How to build a variable speed control for trolling motor? aka, digital maximizer

[Scott Danforth]

A$10 inline CB is dirt cheap compared to a TM

 

[ib18]

A$10 inline CB is dirt cheap compared to a TM

Totally agree, I actually have it when I bought my first minn kota c2 30 lbs trolling motor, but never bother to add it. Now, a lesson learned. I definitely will add it before I hit the water again.

 

[StarTed]

I'm interested in your setup and testing since I hope to put a TM on my boat when the time comes. Here is a thought, many motors do not like pulsed current such as comes with square waves. I wonder if adding a large capacitor between the PWM and the TM might make it run quieter. At least that should round off the edges of the PWM output. Just thinking here without any experience doing this on a TM. I know that a .01 mfd or less capacitor can short out some high frequencies noise on a household circuit whereas a large capacitor will just pass them through. Just use a 400VAC or higher rating.

Since you like testing I'm just curious.

Good luck with your venture.

 

[fishrdan]

I doubt the TM was harmed by the PWM, no difference with the PWM at 100% or connecting the motor directly to the battery. Though it looks like the problem could be due to insufficient wiring. the TM can draw a lot of power as you saw, and thin wire and/or loose connections could cause all sorts of weird issues. Even for short wire runs and testing like you are doing, I would use at least 12ga wire, with all connections crimped and ring terminals bolted onto the battery(s). When you get this installed into the boat you will most likely need to use much larger wiring, 6 or 8 gauge. To calculate what wire you'll need to use, google "blue seas dc wire calculator" and run through their calculator tool. GenuineDealz.com is a good place to buy wire when you go to install the TM into the boat.

The motor won't turn with the end cap(s) removed, so you'll need to put it back together, then check if the motor will turn under power. You should also replace the end cap seals as they are supposed to be replaced anytime the motor is taken apart,,, water getting inside the motor is a kiss of death for a TM. Probably a good idea to oil the motor bushings while it's apart. I used to have that exact same TM for 10 years, worked great without a hitch. Check all of the pedal switch positions as the toggle switch could cause the no-run problem like you're seeing.

For the breaker, just add a 50 amp between the TM's + wire and the batteries + terminal.

 

[ib18]

I doubt the TM was harmed by the PWM, no difference with the PWM at 100% or connecting the motor directly to the battery. Though it looks like the problem could be due to insufficient wiring. the TM can draw a lot of power as you saw, and thin wire and/or loose connections could cause all sorts of weird issues. Even for short wire runs and testing like you are doing, I would use at least 12ga wire, with all connections crimped and ring terminals bolted onto the battery(s). When you get this installed into the boat you will most likely need to use much larger wiring, 6 or 8 gauge. To calculate what wire you'll need to use, google "blue seas dc wire calculator" and run through their calculator tool. GenuineDealz.com is a good place to buy wire when you go to install the TM into the boat.

The motor won't turn with the end cap(s) removed, so you'll need to put it back together, then check if the motor will turn under power. You should also replace the end cap seals as they are supposed to be replaced anytime the motor is taken apart,,, water getting inside the motor is a kiss of death for a TM. Probably a good idea to oil the motor bushings while it's apart. I used to have that exact same TM for 10 years, worked great without a hitch. Check all of the pedal switch positions as the toggle switch could cause the no-run problem like you're seeing.

For the breaker, just add a 50 amp between the TM's + wire and the batteries + terminal.

Thank you! Yes, the thin wires (my guess they are 14 or 16 gauges) between PWM and LCD display meter worries me. I am going to find out if I can run it at full speed next time when I get on the water again. Hope they don't melt. The wires did OK when I was trolling the water at slow speed under 3 amps last time. My wires between TM and PWM are 10 gauges (my guess), so yes I should probably install 8 gauge wires between TM and PWM.
yes, I will crimped down the connections with ring and quick disconnect and get rid of any loose connections and Y-clips.

 

[ib18]

I'm interested in your setup and testing since I hope to put a TM on my boat when the time comes. Here is a thought, many motors do not like pulsed current such as comes with square waves. I wonder if adding a large capacitor between the PWM and the TM might make it run quieter. At least that should round off the edges of the PWM output. Just thinking here without any experience doing this on a TM. I know that a .01 mfd or less capacitor can short out some high frequencies noise on a household circuit whereas a large capacitor will just pass them through. Just use a 400VAC or higher rating.

Since you like testing I'm just curious.

Good luck with your venture.

LOL - I waited for 2 years and finally bit the bullet and bought the TM. Spent a day installing the TM onto my wellcraft airslot 165 sport. The fitting and measuring was time killer. Making holes into fiberglass was no fun. I had to remove my bow light, so I am still to mount the bow light back with some elevated platform for the light to sit on. I had to saw off 4 rusted screws for the front railing and port side of boat cleat. Totally rusted screws and bolts. My TM is really heavy, but now I will be able to enjoy the super power the TM produces. I was testing it last Friday and the TM handles the incoming tide and wind without a problem. I didn't even run it at full speed. Just used a couple amps to push my boat with the heavy 300 pounds Johnson 90 hp dragging in the stern. It was no issue for my TM. I am glad I went with the big 70 lbs/24 volts motorguide instead of a smaller TM.

BTW, neither setup was making noise for my test of 30 lbs minn kota with PWM and 70 lbs motorguide with PWM. PWM was just dead quiet. Didn't hear a thing from it.