I would strongly recommend using only an intermittent-duty contactor for the starter. It is designed with a stronger return spring and fewer turns in the coil, giving a more rapid "make" and "break". This makes it less likely that the contacts will weld upon opening, keeping the starter engaged. I also, I guess, fly against the prevailing wind and would NOT put a clamping diode around the coil. A diode there will slow down the flux decay and increase the likelihood of welding.
Gary Casey
Date: March 30, 2006 10:03:45 PM PST
Subject: Starter Contactor
Does anyone know if I can use the standard continuous-duty relay as a starter contactor?
Typically we use the continuous duty relays, which are actually contactors, to throw the battery onto the power bus, and we use a slightly lighter (1 oz less) and slightly cheaper ($8 less) intermittent duty relay as the starter contactor. My particular installation would be aided by using the metal-can continuous-duty relay as a starter contactor -- it's all about existing mounting holes and clearance to adjacent equipment. The answer would be simple if I knew the rating of the two devices (these are the parts out of Aircraft Spruce or Aerocraft -- the usual suspects), so theoretical answers are not what I'm looking for.
Thanks in advance.