Can this be done. First reason is im running an underdrive pulley and and amp that has a little draw. The second battery I would use for headlight connection,door connections or whatever else. When I did the new engine I saved some weight. I took off all smog including the fuel canister which is where the new battery will go.

 

If you're trying to save weight, adding a second battery isn't going to help. Dump the under drive pulleys as they don't add any power.

If you truely want to be able to charge 2 batteries, you're going to need an isolation circuit to do it.

 

Diesels do it............

 

If you are having charging issues from an underdrive pulley, adding a second battery will make matters worse. pulleys are crap, you'll never feel the 5hp and they couse charging and overheating (on other cars) issues. Either install a smaller pulley on the alternator or put the stock pulleys back on.

The only way I would recomend a second battery is if you have a mondo huge stereo. Then you will also need a battery isolator and to remove the UD pulley as the alternator will need all the RPM it can get to properly charge both batteries.

Re'