If you want a constant 14v at the battery, maybe you should look into better electrical. You dont use a 14v battery for applications like this (commonly). With a good alt, good batteries, maybe regulator on the alt as well, you'll see a constant 14v at the amp all day every day. No need for a 14v battery unless you can charge it at 16v, which will in return fuck up tyhe 12v up front.