Yes, another fried contactor, this time the rear mid-pack unit. It's clear that there is something fundamentally wrong with the precharge setup, and I've changed the circuit scheme three times and still welding contactors shut. One thing that hasn't changed is the precharge resistor. Even though it's been replaced once, the 500 ohm 100 watt unit I've been using may be mis-sized for my 400 volt pack. I still have the precharge resistor and relay that came with the battery pack, and surely it must be a match. Only problem is that I welded those contactors on my first precharge mishap.
Fortunately, the Panasonic contactors used in the Better Place pack can be found from time to time on eBay, and I picked up a couple from a Canadian seller at a very reasonable price. I like the packaging on the Better Place contactor/precharge module and since I designed the mount for it in the first place, it went back on pretty easily.
I took the opportunity to ground the shielding on the inverter cables and revise the wiring to the time-delay control relay. This setup certainly looks cleaner than the former one, and all of the terminals and connections are safely contained inside the plastic housing.
We'll test this in the neighborhood for a bit before we go too far afield, but I'm hopeful that this will solve the precharge challenges. There is lots more I want to do, but this needs to be stable and reliable before moving on.
