Excellent explanation. Should be placed on Wikipedia.
Frank P.
On 4/30/2011 3:21 PM, Derek Engelhaupt wrote:
When you stall anything...it stops. You stall your car engine...it
stops. You stall an electric motor...it stops...well kind of. An
electric motor "stalls" when there is still power applied, but no
motion. If you remove power to the motor during a stall, the motor will
cease "trying" to move. If you keep applying power in a stall, the
motor will keep trying to move even though it can't. That causes the
motor to draw more current (amps) than it would during normal operation.
Continuing to apply power to a stalled motor can cause internal damage
to the motor due to excess heat. Heat=bad. Let's say just for an
example (and the numbers are just theoretical) your motor is 24V rated
at 350W. It may only draw 5 amps during no load operation (ie: not
connected to anything). It may draw 20 amps during loaded normal
operation. At stall, it may draw upwards of 100 amps. That's why I
have put fuses or breakers on my motors. It's so the fuse or breaker
protects the motors from damage. It can also protect the motor
controller. Some motor controllers have built in current limiting
circuits, others do not. Drawing too much current from an ESC can
damage it also. Drawing too much current from a battery too fast
(depending on type of battery) can also internally damage it. So to
make a long story short, stalls on electric motors are bad. My current
ESC and motor setup involves two IFI Victor 883 motor controllers (one
for each motor):
Victor 883
Nominal Voltage
24V
Min/Max Voltage*
6-30V
Continuous Current
*60A*
Surge Current (2 sec)
100A
Surge Current (1 sec)
200A
I use 50A fuses to give it some slush in case the fuses don't blow at
their intended rating. Now I use the motor below which is rated
at 24VDC 350W 385 rpm CCW no load, 1.5A - 375 rpm CW no load 1.4A - 445
in.lb <http://in.lb> of torque - stall at 103A. Nominal current draw of
these motors is between 16 and 30 amps if I remember correctly. Since
my motors are properly fused and my ESC can handle surge currents of up
to 200A for 1 second, I should be covered by the 60A ESC.
http://tncscooters.com/product.php?sku=106115
Derek
On Sat, Apr 30, 2011 at 11:11 PM, Dave D. <degeck...@optonline.net
<mailto:degeck...@optonline.net>> wrote:
Hi Steve, all,
I saw that you recently used the term "stall current" in one of your
posts. I've searched the net and found relatively little on the
subject. Found a model railroader's forum that shed some light
about it, but the question that nags is how it relates to R/C tanks?
I'm guessing that it has something to do with the skid turns (yikes,
I'm forgetting the term you guys use-dopey newbie that I am...LOL)
that a tank makes...the one where the tracks go in opposite
directions...sounds like... anyone good at Charades??? Perhaps it
also has something to do with a sudden change in the tanks
direction/momentum...?
Anyhow, can someone let us less informed tank wanabies know how
stall speed relates to a tank, and are there any dangers inherent in
it, as I'm getting a sense that there may be this issue.
Thanks for the EMF lesson,
Dave D.
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