# re-using the diesel heater coil circuit



## sabahtom (Mar 1, 2011)

I didn't do my homework on my DC to DC so my accessories will be running on 13.2v instead of 14.2v. I bought a Vicor and the modules only trim up to 13.2v.

I wanted to re-use the 60A circuit that warmed up the glow plugs, but the relay coil wires were so thin that there was a 0.8v drop from the ignition switch to the relay. No problem with an alternator at 14.2v, but at 13.2v it didn't work. I was also a bit nervous that there might be some voltage fluctuations when the EHPAS was working hard, maybe enough to open the relay. 

The OEM 60A relay looks like a good one and it closes at 12.8v, a bit lower than the generic Bosch which closes at 13.2 only. I ran a bigger wire from the ignition switch to the relay coil so no voltage drop now, seems fine.

My motor controller requires a 15A fuse. Maybe too much to add to an existing ignition circuit. I also wanted the option of adding other accessories later so I connected it to the glow plug circuit via the 60A relay. I'll daisy chain the vacuum pump relay coil paralell to the motor controller so they both come on from the ignition switch.


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