Originally Posted by
drivesafe
Hi Veebs, with probably 99.5% of USI-160 and the new UST-175 isolators being fitted where both or all three batteries are under the bonnet, as long as you use the correct size cabling, and 3B&S ( 25mm2 ) is the recommended MINIMUM size, you will not need fuses or circuit breakers.
To use fuses or circuit breakers will simply increase the resistance in the circuit while winching.
If you are fitting the second battery somewhere other than the engine bay, you MUST fit fuses or circuit breakers ( circuit breakers being the preferred safety device ).
These must be fitted somewhere in the engine bay, before the cable leaves the engine bay to protect the cranking battery.
And the second battery must have the safety device fitted as close as practical to the second battery's positive ( + ) terminal, so that if a dead short does occur, you dramatically reduce the chances of a fire occurring.