hi-lo switch

A 3PDT switch is commonly used in three-phase electrical systems. You won't find them at Home Depot but 
an electrical supply house will carry them. This is how I switch two battery banks between series (hi) 
and parallel (lo).

      B1        B2
7--1--:|--2--3--:|--4--8   high mode
      -+  A  C  -+     B

                J1
             5------6





      B1  A     J1
7--1--:|--2--5------6--8   low mode
   |  -+  |            B
   |      |
   |  B2  |
   3--:|--4
   C  -+



3PDT Switch

A      C    B    poles

3*     2    4    high mode        *superfluous

2,5    3    8    blades

4      1    6    low mode


1 B1-  batteries   same as 7
2 B1+              same as 5
3 B2-
4 B2+
5 J1   jumper      same as 6
6 J1
7 M-   motor
8 M+