To bring out the best, make your DC trunk at least 12 awg wire and place filtering capacitors close to the application. There are presoldered 100,000uf/35V Rubycon capacitor arrays for sale on eBay. One of the lowest impedance deep cycle batteries is the 94AH Enersys Odyssey PC2150. I use two of these in parallel. They will last almost forever if you keep them topped off above 12V and don't use their deep cycle capability often.