New Contactor

So the car has been in the road for 4+ years and running relatively trouble free. In late November, though, it suddenly shut down on my way to work. I was able to pull over and restart it, but it was troubling. The Zilla error codes pointed to motor over speed, contactor stuck and low 12v supply - the usual hodgepodge of errors I see when the SLI battery is low.

I recharged the SLI battery over night but on the way to work the motor shut down again. It did restart and once I was home again I checked my wiring to the controller, thinking a loose 12v, ground or tach lead could be causing the problem. Everything looked Kosher. 

The next day on the way to work it shut down. I coasted off the freeway and parked. I tried restarting it, but this time instead of the familiar contactor "thump" I heard a sizzling sound. I pulled the pack emergency disconnect, pulled my meter from the glove box and made some quick tests. I quickly found that the contactor points had welded closed - which was probably the sizzling sound I heard.

I was using a Kilovac  EV200 contactor and though rated for up to 2,000 amps and can handle 500 amps at 320volts continuous. EV Source points out that these ratings are based on a very large cable size -300 MCM, which translates to about 4.5/0 where I am using 2/0. I was told the connector bolts would get warm from the resistance and ultimately weld shut (which they apparently did), but they never got warm to the touch in my typical drive ad never discolored to indicate overheating. Evidently the bolt temperature doesn't relate well to the contact temperature inside...

This is how the original EV200 contactor looked in the High Voltage Enclosure:

So naturally I wanted to upgrade to a contactor that wouldn't die on me again.  I looked at Nanfeng and Albright but ultimately decided on a Gigavac. The Tech Support at Gigavac said my 350 amp continuous at 170 volts was within spec for the GX14 as long as I used copper buss bars to dissipate any heat.  

The GX14 is larger than the EV200 has a lower cable connection point than the EV200. After going through numerous mounting plans, I came up with one that  used buss bars to connect the cable from above to the input bolt below and to the Ferraz/Shawmut fuse. 

This is how the Gigavac GX14 looks in the redesigned high Voltage Enclosure:

You can see the copper bus bar on the right middle under the 2/0 cable. The contactor is the black circular unit in the middle. The output of the contactor goes to a short bus bar into the Ferraz/Shawmut fuse positioned vertically. It's bolted to the output cable to the Controller.