Running a TM on yak... Lithium battery?

I run a regular deep cycle marine battery for my 30# TM. It was right at 100$ and gives me plenty of power to last all day. It is by now means broken, BUT it is super heavy (pushing 70#.) That makes me ride with a low drag in the water. It also takes up a lot of room in the tank well. Recently, I heard about lithium batteries for TM.

1) They are expensive, but seem to be worth it in the long run. Do you agree?

*Probably not worth it if someone only goes out goes out a few times per year, like on the 5 major (5 -70 # loading times) holidays. I go out around 100 times per year and also use the same battery for other purposes, so well under 30 cents per use over 10 years with lithium.

2) What size do you need for small TM to run all day? (54aH seems to be good)

*A 54ah lithium will usually perform better than a 80ah lead battery, so I only need around 50% to 65% of capacity compared to lead battery.


3) Lithium seems to be the main ingredient, but there are lots of other combos (IE: iron, phosphorus, etc.) What is the best/best for the money?

*There isn't that much difference in cost for TM sizes, except for very newest lithium version which may not be worth the high price, last time I checked.

4) Trends seem to dictate that prices for these batteries will drop. Should I wait to pick one up?

*Depends on pandemic, import tariff politics, and demand for EVs, etc for china (the present market maker), cost may increase.

5) Right now, I can go about 3 MPH with my TM. If I switch to a lithium battery (and lose 50#), it would stand to reason my speed would increase. Would this increase be enough to justify the >300$ price tag?

*Nope, weight difference has little effect on speed. Changing out the TM weed free prop to APC model air plane prop might get you 3.3 MPH while also using less power draw, but you will tangle a lot more in weeds when around them.

If there is anything else you know about them that you could throw in, I'd appreciate it. Just looking to make an informed decision...

I try to fish 80ish days a year. (If only I didn't have to work...) I'm really trying to get a little more speed and space. Right now I run a heavily modified OK Big Game Prowler. I only weigh 180# so this boat has weight to spare. I was hoping the lithium battery would help shed weight and in turn get me moving faster. My current set-up works great, just trying to improve my scene and weigh my options. I'll probably keep running my 70#er until it starts to give out. At that point, it would probably make sense to get the Li battery. I have read Dakota makes a good one. Do any others come to mind?

Agree that brute force with a torqeedo might increase the speed significantly. But if speed is that important, a 3-4 hp gasoline engine weighing around 60 lbs would probably get you there cheaper, or use a jet ski if cost not important?

Yes sir a gasser is definitely the cheapest route to go at least initially. The down side is having to carry a gas can and in Texas he would also have to carry a throw cushion and a fire extinguisher on board to be legal. Then there's maintenance on the engine and the noise.

Changing the prop is a good point. It might give you a 1 mph increase if you find the right one.

The path of least resistance is to simply purchase a larger TM... a 45-pound thrust will make Kayak scream. However, this will necessitate a larger capacity battery.

3MP in a kayak is not a bad speed... enjoy the scenery and crack a beverage on the way.

my 12V 35AH lead acid battery hooked up to my 30lb thrust only last me about 3 miles or less before becoming obsolete on my yak (45 lbs) with me (150lbs) and maybe another 15-20 lbs of gear. Having to haul the added 40+ pounds from the dead TM, battery, and mount for another 3-4 miles (plus my catch) made me ditch the idea after a few outings. Still considering upgrading to a larger battery for this upcoming season though.

my 12V 35AH lead acid battery hooked up to my 30lb thrust only last me about 3 miles or less before becoming obsolete on my yak (45 lbs) with me (150lbs) and maybe another 15-20 lbs of gear. Having to haul the added 40+ pounds from the dead TM, battery, and mount for another 3-4 miles (plus my catch) made me ditch the idea after a few outings. Still considering upgrading to a larger battery for this upcoming season though.

For model props, No cutting, drilling, or rewiring necessary if a smaller than 12" left hand pitch prop is used. This one fits most troll motors without alterations:


https://www.apcprop.com/product/10x4p-lh/



The downside previously written in post # 3 pg 1 @ 5) above is these props are weed magnets, and severe tangling might bring you to a stop. If you catch the tangling early on, sometimes you can untangle, by tilting the motor so the prop is out of water, then spinning the prop in air, reverse and forward, to fling off the weeds. But severe tangling may require that someone use their hands on the prop to untangle, which means somehow bringing the Motorhead on board. Don't ask me how I know....

Like iConn said, changing props can help. You don't need a wide, fat prop to push a kayak. TM props are made to push a 2000 pound bass boat. I put a 12" model airplane prop on my 40# MinnKota, and cut an inch off each tip. It made no difference in top speed, but I use way less amperage. Most of the "work" is done at the outer inch or so of the prop. A guy in Houston did lots of measurements and he showed a vast reduction in amp draw. I had to reverse the two big TM leads, because the airplane prop turns the other direction. I didn't want 3 forward speeds and 5 reverses. I now have the TM on my aluminum flats skiff(approx. 450 pounds), and pushes it around nicely. IslandJim