10 replies to this topic

[atom]

In the near future I'm going to be needing to run several electrical components from a switched 12v supply (ECU, coilpack, injectors, sensors, etc…).

I don't really want to run them all from the standard feeble looking ignition wire. My original plan was to create a new 12v switched supply for all of the new gubbins, controlled by a heavy duty relay, 12v straight from the solenoid, switched by the original ignition feed.

However, when I tried to use this new supply to run a traditional ignition coil, the relay seemed to keep switching itself off after a few seconds. In the end, I had to go back to the original switched feed.

What was wrong with my original idea?

[Carlzilla]

Relay could have been dodgy, make sure the relay will take a little over the maximum ampage your alternator produces, to be on the safe side.

[atom]

I have a standard alternator, so thats about 40 amps? The high current relay should be able to handle up to 70.

It was working ok, producing a good 12v - but as soon as I hooked up the coil, things went wrong. Is there a reason why the coil specifically won't work with this?

[pikey7]

don't run the coil off it?

You can still keep the original wiring AND add in a separate relayed circuit...

[atom]

Sure, that's what I'm doing at the moment. I'm just wondering why the coil doesn't like it.

[Cerberus]

Could it be that the coil pulses?

[atom]

Ah, so the coil's pulses are affecting the relay... I suppose that would make some sense.

[Brams96]

Is it a latching relay?

[atom]

No, not latching, just a high current relay. You think a latching one would solve the problem?

[Cerberus]

Ah, so the coil's pulses are affecting the relay... I suppose that would make some sense.

I'm not saying that it is.

Just an idea that I thought might make sense.

[Brams96]

Is your circuit something like this one, with the new feed coming from the solenoid, going to the relay and then to a fuse box for the new circuits? Are you taking the switched 12V from the ignition coil side or the other wire like shown?