The small wires can be very dangerous to use with a switch setup. The
old discussion of their use was for relay setups where the relay is
controlled such that the second battery is disconnected unless the
engine is running. The danger is during starting. The starter can pull
100 amps or  more.  If the batteries are connected by a switch, starter
current will be drawn from both during starting. Small wires will MELT.
Always use a fuse between the batteries if small wires are used so the
fuse will blow instead of the wires catching on fire.

Mark

Mike Collum wrote:

><snip> I like being able to use both batteries for
>starting so I use bigass wires too. <snip>
>
>Mark,
>
>I thought the whole idea of using "small" wires to the secondary battery
>is to limit current flow .... effectively providing a trickle charge to
>the secondary and that using "BIG" wires could cause problems.
>
>Of course, use of small wiring would necessitate giving yourself a jump
>(with portable cables) to use both for starting.
>
>Care to share your feelings on this?
>
>Thanks,
>
>Mike
>
>
>