how can i isolate 1 set of batteries while cranking?

[lime4x4]

Below is a crude drawing as to how i want to wire my house bank batteries and starting battery.I need to isolate the house bank set while cranking the engine only. 6 gauge wire is more then enough for my house loads.
guide
6g=6 gauge wire
4g=4 gauge wire
g=ground
hb=house battery
sb=starting battery
The crude circle at the top marked 1 2 c is my perko battery switch

 

[Silvertip]

Re: how can i isolate 1 set of batteries while cranking?

Set the switch to "2" and crank away. If your diagram is correct, only the starting battery will power the starter and if the switch is left in that position only that battery will be charged. After the engine is running, set the switch to "BOTH" to charge all batteries. Setting the switch to "1" (engine off) will allow the house batteries to power everything without running down the starting battery. Do not attempt to start the engine from the "1" setting as the #6 wires will likely go up in smoke.

 

[rbh]

Re: how can i isolate 1 set of batteries while cranking?

try running at least a #10 or #6 (hard time reading print) from batteries to the perco switch just in case you need the extra umph for starting some day.
rob

 

[Silvertip]

Re: how can i isolate 1 set of batteries while cranking?

He already has #6 and #10 is smaller than #6 so that's bad advice. For ultimate flexibility with the switch, all battery wiring should use cable that's the same size or larger than the battery cables going to the engine. You could then start the engine from any of the three switch settings (BAT 1, BAT 2 or BOTH). As the system exists, only the starting battery (BAT 2) can be used because it is wired with #4 cable.

 

[rbh]

Re: how can i isolate 1 set of batteries while cranking?

yes my mistake, "beat head against wall repeatedly"
what I should have said was go with a standard # 4 battery cable to all batteries, so if you require power to start the the boat due to disharged starting battery you can switch over ( do not now why I could not open your print)
rob