We don't run a battery lab. Our picks come from published specifications, checked against what your trolling motor actually draws, with every source listed so you can check our work.
1. Specs come from the maker
Capacity, continuous and peak BMS ratings, weight, case size, low-temperature charging behavior and warranty terms come from the manufacturer's own product page or spec sheet, or from an authorized dealer when the maker doesn't publish a figure. We open each page ourselves, and every guide lists its sources and the month we checked them. Where two sources disagree, we say so, or we leave the battery out.
2. We match the battery to the motor
A lithium battery's BMS shuts it off if your motor pulls more current than it's rated for. We check each pick's continuous rating against the published max draw of the motors it's meant for. A Minn Kota QUEST can pull 60 A, for example, so a 50 A battery isn't on our list for it, however good a deal it is. We recommend a BMS rated for at least your motor's max draw plus about 10%.
3. Runtime is calculated the same way everywhere
Every runtime on the site uses one formula, the same one behind the calculator:
- Draw at partial speed = max draw × (speed %)1.5
- Usable capacity is 90% for lithium and 50% for AGM
- Peukert's law, with exponents of 1.05 for lithium and 1.20 for AGM, against a 20-hour rating
Wind, current, weeds and spot-lock all add to draw, so treat any runtime as a starting point and leave a margin.
4. Price and availability get rechecked
Batteries go in and out of stock, and specs change between model years. We recheck our picks periodically and update the "as of" date when we do. If a pick is out of stock or its listing no longer matches the maker's specs, we replace it.
5. Money doesn't pick the winner
Brands can't pay for placement. We may earn a commission when you buy through our links, and that never decides what we recommend. See our affiliate disclosure.
Spot a spec that's wrong or out of date? Tell us and we'll check it.