You have an 850 & a 1000 in your truck? Does that not cause issues being unballanced like that for your alternator? How does the system know when one battery is full, and the other isn't fully charged? I'm not sure if that can cause alt stress or not, but I always like to keep dual battery systems with matched sets, and keep them in the same state of charge and repair... Maybe I'm just OCD like that, but I not sure if these systems are smart enough yet to know two different battery types apart.. I could be wrong though..

 

not at all...the batteries are the same, 850 cold cranking amps each, and 1000 cranking amps(above 32*) each.

if you look at the labels on the batteries they list what theyre rated for, for cold cranking amps, and cranking amps.

i still have to upgrade my alt to a 136a alt, because i have a 117a currently, and i plow with my truck in the winter, and tow a camper occasionally in the summer. i also just installed a hughes under drive crank pulley, so that will have a little effect on the alt as well.