Introdução
A 24V trolling motor is normally supplied by a dedicated 24V battery bank, commonly two matched 12V deep-cycle batteries connected in series. In some boats, however, owners investigate whether a 12V-to-24V DC-DC boost converter can operate a 24V motor from an existing 12V bank. The conversion is electrically possible only when the converter, battery, cabling, protection, and motor controller are all compatible with the motor’s maximum and dynamic current demand.
This guide explains how to calculate output power, 12V input current, and estimated runtime before considering a converter. It also shows where products in the WEHO DC-DC converter range may fit after the motor manufacturer and WEHO engineering team confirm compatibility.
First Decide Whether a Converter Is the Right Architecture
For most 24V trolling motors, a direct 24V battery bank remains the simplest and most efficient architecture. Two matched 12V batteries in series provide 24V without forcing all motor power through a converter. This approach usually reduces 12V-side current, conversion heat, and the number of high-current components in the system.
A 12V-to-24V converter may be considered when the vessel has a large existing 12V energy bank, restricted battery placement, a charging architecture that must remain 12V, or a controlled duty cycle. It should not be treated as a small voltage adapter. At trolling-motor power levels, the 12V input current can exceed 60A, 100A, or more.
Before selecting any converter, confirm all of the following:
- The trolling motor is designed for 24VDC.
- Its maximum current draw is known from the manufacturer.
- The motor manufacturer permits operation from a regulated converter.
- The converter manufacturer approves the PWM motor-controller load and transient behavior.
- The 12V battery and charging system can supply the required continuous and peak input current.
- Cable, fuse, breaker, disconnect, and connector ratings are suitable for marine service.
If any item is unknown, use the recommended battery architecture or ask the relevant engineering teams before installation.
Size From Maximum Motor Current, Not Thrust
Trolling motors are often described by pounds of thrust, but thrust does not directly specify electrical current. Two motors with similar thrust ratings can have different current draw, control electronics, propellers, and efficiency. Use the motor’s published maximum amp draw at 24V.
Calculate the maximum motor input power:
Motor input power = 24V × maximum motor current
Examples:
| Maximum motor current | Approximate 24V input power |
|---|---|
| 20A | 480 W |
| 30A | 720W |
| 40A | 960 W |
| 50A | 1,200W |
| 60A | 1,440W |
A converter rated at exactly the motor’s maximum current has no allowance for tolerance, temperature, voltage sag, or dynamic demand. For example, a 30A motor already requires approximately 720W at full speed. A 24V, 30A converter is therefore a useful calculation reference, not automatically the correct final selection. Depending on verified motor behavior and environmental conditions, the next higher rating may be required.
Do not assume that percentage headroom alone makes a converter motor-compatible. PWM switching, rapid throttle changes, stalled-propeller conditions, and controller input capacitance can affect the converter. Compatibility must be confirmed.
Calculate the 12V Input Current
The converter cannot create energy. It doubles voltage by drawing proportionally more current from the 12V source, plus conversion losses.
Estimate input current with:
12V input current = 24V output power ÷ (12V input voltage × converter efficiency)
For a 24V motor drawing 30A, output power is 720W. At 12V and 94% efficiency:
720W ÷ (12V × 0.94) = 63.8A
If the battery falls to 10V at the converter input under load:
720W ÷ (10V × 0.94) = 76.6A
For a 40A motor, the 24V output power is 960W. At 12V and 94% efficiency, input current is approximately 85.1A. At 10V, it rises to approximately 102.1A.
These calculations show why voltage drop on the 12V side is critical. A battery that measures 12.6V at rest can fall substantially at the converter after cable and connection losses. Low input voltage increases current, heat, and the risk of shutdown.
Match WEHO Models to the Verified Output Requirement
WEHO offers a range of sealed, non-isolated boost converters with a published 10V to 16V input range and fixed 24V output. The category page is the best starting point because motor requirements vary widely.
| WEHO model | Rated 24V output | Published efficiency | Selection note |
|---|---|---|---|
| WH-B122420 | 20A / 480W | 93% | Small verified loads below 20A; not a default motor recommendation |
| WH-B122430 | 30A / 720W | 94% | Calculation reference for a 30A maximum load; little current margin |
| WH-B122440 | 40A / 960W | 94% | Candidate only after peak and thermal validation |
| WH-B122450 | 50A / 1,200W | 94% | High-current candidate requiring a very strong 12V source circuit |
| WH-B122460 | 60A / 1,440W | 94% | Highest listed output; source current can exceed 120A near low input voltage |
This table does not certify any model for a particular trolling motor. Submit the motor datasheet, maximum amp draw, control type, battery voltage range, duty cycle, ambient temperature, and cable length to WEHO for review.
Estimate Runtime From Energy, Not Only Amp-Hours
Amp-hours cannot be compared directly across different voltages without conversion. A 12V, 200Ah bank stores approximately:
12V × 200Ah = 2,400Wh nominal energy
Usable energy depends on battery chemistry, age, temperature, discharge rate, battery-management limits, and the depth of discharge allowed by the manufacturer. Estimate runtime with:
Runtime = battery voltage × battery Ah × usable fraction × converter efficiency ÷ motor input power
For a 12V, 200Ah bank, 50% usable energy, 94% conversion efficiency, and a 720W motor load:
12 × 200 × 0.50 × 0.94 ÷ 720 = 1.57 hours
If a battery manufacturer permits 90% usable energy under the same conditions:
12 × 200 × 0.90 × 0.94 ÷ 720 = 2.82 hours
These are energy estimates, not guarantees. Boats rarely operate a trolling motor at constant maximum speed for an entire trip, while wind, current, vegetation, propeller condition, and control setting change consumption. Battery voltage sag can also cause the converter to reach its low-input limit before all nominal energy is used.
Wiring a High-Current 12V-to-24V System
A converter-based motor circuit requires protection and switching on both voltage sides:
12V battery positive → battery-side fuse or breaker → disconnect → converter input
Converter 24V output → approved output protection → trolling-motor receptacle or fixed connection → motor
Follow the motor and converter manufacturers’ protection requirements. Protection must be able to interrupt the available battery fault current and must protect the installed cable. Do not choose a fuse only from normal operating current.
The 12V Cable Is the Most Demanding Section
For the same power, the 12V input carries roughly twice the current of the 24V output. Size cable using current, complete round-trip length, allowable voltage drop, insulation temperature, bundling, engine-room conditions, terminal ratings, and applicable marine standards. High-quality tinned cable and properly crimped, sealed lugs are normally required in corrosive environments.
Keep the 12V run short. A small resistance at 80A or 100A causes meaningful voltage drop and heat. Support every heavy cable so vibration is not transferred to converter terminals.
Non-Isolated Grounding Requires Review
The listed WEHO boost converters are non-isolated. The input and output negative share a common reference. Confirm that this grounding arrangement is compatible with the boat, charger, motor electronics, bonding system, and other onboard equipment. Do not assume galvanic isolation.
Waterproof Does Not Mean Submersible
A sealed converter still needs a protected location with airflow for natural cooling. Mount it above possible bilge water, away from fuel vapors, spray paths, and direct engine heat. Use drip loops and sealed cable entries where appropriate.
How to Commission the System
- Verify polarity and open-circuit voltage before connecting the motor.
- Measure voltage directly at the converter input and output.
- Test at the lowest expected battery state of charge.
- Increase motor speed in stages while recording input voltage, input current, output current, and converter temperature.
- Test steering and rapid speed changes if approved by both manufacturers.
- Confirm that the converter does not cycle in and out of overcurrent or low-voltage protection.
- Inspect cables, terminals, fuses, and breakers for abnormal temperature.
- Repeat the test after an extended run in the actual mounting environment.
Stop testing if voltage collapses, protection cycles, cables heat excessively, noise affects electronics, or the motor controller behaves abnormally.
When a Direct 24V Battery Bank Is Better
A direct series-connected 24V bank is usually preferable when the motor operates for long periods near maximum power, the vessel has space for matched batteries, or input current would make the 12V cable and protection system impractical. It also follows the normal architecture shown by major trolling-motor manufacturers.
A converter can make sense only when the full electrical design supports it. The decision should compare battery layout, charging, redundancy, conversion loss, cable mass, maintenance, and failure modes—not only the purchase price of a converter.
Perguntas frequentes
Can a 30A converter run a 24V motor rated at 30A maximum?
It matches the nominal maximum current on paper but provides no current margin. Dynamic motor behavior, temperature, voltage sag, and protection thresholds may make it unsuitable. Obtain written compatibility confirmation before use.
Will a converter make a trolling motor run longer?
No. Runtime comes from usable battery energy. The converter consumes some energy as heat, so runtime is lower than an ideal lossless conversion calculation.
Can one 12V starting battery power a high-current 24V trolling motor through a converter?
This is generally a poor architecture. Starting batteries are not normally intended for repeated deep cycling, and the converter may demand very high continuous current. Use a battery system designed and rated for the duty.
Can converter output be connected in series or parallel?
Not unless the manufacturer explicitly approves the exact configuration and provides wiring instructions. Use a single correctly rated solution or the motor manufacturer’s recommended battery bank.
Conclusão
A 12V-to-24V converter for a trolling motor must be selected from maximum motor current, source voltage under load, converter efficiency, battery energy, thermal conditions, cable length, and motor-controller compatibility. In many boats, two matched 12V batteries in series remain the better 24V source. Where a converter architecture is justified, it requires high-current engineering and controlled testing.
Explore the WEHO DC-DC converter range e contact WEHO with the motor datasheet and battery-system details before selecting a model.
