Mount the batteries in the tool box and connect in series using the four gauge wiring and crimp-on connectors. It is a good idea to put several holes in the box to vent gases that build up in the charging and discharging cycle.
Also always open the box when using the starter to avoid a fire or explosion due to built up gases. Mount the range female plug outlet and 12 volt cigarette in the side of the box to the front side. Block, using wood blocks, the batteries in place. You do not want them sliding around next to the relays. Connect the 12 volt outlet, from the cigarette lighter outlet, to only one battery. You only want 12 volts. I used four gauge wire inside of the battery box to minimize voltage losses. The ground wire of the second battery goes to one of the large terminals of the Ford car starter relay. The positive lead of the first battery goes to the plug receptacle, outside connection of the plug or wire. Connect a four gauge jumper from the positive of one battery to the negative of the other battery. Instant 24 volts.

Note: Do not make this connection until all other wiring is completed to avoid shorts during assembly.!!! Total 24 volts. The ground of the solenoid goes to the ground of the second battery. Use 12 gauge wire for this connection. Note, this is not the small terminal marked "I", it is the base plate of the relay.Yes, the relay is for 12 volts, but works fine for this purpose. Run another four gauge wire from the relay's other large terminal to the 50 amp plug outside wire connection. Connect the three wires, of the 50 amp range cord, to the starter motor and switch. Securely mount the large range power wire to the screws at the back of the handle on the starter motor. I used a small metal strap to hold the cord to the back of the starter. Do not crush the wires and short them out. The outer wires, of the cord, go to the power wires of the starter. The positive lead from the starter goes to the positive lead of the first battery via the 50 amp plug. The negative lead goes to the remaining large terminal at the
starter relay, via the plug.

The original switch in the handle is to trigger the relay. It is too light to handle the current of big gas engines.I put one lead of the switch to the positive lead from the battery wire, at the starter, and the other to the third wire ( what was once the ground or common wire) of the 50 amp range cord. The third lead (or common wire) goes to the relay trigger terminal small terminal marked "S", back in the box via the plug. Use 12 gauge wire to connect the common wire of the plug to this terminal at the relay. Connect the jumper wire from the two batteries together in the box to complete the power circuit. Insert the drier plug into the female receptacle on the side of the box and you are all set...Power!! ARG-ARRGG!! Press the switch in the handle of the Sullivan starter to test. Unless you hooked up the wires to the motor backwards! It is not advisable to turn the starter free in the air for very long.....It really spins up and could be hard on the armature. I have no idea how fast it turns my engines ( give me a break, my hands are full!), but the prop blast blew all of the debris on my work bench, all over the room while testing it (with no fuel) in those ZDZ monsters!!!!!

Ok, so it now weighs around 18 pounds, but I still have five fingers on each hand to lug it!!! Then I outsmarted myself and got a good deal on another P-38. ( Try negotiating a second 100 plus inch P-38 with the wife!!!!!!! OK, so I married outside my class in life!) You guessed it......It has counter rotating engines!!!!! Now, I had to go back and add another starter relay, wiring,and plug, for the reversed engine!! Each time I must start the reversed Super Tigre 3000 engine on the new P-38, I change the plug to the second range plug, at the box, for the counter-rotating engine.