The Evinrude trademark appeared on electric trolling motors for five model years, 1974 through 1979. The Evinrude 12-24 electric trolling motor has three wires: one red, one white and one black. Only one jumper wire is needed to connect the two batteries because the only negative connection required -- the only ground -- is supplied by the black motor wire. At first glance, the wiring seems counterintuitive, but the wiring avoids the need for a second jumper wire between the batteries and a connection to the boat's common ground.
Items you will need
3/8-in. open-end wrench
5/16-in. open-end wrench
8-gauge wire
Wire strippers
2 ring terminals
Pliers-type wire crimper
Remove the nut from the positive post of the first battery in your battery box, using a 3/8-in. open-end wrench. Set the ring terminal of the red motor wire around the post. Return the nut to the post, tightening it securely.
Remove the nut from the negative post of the same battery, using a 5/16-in. open-end wrench. Place the ring terminal of the white motor wire around the post. Return the nut to the post, but do not tighten it fully.
Remove the nuts from the positive and negative posts of the second battery in your battery box. Strip 1 in. of insulation from each end of the length of 8-gauge wire with a pair of wire strippers. Crimp a ring terminal on each end with a pliers-type crimping tool to create a jumper wire. Place one ring terminal of the jumper wire around the negative post of the first battery and tighten the nut securely with the 5/16-in. wrench.
Install the ring terminal on the remaining end of the jumper wire on the positive post of the second battery. Return the nut to the post and tighten it with the 3/8-in. wrench.
Set the ring terminal of the black motor wire around the negative post of the second battery. Thread the nut onto the post and tighten it snugly with the 5/16-in. open-end wrench.