What Size Battery Do I Need for a 30 lb Trolling Motor?
This is the smallest motor in the set: one 12 V battery, and the longest worst-case runtime of the four.
Direct answer: Minn Kota lists a 30 lb trolling motor at 30 A and 12 V, and says to use a deep-cycle marine battery of at least 110 Ah (Minn Kota battery chart). Thrust at or under 55 lb uses one 12 V battery, and the runtime guide is 110 Ah per battery for about 6–8 hours (Minn Kota power article). At the 30 A maximum, 110 ÷ 30 is about 3.67 hours, and that maximum is intermittent, so 3.67 hours is a worst case rather than a cruising average (Minn Kota battery chart).
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Minn Kota publishes the amps, the voltage, the 110 Ah guide, and the group table. The hour figure is 110 divided by that max amp draw, labeled as a worst case because the chart says the maximum is intermittent.
Read the motor, not a generic "trolling" number. The chart puts a 30 lb thrust motor at 30 A and 12 V (Minn Kota battery chart).
Battery count follows thrust. At or under 55 lb, the system is one 12 V battery. Motors are wired in series only when there is more than one battery; this motor does not need that (Minn Kota power article).
Both Minn Kota sources ask for at least 110 Ah. The chart says a deep-cycle marine battery with at least a 110 Ah rating. The help article says 110 Ah per battery for 6–8 hours (Minn Kota battery chart; Minn Kota power article).
Worst-case runtime at the published maximum is 110 ÷ 30 = 3.67 hours. The chart says maximum amp draw happens only intermittently and should not be used as a continuous load rating, so 3.67 hours is the floor at full power, not a day of trolling (Minn Kota battery chart).
Group sizes on the same chart are Good, group 24, 70–85 Ah; Better, group 27, 85–110 Ah; Best, group 31, 95–125 Ah. Group 24 never reaches 110 Ah. Group 27 reaches it only at the top of the range. Group 31 is the tier whose range goes past 110 Ah, which is why the battery search on this page is a group 31 deep-cycle marine battery (Minn Kota battery chart).
A second battery in parallel is how Minn Kota says to add runtime, and it stays 12 V (Minn Kota power article). Two 110 Ah batteries in parallel are 220 Ah. That parallel 220 Ah is not the same object as a 220 Ah lead-acid nameplate: about 50% depth of discharge means the lead-acid nameplate only delivers about 110 Ah usable (Battle Born chemistry guide). Lithium in the manual is 100% usable (Battle Born 100 Ah manual).
On lithium, the battery has to supply the motor's max amp draw continuously. 30 A is well inside a 100 A continuous rating (Battle Born 100 Ah manual; Minn Kota power article). Brushed motors on lithium should still be held to 85% or speed 8.5 or lower (Minn Kota power article). A 100 Ah lithium battery meets the current test and misses the 110 Ah runtime guide.
The chart says breakers are 50 A or 60 A as listed for the motor (Minn Kota battery chart). The accessory search below is a 50 amp breaker.
What size battery do I need for a 30 lb trolling motor?
One 12-volt deep-cycle battery of at least 110 Ah. The Minn Kota battery chart lists 30 lb at 30 amps and 12 volts, and both that chart and the Minn Kota power article call for at least 110 Ah for about 6–8 hours.
How long will 110 Ah last at full throttle?
About 3.67 hours in the worst case, because 110 ÷ 30 = 3.67. The Minn Kota battery chart says maximum amp draw only occurs intermittently and should not be used as a continuous rating.
Which group size reaches 110 Ah?
Group 31, labeled Best at 95–125 Ah. Group 24 Good is 70–85 Ah and group 27 Better is 85–110 Ah (Minn Kota battery chart).
Can the motor run on a 100 Ah lithium battery?
It can supply the 30 amp draw: the Battle Born 100 Ah manual rates the battery at 100 amps continuous and 100% usable. Brushed motors should stay at 85% or speed 8.5 or lower, and 100 Ah is still below the 110 Ah runtime guide (Minn Kota power article).