just get a HO alt they are not that expensive...dont waste your money on caps, batteries, and other bull shyt solve it from the source and upgrade your output bro, you can add power storage to help it (cap, better battery) but thats more work on the alt to charge them, once you drain those your alt is like...i ran through alll that shyt and ended up with an alt but now i sold the system for go fast parts
get an alt you will thank me and with the HIDS they will dim less with HIDS because they draw ALOT less current than halogen bulbs....so you'll be fine still get an alt...you dont wanna over draw your entire car of voltage its just asking for electrical issues...
here-> HID FAQ