I am designing a pre-charge circuit for an electric vehicle. I have a 50 W, 100 Ω resistor, and the capacitors in whole system are 1 mF in total. That gives me about 210 J of energy dissipated during the entire time of the precharge.
Would this fry the resistor? Is this a viable solution for long-term use?
Peak power is over 4kW (almost 100x steady-state rating). There's a chance the resistor won't just fry, it might literally explode.
I strongly suggest you pick a resistor with a pulse power rating that fits your application, either from datasheets or from consultation with the manufacturer's engineering department. Here is a 50W chassis mount resistor, and, as you can see, the manufacturer thinks it's only good for 10 or 20J.
There is also a plot of allowable overload vs. time, which again comes up short by a large margin:
