Trolling motor/battery pairings and recommendations

My needs:
I want a light battery, so I'm primarily looking at Lithium battery options.

I have a 2016 outback with an added outrigger/pontoon I made up, its very light and has good hydrodynamics so there's not a ton of drag.

I want to be able to troll for a full day if choose to, and do not want to deplete the battery completely to do so. I will likely be supplementing engine power with the mirage drive since the motor will be side mounted. I do not need a lot of speed, just the ability to troll effectively with current for long periods of time.

My first attempt:
-Newport Vessels 55 pound thrust trolling motor, kayak series.
-Dakota Lithium 54 ah battery
* based on some other posts I have read, this is the combo that some members here use and have been happy with, not sure why my results seemed less impressive than theirs?

I took it out for a test run on lake Berryessa and was able to troll 8 miles over 5 hours using settings 1, 2, and 3 (max setting of 5). The battery was completely depleted at the end of 5 hours.

Not happy with those results, I returned the 55 pound thrust and picked up a 36 pound thrust engine instead. It has an amp draw of 29 compared to 52 for the 55# thrust engine. I figured this would work well paired with a 100ah Dakota Lithium battery.

All that said, I am having second thoughts and have not pulled the trigger on the 100 ah battery yet.

Was returning the 55 pound thrust engine a mistake?
I wonder if the 36 pound will have the power I want to troll effectively in ocean currents, in a kayak that weighs approximately 400 pounds (weight of hull, boater, and gear combined).

I am also wondering if I should go bigger with the battery too. Dakota sells a 135 ah battery as well...

Would 135 be major overkill?
-It's damn expensive that much is for sure!

I appreciate any feedback from those with experience or battery knowledge. I have another 25 days to return the trolling motor if I end up needing to go back to the 55# model.

Chet, if you end up reading this and are making a battery suitable for trolling these days, I'd be interested to hear the specs

I would recommended the PWM modification to extend your battery life.  See my link below:
https://www.norcalkayakanglers.com/index.php?topic=99650.0

I was thinking a 46lb motor with 100ah and PWM would make a really good combo.  I think most of these motors are made for dinghies and bass boats, and many bass boats come equipped with 35 or 46lb trolling motors and a group 27 battery. 

Because a kayak is a displacement hull, the size of motor isn't really going to change your overall top speed, but it will definitely impact your acceleration - especially factoring wind and current into the equation. Sail area can have a huge impact on performance, especially so on a windy day, so you might want to consider your configuration with that in mind. For example, I notice a huge difference if my net is vertical or laying on deck when drifting and when trolling.

I will likely rig a trolling motor on one of my kayaks this summer - please update when you get yours sorted!   

I would recommended the PWM modification to extend your battery life.  See my link below:
https://www.norcalkayakanglers.com/index.php?topic=99650.0

This post was a good read. After watching a few YouTube videos, I at least understand how to complete an install. The results you got are encouraging enough to give it a shot. Do you have any thoughts on whether or not I can get away with a 36 pound thrust engine?

I was thinking a 46lb motor with 100ah and PWM would make a really good combo.  I think most of these motors are made for dinghies and bass boats, and many bass boats come equipped with 35 or 46lb trolling motors and a group 27 battery. 

Because a kayak is a displacement hull, the size of motor isn't really going to change your overall top speed, but it will definitely impact your acceleration - especially factoring wind and current into the equation. Sail area can have a huge impact on performance, especially so on a windy day, so you might want to consider your configuration with that in mind. For example, I notice a huge difference if my net is vertical or laying on deck when drifting and when trolling.

I will likely rig a trolling motor on one of my kayaks this summer - please update when you get yours sorted!

I’m thinking you are probably right, the shaft is only 6” longer than the one on their kayak series. That could still work with my set up

I would recommended the PWM modification to extend your battery life.  See my link below:
https://www.norcalkayakanglers.com/index.php?topic=99650.0

This post was a good read. After watching a few YouTube videos, I at least understand how to complete an install. The results you got are encouraging enough to give it a shot. Do you have any thoughts on whether or not I can get away with a 36 pound thrust engine?

If you plan to troll and want the battery to last all day,  I would upgrade it to 100AH LiFe PO4.  You probably get away with your current 36lb thrust trolling motor but might not get the 6-7 mph top speed.

In order to figure out how big of a battery you'd need, you have to know how much your motor draws, and how many hours you'd like it to last.
Your 54ah battery only lasted 5 hours means your motor (at the settings you used) on average drew 10.8a per hour. If you want it to last 8 hours, you'd need a 86.4ah battery. 108ah if you want it to last 10 hours.

When you get a different motor, the draw is going to be different, then the size of battery you'd need is also different. You should get an amp meter to help you determine how much your motor draws, so you can pick the right size battery.

Many cheap motors use power resistors instead of PWM. Those power resistors are inefficient and would eat up more juice than if it had a PWM. If your motor doesn't have one built in, you should consider modding it to use a PWM. It would help you save a lot of power if you go slow.
PWM only helps if you don't go full blast.

The faster you run the motor, the higher the draw. The amount of power you give the motor vs the speed gain is not proportional. To go 3mph your motor might draw 15a, but to go 3.5mph it might require 25a. The speed vs power consumption is not a linear increase.

I troll with a small 18lb thrust WaterSnake. On my Revo 13, I can troll at 2-2.2mph with 3a draw. I built my own battery packs with whatever capacity I need. My tiny 30ah battery would last me 10 hours. The motor and battery together weight 13.5lbs.

What I'm trying to say is, the motor you select, the amount of time you want to last, and the way you use it, would determine how big of a battery you'd need.

A rough estimate of power draw can be determined by the thrust rating. They are roughly equivalent. So if you have a 55 lb thrust motor, it would roughly draw 55a per hour at top speed.

Good luck in your search.

One thing I've read online is that higher thrust motors draw less amps than lower thrust motors when both motors are creating the same thrust. Something to do with the diameter of the motor and torque. My takeaway was that a 55lb motor might be more efficient than a 36lb motor when creating say, 36lbs of thrust.

Hoping someone can speak to this... All I know about electricity is that it will kill you.

One thing I've read online is that higher thrust motors draw less amps than lower thrust motors when both motors are creating the same thrust. Something to do with the diameter of the motor and torque. My takeaway was that a 55lb motor might be more efficient than a 36lb motor when creating say, 36lbs of thrust.

Hoping someone can speak to this... All I know about electricity is that it will kill you.

This definitely makes sense - you would be using less of it's total capacity.  You can see this in cars too sometimes - the more powerful engine option often gets better economy at slower speeds because it is using less of the total capacity of the engine.  I wonder how different total motor speed of a 36 vs a 55 lb motor is?  Is the motor significantly faster, or is the propeller larger, and I wonder which has more of an impact on performance and battery life?

I would imagine there are a ton of factors that play into also, like propeller size/shape, gearing, and the motor, shaft and wiring configuration.  And that is before factoring in the vessel it is installed on, how it is installed and configured, and what power source it is using.  I would imagine different types of batteries and even different brands of the same types provide different levels of power and capacity, impacting performance.  Environmental factors also play a role; wind and current are the probably the biggest, but I would also imagine air and water temp factor in as well. 

I just went through this. I started with a NV36 and a 55ah SLA battery. The NV36 does not have a built in PWM do it draws the same amount from the battery regardless if you're running at speed 1 or 5. Basically it uses resistors in the head to burn off the extra power as heat when running anything less than speed 5. When my SLA was new, I could easily run a day and a half at speed 1. That was fine as I only use it to troll for Kokanee or trout. However, after a year, the battery started to not last as long and would barely get me 6 hours. Ended up getting a 55ah LiFePo4 and a Minn Kota PWM. The PWM will double the life of the battery and the LiFePo4 has double the life of the SLA. I can easily get two days running at low speeds. Another advantage With the PWM is that the speed control is far superior. The PWM uses a Potentiometer so you're able to run the motor at any speed you want, from 1rpm to max rather that just 5 preset forward. This allows you to precisely dial up the speed you want. Big advantage for me especially when trolling for Koke's, as the slowest speed was still to fast on the NV36. There area ton of how to video's and other info on Motorized kayak fishing - Facebook.
The newest thing now is using a ESC. I'll probably change to this setup. They are waterproof, way smaller and will last longer than a PWM.

Kevin

I just went through this. I started with a NV36 and a 55ah SLA battery. The NV36 does not have a built in PWM do it draws the same amount from the battery regardless if you're running at speed 1 or 5. Basically it uses resistors in the head to burn off the extra power as heat when running anything less than speed 5. When my SLA was new, I could easily run a day and a half at speed 1. That was fine as I only use it to troll for Kokanee or trout. However, after a year, the battery started to not last as long and would barely get me 6 hours. Ended up getting a 55ah LiFePo4 and a Minn Kota PWM. The PWM will double the life of the battery and the LiFePo4 has double the life of the SLA. I can easily get two days running at low speeds. Another advantage With the PWM is that the speed control is far superior. The PWM uses a Potentiometer so you're able to run the motor at any speed you want, from 1rpm to max rather that just 5 preset forward. This allows you to precisely dial up the speed you want. Big advantage for me especially when trolling for Koke's, as the slowest speed was still to fast on the NV36. There area ton of how to video's and other info on Motorized kayak fishing - Facebook.
The newest thing now is using a ESC. I'll probably change to this setup. They are waterproof, way smaller and will last longer than a PWM.

Kevin

ESC (Electronic Speed Control) is a device, PWM is a technique.  All ESC using PWM in one form or another.

Agreed, There are many types of PWM's available. Most people tend to use the the cheap $25 Chinese ones. The problem with those is they are big, 6x10x2", get hot, burn out and they are not waterproof. I went with the $80 the Minn Kota model. It's smaller, about 4x4x1", has a much better heat sink and is waterproof. The best set up now is using the $35 Hobbywing 880 ESC. It's only 1x1x1", comes with a fan to keep it cool and is waterproof.
As you know, space and weight are everything on a kayak. When/if my Minn Kota PWM dies, the Hobbywing 880 will be the way to go.

Great info here, thanks for posting your experince!

So many knowledgeable people in this community, thanks for the thoughts and intel, it’s all helpful since I also feel like electrical properties and hardware continue to be a challenging things for me to understand.

I’m going to keep waiting, reading feedback here, and researching all of these great suggestions.

At this moment, I’m thinking the 36 pound thrust engine may work, especially with the PWM or ESC incorporated. I feel pretty good about going with a 100 ah battery as well. All subject to revision of new/better options reveal themselves.

Sea-bree, here are a few video's I used to help me set up mine.







I also added a outboard motor kill switch so if I go overboard the kayak wont motor away from me.