MoTeC Global Forum

Is this a good idea?

Because I am broke, can I use Auxillary output 5 via a 'relay' the trigger the starter motor? I would be triggering vvia a CAN message.

Will get a PDM when I have the money, just looking for a short term CAN based solution.

What would be sending the CAN message? How would you be triggering and controlling the starter?

I would personally just setup a standalone momentary switch (20A minimum if directly wired) to control the starter solenoid, and not use the M1.

The CAN message will sent from a Motec MDD with 12 switches/rotaries etc attached. It might end up going via a CDL3, not sure yet.

The long term aim is to have a PDM triggering the starter motor. In the short term I was planning to use the M130 to trigger the starter via a relay using auxiliary 5 which looks it can trigger from a CAN message. As this is a temporary solution I didn't want to bother installing an extra switch and wiring temporarily when I could use the ECU and just swap over the wiring to a PDM later on (they even use the same connector/pin!).

I've done this on our Formula Student car with an M130 and a CAN message from a self-designed control unit. It did work, but is a lot easier if you switch the positive voltage of the relay (I had to switch the negative one as we used a semiconductor relay).
We experienced that the problem could occur that the starter motor was staying on in some CAN communication error cases, which is fatal if you use overtuned aprilia engines. When using only motec equipment and a robust starter motor, this should be less of a problem.

TobyOctane wrote:We experienced that the problem could occur that the starter motor was staying on in some CAN communication error cases, which is fatal if you use overtuned aprilia engines. When using only motec equipment and a robust starter motor, this should be less of a problem.

Err, I'll watch out for that one, doesn't sound very good! Thanks for the input.

Because we used a very fragile starting motor (and it was already the third one that year in june), we tested all problems we could think of. So the problems were mainly occuring when the CAN communication broke down or became faulty when the start button was still being pushed. When the messages kept on coming, it worked nicely