Probably a dumb question but I have a couple of deep cycle batteries and I was thinking about putting them in parallel to run a couple Piaa atp lights on my 86 gl10. Would this work? Or would it just be better to take the time to upgrade to a larger altenator? If so which alternator is easiest to swap with? Thanks and sorry if this question has already been asked.

The extra battery capacity will only work for a while. The alternator just doesn't make enough juice to keep up. There's a post here for swapping in a Nissan Maxima alternator. It has the amperage you'll need and its a bolt in swap.

Yep - do the Maxima swap. I build them for people if you are interested - contact me by PM, etc.

 

http://www.ultimatesubaru.org/forum/showthread.php?t=100559

 

GD

Note: Once the car is started and the motor is running, ALL the current is supplied by the alternator unless the load exceeds the alternator's capability and THEN the load draws on the battery for the needed current until the battery runs out of charge. Putting in a 2nd battery won't help the situation any; except for the short term needs of the extra lighting you are adding. Go for the high output alternator to supply the extra current when it is needed.