Minn Kota Trolling 55lb

Transom-mount 12 V trolling motor: 55 lb thrust, a 36" or 42" composite shaft, five forward and three reverse speeds on a twist tiller. Minn Kota lists maximum amp draw at 50 A and specifies a 60 A circuit breaker at 12 VDC. The manual is explicit that the maximum figure occurs only intermittently and should not be used as a continuous amp load rating. It gives no figure for the lower speeds, and Minn Kota's help center says plainly that it cannot specify the draw at any speed other than max power — too many variables in wind, waves, current and battery condition. It is a freshwater motor — the warranty excludes saltwater and brackish use.

Two leads, straight to the battery; the motor ships with 5 ft of 10 AWG red and black. Speed selector to OFF first, then the red positive lead to the battery positive and the black negative lead to the battery negative. Over-current protection goes in the positive lead, as close to the battery as possible. The manual relays the Coast Guard requirement that each ungrounded current-carrying conductor be protected by a manually reset, trip-free circuit breaker or fuse, citing 33 CFR 183 and ABYC E-11, and names Minn Kota's own MKR-19 60 A breaker for motors requiring a 60-amp breaker. The motor wiring diagram printed in the manual does not show it — that page carries a notice saying over-current protection devices are not shown in the illustration.

Run length is what drives the gauge. Minn Kota measures it from the batteries to the trolling motor leads, and its table for the 50 and 55 lb motors reads 8 AWG at 5 feet, 6 AWG at 10 feet, 4 AWG at 15 and 20 feet, and 2 AWG at 25 feet. The chart sizes the extension of both leads, red and black, not the positive alone. It holds only under three stated assumptions: no more than two conductors bundled together inside a sheath or conduit outside of engine spaces, 105 °C insulation on each conductor, and no more than 5 % voltage drop at full motor power. Past 25 feet Minn Kota stops publishing a size and refers the job to a qualified marine technician.

On the battery side, any lead acid deep cycle marine 12 volt battery, and for best results one of at least 105 Ah, kept separate from the cranking battery on a boat with a gasoline outboard. Two batteries in parallel are wired the way the Minn Kota battery and wiring guide shows: a connector cable across each pair of like posts, then the red lead to the positive post of one battery and the black lead to the negative post of the other. One constraint catches people building a house system around the motor — the motor may be designed with an internal bonding wire, and a DC or alternator charger that ties the trolling motor battery's negative to the crank battery's negative can damage connected electronics and void the warranty. Radios and sonar units are not meant to share a trolling motor battery system at all.

Fitting an auto-resetting breaker. Both Minn Kota and the Coast Guard rule it cites call for a manually reset, trip-free device, and installers describe why: an auto-reset breaker trips, the bimetal strip cools, it closes again, and it keeps re-feeding whatever tripped it, so a fault that should have stopped the boat instead cycles current back into the motor's internal wiring.

Undersizing the breaker and the extension at the same time. In one thread about a Minn Kota Edge 55 — a different model, but the same "50 lb., 55 lb." row of Minn Kota's sizing table as this motor — a 40 A breaker tripped repeatedly on speeds 4 and 5, and the thread's replies note that repeated tripping then weakens a breaker until it opens below its stamped rating. The wire was the other half of it: 8 AWG over an 18-foot run, where Minn Kota's table asks for 4 AWG at 15 feet.

• 60 A manually reset, trip-free circuit breaker or fuse in the positive lead as close to the battery as possible; the manual names Minn Kota's MKR-19 for motors requiring a 60-amp breaker
• Extension cable for both leads, sized from Minn Kota's table against the battery-to-lead distance
• A lead acid deep cycle marine 12 V battery, at least 105 Ah for best results, dedicated to the motor rather than shared with the outboard's cranking battery
• A charger confirmed compatible with a motor that may carry an internal bonding wire