Jinx wrote:
>
> > > >(2A) relay is closed before the power (8A) relay, then the

> I did purposefully choose an over-specced relay for the power
> as it will do all of the active switching.

> Is there any mileage in trying to use something like an LM317
> (but bigger) to limit the initial motor current, or is it normally
> unnecessary or not worth the effort if the power relay is over-
> specced by a wide margin anyway ? This is for a 12VDC motor
> running on a battery,


Have you measured the stall (or start) current
of the motor?? That is where you will get the
potential problems and maybe with accel/decel
current, ie it might be wise to actually monitor
motor current.

If energy efficiency is not critical you could use
a 5% or 2% drop resistor, same principle as the
light bulb resistor it wont do much when the motor
is running but will make a huge difference at startup
and in the case of a stall.

Likewise if the motor will be stopped/started a
lot you will always be switching the relay at the
full stall current of the motor when starting it,
and your 8A relay might not be up to the job. :o)
-Roman

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