Setting Up Milti-Motor Electrics

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Note from the editor – The above article is excellent but to avoid asymmetric thrust due to one motor quitting there are a few things I do when I set up a twin:  (1) The low voltage cutoff in the ESC is there to save your Li-Po from over-discharging.  This is at the expense of your plane.  In a single engine plane you can usually glide and land after it kicks in.  On a twin you will probably see one ESC go into LVC before the other.  This will give full power to one motor and no power to the other.  If this happens on climb-out you will be astonished how fast your plane can screw into the ground.  I program the low voltage cutoffs in the ESCs so they will not cut off until the battery voltage is below 2 – 2.5V per cell.  This saves the plane at the expense of the battery.  Most of us rarely fly into the cutoff anyway.  Know your plane and do not fly too long.  (2)  The ESCs I use also have over-current protection.  The ESC will cut off if the current is too high.  Naturally, this would happen to one ESC first thereby causing asymmetric thrust and your plane will perform a “helix” maneuver into the ground.  Since it is an over-current protector it would most likely happen during climb-out.  I turn off the over-current protection on my twins’ ESCs.  If you have done your setup correctly, and tested the current at full throttle afterward, you will never need the protection anyway.  (3)  I use an RX battery or UBEC rather that depend on one of the ESCs for radio power.