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James Sweet James Sweet is offline
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Default Powering cordless drill motor with DC transformer


"William Sommerwerck" wrote in message
. ..
wrote in message
oups.com...
On Nov 2, 4:44 pm, "William Sommerwerck"
wrote:


As to a car battery damaging a drill rated at 13.8 V or higher --
absurd.



Read my post below. If the motor does not turn at the correct speed, a
car battery that is capable of nearly-infinite amperage will fry the
windings in short order.


So you're arguing that a low voltage will cause too much current to be
drawn. Okay. It happens with air conditioners during brownouts.




That's because air conditioners use induction motors which are inherently
constant-wattage devices, lower the voltage and the motor pulls more amps to
maintain power. A permanent magnet drill motor does not behave that way.
Drop the voltage down and the amperage follows it and torque is reduced. If
you have an effectively unlimited amperage available from the power source,
it's possible to load the motor enough that the airflow through it is
insufficient for the power it's dissipating, but lowering the voltage does
not automatically cause this.