My thanks to David of Aircraft-World for the supply of the Emeter for review.
The Hyperion Emeter is a small device designed to be used to measure all
of the important variables in setup of electric aircraft and helicopters.
This review will cover the helicopter relevant parts of the device but
I will make mention of the additional functionality for those who also
fly planes.
To give some perspective to what is being reviewed, here are a few of pictures
of the Emeter :
The device is really quite small, fitting into the palm of the hand or
a pocket very easily. The dimensions of the device are approximately the
following : 10cm x 5cm x 1.5cm
An easier comparison would be to say that it is the size of a modern mobile
phone. AirCraft World's website contains a very nice data sheet which summarises
all the functionality of the device so rather than retype all the information,
here is a link to their data sheet.
For the purposes of this review I have experimented with various functionality
on the device and compared the data to that of the Medusa Power Analyser
to see if the devices agree on the values measured. However, it should
be noted that the Emeter has more functionality than the Medusa Analyser
so I have also had to test the tachometer against my own separate tachometer
to check that the devices are measuring within the same RPM range.
The following functionality has been tested :
Tachometer
Battery check
Battery charging monitor
Memory
Volts, amps and watts measurement
ESC programming
Connectivity to a computer to generate csv and xls files
Battery Check
This is one of the simpler functions of the device and actually quite clever
in terms of what effect there is on the Emeter from connecting a battery.
To explain this further, the Emeter will give a volts reading for the pack,
fairly normal. However if you turn off the Emeter using it's side switch
and leave a lipo connected it charges the Emeter's internal battery. Very
neat idea. The Emeter has a 4 cell NiMh battery, which from fully charged
will last approximately 6 hours before the low battery indicator comes
on. The charging circuit is capable of being connected with up to a 60V
battery but with these high voltages overheating may occur if left plugged
in continuously. The charging process takes approximately 6 hours from
fully discharged.
A quick shot of the battery checking screen is below :
The data displayed gives you the current voltage and the peak voltage since
connecting the battery.
Battery Charging Monitor
This uses the same screen as the battery voltage checking screen. The Emeter
is connected between the battery and the charger and records the mAh supplied
to the battery by the charger. The Emeter comes with what is called a 'shunt'.
This is a small device on the end of a cable that plugs into the circular
DIN connection at the bottom of the Emeter. The shunt can be 20A or 100A
and depending on which you buy this specifies the maximum current it can
handle. For applications such as the T-Rex the 100A shunt is the correct
rating. A picture of the shunt can be seen below :
The battery charging mode can be used to monitor both a charge and discharge
and in each case the appropriate mAh figure (mAh in, mAh out) will be updated
to reflect the charge or discharge status. In order to test the accuracy
of the Emeter I monitored the charge of a Kokam 2000mah pack and compared
the two status panels on the charger and Emeter. I stopped the Emeter timer
a minute late, which is my fault rather than any fault with the Emeter's
timer. The results can be seen below. The Emeter was less than 1% away
from the chargers reading, which is excellent.
ESC Programming
The Hyperion brand also manufacture the Titan ESCs. All of these ESCs can be programmed directly by the Emeter. A small separately purchased cable plugs into the side of the Emeter and connects to some gold pins on the Titan ESC. Once connected the Emeter can be switched on and immediately goes into ESC programming mode. The Emeter will display all the settings for the Titan ESC and all can be changed very quickly and easily using the buttons on the Emeter. This is one of my favorite functions on the Emeter as it is so quick and easy to reprogram the ESC, particularly with all the motor and lipo changes that I go through when testing motors/lipos for TrexTuning.
The entire sequence of ESC programming can be seen in the below run of
pictures. There are ten options in all, each of which can be changed by
pressing the 'cfg' button highlighted on the screen. Paging through the
settings in achieved buy pressing the 'next' button. At any point you can
press the 'esc' button which downloads all of the settings into the ESC.
The connection for the ESC cable and the cable itself are pictured below
:
The entire sequence of ESC programming can be seen in the below run of
pictures. There are ten options in all, each of which can be changed by
pressing the 'cfg' button highlighted on the screen. Paging through the
settings is achieved by pressing the 'next' button. At any point you can
press the 'esc' button which downloads all of the settings into the ESC.
Tachometer
The Emeter has a small sensor on the top end which is in fact the Tachometer
sensor. The Emeter in tacho mode will allow you to select from 2 to 7 bladed
props. Obviously for T-Rex we specify two blades. The tachometer works
very well, even in limited light where getting a reading can become difficult.
The Emeter sensor appears to be quite sensitive and so far I haven't had
any problems with getting a reading regardless of the lighting conditions.
The 7 bladed option is mainly for ducted fans and it's unlikely these higher
bladed options would ever be picked for a helicopter. Having checked the
Emeter aginst my standalone tachometer the accuracy of the Emeter tacho
function is fine.
Memory
The Emeter has five inbuilt memories which can hold the values at a single
point in time from either the tacho, efficiency or battery displays. The
data is saved and can be recalled later from the memory positions labeled
1 - 5.
Volts, Amps, Watts and RPM measurement
The Emeter can be used as a standalone point in time device to display
amps, watts, volts etc etc or it can be used with PC software to record
values over time to generate graphs.
The Emeter can be connected to a serial cable and that serial cable into
the port of a computer. In my case I had to extend the cable using an RS232
to USB converter cable as I use a desktop and the standard cable is really
quite short and intended for use with a laptop alongside the model being
monitored.
Once connected the Emeter software can be started and a connection made between Emeter and PC. The software now records all of the data that the Emeter is capable of measuring against time into the PC software program. A couple of pictures of the PC program can be seen below:
The first graph shown is amps plotted against volts, which doesn't make
for very sensible reading but does show that you can pick any measurement
to be on the axes. The second picture shows amps against time which is
a more sensible graph. The axes can be changed as required to plot what
ever data the Emeter has recorded. The software will also output the data
to CSV or XLS file formats. This is where I have been experimenting with
the software to produce graphs showing similar information to that produced
for my motor tests using the Power Analyzer from Medusa Products. Due to
the use of XLS format I have been using the charting capabilities of Excel
to display the recorded data in different graphs and overlayed onto a single
graph. Which is all very useful if you are familiar with the workings of
Excel.
I'm still working on my own custom charts which I hope to use here on T-Rex
Tuning in future motor tests but the fact that this device can measure
volts, watts, amps and RPM gives it a significant advantage in the market
of power analysers which typically don't measure RPM but do cover the other
more obvious electrical values.
As an example of the graphs I'm working on (but made possible by this software) here is a simple volts/amps against time chart and below that an Amps/RPM against time chart (based upon this CSV file created by the Emeter software) :The second chart is a little odd in that
I accidentally obstructed the tachometer and the RPM is seen dropping to
zero in a couple of places but for illustrative purposes I think it shows
the power of the software created CSV file.
Additional Functions for Planes
The Emeter can measure efficiency of a motor by using the input of prop
constants. There are two values that can be input, the 'prop constant'
and the 'power factor' which is preset to three (because of the cube law
relationship between RPM and Watts). Both values can be input and changed.
If the motor is then run with the tacho recording RPM and the Emeter shunt
recording watts, amps and volts the Emeter can calculate the output power
as a percentage of the input power, giving an efficiency measurement for
the motor, wires and ESC.
Conclusion
Given the wealth of functionality and the fact that it all fits into a
hand held device no bigger than a mobile phone I can't think of a more
useful multi-function device in the world of electric helicopters. Since
receiving the Emeter it has been in constant use on all of the site test
models and has proved itself to be an invaluable tool. Being able to just
slip this into a pocket but in doing so have to hand a tacho, battery monitor,
charge/discharge monitor and ESC programmer (providing you have a Hyperion
Titan ESC) cannot be under valued and the Emeter is now firmly in my list
of essential equipment and a permanent part of my field box. Added to this
the connection to a PC gives me the opportunity to do in depth analysis
of motor and battery perfromance and produce charts to my own specification
due to the CSV file creation. Due to all of this the Emeter comes very
highly recommended.
If you own the Emeter please use the TRexTuning rating system to rate it
below :
