Trolling Motor PWM problem- no reverse direction

[Don Towery]

Hi There,

 

I decided I wanted to try to put a trolling motor on my kayak and control speed and direction with a PWM.  I'm running into a bit of a problem and for the life of me, i can't figure out what the issue is.  I'm hoping someone on here may have seen a similar issue before and can help point me in the right direction.

 

I have the battery, trolling motor and PWM all hooked up.  I've created a wiring harness to extend the PWM controls to a smaller "remote" box away from the PWM so that I can limit the length of wire between the battery and the trolling motor so I can use 10 AWG with limited voltage drop.  I'm using a Newport Vessels 55lb thrust kayak trolling motor with a VMAX 85 AH deep cycle marine battery.  

 

The PWM controls consist of a 3 way (forward, neutral, reverse), polarity reversing switch and a potentiometer knob to control speed.  When I flip the switch to forward and increase the speed knob, the trolling motor kicks on and works as intended.  I flip the switch into reverse mode, and nothing happens.  If I manually reverse the power and ground wire of the motor at the PWM and test again, I get reverse working as it should, and no forward.  It seems the like 3 way polarity reversing switch isn't working.

 

Here's what I've tried / tested so far:

 

1.  I've done continuity testing across the 3 wires in the switch and they all have good connection from one end to the other (all the way to the back of the pins on the PWM board and to the solder joints on the switch)

2.  I've tested multiple switches

3.  I've tested multiple PWM units / controllers

4.  I've bypassed the speed / direction controls in the trolling motor head and wired directly to the motor itself

5.  I've manually reversed the trolling motor power / ground wire at the PWM to make sure the trolling motor would run in forward and reverse directions

 

at this point, the only thing I can think is that maybe BOTH of the 3 way switches are bad ?  I have more switches coming from amazon today to test that theory, but if anyone has any other ideas I can try, please let me know.

 

Thanks in advance!

[Bankc]

What kind of switch is it?  Is a 3pdt switch?  Also, what PWM are you using?  It sounds to me like the switch might not be hooked up properly.  And it might not be due to the wires hooked directly to the switch.  It might be a bad production run of the PWM boards.  Like they might have ran out of parts and switched some stuff around, thinking it would work just fine, only it doesn't.  Or something along those lines.  If you tested the switch yourself with a DMM, and it looks fine, then something is amiss with the board.

 

The motor is fine.  If a DC electric motor runs one way fine, it'll run the other direction if the power is reversed.  So we can rule out the motor.  If the switch looks good on a DMM, then we can rule out the switch.  That leaves us with the board or the wiring. 

 

On a weird side note, on the PWM controller I bought for my kayak trolling motor, the positive stays on constantly and it's the ground that gets modulated by the PWM to control speed.  I would have thought it would be reversed, but it works the same either way.  My guess is they ran out of parts to modulate the positive, and just switched it around to control the negative.  Or it was cheaper to do it this way.  My PWM is just a one direction controller, and I reverse direction by using a 3pdt switch on the output.  It's rated to 30 amps at 120VAC, and my trolling motor only pulls 30 amps @ 12VDC, so I figure it'll be fine.  With a 55# trolling motor, you'll likely need something more heavy-duty to do the same.  Or just return the PWM and buy a different brand.  Be weary though, they tend to sell the same things under a hundred different brand names on places like Amazon, so I'd opt for one that looks physically different, just to make sure it works for you.  And honestly, I'd avoid the ones that come with a built-in cooling fan.  There's not a good way to circulate that much air in a kayak, without risking the board getting wet.  And if the circuit generates enough heat that it requires a cooling fan, it's probably a bad design.  

[Don Towery]

I think the problem is the type of switches I'm trying to use.  The switches that came with the PWM are single pole double throw switches and they're not reversing polarity when toggled in the reverse position.  I ordered a double pole double throw switch, should be here tomorrow.  I think this may fix the issue.