Calculator
Trolling Motor Battery Runtime Calculator
Thrust rating, the speed you actually troll at and your bank size, returning hours on the water and the bank you need for a full day.
From the motor's plate, at full throttle. A 55 lb thrust 12 V motor is typically 50 to 55 A.
Most fishing is done between 30 and 60%. Draw falls away fast below half throttle.
Your numbers
12.3 h
At 50% throttle, drawing 6.5 A
| Draw at this setting | 6.5 A |
| Usable capacity | 80 Ah |
| Runtime | 12.3 hours |
| Bank for a six-hour day | 50 Ah |
Calculator assumptions and limits
- Draw scales with the cube of throttle setting, from the motor's rated maximum draw
- 80% usable capacity on LiFePO4
- Continuous trolling; intermittent use extends runtime proportionally
Every assumption here is versioned and dated on the methodology page. If you disagree with one, the working is there to argue with.
The other calculators
House bank calculatorYour loads, your nights away from shore power, your solar and your alternator, returning the bank, the DC-DC charger, the AGM equivalent and the weight off the boat.DC-DC and alternator sizingAlternator rating and bank capacity, returning the charger to fit and the time to refill from your engine.Solar top-upPanel watts against your daily draw, returning the average daily return and whether the array covers your consumption.AGM to lithium swapYour existing AGM capacity, returning the lithium bank that delivers the same usable energy and the weight you take off the boat.