Charging system wire around 6 or 8ga

Sounds like I need to go to a heavier wire !
I dont have any trouble w/ anything , except hot starts , never starts on the first turn of the key , but hit it quick a second time and it fires up . ??????????????????
any ideas ? Been this way since day one , scares me , but hasnt failed me yet .--????????????

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ANYONE ??