Question about trolling motor performance

[ninhalo5]

Hi, I just purchased a 40 lb minn Kota c2. This is my first trolling motor. I have a question about it. I'm thinking there may be an issue, but how fast should that prop spin? When I look at it it's moving at full speed about as fast as a ceiling fan that you turned off 10 seconds ago. And forward gear #5 looks to be going the same speed as reverse gear #3. The blade looks even slower in the water and hardly even flung water when I had it skimming the surface.

Needless to say the motor did absolutely nothing for moving the boat except extremely slowly helped me steer it while going down stream.
I would have thought that blade would spin as fast as a fan at full speed. If this trolling motor is working as it should, then I better find me a 1000lb thrust one for my lil boat.

Thanks

 

[Silvertip]

Re: Question about trolling motor performance

Do have a good battery and is it fully charged
Battery should be a group size 24 minimum.

 

[ninhalo5]

Re: Question about trolling motor performance

Yes, it's was a fully charged deep cycle maxx-24d. I know one thing that trolling motor ate 1/2 of the batteries power just running it for 15 minutes. Where that same battery would run the tilt/trim and my electronics on my 19' bass boat. Seems rediculous to me, but I don't know.

 

[glenn property of pam]

Re: Question about trolling motor performance

what size wire are you using between the battery and the trolling motor and over what distance. You might be just burning energy making a nice heater wire rather than getting the power to the trolling motor.

 

[Silvertip]

Re: Question about trolling motor performance

Current draw for periodic operation of the trim system and operation of general electronics like a locator are a drop in the bucket compared to what the troller draws since it runs steady. You need to have that battery fully charged and load tested. If it were a good battery the troller could not possibly use half it's charge, unloaded or loaded in 15 minutes. With power disconnected, try turning the prop by hand (either direction). It should turn freely but it may have a slight jerkiness to it which is normal. If it turns relatively hard, something is bound up and that would suck current at a high rate and also cause performance problems. I would bet through that you have a weak battery (one that won't hold a charge) or some bad wiring.

 

[fishrdan]

Re: Question about trolling motor performance

Charge the battery and re-test the trolling motor. Put a meter on the battery to see what the voltage is when the TM is off and when the TM is running in water. With a completely charged battery the voltage should be 12.7>12.6V at rest, and shouldn't drop significantly when the TM is turned on. (Turn on the TM for a minute or two to scrub off the battery's surface charge before testing.)

How is the TM connected to the battery, directly bolted on with wing nuts, through additional wiring, alligator clips? Are the terminals of the battery cleaned up and shiny? How is the electrolyte (water) level in the battery?

 

[ninhalo5]

Re: Question about trolling motor performance

what size wire are you using between the battery and the trolling motor and over what distance. You might be just burning energy making a nice heater wire rather than getting the power to the trolling motor.

Just the stock wire on the motor, attached directly to the battery.

 

[ninhalo5]

Re: Question about trolling motor performance

My battery is virtually brand new. I originally bought it for my Procraft 3 months ago and only used it to raise and lower the engine once in awhile while I was working on the boat. I've only had to charge the battery once and then I gave it a top off on Saturday and it was at 96% charge at the time I hooked it up to the charger.
I'll try the tests both silver tip and fishrdan mentioned and report back.

Me saying it ate 1/2 the battery power might not be fully accurate. I got that reading from an old Craftsman auto analyzer, all my multimeters are in need of batteries too.

 

[colbyt]

Re: Question about trolling motor performance

Unless you are in a very clear stream or lake you should not be able to see the prop when the Troller is properly mounted. Trolling motors are much better at pulling than they are at pushing.

Some where I read a very detailed article about speed positions on a Minn Kota. The final point was that the highest speed is wasted as it consumes a disproportionate amount energy for the additional thrust provided.

I surely did not have a stop watch going but my 30 never drained my class 27 battery last summer and it was the primary motor.

 

[pikefisherman]

Re: Question about trolling motor performance

My 30# spins like a fan on high, maybe the motor is bad, I would try what silver tip suggested.

 

[ninhalo5]

Re: Question about trolling motor performance

Unless you are in a very clear stream or lake you should not be able to see the prop when the Troller is properly mounted.

The water was fairly clear on Sunday, I could see the bottom of the river which was about 3-4'. Yeah, that prop was going around at full speed so slow I could make out the gap between the blades and if it weren't razor sharp, probably could have stopped it with a finger with no problem

 

[colbyt]

Re: Question about trolling motor performance

You said purchased. I assumed new. Was it new or am I the first part of assumed?

Used anything is possible. Bad switches and burnt leads can cause them to run slow.

 

[ninhalo5]

Re: Question about trolling motor performance

Yes, brand new, bought on Saturday. Though I got it from Wally World, which really don't account for too much

 

[fishrdan]

Re: Question about trolling motor performance

Try hooking the TM up to a car battery, to see if it changes how the TM operates,,, rule out a bad battery. Does the TM have distinct changes in speed from 1-2-3-4-5. If the TM doesn't operate properly on the car battery, call MK and let them know what's happening.

Some where I read a very detailed article about speed positions on a Minn Kota. The final point was that the highest speed is wasted as it consumes a disproportionate amount energy for the additional thrust provided.

Was that due to the prop being inefficient at high speeds? On an old-tech speed coil TM like the OP has, the TM uses about the same power at any speed. Speed coils shunt power around the motor, so even though the motor is spinning slower, the same amount of power is being used,,, the speed coils waste power, scrub it off away from the motor. If this were a digital TM, power usage would ramp up with speed, and probably less efficient at top end due to the prop.

 

[colbyt]

Re: Question about trolling motor performance

Yes, brand new, bought on Saturday. Though I got it from Wally World, which really don't account for too much

Something isn't right. My C30 moved a small 12 foot boat with 600 pounds of lard in it. There was a noticeable difference in the forward speed between the various settings. I haven't tried it on the new boat but hope to do so this weekend

I would use a bucket of water and my car battery to test it at home as suggested above as either your battery, the motor or the connection is bad. Before I took any action I would also test my battery per the instructions above, fully charged and take someplace that sells batteries for a 20 second test. Either could be bad even if they are both new.

Within 30 days with receipt I am fairly sure Wally world will exchange or take it back. If not call the 800 number in the manual

 

[colbyt]

Re: Question about trolling motor performance

Was that due to the prop being inefficient at high speeds? On an old-tech speed coil TM like the OP has, the TM uses about the same power at any speed. Speed coils shunt power around the motor, so even though the motor is spinning slower, the same amount of power is being used,,, the speed coils waste power, scrub it off away from the motor. If this were a digital TM, power usage would ramp up with speed, and probably less efficient at top end due to the prop.

It was the C30 or C40 but you may have misunderstood my point, the minor speed gain does not make for efficient use of the battery. Up to 4 speed the increase justifies the drain on a sliding scale. Full powers uses more than its fair share of amp hours.

 

[gm280]

Re: Question about trolling motor performance

This may sound really silly, but are you absolutely sure the prop is tightened on the TM?

 

[fishrdan]

Re: Question about trolling motor performance

It was the C30 or C40 but you may have misunderstood my point, the minor speed gain does not make for efficient use of the battery. Up to 4 speed the increase justifies the drain on a sliding scale. Full powers uses more than its fair share of amp hours.

I'm not exactly sure what you're saying, though I do agree that prop inefficiency could cause top speed to be less efficient.

Old style (inexpensive) speed coil TM's use almost the same power in speeds 1-4 as they do in speed 5, could actually be the same as I've never measured it. The speed coils cause this by draining off extra power and making the motor turn slower, old-tech and very inefficient. Kind of like standing on the car's brake pedal while the gas pedal is floored, the car goes slower, but it's still using the same amount of gas. Newer digital trolling motors use a controller to pulse the motor with short bursts of power and are very efficient, sliding scale, and the slower the motor goes, the less power it uses. Efficiency really depends on what type of trolling motor is being used, but the OP's MK C2 is an inefficient speed coil TM.

 

[Silvertip]

Re: Question about trolling motor performance

Trolling motors are no different than gas engines when pushing a boat. Throttle movement and speed is not linear. As speed increases beyond a certain point (every hull is different and the power curve of every engine is different) it takes much more power to increase speed. So NO! The difference between speeds is not linear under load.

 

[fishrdan]

Re: Question about trolling motor performance

^^^ I do agree with that, and maybe that's what colby was getting at.

Though battery usage wise, it's going to take the same amount of power (AH) creeping along at speed 1 as compared to wide open at speed 5, with an old speed coil TM.