How big should your trolling battery be?

The most common question we get in the workshop is simple: which battery should I pick for my electric motor? There is no one short answer, because it depends on the motor draw, the length of your sessions and your fishing style. The good news is that once you understand the formula, the choice becomes obvious.

We start from the average current the motor pulls, measured in amps. A Minn Kota Endura 55 draws around 22 A at cruising speed and tops 50 A at full power. For the calculation we use the real on-water average, not the peak on the label, because you will rarely fish with the throttle planted.

We multiply the average current by the hours actually spent on the water. A typical trolling session on the Danube means four or five hours of continuous running with short breaks. The result, in amp-hours, is the raw consumption of the session.

On top of that consumption we add a 30 percent safety margin. The margin covers headwind, river current and the natural capacity loss of a battery as it ages. Without it you risk running out of propulsion exactly when you need to head back to shore.

For most 4 to 6 metre boats, a 12V LiFePO4 battery between 100 and 140 Ah comfortably covers a full day. Lithium iron costs more upfront, but it delivers three times the cycles of lead acid and weighs half as much, which matters a lot on a small boat.

If you are still unsure, use our autonomy calculator or give us a call. We configure the right battery, winch and charger together for the waters you fish.