In addition to what Alex suggested, does the Tympanium actually have a good ground? What you have told us points to a problem with the charge control unit.
Do a search on this site on grounds. There has been a lot posted. Grounding is more than hooking the battery
up to the frame with a wire.
Which is better? Probably which ever one you have installed and is working. Alex has a Tympanium he is happy with, I am happy with Podtronics
. Both do the job and do it more efficiently than the stock rectifier/diode.