I know that everyone here is into cap bashing, but, an installer friend of mine told me that he has successfully utilized a capacitor to solve the Honda ELD problem. Basically, he claims to have figured out how to make the ECU see the capacitor as a "load" and said that the charging voltage will never drop below the 14s because ELD will NEVER kick in. I need to ask him how he did that.
The only other thing I have successfully used a capacitor for was as an inline filter for a noisy power wire.
Oddly, I have never tried using a capacitor for what the mass market advertises them for because I know that they ARE NOT a substitute for an inadequate electrical system.