Hyperion Emeter Manual
by Mark and Phil Connolly for Hyperion HK

• This is a sophisticated unit which will be an important tool in your Electric Flight program. Please be careful with it!
• We recommend a case of some sort and, like any electronics, keep the Emeter well away from dirt or water.
• Take special care not to press on the LCD surface as this can cause damage
• See the notes on polarity below.  DO NOT reverse input polarity!
• Do not exceed a maximum of 60 volts for the flight pack

Terminology

• Emeter is the Electric Flight Metering Unit
• The shunt lead or probe is the device which connects the Emeter to the power system to be monitored. This has a Deans ULTRA plug and socket with an built-in low resistance shunt. 
• The flight pack is the set of cells used to power the model aircraft
• The ESC is the Electronic Speed Control which controls the speed of the model's motor(s)

Power and recharging

• The Emeter is supplied with an in-built 4 cell NiMh pack which will last about 6 hours before giving a Low Battery indication. If left on further without re-charging, this warning will disappear.
• All memorised data, including prop constants will be retained, even if the Emeter battery is fully discharged.
• The Emeter is re-charged simply by connecting it, via the shunt “battery” connector, to a flight pack of 6 to 20 Nicads/NiMh cells, or two to six Lithium cells. Alternatively, it may be connected to a car battery, taking full care to ensure the correct polarity. A lead which plugs in to the cigarette lighter in your car is recommended. The Emeter power switch must be in the 'off' position for charging to occur.
• Connection and use with Flight Packs of up to 60 volts is possible, but do not leave the Emeter continuously connected with these higher voltages or overheating of the charging circuitry may occur
• The flight pack must have a minimum of 150 ma-h spare capacity
• From a fully discharged state, charging will take between 6 hours for a 12 cell  Nicad/NiMh cell flight pack (20 ma),  up to 12 hours for a 6 cell NiMh/Nicad flight pack (10 ma).

Shunts

• Two shunts or probe leads are available one for currents of up to 100 amps and one for 20 amps. The former is suitable for high power motors, but will have less accuracy for measuring low currents such as those used for indoor flight.
• The figures of 20 and 100 amps are indicative only and are not necessarily the maximum figures which can be recorded by each probe
• For continuous use, it is recommended that you limit the current through the shunt to about half the shunt rating; it is normal for the shunt to become warm during high current measurements
• If the maximum current for the given shunt is exceeded, then no damage  will occur, but the unit  will indicate '>Max' in the Amps and Watts displays. Motor efficiency will not be shown under these circumstances 
• The 20 amp probe is for use with lowered powered models and will give more accurate readings when measuring charged or discharged capacity of packs at low currents. We recommend it for monitoring of battery charge/discharge cycles
• The Emeter detects which shunt or probe is in use and shows this briefly at startup. It also displays currents differently with 2 decimal places for the 20 amp probe but only one for the 100 amp case.
• Note that, due to manufacturing tolerances, interchanging probes between two separate Emeter s may cause variations in current readings. These can be overcome by a special calibration facility, covered later

Modes of Operation

On switching on, the unit will display a Startup screen for 2 seconds, before displaying the Tacho screen. 

All monitoring modes refresh the display each second and may be used to transmit data to a personal computer via an optional interface

Tacho Mode

• This is the first mode displayed after startup. The Emeter assumes a two bladed prop. Press button C to change this to alternatives in the range of 1 - 7 blades. The higher blade counts are for ducted fan units. It may not be possible to measure ducted fan speeds when installed in a model, depending your duct design and available lighting.
• Tacho mode does not require a shunt or probe to be plugged in. Beware of using the tacho with strong fluorescent lighting which will give false readings, such as 3000 or 3600 rpm.
• The RPM sensor will function over a large range of propeller sizes, RPM and lighting conditions. Experiment with the different sensor positions, but avoid pointing directly at bright sunlight. With the motor running, move the optical sensor at the top of the Emeter to about 10 - 20 cms of the prop., taking all due care. Small propellers may require closer positioning.
• The unit will display a 2 bladed prop speed to the nearest 15 RPM, if turning at below 9,000  RPM or to the nearest 30 RPM if above. For 3 or 4 bladed props, these figures are reduced proportionally. It is normal for the tacho to take about 3 seconds to give a steady reading, while it counts the revolutions to this level of accuracy. Wait for a steady reading to occur.
• The button D (hold) may be used to hold the present values on the screen .
• If you know the constants for the prop in use, then these may be entered by pressing button C. Instructions for this step are given later. On return to the tacho screen, the Emeter will show the output power of the motor in both watts and BHP. Information on prop constants may be found on the Hyperion Website.

Motor Mode - Part 1

• Motor mode is selected by pressing button A. This will show the voltage, current and RPM of a motor when running. To set up for this mode of use, connect the Emeter to the flight pack and ensure that the Rx pack (or the BEC switch) is turned off. Connect the ESC to the Emeter unit, taking precautions to keep clear of the propeller. Switch the Transmitter on and select motor off stick position. Switch the Rx pack/BEC on and, with the model secured firmly, move the tacho sensor into position. Switch the motor on via the transmitter and voltage, current and  RPM will display, along with the input power to the ESC
• The button D (hold) as usual, may be used to hold the present values on the screen and, on pressing a second time allows the activity to continue as if no interruption had occurred
• Note that motor mode will not record a current which is flowing in the opposite direction to that expected. (unlike Battery Mode)

Motor mode - Part 2 - Efficiency measurement

• The input power to the ESC and motor is simply the product of the voltage and the current and is shown expressed in watts. The Emeter allows for the capture or entry of two propeller parameters. The first of these is here termed the ‘prop constant’; it is determined, largely, by the prop pitch, diameter, number of blades, and prop shape.
• The second parameter is a ‘power factor’ which is often given a value of 3.0 to indicate an exact cube law relationship between the power required to drive the prop and the RPM which result.
• With the Emeter, it is possible to specify power factors other than 3.0 for increased accuracy. Further details of the actual values and use of these parameters are given on the www.hyperion.hk website.
• The formula used for calculation of motor output power parallels that used by various computerised Electric Flight performance simulators and can be determined by the measuring the propconstant and the power factor
• In order to set these parameters, press button B (Cfg - Configuration) when in Motor Mode. This will display the existing values. You may then increment or decrement the Prop Constant and Power Factor figures by buttons B and C, using button D to skip to the next number to be changed. When you have the correct values, press button A to save these results.
• On returning to the Motor display, the Emeter then calculates the output power and expresses this as a percentage of the input power, thus giving an efficiency for the ESC, wiring, connectors and motor
• If the prop constant is not entered, or yields a result which exceeds 100% efficiency, then the efficiency line will not be displayed on the motor mode screen
• Any prop parameter values entered will be retained by the Emeter , even after switching off

• Note that prop constants may be entered after the volts, amps and  RPM measurements have been memorised - see the 'Useful Tricks' section later
• Beware that these efficiency figures are only as accurate as the data supplied for prop constants. We are continuing to test various brands of propellers in order to build an accurate database of prop constants, so please check the site from time to time.
  
  The Emeter gives a measure of the overall efficiency of the motor, the controller the wiring and the connectors. For low cell counts and high currents, this overall efficiency may seem much lower than you might expect. While some motors are capable of attaining 80% efficiency under ideal circumstances, the way we load motors in RC use often means that efficiency will be much lower.  What is more important, however, is that you now have a tool to quickly and accurately COMPARE different combinations.

Battery Mode

• This mode can be selected by pressing button A twice after startup and allows either or both of the charged or discharged capacity of a flight pack to be measured. It is intended to supplement cheaper battery chargers which do not have such recording capability
• Connect the Emeter probe between the charger and flight pack, select Emeter battery mode and commencing the charge or discharge as normal on your charger. Set the Emeter timer running by pressing button C (start) - the clock will record seconds, minutes and hours. If needing to conduct lengthy test over many hours, then first ensure that the Emeter NiMh cells are  fully charged
• While the timer is running, the milliamp hours will be accumulated and displayed either as an 'in' or an 'out' figure. Pressing the button C (which now says 'stop') will stop both the clock and the accumulation. This would allow you to have a temporary pause in the timing.
• The button D (hold) as usual, may be used to hold the present values on the screen and, on pressing a second time, allows the activity to continue as if no interruption had occurred
• During the charge or discharge, the peak and latest battery voltages are displayed. This is especially useful as an indication of when a peak detect charge is about to stop

• Button B (Clr) allows for readings to be zeroed
• If a charger is in use which allows a charge and discharge cycle of the flight pack, then both cycles will be recorded

Memory

• Any combination of tacho, efficiency or battery displays may be stored in one of five sets of memory numbered 1 - 5. To store data, first select button D (hold) on the activity being monitored. Button C will change to save and when pressed, will take you to the memory screen.
• By default, the cursor will be positioned on the first vacant memory number. Press button C again to save in this location or Button D (next) to select a different memory, followed by button A (Save)
• You will be informed of the memory location used to save the data, and the Emeter  will automatically switch back to the original display and continue the monitoring process
• Memorised data may be recalled by pressing button A until the memory screen is shown and selecting the required memory number by pressing button D (next)
• Memorised data is retained even if the Emeter is switched off. In order to clear unwanted data, switch to memory mode, select the required memory number  and, with the data displayed, press button C (Clr) 

Special Features

Calibration – the Emeter comes with a default factory calibration of the voltage and current measurements and these will be sufficiently accurate for most purposes. The currents displayed with either shunt, however, are subject to manufacturing tolerances in the shunts and you may observe small differences if, for example, you borrow a different shunt.

Follow these steps if you wish to recalibrate your shunt, or have made you own custom shunt:

• To switch to calibration mode, press both button A and B, whilst switching power on to the unit. Release the buttons to display the Calibration Screen. If you know the calibration values to be used for current and voltage, then simply use the 'increment' , 'decrement' and 'next' buttons B, C and D to set these values. If you do not know the calibration values beforehand, then connect the Emeter into circuit with a constant voltage and current which is also monitored by two independent, accurate, meters.
   
• With no current flowing, use buttons B and C to increment or decrement the voltage until it matches the standard meter. Press button A 'save'. This is a permanent change which cannot be undone, except by repeating the calibration steps. 
• In order to prevent accidental recalibration, you will be asked to repeat the 'Save' command this time pressing button D. Once this is done, your new setting will be retained for all further Emeter use. If you do not wish to proceed with the re-calibration, then press button A 'Esc' instead of the repeat 'Save'
• Use button D (Next) to switch to Amps calibration and repeat the above procedure. Note that it is possible to calibrate both a 20 amp and a 100 amp shunt separately
• Re-zero amps under some circumstances (usually incorrect connection sequence) you may have a value in the amps readout of the battery or efficiency modes when no current is actually flowing. This can be corrected without switching the unit off, by pressing the button B for at least two seconds. You will receive a message indicating that amps have been re-zeroed and may then continue to use the unit. This has no bearing on the amps calibration described above, although, without the re-zeroise, the actual amps readout would be affected by both features.

Useful Tricks

• Increasing Measurement Accuracy – for most motor measurements, you will find that the voltage and current can change significantly during the first 3 seconds of motor run. It is wise to wait for 3 seconds before holding data via the button D.
• Efficiency and part throttle use The Emeter can be used to show the effect on efficiency when operating at less than full power. For various reasons, brushless systems in particular will usually have reduced efficiency when operating at part throttle. This may be observed very simply using the five memory locations. First, clear all memory locations on the Emeter.  Couple up the unit in the normal manner for efficiency measurement and input the prop constants.
• Now set the motor running at full power and press the hold button (D) once and the save button (C) twice. Throttle back slightly, wait for the RPM to steady and repeat this save process up to five times. Switch off, disconnect the Flight Pack and study the memorised results by recalling memories 1 - 5. You may be surprised at what you find!
  
  Beware running a powerplant for lengthy periods on the test-bench at partial throttle with an ESC which is close to its maximum rating. Extra heat may well result from the part throttle operation and cause damage to the ESC or motor.
   
• Deriving your own prop constants If you have a prop with an unknown prop constant, then you can get an approximate value by running the powerplant with a known  prop which gives a similar load (ie amps draw) on the same number of cells.
• The voltage and current determine the efficiency of a motor, regardless of the prop which is being driven. However, small variations in the voltage and current will not cause significant changes to the efficiency.
• Use a trial and error approach in setting the prop constant for the unknown prop until you match the efficiency given by the known prop. For example, if  the known prop gives 75% and the unknown prop gives 65%, then for your second trial, increase the prop constant figure by 75/65 and then retest.

The Emeter simplifies the 'trial and error' process. Record the volts, amps and RPM in one of the five memory locations as previously explained. Dis-arm the powerplant and disconnect the Emeter (you may even switch it off, if you wish to carry out this process at a later date). 

Now call up that memory location where you have recorded the motor performance data and press button B (Cfg). Set the new values for Prop Const and Pwr Fact as described previously and then press 'Save (button A). You will now be returned to the Memory Display screen with the new efficiency figure re-calculated

• Assessing Battery Condition The battery condition plays a most important part in Electric Flight performance. If you have a standard load, perhaps comprising car headlight globes, then you can use the Emeter to monitor trial discharges, using the 5 memories.
• The two factors of interest will be the voltage (which determines the performance  level of the model) and the milliampere-hour capacity (which determines the flight time)
• Suppose you want to simulate and record the performance for a 4 minute full power flight. Start the discharge and the timer clock and press the hold and save buttons at, say 10 seconds, 1, 2, 3 and 4 minutes. Make sure that the cells do not discharge below their safe minimum, eg 0.9 volts per cell for Nickel chemistry and 3 volts for Lithium.
• After the test is complete, record the results from Memory 1-5 along with details such as pack identification, date and temperatures. Remember that it is not only the milliamp-hours figure that is important, but also the voltage. Especially with NiMH cells, you can experiment with different charge temperatures easily recording results for comparisons.
• Keep your records and compare the flight pack performance from month to month to determine how well the pack is performing

Happy experimenting!


The Hyperion RC Team


The Hyperion Emeter is warranted against defects in material and workmanship for a period of 6 months from date of purchase.  For warranty or repair issues please contact your selling dealer.