Anyone know of a quality PWM for purchase? I have been through 3 of them.

I had to look it up as I'd never heard the term. Now I know why, I don't need one, yet! When I read what it was, my immediate thought was they get wet. Everything electronic I've had on a kayak eventually stops working... especially in the salt water. I don't even carry vhf radios any more. I did a little googling and it seems the problem is if you buy or make it waterproof, it overheats, if you vent it, it gets wet. Found the discussion below on another site.

Good Luck!

As a result of vigorous testing I come to the following conclusions

1.PWM controller does in fact extends the motor running time on one charge.

2.It does cause RF interference with the fish-finder ( reason might be close proximity to transducer and display unit in my case) could be solved by buying the shielded board or placing the board into metal case.

3. This thing will heat up significantly under load. Two ways to deal with it.

a.Get one with active cooling (which is compromising the idea of waterproofing it)

b.Buying the board with really high continuous flow rating. The board above was advertised as 60A max but got fried after few hours serving 30A motor.

4. Fuse rated same Amp as the motor does heat up and eventually blows under load. Remedy is either fuse with higher rating than the motor or semiautomatic fuse that resets after power disconnected.

5. Originally I did wire the motor trough the switch and realized that switches should be capable of sustaining the load as well.

At this point I am back to getting the parts and assembling new and improved PWM controller 2.0

Parts I am going to test next are

PWM https://www.aliexpre....21954c4d8HGDz8 Rated for 70A has aluminum casing that will help with RF pollution and cooling. Case seem to be at least splash proof.

Switches waterproof https://www.ebay.com...872.m2749.l2649

Fuse 50A https://www.ebay.com...353.m2749.l2649

I never even considered pwm for marine based motor speed control. Didn't know it was a thing.

1. Makes sense being that current flow is turned off for part of the cycle.

2. Lots of ways to rectify this issue.

3. Passive cooling with moderate heat sinks can dissipate a good amount of heat. As for waterproofing you could blob the whole thing in potting compound, leaving the heatsinks sticking out. Not sure on efficiencies without testing that.

3a. Closed loop watercooling system with the PWM controller encased in plexiglass and filled with mineral oil ala submerged PC? Sounds laborious but could be bad [censored].

4. Fuse should generally be rated quite a bit higher than the rated current draw of the motor to account for startup or in rush current. For example my electric anchor draws about 5amps but comes with a 20amp fuse from the manufacturer. It's generally not the continued operation at rated amperage that blows a fuse.

5. Yes they should be rated to carry the full current. And if you are wiring directly through switches( not through your controller) you should use a snubber circuit to dissipate the energy stored in the magnetic field around any permanent magnet motor. That energy has to go somewhere when the field collapses and without snubber diodes it will cause arcing at the contacts of your switch. Lifespan is drastically reduced in that case.

Sounds like a fun project!

If you are talkin about an external pwm, that is not built into your trolling motor head, the easiest way is to build a vented open box around to make it as splash proof as possible, and to buy one that has a good passive heatsink and is rated for shock current loads. Or you can go with a pwm that is rated much higher, say 10x your Motors rated current and don't cost 10x as much. It might be hard to find a better heavy-duty pwm that would fit inside your Motorhead control.

I like circuit breakers better than fuses, fuses can corrode especially in saltwater atmosphere at the spring loaded contacts, producing heat that trips them, plus spare fuses can be a hassle to replace in darkness or when the weather gets bad, or if you have to clean away corrosion. If you are using switches, there are switches that are designed to minimize arcing, or you can go with a much higher rating like on the pwm.

If you'er frying 3 PWMs then you have an issue with either too much current or heat. I broke 2 b4 I found out my issue.
First, you MUST measure your amperage draw under worst conditions, then, buy a PWM that is at least rated 20% more than that.
Second, and most important, is heat removal. I use a 50 amp rated PWM on my #30 MK motor.
Of course, your PWM needs to be water resistant but one can conclude that it should be in a sealed unit but that only makes the problem worse.
What I did was mount my PWM board in an approx 12x8x6" pelican box. The box was mounted to the kayak gunnel using plastic inserts to raise it up about 1/4".
The PWM is mounted inside the box in similar fashion...raised. Directly below the PWM, I perforated the box with a lot of 3/8" holes. This allows air flow into the box directly under the hot PWM.
Next, I mounted a computer cooling fan as high up on the inboard sidewall cutting a hole in the sidewall to discharge air. This draws air accross the board.
Finally, I wired the fan to the input side of the PWM so it runs constantly whenever 12VDC is applied (ie-battery hooked up)
This setup has worked fine for me the past year.
As Im running, I can feel the heat being discharged on my thigh and it is HOT! Nice thing about PWMs is that when they fail, they default to WOT.Also, the sun shining on the PWM contributes to the heat issue.

Good information on all of the above posts!

The current draw at worst conditions is called stall current, it may be up to 10 times the rated current, depending on the motor. The stall current situation happened to me one time when weeds and fishing line Tangled in the prop so that it could no longer turn, it came to a stop and I immediately pulled up the motor. The Minn Kota I was using did not come with a fuse or a pwm, it was a 5-speed, and in a way that was good- because it would have burned a standard PWM for sure. I installed an inline circuit breaker after that experience.

A standard pwm can also be burned if a motor is run continuously with the prop partially Tangled with weeds. That extra power drain with partial tangling is harder to recognize, because it may just slow down your motor a little bit. The circuit breaker may not respond to partial tangling, but after a while it will usually stress a less beefy standard pwm until it burns- unless the weeds are removed. That's my experience anyway.

Hope this helps.