, 2006, 10:10 PM
Just one more plane!
JWarren's Avatar
Port Saint Lucie, Florida, United States
Joined Aug 2004
2,537 Posts
Roger that! Good luck!
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Old Mar 09, 2006, 03:00 PM
Registered User
Joined Dec 2003
4 Posts
Analyser Realtime PC Viewing

Hi Gents,

I could not tell if you can view the data on the PC real time. I know you can store the test file but for me I need to be able to do both...

Can it do that ?

thanks in advance,

pete
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Old Mar 09, 2006, 07:45 PM
Just one more plane!
JWarren's Avatar
Port Saint Lucie, Florida, United States
Joined Aug 2004
2,537 Posts
Hi pete,

Welcome to RC Groups!

Yes you can view the data in real time as well as save the data or export it to other programs.

The real time screens are customizable with lots of gauges and meters to select from.

Hope that helps!

John
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Old Nov 14, 2006, 03:50 PM
Registered User
bob_nj's Avatar
Vineland, N.J.
Joined Sep 2003
740 Posts
Diggin it up

Sorry to dig up an old thread, but I'm having some difficulty with an older
PA+ while trying to charge, discharge and plot some info using a Triton and the view software.

I have a USB to Serial adapter that seems to work OK with everything else I use it for.

I can't seem to get any discharge info to plot.
Here is another thread that isn't getting any attention.

Maybe one of you guys can help

Thanks_bob

Discharge Curve Link
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Old Nov 14, 2006, 04:41 PM
Just one more plane!
JWarren's Avatar
Port Saint Lucie, Florida, United States
Joined Aug 2004
2,537 Posts
Hi Bob,

Not a problem digging up an old thread.

I' am not fimiliar with the PA+ unit. But maybe this will help.

I know with the PAP unit, when you graph discharge voltage, the voltage shows on the graph to the positive. When you graph charge voltage, the direction of the voltage is opposite that of discharge and shows on a graph to the negitive (below zero). There may be the possibility that your are not allowing the graph to show voltages below zero.

Check your graph XY settings and change them from 0 to, lets say -100 and then see if your charge voltage shows on your graph as it should below zero.

If that dosent work, MedUSA will answer you in the forum that you posted into.

John
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