Have you ever wanted to own an electric car? or have you ever wanted to drive a Porsche 911? I wanted both, so I decided to build one. This blog is here to document my journey as I convert a 2002 Porsche 911/996 Carrera 2 from a gas guzzler to a completely electric vehicle - not a hybrid!

Sunday, January 13, 2013

Bigger is Better

I spec'ed out a new relay that better supports the switching current and voltage requirements for the heating elements with a 50% margin.  I was surprised when I received the part because it has some serious heft to it.  It has considerable weight and is about 3-4 times the size of the typical automotive relay.  Before mounting into the car, I tested turning it on and off a few times with my custom circuit.  It worked.  Now with the heating elements running, I was able to heat the fluid and actually warm up the cabin of the car.  I took it for a test drive and it worked -- it was only 10F outside and the cabin stayed warm.  One anomaly to figure out: when press down on the break pedal, the latching circuit for the heater moves to the off state and turns off the relay and heating element.  I have a suspicion that the reset chip I used to set the default state of the cross-coupled NOR circuit is tripping when I press the break pedal.  I suspect there is a voltage droop because the vacuum pump typically turns on for a second or two to regenerate the vacuum in the reservoir.  I plan to add some capacitance to the power rail of the circuit today to see if that solves the problem

1 comment:

  1. Make sure your relay is rated for DC current, very sure that the first one was AC rated. When you use DC with an AC rated switch it fail by welding contacts in ON position.