mahargonator

I have a 1980 DT175 that i have been riding as trail bike only, but now i am thinking about putting it on the street. It has all the lights and signals on it and they all work, i threw a new battery in it when i first got it and everything worked, but everything was very dim and the battery died within a few days. so i am thinking that since i have heard many things about the 6 volt system being horrible and mine isnt recharging properly. i was wondering if it was possible to change over the system to a 12 volt system? thanks