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

[ib18]

how many amps (DC current) does a trolling motor draw? 12v Minn Kota c2 30 pounds

how many amps (DC current) does a trolling motor draw? 12v Minn Kota c2 30 pounds. I was told when I bought my minn kota to install a 50 amps breaker to save the motor just in case of a short. I was wondering about how many amps does it draw. Now, I finally got answers for myself.

Attached pictures show you what I found so you don't have to do it if you have the same Minn Kota Endura c2 trolling motor.

Also watch my video to learn if you would like to check your specific trolling motor - how much amps they draw under water and in the air.

I am planning to do the same amp test on my 70 pounds motorguide (24 volts system) foot controlled trolling motor to see how much it use and report back to everyone.

 

[ib18]

[No message]

 

[ib18]

I also build a "variable speed controller" aka digital speed maximizer for my trolling motor with LCD digital display to show you the difference with and without it - watch here
2 advantages of a variable speed controller
(1) so i can increase my battery run time when i troll in the water
(2) so i can be quiet to get close or on top of a school of crappies with speed between the fixed trolling motor gear intervals.

 

[fishrdan]

Interesting, thanks for sharing.

Trolling motors are supposed to draw about 1 amp / # of thrust,,, at motor stall speed. And of course, 24V TM's will draw less or about .5 amps/#. TM's will draw less power with less load applied, and having the TM in a barrel where it can draw in air and recirculate the water, could skew actual real world power draw where the TM will see varying loads and clean uninterrupted water. Good test to see what's happening though, will be interesting to see what the current meter shows when on the water.

I recently bought a couple low amp PWM motor controllers from China that were dirt cheap, $3-4. The 3 amp controller produced an annoying motor whine, while the 10 amp controller was very quiet, both were driving small 12V fans. Motor whine is one of my complaints about PWM TM's, compared to speed coil TM's, so that's something you may want to look into, how loud is the TM running off the speed coils, compared to running off the PWM controller. You'll have to pull it out of the water to listen to the motor.

 

[gm280]

If you had the capability to measure micro ohms, you could simply turn the motor to the highest setting, read the resistance and using Ohm's law figure the current draw without such setups. JMHO!

 

[gm280]

Fishrdan, some PWM circuits allow you to also control the frequency and then you can adjust the frequency to move the sound out of your hearing range. JMHO!

 

[bruceb58]

If you had the capability to measure micro ohms, you could simply turn the motor to the highest setting, read the resistance and using Ohm's law figure the current draw without such setups. JMHO!

That will not work unless you want the stall current of a motor which isn't useful. Also, current will always depend on the load on the motor.

 

[ib18]

wow, many thanks to your generous and detail comments. Yes. I will look into the tips you kindly provided. Yes, that was a great suggestion. I will also report back my findings when I take my trolling motor out on the lake. I suspect. The amps will be higher than what I see in the pic and videos.

 

[fishrdan]

wow, many thanks to your generous and detail comments. Yes. I will look into the tips you kindly provided. Yes, that was a great suggestion. I will also report back my findings when I take my trolling motor out on the lake. I suspect. The amps will be higher than what I see in the pic and videos.

Here are a couple scenarios to consider testing current draw:
- Going from a dead stop to instantly full power on the TM
- Boat tied to dock and TM at full power
- Driving the motor through some thick weeds at full power

See how those conditions affect power draw compared to the motor just running at full power in calm open water. Also would be interesting to see how speed affects current draw, 1mph, 2mpg, 3mph, 4mph, top speed.

Also, for the breaker, it's needed first to protect the wire from burning due to a short (so you boat doesn't burn down), then secondary to protect the TM. Thus the breaker needing to be located within 1 foot or less from the battery. I have my breakers mounted direct on the battery terminal. The breaker should also be a manual reset, not an automatic reset.

 

[ib18]

Here are a couple scenarios to consider testing current draw:
- Going from a dead stop to instantly full power on the TM
- Boat tied to dock and TM at full power
- Driving the motor through some thick weeds at full power

See how those conditions affect power draw compared to the motor just running at full power in calm open water. Also would be interesting to see how speed affects current draw, 1mph, 2mpg, 3mph, 4mph, top speed.

Also, for the breaker, it's needed first to protect the wire from burning due to a short (so you boat doesn't burn down), then secondary to protect the TM. Thus the breaker needing to be located within 1 foot or less from the battery. I have my breakers mounted direct on the battery terminal. The breaker should also be a manual reset, not an automatic reset.

Good idea! I will try some of your scenarios and report back! LOL - you really prompted my curiosity on this DIY project!!

Gosh! Thanks for the breaker location tip. I don't have a breaker installed yet for my minn kota 30 pound push used exclusively on my canoe. neither is my fishing buddy who has a 45 pound push used on his 12-foot aluminum boat. We are lucky not to burn the boats or the TM yet - LOL:laugh:. I know I will need to add a breaker on my foot controlled motorguide 70 pound push big TM when I am ready to mount it onto my wellcraft 165 airslot sport open bow boat.

 

[ib18]

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

 

[gm280]

ib18, I understand fully what you're trying to explain. But in all honesty that exact same circuit can be purchased for about ~$13 dollars and some change delivered, from a China manufacturer listed on EBay. I know because I actually bought that exact same circuit in the last two weeks myself. It is a 60A 0-50 volt input range PWM /digitizer circuit. And I am sure some folks are wondering why I bought one instead of building one. I have built a few now, but I can't even buy the 12 power MOSFETS for $13 dollars let alone the heat-sinks and support circuitry. So I bought one. And yes, I do plan on testing it to see how hot it actually gets before installing it behind the trolling motor panel in my boat project. I may even install a temperature controlled fan to blow across the heat-sinks if it gets too hot. JMHO!

 

[gm280]

Obviously a stalled trolling motor with a totally fresh charged battery source will draw more amps then one spinning freely. So stop the propeller and see what the draw is. But only for a very short period of time because it also heats up the windings and everything else passing that current. JMHO!

 

[fishrdan]

I don't have a breaker installed yet for my minn kota 30 pound push used exclusively on my canoe. neither is my fishing buddy who has a 45 pound push used on his 12-foot aluminum boat.

Myself, I don't think the breaker is a huge issue if the TM is being clipped directly to the battery with alligator clips, as long a you can just yank the cables off if needed. Though, most TM's have ring terminals attached to them now, and it would be difficult to remove the wires quickly in the event the TM or wiring was shorted out. Ring terminals are far better than cheap alligator clips that could limit current, but then there is the safety issue. If the wiring is hidden or the connection covered, then the breaker is important, kind of a CYA thing to save you if the worst happens, probably won't, but....

Your post and testing is showing info that's not readily available, and showing info that I' have wondered about for a long time, so a big thanks for posting up the info you have.

 

[jrttoday]

thank you thank you thank you both! For years I've been trying to figure/find out how to do this. Have a 40lb Kota on a 12' john and the maximizer quit years ago. I had really rather skull the boat when hunting big Bass, but even with a $5,000 fine for feeding the gators, somebody is doing it because some are losing their fear of people. I don't want to lose an arm or worse just fishing!!!

 

[ib18]

ok, i was able to test my Digital maximizer system on my big foot controlled motorguide 70 lb TM (trolling motor) under 24 volts and it worked beautifully until I fried my TM because I didn't have 50 amps circuit breaker added. Need to troubleshoot it or buy another TM. These big boys are really expensive $500+ for new and $250 for used from my quick research. Bummer.
1. How do i troubleshoot my TM? I guess i need to open up the trolling motor to check but what exactly do i look for?
2. How do i add an inline circuit breaker for a 24 volts system if i am lucky to get it back to work?

 

[ib18]

Here are a couple scenarios to consider testing current draw:
- Going from a dead stop to instantly full power on the TM
- Boat tied to dock and TM at full power
- Driving the motor through some thick weeds at full power

See how those conditions affect power draw compared to the motor just running at full power in calm open water. Also would be interesting to see how speed affects current draw, 1mph, 2mpg, 3mph, 4mph, top speed.

Also, for the breaker, it's needed first to protect the wire from burning due to a short (so you boat doesn't burn down), then secondary to protect the TM. Thus the breaker needing to be located within 1 foot or less from the battery. I have my breakers mounted direct on the battery terminal. The breaker should also be a manual reset, not an automatic reset.

I am reporting back about your 3 scenarios:

1. Going from a dead stop to instantly full power on the TM (motorguide 70 lbs with 24 volts) - bad idea without circuit breaker - I think I fried my TM when I dialed my PWM radio button from zero to full speed with TM gear in F5, in the process of troublshooting and buy a new or used one.

Probably should always turn the radio button slowly, maybe that's why TM are designed to go from zero to F1, F2 to F5.

 

[ib18]

Myself, I don't think the breaker is a huge issue if the TM is being clipped directly to the battery with alligator clips, as long a you can just yank the cables off if needed. Though, most TM's have ring terminals attached to them now, and it would be difficult to remove the wires quickly in the event the TM or wiring was shorted out. Ring terminals are far better than cheap alligator clips that could limit current, but then there is the safety issue. If the wiring is hidden or the connection covered, then the breaker is important, kind of a CYA thing to save you if the worst happens, probably won't, but....

Your post and testing is showing info that's not readily available, and showing info that I' have wondered about for a long time, so a big thanks for posting up the info you have.

here is a my amp data on my big 70 lbs foot controlled motorguide TM with 24 volts setup before I fried it without circuit breaker.

 

[ib18]

In warter under load - 70 lbs foot controlled motorguide TM with 24 volts

 

[jbcurt00]

Not sure why this is under freshwater fishing, moved to electronics and trolling motor forum and merged w your other topic about this trolling motor control mod.

Sorry to hear the TM's fried though, bummer