Electric Setup Basics
12-31-2004, 07:26 PM
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Electric Setup Basics
Hi - Here's my brief story. I have been flying gas planes for a number of years. I just received a shockflyer for x-mas. Unfortunately, I don't know jack about the setup for electric flight. My electric knowledge is limited to the following basic understandings:
[ul][*] the number of cells x the voltage of each cell gives the voltage of the pack[*] more volts = more power (servos move faster!)[*] the higher the mah of pack the longer it will last[*] charging at 1C or greater is considered "fast", and charging at .1C is considered normal
[/ul]
So anyways, I need to outfit this shockflyer and I am trying to learn as much as possible before purchasing anything. I don't want to just get a "pre-built" package of stuff (motor, battery, esc), but I would rather understand what I am actually doing.
Does anyone know of a good webpage or posting that explains all of the basics? Things like an explanation of the relationship between the motor, ESC and battery, or how the voltage of a battery, the current draw of a motor and the capability of the esc affect each other and so on.
I *think* the ESC has to be able to support the current draw of the motor. For example, i pick a motor that draws 6 amps, i need an ESC that is rated to handle at least that much. But how does the voltage and capacity of the battery pack come into play here? Because a battery is capable of discharging at a much higher rate, say 20 amps, does that mean it always does even though though the motor only draws 6 amps?
Does one start with a motor, then build around it? Or does one start with the esc and then build around it?
Edit#1 - if an ESC is rated at 8 amps, does that mean it can never never never exceed 8 amps? Or is the amp rating on an ESC more like an acceptable "average" amp rating? For example, I see that the AXI 2208/34 can draw 8.8 amps with a 3cell Li-Poly battery, could i use an 8 amp esc for this?
Edit#2 - what does it mean that a cell can discharge at "up to over 6 amps" - does this mean it can produce up to 6 amps per hour? per minute? per instant?
Edit#3 - does the Kokam 2 Cell 7.4V, 340 mAh Li-Poly Battery have the 2 cells in series or in parallel? I think in series because i believe the voltage of a single li-poly is 3.7 volts. in series = voltage, in parallel = amps.
Edit #4 - if a battery is a 7.4 volt 340 mah 2 cell pack and the motor draws 6.6 amps, how long would it take the battery to discharge (assuming the motor draws the 6.6 amps continuously)?
Any help would be greatly appreciated!
[ul][*] the number of cells x the voltage of each cell gives the voltage of the pack[*] more volts = more power (servos move faster!)[*] the higher the mah of pack the longer it will last[*] charging at 1C or greater is considered "fast", and charging at .1C is considered normal
[/ul]
So anyways, I need to outfit this shockflyer and I am trying to learn as much as possible before purchasing anything. I don't want to just get a "pre-built" package of stuff (motor, battery, esc), but I would rather understand what I am actually doing.
Does anyone know of a good webpage or posting that explains all of the basics? Things like an explanation of the relationship between the motor, ESC and battery, or how the voltage of a battery, the current draw of a motor and the capability of the esc affect each other and so on.
I *think* the ESC has to be able to support the current draw of the motor. For example, i pick a motor that draws 6 amps, i need an ESC that is rated to handle at least that much. But how does the voltage and capacity of the battery pack come into play here? Because a battery is capable of discharging at a much higher rate, say 20 amps, does that mean it always does even though though the motor only draws 6 amps?
Does one start with a motor, then build around it? Or does one start with the esc and then build around it?
Edit#1 - if an ESC is rated at 8 amps, does that mean it can never never never exceed 8 amps? Or is the amp rating on an ESC more like an acceptable "average" amp rating? For example, I see that the AXI 2208/34 can draw 8.8 amps with a 3cell Li-Poly battery, could i use an 8 amp esc for this?
Edit#2 - what does it mean that a cell can discharge at "up to over 6 amps" - does this mean it can produce up to 6 amps per hour? per minute? per instant?
Edit#3 - does the Kokam 2 Cell 7.4V, 340 mAh Li-Poly Battery have the 2 cells in series or in parallel? I think in series because i believe the voltage of a single li-poly is 3.7 volts. in series = voltage, in parallel = amps.
Edit #4 - if a battery is a 7.4 volt 340 mah 2 cell pack and the motor draws 6.6 amps, how long would it take the battery to discharge (assuming the motor draws the 6.6 amps continuously)?
Any help would be greatly appreciated!
12-31-2004, 08:46 PM
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RE: Electric Setup Basics
Look around for postings by yours truly. I've explained this many many times, so I'm pretty good at it. 
Actually, you start with the BATTERY, and build around it. You need power to spin the prop. The motor doesn't produce power, it transfers it from one form into another. It's the battery that actually produces the power.
Actually, you start with the BATTERY, and build around it. You need power to spin the prop. The motor doesn't produce power, it transfers it from one form into another. It's the battery that actually produces the power.
