Full size electric boat controller questions

[BrianG]

An ESC in brushed mode using a servo tester would be the easiest and give you variable speed.

But, if you want to use common automotive relays:



Some notes:

- Make sure the relays can handle the current you are running.

- The SPST switches are low current (less than 1A) so pretty much anything will work

- The reversed diode is meant to shunt the inductive kickback from the coils to prevent damage to the power source. But if it's a battery, it's not needed. If you do use it, any 1A+ diode with a PIV of 50v or more will work.

- The thicker lines are the high current paths. The thin lines are the low current paths and will be passing less than 1A.

- The green and blue wires don't have to be those colors. They are colored different just to show that they are different wires and do not connect together.

The top relay is your system on/off relay. This could be replaced with a SPST switch capable of whatever current you are running, but switches that large tend to be expensive and/or not meant for continuous duty.

The other two are the reversing relays. I set up the wiring so that when the reversing relays are not powered, the motor runs forward. I figure you'll be running forward 99% of the time, so no need for the coils to suck power (albeit really little) for nothing.

I suggest getting the matching sockets for the relays. That way, if a relay blows, simply plug another in and you don't have to re-do the wiring. You just have to find a socket that is rated for the current levels you'll be running; if you can't, you'll just have to wire up replacements manually.

EDIT: Oh, and if are sharp enough to notice that the coil terminals (#85 and #86) have the polarity switched around on the reversing relays: that's not a problem. The coils in these relays are not polarized so you can hook + and - to whichever terminals you want and it will work fine. Doing it this way in the diagram simply made for a cleaner looking schematic...