I am building an 04 ccsb Z71 for offroad and possibly overlanding. I have Rough Country front fog lights, rear back up lights, bed lights, rock lights, Ham radio and soon a winch and possibly a 12v fridge. I already built a fuse panel where most of that runs off of. I want a second battery for deep cycling while the engine is off. I plan to add said battery behind the coolant resevoir on the passenger side. I have looked into some information for it but would like to get a more "first hand" knowledge base. So here are a few of my questions/concerns.
-Stock battery is 34/78 sized battery, can I fit a group 31 in the space as they are larger because of the larger AH rating?
-I am looking into a possible solar power addition for charging, but that may be down the road so with cost and specific charging needs I think Lithium is out. I might be going with AGM. Does this have specific charging needs? If I link the starter battery and secondary through a Voltage Sensitive Relay (VSR) will the vehicle's alternator be sufficient or will a dedicated charger be needed?
-Does the alternator only flow what is needed in amps? I see some set ups with an 80 amp circuit breaker to the second battery when I know the alternator can be around 120-140 amps. If this is the case I can get away with an 8 AWG wire instead of a 4 AWG? As the line traveled will be around 8ish feet.
-Should I stick with the 4 AWG wire in that it will help with the winches amp draw?
-Is the engine bay temperatures eliminate any battery types or brands that may be sensitive to heat?
-Any recommended batteries, set ups, things I may need to pay attention to or may have overlooked, any other advice?
Thank you for help as I know a winch will be a heavy draw and with all the add ons there will be a steady draw warranting a second battery, to not overwork or stress the starter battery.
I plan to use identical batteries. I may not be able to buy at the same time, but they will be. The voltage relay breaks connection between the batteries when the starter side goes before 13.3v, but when the truck is running and producing 14.8v the relay will make connection so I can charge the secondary and also draw when I use the winch. Relay I plan to use https://www.amazon.com/dp/B00WTAFR84/?coliid=I16QUNO8T7HO2X&colid=3BDGLR9PML5OD&psc=1&ref_=lv_ov_lig_dp_it Battery options at the moment https://www.batteriesplus.com/productdetails/battery/car-and-truck/chevrolet/silverado-1500/2004/v8-5.3l-770cca-optional/sli78agmdp https://www.optimabatteries.com/products/yellowtop-d34-78 I am open to other suggestions and ideas, like if the group 31 batteries fit, which do I use? Thank you