What’s the Best Trolling Motor Battery for Long Fishing Trips?

Hello everyone.

I’m looking to upgrade the battery for my trolling motor and would appreciate some advice from experienced anglers. I’m mainly interested in finding the best trolling motor battery that offers a good balance of runtime, reliability, weight, and overall value.

I’ve seen lithium, AGM, and traditional lead-acid options, but I’m unsure which type is worth the extra cost.

My trolling motor is used for several hours at a time, sometimes on longer fishing trips.

What battery brands or models have worked well for you?

Are lithium batteries really worth the investment compared with AGM?

thanks in advance for any help

Current lithium are the best, no question about it. The main downside is charging and using them at below freezing temperatures, but there are self heating models.

Li all the way. Lowest weight to power ratio and lowest volume to power as well.

Normally I would say lithium all the way..

Check to see if your existing troll motor, is compatible with Lithium, some have been damaged using them. There were some bulletins put out by some troll motor manufacturers warning about this a few years ago, but it may not apply to your situation. Several hours at a time especially at full speed might cause overheating because some lithiums are capable of much higher amp delivery.

If your system is stationary and occupies a particular spot to balance the weight on your craft, it might be a consideration. Unless it is just one battery that you can move around?

What things do you dislike about your current system? Lithium may improve on some of these.

I don't know what's marketed specifically for electric boat motors, but the motor doesn't know either. There are a number of different kinds of lithium batteries. I've used, and like, lithium iron phosphate batteries for other purposes. For instance. I have one in my lawn mower, which was originally meant for some type of 12V lead acid battery. I use the charger that came with the mower. I don't recall if the battery has a built in battery management system. In any case, it out-performs the lead acid types I've had in the mower and is much lighter. I chose lithium iron phosphate because it's supposed to be safer, i.e. less likely to burn. It's not quite as light as a vanilla lithium battery, but it is light enough. There are other variations out there, which I'm not very familiar with.

portacruise said:

Normally I would say lithium all the way..

Check to see if your existing troll motor, especially if you’re choosing the best trolling motor battery, is compatible with Lithium, as some have been damaged using them. There were some bulletins put out by some troll motor manufacturers warning about this a few years ago, but it may not apply to your situation. Several hours at a time, especially at full speed, might cause overheating because some lithiums are capable of much higher amp delivery.

If your system is stationary and occupies a particular spot to balance the weight on your craft, it might be a consideration. Unless it is just one battery that you can move around?

What things do you dislike about your current system? Lithium may improve on some of these.

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thank you so much for your suggestion

portacruise said:

Normally I would say lithium all the way..

Check to see if your existing troll motor, is compatible with Lithium, some have been damaged using them. There were some bulletins put out by some troll motor manufacturers warning about this a few years ago, but it may not apply to your situation. Several hours at a time especially at full speed might cause overheating because some lithiums are capable of much higher amp delivery.

If your system is stationary and occupies a particular spot to balance the weight on your craft, it might be a consideration. Unless it is just one battery that you can move around?

What things do you dislike about your current system? Lithium may improve on some of these.

Click to expand...

I don't know if you can get them, but a propeller with slightly less pitch or a slightly smaller diameter might help with this. Or a boat that has less resistance. Maybe in a canoe this problem would be reduced. I wonder if the problem wasn't extra voltage, leading to more current, rather than an inherent capacity for more current. Aren't lead-acid batteries usually rated for hundreds of "cold cranking amps"? If you can measure the amps going through the motor, you may be able to tell if you have a problem.

rnlock said:

I don't know if you can get them, but a propeller with slightly less pitch or a slightly smaller diameter might help with this. Or a boat that has less resistance. Maybe in a canoe this problem would be reduced. I wonder if the problem wasn't extra voltage, leading to more current, rather than an inherent capacity for more current. Aren't lead-acid batteries usually rated for hundreds of "cold cranking amps"? If you can measure the amps going through the motor, you may be able to tell if you have a problem.

Click to expand...

Yes, most lithium systems have a lower internal resistance which can mean much less of a voltage drop and higher amps. Flooded battery CCA for example are measured at 0 degrees F, for 30 seconds only, and to the Voltage Drop limit of 7.8v (VD not necessarily the same as discharge to empty limit) compared to the normal open circuit 12.8v. Presumably a lithium would not drop as much in voltage, means attempting to push more amps through a speed control and wiring not built for it. It is not possible to run hundreds of amps through a troll motor because of the much smaller diameter wire windings would burn instantly, compared to a starter motor with large guage copper wire windings. My older troll motors were not fuse/breaker protected, as there were no lithium batteries alternatives at the time, but I don't know about the newer models.

portacruise said:

Normally I would say lithium all the way..

Check to see if your existing troll motor, is compatible with Lithium, some have been damaged using them. There were some bulletins put out by some troll motor manufacturers warning about this a few years ago, but it may not apply to your situation. Several hours at a time especially at full speed might cause overheating because some lithiums are capable of much higher amp delivery.

If your system is stationary and occupies a particular spot to balance the weight on your craft, it might be a consideration. Unless it is just one battery that you can move around?

What things do you dislike about your current system? Lithium may improve on some of these.

Click to expand...

Any idea what caused the damage?

HelmutSheina said:

Any idea what caused the damage?

Click to expand...

Some years ago, I asked at repair shop for my area, and speed control board over load (presumably from drawing high amps over design parameters) was causing a burnt trace- is the most frequent repair. Besides Li battery over current possibility, there's also over current drains with flooded lead batteries when weeds partially tangle in the prop and the operator doesn't notice to remove them and just keeps going. Prop big Tangles at close to stall can also do the same but the user notices it, and quickly cleans them immediately. Stall draws huge amps compared to a clean prop. Even with cheaper older resistance wire 5 speed controls- the resistance wire or motor windings overheat and melts somewhere along the length, to create an open circuit. Ohm's law E= I x R is the way to calculate current amps (I) or any one of the 3, if the 2 of the others are known, E=volts, R=resistance in ohms. Salt air humidity corrosion to electronics over years, or Water leaks into the submerged motor case (usual leaks at the packed prop shaft seal) plus hard mechanical impacts to the case can crack or unglue the field magnets (glued to the outer case) so that small pieces of magnet stick to the spinning armature and slow or stop the spin, are some other failure modes.

There's also tricks to increase the power/ thrust/ range or any troll motor by using an external speed control and higher than rated voltage and/or adjusting the propeller pitch and diameter, as was referenced above (up to at least 2X), without damaging the troll. U-tube has some examples of how to do it.

Hope this helps.

Thanks very much. I am moving from petrol outboard to electric to push a couple of small displacement boat around and would rather know some pitfalls beforehand.