I think Steve is onto something here. If you run the starter off the other battery, it is likely to solve the problem reguardless of cause just like your test run with an external battery.
With reguard to the actual cause, I tend to side with Tracy in that is more likely to be CAS interference rather than low voltage. I have left my master on for several hours. Enough that when the started turned (and it barely turned) the voltage dropped low enough to really dim the cocktpit lights and shut down the music radio, but the EC2 had enough juice to get the engine going.
On Sat, Nov 21, 2009 at 10:40 AM, Steven W. Boese <SBoese@uwyo.edu> wrote:
Steve,
I was able to produce symptoms similar to what you describe by inserting a 1.5 V flashlight battery into the CAS return wire such that the CAS end of the wire was 1.5 V more negative than the CAS return wire going to the EC2:
CAS ----- battery ++++ EC2
The opposite polarity didn't cause problems. With the battery installed, there are one or two sparks when starting to turn the CAS and then no more sparks until the CAS sensor is turning significantly faster than would be the case when turning the engine with the starter.
It seems that you may have the CAS return grounded in addition to the connection to the EC2. If this is the case, then the voltage drop from the starter current may shift the CAS return voltage similar to what I did with the test setup. If I disconnect the CAS from the EC2 at the EC2 connector, all the CAS wires show infinite resistance to ground. It might be useful to see if your wiring is similar.
Steve Boese
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