How many amps does a stock SR5 need to run
 

For the sake of this argument lets say I have a stock 86 SR5. How many amps does it need to run?
I'm adding stuff like a second battery. But if the truck needs 50 amps ( I have a 60 amp alternator) Then I have up to 10 amps to charge the second battery and other things.

I'm wondering if I need one of the bigger alternators to charge the second battery. I don't care if it just charges slowly.

When driving down the road it needs about 5 amps. If you start turning on the headlights or letting the battery run down, etc., then it can need lots more. But as you figured out, 60 is plenty and then some for almost all regular use.

Why the second battery? Do you plan to run a bunch of arc-welders and run down both batteries, then try to start the truck on a -25° day? If you're trying to constantly charge a battery (whether one or two) you're going to need more amps.

Last, if you don't care if the battery charges slowly, then you're already there. If you only had 10 amps of head room, and you had to split it between two batteries, then each would get 5 amps. Problem solved.

what are your plans for battery location, charging and isolation?

I am using a full duty battery isolator. The battery is a AGM battery I'm going to put it in the bed of the truck and vent it to the outside if it ever over charges or needs to vent.
I will be powering a ham radio as well as a 1500/3000 Xatrax Inverter. But small stuff on the weekends I plan to do a lot of camping out of the truck.
So it will have all week of normal driving to recharge.

The ham radio is 2 fold One play time and two I will set up a raspberry pi and run a gps/Automatic Packet Reporting System. This will give out an automated Gps location . So my wife know where to find me/ the truck if i don't return/something bad happens to me. http://www.aprs.org/ for more info on that.
Here is a Global real-time APRS map view, updates automatically without reloading. http://aprs.fi/

I would think that the stock alternator should be fine. Once the main battery is charged, which it will be shortly after starting if it was not drained, then most of the excess amperage can go to your auxiliary deep cycle battery to charge it, while keeping the truck running.

You can help maximize the efficiency of charging system and life of the battery by getting a small solar charger to help keep up the auxiliary battery while you are using it. A continuous duty solenoid type battery isolator is more efficient at charging than a diode type as they lower the charging voltage slightly. If you really want to maximize efficiency, then both batteries should be the same type and age so they charge evenly (this is usually not practical with a small starting battery and the need for a deep cycle). I just did a Subaru EJ22 swap into a VW Vanagon camper, and I used a solenoid type isolator for the house battery. The stock Subaru alternator, which I believe is only 60 amps, seems to charge both batteries fine.