What Size Battery Do I Need for an 80 lb Trolling Motor?
Above 55 lb the system becomes 24 V: two batteries in series. Series raises voltage and does not raise amp-hours.
Direct answer: Minn Kota lists an 80 lb motor at 56 A and 24 V, and the battery count for thrust above 55 lb up to 80 lb is two 12 V batteries wired in series (Minn Kota battery chart; Minn Kota power article). Each battery should be at least 110 Ah for the 6–8 hour guide. Because series keeps the string at the amp-hour rating of one battery, 110 ÷ 56 is about 1.96 hours at the maximum draw, and that maximum is intermittent (Minn Kota battery chart).
Affiliate disclosure: as an Amazon Associate, we earn from qualifying purchases — at no cost to you.
Voltage comes from the thrust class. 80 lb is 24 V and 56 A on the chart, not a 12 V motor you can feed with one battery (Minn Kota battery chart).
The help article's count is two batteries from just over 55 lb through 80 lb, wired in series. A third battery is the next class, above 80 lb (Minn Kota power article).
Series adds voltage and leaves amp-hours unchanged. Two 110 Ah batteries in series are a 24 V string that is still 110 Ah, not 220 Ah. Worst case on that string is 110 ÷ 56 = 1.96 hours at the published maximum (Minn Kota power article; Minn Kota battery chart). The chart's warning applies here in particular: 56 A is a maximum that occurs intermittently, so 1.96 hours is the full-throttle floor.
More runtime means a parallel string, not a third battery in the same series set. The help article says to add batteries in parallel for runtime (Minn Kota power article). A second series pair would double the 110 Ah while staying at 24 V.
Each of the two series batteries has to meet the 110 Ah guide on its own. Group 24 at 70–85 Ah does not. Group 27 reaches 110 Ah only at the top of 85–110 Ah. Group 31 at 95–125 Ah is the Best tier that can clear 110 Ah (Minn Kota battery chart).
Lithium current is the full 56 A through each battery, because series does not split amps. The battery must be able to supply that maximum continuously (Minn Kota power article). 56 A is inside a 100 A continuous rating (Battle Born 100 Ah manual). This 56 A figure is the highest maximum in the 30/55/80/112 set, so the brushed-motor cap matters here: stay at 85% or speed 8.5 or lower on lithium (Minn Kota power article).
Lead-acid does not get to share one oversized battery across the voltage. About 50% depth of discharge means each battery in the series string needs about a 220 Ah nameplate to provide 110 Ah usable, and you still need two of them in series. The string's usable amp-hours remain 110 Ah, not 220 Ah times two (Battle Born chemistry guide; Minn Kota power article).
Breakers are 50 A or 60 A as listed per motor (Minn Kota battery chart). The search linked here is a 60 amp breaker. A 24 V system does not change that sentence into a different breaker amp value; the chart simply does not print the per-motor breaker in the excerpt used here.
What size battery do I need for an 80 lb trolling motor?
Two 12-volt batteries in series, each at least 110 Ah. Minn Kota lists 80 lb at 56 amps and 24 volts, and thrust above 55 lb up to 80 lb uses two batteries (Minn Kota battery chart; Minn Kota power article).
Does series wiring double the amp-hours?
No. Series makes 24 volts and the string stays at one battery's amp-hour rating. Worst case on a 110 Ah string is 110 ÷ 56 = 1.96 hours at the 56 amp maximum (Minn Kota power article; Minn Kota battery chart).
How do I get more than that worst-case runtime?
Add a parallel string. The Minn Kota power article says to add batteries in parallel for runtime, which doubles the 110 Ah figure and keeps 24 volts.
What is the lithium limit on this motor?
The battery must supply 56 amps continuously, and brushed motors should stay at 85% or speed 8.5 or lower. 56 amps fits a 100 amp continuous rating, but each battery should still be at least 110 Ah for the 6–8 hour guide (Minn Kota power article; Battle Born 100 Ah manual).