What size cable do I recommend?
#4 wire gauge works great for accessory leads and alternator wiring. Many new sub-compacts use this as battery cable.
Use #2 wire for 4 cylinder and small 6 cylinder automotive engines, hi-power accessories (like winches, power converters, 200 amp alternators), golf cart battery banks, and tow truck jumper cable kits.
1/0 makes great battery