My thoughts on why I opted for a relative high value resistor, was to not put so much strain on the precharge relay.
I now have a industry type 11pole relay, capable of handling 10A or so.
If it's like this
, then it's rated at 28 VDC. This is probably a major source of your problems. As the contacts close and the contacts bounce, they will be arcing, and they likely won't last long. In a conversion I helped with, the pre-charge relay was another EV200 contactor. Way over-kill, but at some $50 from Ebay at the time, they were cheaper than smaller relays that could handle the voltage and 10 A or so of current. Now those cheap EV200s are gone, but EVC500s are similar and aren't too bad at about double the price.
Any relay or contactor rated at at least 400 VDC and about 10 A would do, but these are harder to find than you might think.
To draw a peak of 10 A at 360 V would require a 360/10 = 36Ω resistor; next highest E12 preferred value is 39Ω. That's 13x lower resistance than 500Ω. So your relay wasn't suffering from too much current.
But 10 A @ 360 V is 3600 W. Even with a 25x overload rated resistor like the HS series, you'd need a 3600/25 = 144 W part; next highest value would be 150 W or maybe 200 W. To use a nominal 100 W part, i.e. keep the peak power under 100 W x 25 = 2500 W, you'd want a peak current of 2500/360 = 6.9 A, or a resistance of 360/6.9 = 52Ω, use 56 Ω. Or perhaps 68 Ω for a little more margin, and in case your battery voltage might sneak over 360 V when recently charged.
A lower value resistor for the precharge means more current through this relay as well.
Yes, but that current reduces to zero very quickly. When bypassed with the main contactor soon after, there is zero voltage and current. It's the voltage that is probably killing your pre-charge relay.
And I´m actually wondering if it might be this one that has burnt its contactors and sticking a bit, never switching over to pull the main contactor.
With the 500Ω resistor, it would switch a maximum of 360/500 = 0.72 A, quickly dropping to zero. It will have a lazy life, as long as its contacts are rated for 360 VDC.
I came to this conclusion because one time I say my full battery voltage on my meters, and when applying throttle it went away. This indicates that the precharge indeed had excecuted, charging the caps, both in the chargers and later in the controller, making it think everything was ok to run.
Why later in the controller? Perhaps you separately pre-charge the chargers and controller, so you don't have to have the controller energized when charging.
Be very careful depressing the throttle when the pre-charge resistor is in circuit. With the 500Ω resistor, the power is E²/R = 360²/500 = 260 W, which a 100 W resistor could stand for a second or so perhaps. If you were using say a 38Ω resistor, you'd be dissipating around 360²/39 = 3.3 kW in the resistor. Even one second of this sort of power will cause it to open circuit or likely explode. I've seen it happen and smelled the result for a week