Lithium Trolling Motor Battery Run Time: How Long Will It Last?
Reading time: 4 minutes
Introduction
For Canadian anglers, trolling motor battery run time can make or break a day on the water. Whether you are fishing for bass in Ontario, walleye on a northern lake, pike in weedy bays, or trout on a quiet reservoir, you need a battery that can handle wind, current, cold mornings, and long hours away from shore power.
A lithium trolling motor battery can last for several hours or even a full day of fishing, but the exact run time depends on battery capacity, motor amp draw, speed setting, boat weight, water conditions, and other electronics connected to the same battery.
This guide explains how to estimate run time, how current draw changes with throttle level, and how to get more hours from your lithium trolling motor battery.
Battery Capacity: What Amp-Hours Really Mean
Battery capacity is measured in amp-hours, often written as Ah. It describes how much current the battery can theoretically provide over time.
A 100Ah lithium battery can theoretically supply:
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100 amps for 1 hour
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50 amps for 2 hours
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20 amps for 5 hours
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10 amps for 10 hours
The basic formula is:
Run Time (hours) = Battery Capacity (Ah) ÷ Total Current Draw (A)
If a 100Ah battery powers a trolling motor drawing 20A:
100Ah ÷ 20A = 5 hours
This is a starting point. Real-world fishing conditions will change the result.
Why Trolling Motor Amp Draw Changes So Much
A trolling motor does not use the same current at every speed. Low throttle may draw only a few amps. High throttle can draw more than 50 amps, depending on the motor and voltage system.
This matters because small speed adjustments can make a big difference. If you run at 40% to 50% throttle, your battery may last much longer than it would at 90% or full power.
24V Trolling Motor Current Draw Example
| Throttle Level | Approximate Thrust | Current Draw | Estimated Run Time with 100Ah Battery |
|---|---|---|---|
| 10% | 6 lbf | 2A | 50 hours |
| 20% | 10 lbf | 3A | 33 hours |
| 30% | 16 lbf | 6A | 16.7 hours |
| 40% | 23 lbf | 9A | 11.1 hours |
| 50% | 31 lbf | 14A | 7.1 hours |
| 60% | 41 lbf | 21A | 4.8 hours |
| 70% | 52 lbf | 29A | 3.4 hours |
| 80% | 65 lbf | 40A | 2.5 hours |
| 90% | 78 lbf | 54A | 1.9 hours |
| 100% | 80 lbf | 57A | 1.8 hours |
At lower speeds, a 100Ah battery can last a very long time. At high speed, run time drops quickly.
36V Trolling Motor Current Draw Example
| Throttle Level | Approximate Thrust | Current Draw | Estimated Run Time with 100Ah Battery |
|---|---|---|---|
| 10% | 5 lbf | 1A | 100 hours |
| 20% | 9 lbf | 2A | 50 hours |
| 30% | 16 lbf | 4A | 25 hours |
| 40% | 23 lbf | 6A | 16.7 hours |
| 50% | 32 lbf | 10A | 10 hours |
| 60% | 43 lbf | 15A | 6.7 hours |
| 70% | 55 lbf | 21A | 4.8 hours |
| 80% | 69 lbf | 29A | 3.4 hours |
| 90% | 84 lbf | 39A | 2.6 hours |
| 100% | 100 lbf | 54A | 1.9 hours |
For larger boats, 36V systems can offer strong performance with efficient current use. Still, battery size should match your fishing style and water conditions.
Other Electrical Loads on the Boat
If your trolling motor battery also powers other gear, include those loads in the calculation. Common examples include fish finders, sonar, livewell pumps, navigation lights, phone chargers, and deck lighting.
For example:
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Trolling motor: 20A
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Fish finder: 2A
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Navigation lights: 3A
Total draw:
20A + 2A + 3A = 25A
With a 100Ah battery:
100Ah ÷ 25A = 4 hours
If you run electronics all day, they can noticeably reduce remaining trolling motor time.
Real-World Run Time on Canadian Waters
Canadian fishing conditions can be demanding. Wind on open lakes, cold water, current in rivers, and heavy vegetation can all increase motor use. A battery that lasts all day on a calm lake may drain faster when holding position in wind or pushing through weeds.
| Battery Size | Common Setup | Practical Run-Time Expectation |
|---|---|---|
| 50Ah Lithium | Kayaks, canoes, small aluminum boats | Several hours to a short fishing day |
| 100Ah Lithium | Fishing boats, jon boats, small pontoons | Often a full day at moderate throttle |
| 100Ah+ Lithium Bank | Long trips, windy lakes, heavier boats | Full day or multi-day use depending on draw |
For many anglers, a 100Ah lithium battery is a practical choice because it offers strong usable capacity without the weight of a comparable lead-acid setup.
Factors That Reduce Battery Run Time
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Wind: Holding position against wind increases current draw.
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Current: Rivers and moving water demand more motor power.
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Cold temperatures: Cold weather can reduce available capacity.
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Boat weight: Extra passengers, fuel, tackle, and coolers increase load.
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Weeds and debris: Anything wrapped around the prop reduces efficiency.
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High throttle: Full-power running drains the battery quickly.
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Accessory loads: Electronics and lighting reduce total run time.
Tips to Make Your Lithium Trolling Motor Battery Last Longer
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Use lower throttle when possible: Moderate speed can extend run time dramatically.
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Choose enough capacity: Size the battery for wind, current, and return distance.
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Keep the prop clear: Remove weeds, fishing line, and debris often.
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Monitor state of charge: A battery monitor helps you avoid guessing.
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Use a compatible charger: LiFePO4 batteries should be charged with the correct profile.
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Protect the battery in storage: Follow the manufacturer’s storage charge guidance.
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Avoid charging below 0°C: Unless the battery includes low-temperature charging protection or heating.
Final Thoughts
A lithium trolling motor battery can last from a few hours to a full fishing day or more. The main formula is simple: Run Time = Battery Capacity ÷ Total Current Draw. A 100Ah battery running a 20A load may last about 5 hours, while lower-speed use can stretch that time much further.
For Canadian anglers, the smartest setup is one that accounts for wind, cold mornings, current, weeds, electronics, and the distance back to shore. Choose enough battery capacity for your real fishing conditions, not just ideal numbers on paper.
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