To wire a 24 volt trolling motor, connect two 12-volt deep-cycle batteries in series: a jumper cable runs from the positive terminal of battery 1 to the negative terminal of battery 2, the motor’s negative lead goes to the open negative terminal on battery 1, and its positive lead goes through a circuit breaker to the open positive terminal on battery 2. A 36 volt motor works the same way with three batteries. Your motor manufacturer’s wiring diagram always takes priority over a general guide like this one.
Before you start
- Disconnect power. Switch the motor off and unplug it before touching any wiring. Remove rings and watches, and keep metal tools from bridging battery terminals; a short circuit across a battery can cause sparks and burns.
- Read the motor manual. It specifies the circuit breaker rating and the wire gauge for your cable length. We do not list sizes here because they vary by motor and by run length.
- Match the batteries. Use batteries of the same type, capacity and age. Mixed batteries charge and discharge unevenly.
- Ventilate. Flooded lead-acid batteries can release hydrogen gas while charging, so keep the battery compartment ventilated.
How to wire a 24 volt trolling motor
- Secure both batteries with straps or in battery boxes so they cannot shift.
- Connect a jumper cable from the positive (+) terminal of battery 1 to the negative (-) terminal of battery 2, using the cable size your manual calls for.
- Check the bank with a multimeter: across the open negative on battery 1 and the open positive on battery 2 you should read roughly twice the voltage of one battery, the nominal 24 volts.
- Mount the circuit breaker in the positive lead, positioned where the manual directs. If your breaker can be switched off, leave it off until all connections are tight.
- Connect the motor’s negative lead (usually black) to the open negative terminal on battery 1.
- Connect the motor’s positive lead (usually red), through the breaker, to the open positive terminal on battery 2.
- Tighten every terminal, fit terminal covers, reset the breaker and test the motor with the prop in the water.
Browse motors built for this setup in our 24-volt trolling motors.
How to wire a 36 volt trolling motor
A 36 volt system uses three 12-volt batteries in series and two jumper cables. Run one jumper from battery 1 positive to battery 2 negative, and a second from battery 2 positive to battery 3 negative. The motor’s negative lead goes to the open negative on battery 1, and its positive lead goes through the breaker to the open positive on battery 3. Your meter should read about three times the voltage of one battery across those two open terminals. See our 36-volt trolling motors.
Lithium batteries and charging
A single 24V or 36V lithium battery replaces a series bank: the motor leads connect straight to its two terminals, with the breaker in the positive lead and no jumpers. If you plan to put 12V lithium batteries in series, first confirm the battery maker allows it and follow its limits. Charge any bank with a charger designed for that battery chemistry; a multi-bank charger charges each 12V battery on its own circuit. Our guide to 12V, 24V and 36V trolling motor batteries covers battery choice in more detail.
How long does a trolling motor battery last?
There is no single figure, because run time depends on several things:
- Amp-hour capacity. More amp-hours means more stored energy.
- Speed setting. Higher speeds draw far more current than low ones.
- Conditions. Wind, current, waves, boat weight and how often you hold position all add load.
- Battery chemistry. Lead-acid batteries should not be run flat and deliver less of their rating at high draw; lithium lets you use more of its rated capacity.
- Age and temperature. Older and colder batteries give less.
To estimate, divide the battery’s usable amp-hours by your average current draw at your usual speed. Wiring in series raises voltage but not amp-hours, so a 24V bank of two batteries has the amp-hour rating of one of them. The motor manual lists maximum draw, and you will usually run well below it, so treat the result as a rough guide and time a few real days on the water. In years of service, battery life depends on chemistry, how deeply you discharge it, and charging habits; recharging after each trip and storing batteries as their maker recommends both help. If you need more run time, a higher-thrust motor run at a lower setting is one option; our trolling motor size guide explains thrust and voltage.
More guides: trolling motor troubleshooting · charging a 24V bank · deep cycle vs starting battery · 12V vs 24V trolling motors · trolling motor wiring · 24V vs 36V trolling motors · how many amp hours you need for a trolling motor.
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