Originally Posted by CoronaVan

The second battery is a deep cycle battery that exclusively runs the van's entertainment system. That system includes a 1000W inverter that runs a TV, BluRay, gaming system, etc. The inverter can also run other appliances that require "house power" (120VAC). Having a second battery on a battery isolator allows key-off use of the entertainment system without the risk of draining the van's starter battery. Hope this helps.

Originally Posted by trishab

what is your shopping list for the second battery and do you know what type of mechanic can do the work?

Originally Posted by coronavan

part price qty
a manual reset 150 amp circuit breaker $16.99 3
b soundbox 0 gauge red 1/0 wire 25 feet $28.95 1
c stinger sgp32 200 amp battery relay isolator and relay $43.76 1
d blue sea systems ato/atc fuse block (4-circ w/cover) $19.99 1
e installgear in-line agu fuse holder with 80 amp fuse $6.53 2
f pac pac-80 80-amp relay battery isolator $14.67 1
g upg 12v 100ah deep cycle vrla battery $179.99 1
h qc 3.0 usb charger socket panel $16.87 2
i qc 3.0 dual usb charger socket panel $22.99 1

i also used two sets of installgear 0/4/8/10 gauge battery terminals ($17.95), one feature that attracted me to these battery terminals is that they don't need terminal lugs crimped onto the wires​​​​​​. The 150a circuit breakers are the same way.