I'm building a simple electric boat out of a salvaged jet ski hull and an old trolling motor with directional control.
The plan is to have a joystick controller for simple on and off (ie no speed control) operation AND reversing of current for reverse and steering.
The kicker is that I was unable to find a joystick that could handle the 35 or so AMPs that would be pouring through it.
I understand that I need a relay. So, I did some chatting with the Digi-Key folks and they sold me these two parts, however, I think the relay needs to be a dual pole.
Anyhow, even if I had the correct parts I don't know how to wire up a relay. Below are the URLs of the two parts I bought.
Attached is my rough sketch of how this will layout - ie two DC motors each needing forward and reverse.
I am a complete newbie. Any help or direction is appreciated.
Thank you in advance I'll look for your response.
You need a double-pole double-throw relay to reverse a DC electric motor.
You will also need a SPST (or SPDT) relay to turn the motor on or off.
Be sure the relay contacts are rated for the motor amperage. The attached
drawing shows how to hook it up. The diodes are necessary so that the
reversing relay is not turned on in forward mode.
It might be hard to find a DPDT relay with the contact ratings you need, but
you can accomplish the same end using 8 SPST relays like the one you
already have. Each joystick switch turns on 2 relays that connect the
battery + and battery - to the motor leads. You should connect
reverse-biased diodes across each set of relay coils to suppress the voltage
spike that would otherwise occur when the relays are de-energized.
The motors will also produce spikes unless you connect a reverse-biased
diode from each motor lead to the battery + and another reverse-biased
diode from each motor lead to the battery -. Diagram attached.