Most car audio specific capacitors should come with a circuit board to charge up your capacitor. Basically you hook it up to 12V on a test bench for about 5 minutes and it charges up slowly to avoid a spark. LED goes out when it's all charged. Now if you don't have one or it didn't come with one I would recommend checking out monstercable.com or rockfordfosgate.com or something because they might have listed values. I'm not at work right now but next time I'm there I'll grab one of my boards and check resistor values and let you know.