On this page
01 Start with the motor, not a generic chart02 A practical sizing sequence03 Why 50Ah is sometimes enough—and sometimes unsafeSize by maximum current, how you use the throttle, and the reserve you want—not by thrust alone.
01
Start with the motor, not a generic chart
Two motors with similar thrust can publish different maximum current draw. That current determines the minimum BMS output, breaker, and the worst-case demand your battery must tolerate.
For runtime, maximum draw is deliberately pessimistic because most trips are not spent at full throttle. RigCurrent models a duty cycle and then shows a range instead of pretending one number will survive wind, current, load, and temperature.
02
A practical sizing sequence
Choose a battery whose voltage matches the motor exactly. Then make sure continuous BMS output is above the motor's published maximum draw. Finally, size amp-hours for the trip and keep a reserve.
- Match system voltage: 12V motor to a 12V-class battery system.
- Keep BMS continuous output above published maximum motor draw.
- Estimate average draw from how the motor will be used.
- Reserve at least 15–20% for wind, cold, and the trip home.
- Use a lithium-compatible charger for LiFePO4 batteries.
03
Why 50Ah is sometimes enough—and sometimes unsafe
A 50Ah LiFePO4 battery can be a smart lightweight match for a 29A kayak motor. It can still be the wrong choice for a 52A motor if the battery's BMS is rated for only 50A, regardless of the runtime calculation.
Sources
Primary references
We link to manufacturer material so you can check the exact wording and current revision before installing or buying.
Minn Kota wiring and battery guide ↗Newport Kayak Series specifications ↗