How long will a 12 volt deep cycle battery run a trolling motor?

Key Factors Affecting Runtime

1. Battery Capacity (Ah Rating):
   • The capacity of the battery is measured in amp-hours (Ah). A higher Ah rating means that the battery can provide power for a longer period. For example, a 100Ah battery can theoretically provide 100 amps for one hour or 10 amps for ten hours.
2. Power Draw of the Trolling Motor:
   • The power draw varies based on the motor’s thrust rating and the speed setting. For instance, if your trolling motor draws 50 amps at full power, you can calculate runtime as follows:
     • Runtime (hours) = Battery Capacity (Ah) / Current Draw (A)
3. Efficiency Considerations:
   • Real-world conditions, such as water currents and wind resistance, can affect efficiency. It’s common to operate at lower power settings (around 30% to 50% of maximum), which can extend runtime significantly.

Example Calculations

• If you have a 100Ah battery and your trolling motor draws 50 amps, the calculation would be:
  • Runtime = 100Ah / 50A = 2 hours
• However, if you operate at half power (25 amps):
  • Runtime = 100Ah / 25A = 4 hours

General Guidelines

• A fully charged 12V lithium battery can run a trolling motor with moderate thrust for approximately 6-8 hours, depending on usage patterns.
• For lead-acid batteries, it’s recommended to avoid deep discharges to prolong lifespan. Typically, you should use only about 50% of their capacity to maintain health.

Conclusion

In summary, the runtime of a 12-volt deep cycle battery for a trolling motor will vary based on its amp-hour rating and the current draw of the motor. By understanding these factors and performing some calculations, you can estimate how long your setup will last on the water. Always consider real-world conditions that might affect performance for more accurate planning during your outings.