Capacitors need attention occasionally....Usually a capacitor will have a resistor supplied with it...If, for any reason you need to discharge the battery {as in disconnect the battery terminal} you need to discharge the capacitor also before working on the vehicle..And in turn when you reconnect the battery terminal that supplied resistor goes in place of the capacitor's fuse so it charges slowly up to 10-11 volts{+ or-}then you pull it and slide the fuse in and it's ready...
But I'm thinking a 30A alt is just too small even with one to level out the spikes...Might as well upgrade and save the drama down the road..Literally...