when I had my first system, i had a 68 Chevelle, and had two amps running off of one battery, and everything i turned the car off, the battery would always be dead, so i'd always have to be jumped off.... or downgrade to one amp.... and now that i'm a little smarter about it, i'm trying to keep from having to replace everything atleast once a year... (i've been doing good on these speakers so far... i've had them for two years running ... sounds good in the box i built. seing as it's the first box) how ofter would you have to charge the 2nd battery? and would it be good to run anything other than the amp off the 2nd battery?