Selecting Electric Power Setups John Hoddinott, 21 May 2015 Components of the Setup Brushless Motor Electronic Speed Controller (ESC) Battery (Usually LiPo, but could be NiCad, NiMH, LiFe, etc) Propeller ConnectorsWiring Why Brushless
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01
Selecting Electric Power Setups John Hoddinott, 21 May 2015<br>
02
Components of the Setup Brushless Motor
Electronic Speed Controller (ESC)
Battery (Usually LiPo, but could be NiCad, NiMH, LiFe, etc)
Propeller
Connectors/Wiring<br>
03
Why Brushless Motors? Brushless motors offer several advantages over brushed DC motors (according to Wikipedia!):
high torque to weight ratio
increased efficiency
increased reliability
reduced noise
longer lifetime (no brush and commutator wear)
reduction of electromagnetic interference<br>
04
Size Matters!<br>
05
Why is the Setup Important? Performance
Efficiency (longer flight times/smaller & cheaper batteries)
Safety<br>
06
Getting it Wrong!<br>
07
Some Definitions V - Voltage (Potential Difference) in Volts (V)
I - Current in Amperes (A)
P - Power in Watts (W)
P = V x I (Ohm’s Law)
RPM - Rotations per Minute
kV - RPM per Volt
mAh - milliamp hours (a measure of battery capacity)
C rating - A measure of the discharge (or charge) rate of a battery as a multiple of its capacity<br>
08
My Process Estimate Power Needed
Decide on Maximum Flying Speed
Calculate Ideal Thrust
Calculate (or Measure) Maximum Propeller Diameter
Select Preferred Battery Voltage
Find a Setup
Test/Check the Setup<br>
09
Step 1 - Estimate Power<br>
10
Step 2 - Flying Speed<br>
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Step 3 - Thrust How much thrust do we need to fly?
Less than you might think!<br>
12
Step 3 - Thrust to Weight Examples<br>
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Step 4 - Propeller Diameter Bigger is better (usually)<br>
14
Step 5 - Battery Voltage Use Ohm’s Law to calculate the battery voltage that provides the desired power with sensible current level.
P = V x I
Therefore V = P / I
But what is a sensible current level?<br>
15
Step 5 – Battery Current Capacity Battery current capacity is calculated by multiplying the pack capacity (in mAh) by the C rating.
Example – a 2200 mAh pack rated to 25C can produce:
2200 x 25 = 55,000mA = 55A<br>
16
Step 5 - Connector Current Capacity Deans - 100A XT Series - 30/60/90A
EC3 - 60A
EC5 - 120A
JST - 3A<br>
17
Step 6 - The Setup Using the data we now have (power, flying speed, thrust, propeller diameter and voltage) we now have all the information to find a setup that works.
But how? Get on the internet and search!<br>
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Step 6 - Typical Motor Specs<br>
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Step 6 - Some Good Web Sources AXI Motors http://www.modelmotors.cz/index.php?page=1
Hacker http://www.hacker-motor-shop.com/?shop=hacker
Scorpion Power Systems http://www.scorpionsystem.com
Eflite http://www.e-fliterc.com
Emax http://www.emaxmodel.com<br>
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Example Setup for Seagull E-Pioneer<br>
21
Example Setup for the Yak 54 120e<br>
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Step 7 - Testing Physical Testing Using a Watt Meter<br>
23
Step 7 - Testing Testing using ESC Data Logging Capabilities<br>
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Step 7 - Testing Testing using a Calculator Tool (e.g. eCalc)<br>
25
Summary Estimate Power Needed
Decide on Maximum Flying Speed
Calculate Ideal Thrust
Calculate (or Measure) Maximum Propeller Diameter
Select Preferred Battery Voltage
Find a Setup
Test/Check the Setup
Charge Batteries
Go Flying!<br>
26
Thank you That's it, I'm off ohm...
That’s it,I think you’ve heard Amp’le from me.
I’m off Ohm...<br>
