Electric Trolling Motor Battery Run Time: How Long Will Lithium Last?
Reading time: 5 minutes
Introduction
A lithium battery can power an electric trolling motor for several hours, but the actual run time depends on how the boat is used. Slow positioning on a calm lake uses far less energy than pushing against wind, river current, weeds, or running near full speed for long periods.
For anglers using small boats, dinghies, canal boats, inflatable boats, or fishing kayaks, understanding battery run time helps avoid being caught short on the water. The key factors are battery capacity, motor current draw, voltage, throttle level, and any additional electronics powered by the same battery.
This guide explains how to estimate the run time of your lithium trolling motor battery, how current changes with speed, and how to improve battery performance during a day’s fishing.
Battery Capacity: Why Amp-Hours Matter
Battery capacity is measured in amp-hours, or Ah. This rating tells you how much current a battery can theoretically deliver 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)
For example, if your motor draws 20A and the battery is rated at 100Ah:
100Ah ÷ 20A = 5 hours
This gives a simple estimate. Real run time will vary with wind, current, boat weight, speed setting, water conditions, battery age, and temperature.
Motor Current Draw Changes with Speed
Trolling motors do not draw the same current at every setting. At low throttle, the motor may use only a few amps. At higher throttle, current demand rises sharply.
This is why reducing speed slightly can add a lot of extra time on the water. Running at 40% or 50% throttle is far more efficient than holding full power for long periods.
24V Electric 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 |
The difference between low and high throttle is dramatic. A battery that lasts much of the day at moderate speed may drain in less than two hours at full power.
36V Electric 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 |
A 36V setup can be a good choice for larger boats or stronger motors. It can provide strong thrust while managing current efficiently, but battery capacity still needs to match the way you fish.
Other Electrical Loads to Include
If your trolling motor battery also powers other equipment, include those loads in your estimate. Common examples include fish finders, sonar units, navigation lights, bilge pumps, livewell pumps, phone charging, and deck lighting.
For example:
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Trolling motor draw: 20A
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Fish finder draw: 2A
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Lighting draw: 3A
Total current draw:
20A + 2A + 3A = 25A
Estimated run time with a 100Ah battery:
100Ah ÷ 25A = 4 hours
For longer trips, it may be better to run electronics from a separate battery so the trolling motor battery is reserved for propulsion.
Practical Run Time on Lakes, Rivers, and Canals
Field use is rarely as neat as a formula. On calm canals or sheltered lakes, a lithium battery may last a very long time because the motor runs at low speed. On open water or rivers, wind and current can increase draw quickly.
| Battery Size | Typical Boat Setup | Practical Run-Time Expectation |
|---|---|---|
| 50Ah Lithium | Fishing kayak, dinghy, small inflatable boat | Several hours to a shorter fishing session |
| 100Ah Lithium | Small boat, lake fishing, canal use, moderate loads | Often a full fishing day at moderate throttle |
| 100Ah+ Lithium Bank | Longer trips, windy areas, heavier boats | Full day or multi-day use depending on draw |
For many anglers, a 100Ah lithium battery offers a strong balance of usable capacity, lighter weight, and reliable voltage compared with traditional lead-acid batteries.
What Reduces Battery Run Time?
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High throttle: Full-speed use drains the battery quickly.
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Wind: Holding position against wind increases current draw.
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Current: Rivers and tidal areas require more motor power.
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Boat weight: Extra gear, passengers, and batteries increase load.
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Prop drag: Weeds, line, or debris around the prop reduce efficiency.
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Cold weather: Low temperatures can reduce available battery capacity.
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Accessory loads: Electronics reduce the capacity left for the motor.
How to Maximise Lithium Trolling Motor Battery Performance
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Use moderate throttle: Small speed reductions can significantly increase run time.
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Choose the right capacity: Larger boats and longer sessions need more Ah.
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Keep the prop clean: Remove weeds, line, and debris regularly.
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Reduce unnecessary weight: Carry only what you need for the trip.
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Use a battery monitor: State-of-charge tracking helps avoid surprises.
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Charge with a compatible lithium charger: Use the correct LiFePO4 charging profile.
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Store properly: Follow the manufacturer’s guidance for storage charge and temperature.
Final Thoughts
A lithium trolling motor battery can last from a few hours to a full day or more, depending on capacity and total current draw. The basic formula is simple: Run Time = Battery Capacity ÷ Total Amp Draw. A 100Ah battery running a 20A load may last about 5 hours, while lower-speed use can stretch run time much further.
For European anglers using electric trolling motors on lakes, rivers, canals, or sheltered coastal waters, the best approach is to size the battery for real conditions. Consider wind, current, boat weight, electronics, and the distance back to shore. A properly sized lithium battery gives you more confidence and more time to fish.
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