Troubleshooting Trolling Motor Power Issues

The steps below will walk you through  diagnosing if you have an issue with your power, what that issue is and where it is located. If you find an issue with your power, you will need to resolve it for proper operation of your trolling motor.

Verifying Appropriate Batteries

Your batteries need to be capable of providing proper power to your motor. If the batteries are insufficient, you can have issues with using the motor including the motor only working for a short time, the motor working erratically, or the motor not working at all. Click this link for additional information on verifying you have appropriate batteries.

  • Lithium Batteries and Continuous Discharge Amperage

    When using lithium batteries, you want to ensure the battery(s) provide(s) enough continuous discharge amperage to run the motor at its max amp draw. The chart below shows the max amp draw by motor thrust. If the motor is not getting enough amperage, it will have issues including working for a short time and then shutting off, being able to turn on the motor but not turn on the prop, steering issues, issues with Advanced GPS Navigation such as Spot Lock not working or being erratic. If you are having any issues with your motor and you are using Lithium batteries, verify you have enough continuous amperage available for the motor to pull its max amp draw.
    RequiredContinuousDischargeAmperage.png

Load Testing

Consistent voltage is critical to reliable operation of your motor. A “Load Test” is a good way to determine the ability of your battery to maintain voltage during operation. A check of resting voltage is not enough to suggest a battery is good.
Caution: If you are unsure of how to use a Load Tester safely do not attempt and consult a technician.  Handled improperly there is a risk of electrical shock or burns.

Load Testers do vary in the load they apply so the rating on the load tester, usually “Good”, “Weak”, “Bad”, should be trusted. For motors with GPS Navigation, only “Good” batteries should continue to be used. Loose or corroded connections and inadequate wiring also affect the voltage getting to the motor.
Caution: If you are unsure of how to use a VOM to safely Measure Voltage while the Motor is in use do not attempt and consult a marine installer. Handled improperly there is a risk of electrical shock or burns.

It may be possible to use a Volt Meter and your motor to Load Test your entire power supply; on the water, use the VOM to probe the power supply as close to the motor as you can, read the voltage when the motor is not running and when the motor is running on high. The difference between the resting voltage and the voltage when the motor running on high in the water should be less than 5%. 5% of 12 volts is 0.6, 24 volts is 1.2, and 36 volts is 1.8.

As batteries age the chemistry inside changes and they are less able to provide as much current at once and the internal connections degrade with use, this is why they will eventually fail a load test with age. If a battery has an internal short which could be caused by dropping the battery and causing the plates within to shift so they are no longer separated it will fail a load test because of this damage.

Verifying Power

You can check your power by using a voltmeter to test the voltage coming off of your battery(s) and then comparing it to the voltage at the Quick Disconnect or Plug and Receptacle if you are using one and then again at the motor. The voltage at the Quick Disconnect/Plug and Receptacle and at the motor should match the voltage from the battery(s). If it does not, you are dropping power between the battery(s) and Quick Disconnect/Plug and Receptacle or Quick Disconnect/Plug and Receptacle and the motor or if you are not using a Quick Disconnect/Plug and Receptacle, between the battery(s) and the motor.

Connections

If you are having issues with your motor and the batteries are charged, have been load tested (FLA, AGM or Gel) and are testing good, you will want to check the connections between the trolling motor and battery(s). The connections should be clean and tight. If there is any corrosion, buildup, or anything contaminating the terminals or connectors, they should be cleaned and then reconnect the terminals or connectors.

Quick Disconnects and Plug and Receptacles

If you are using a Quick Disconnect or Plug and Receptacle, check the connections coming from the motor into the quick disconnect or the plug to verify the connections are secure and the polarity is correct. Also verify the connections are clean with no buildup and no damage to connectors. Damage, corrosion, buildup, and loose connections can cause issues with power transfer. Next check the connections coming from the battery(s) to the quick disconnect or receptacle. Again you want a clean and tight connection with no buildup and no damage to prevent power transfer.

Circuit Breaker

The circuit breaker should be appropriate to the trolling motor. The chart below will show what circuit breaker is needed by motor. Verify the circuit has not been tripped and is in good condition. Also verify the circuit breaker connections are clean and tight and there is no buildup on the terminals.
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Boat Wiring

The rigging should be of a suitable gauge and in good condition. The chart below will show you what gauge the rigging lines need to be based on motor and distance from the battery lead lines to the battery. If you have wear on the lines or there is a break in the lines, you will have issues with power reaching the motor and could have a fire onboard. The chart below will assist in determining what gauge wire you need for the motor and the distance between the battery leads coming off of the motor and the batteries.
Visually inspect your rigging lines looking for any wear marks, kinks, or cuts. If you see any, replace the rigging lines. You can test for breaks in the lines by testing each line for continuity with a continuity tester. Another method, although not as reliable, is to feel the lines while they are in use, any warm spots indicate an issue.
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