batteries keep dying

[afromack34]

i have a lot of accesories installed in my with second battery in the back, ive taken it to two different installers to see why my batteries is not being charged. The alternator is working fine, so they say, but when they test the cable before the battery it reads below 11 volts. the alternatorn i have is 200 amps, but i had it rebuilt because it blew out because it was hooked up wrong i guess. what i getting at is if the alternator is working fine, why are the batteries constantly dying? and if thats not the case how can my car run with a bad alternator after i charge the batteries?
Can any one help me out?

 

[StincolnLincoln]

check to see if the the battery cables and or terminals are not dry rotted inside

 

[afromack34]

Good tip, because the cables from the isolator to the back battery were burned out. I will have the positive wire replaced.
thanks !!!
Afromack

 

[afromack34]

Good tip, because the cables from the isolator to the back battery were burned out. I will have the positive wire replaced.
thanks !!!
Afromack

 

[Jibit]

how do you have the second battery installed? Is it just wired in parallel with the other battery or do you have something separating the two and controlling the current flow? Also, with all the accessories, are you sure the 200A is enough?