Written by Ashley Davis Saturday, 23 April 2005 00:00
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 :
Battery charging monitor
Volts, amps and watts measurement
Connectivity to a computer to generate csv and xls files
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.
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.
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.
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:
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.
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.
( 3 Votes )