Garmin Force Pro battery setup

Garmin is a trademark of its owner. Amp Hour Supply isn’t affiliated with Garmin.

The short answer. Give the Force Pro a 24 V or 36 V bank that can hold 60 A continuously, a 60 A breaker stamped 42 VDC or higher, and 6 AWG wire for the first 10 ft. Garmin doesn’t name a battery type or size. On lithium, set the battery type in the motor or the gauge will lie to you.

Two things that trip up Force Pro installs

The breaker voltage. Garmin wants 60 A continuous and a rating of 42 VDC or greater. Amps alone don’t cut it. Garmin allows a bigger breaker, up to 90 A, only where heat or a shared circuit keeps tripping the 60. Keep the breaker off until the wiring is done.

The gauge. Garmin writes that the battery level icon is optimized for lead-acid and “may be inaccurate” on lithium-ion. There are two fixes in the motor’s menu: set the battery type under Battery Setup, or switch the indicator to a numeric voltage. Do one of them before you trust the icon.

Garmin’s numbers

24 V bank 36 V bank
Full thrust (setting 20) 90.0 lbf at 58.9 A 114.7 lbf at 55.9 A
Setting 16 61.7 lbf at 32.0 A 65.0 lbf at 23.1 A
Full reverse (setting -20) 48.0 lbf at 57.4 A 62.3 lbf at 55.1 A
Input range 20 to 45 Vdc
Breaker 60 A continuous, 42 VDC or greater
Wire, batteries to motor 6 AWG to 10 ft; 6 min / 4 optimal to 20 ft; 6 min / 2 optimal to 30 ft

Garmin measured those at 25.6 V and 38.4 V, with a 5 lbf and 5 A tolerance. Reverse is the row to notice: full reverse pulls almost as many amps as full forward for half the thrust. Garmin says reverse is louder, less efficient and to use it sparingly. Your bank will agree.

The power cable from the motor is 4 ft on the 50 in model and 3.5 ft on the 57 in. Wire should be single-conductor stranded, 75 C, not bundled. Plug and receptacle, if you fit one, 60 A or more.

Packs that meet 60 A continuous

Garmin’s only sizing rule is “60 A continuously”. These clear it, by our reading of the makers’ sheets:

Pack Volts Ah Continuous discharge
Pro-Guide 24VM90 24V 90Ah lithium 24 90 90 A
Pro-Guide 24VM115 24V 115Ah lithium 24 115 100 A
Pro-Guide 36VM60 36V 60Ah lithium 36 60 60 A
Pro-Guide 36VM75 36V 75Ah lithium 36 75 75 A

The 36VM60 sits exactly on Garmin’s 60 A line. If you spend time at setting 20, the 36VM75 has margin.

Run time by setting

Math from the Run time calculator trolling mode: 80% of the amp hours divided by Garmin’s amps for that setting. An example, not a test.

Pack Setting 20 Setting 16 Full reverse
24VM90 1 h 13 min 2 h 15 min 1 h 15 min
24VM115 1 h 34 min 2 h 53 min
36VM60 52 min 2 h 05 min 52 min
36VM75 1 h 04 min 2 h 36 min

Setting 16 is still over 60 lb of thrust. The full-draw column is the floor, not the day.

Hooking up and charging

A single 24 V or 36 V pack: positive through the breaker, negative straight to the motor’s black lead. Series banks of 12 V batteries work too; Garmin doesn’t draw them, so use the steps in Trolling motor battery: 12V, 24V or 36V, wired right.

Charging isn’t in Garmin’s manual at all. Follow the pack: Pro-Guide 24 V charges to 28.8 V, 36 V to 43.2 V. We don’t list a charger at either voltage yet, and no 42 VDC-rated 60 A breaker yet. Garmin’s own maintenance list has you checking and cleaning the power cables each season, and it ties the warranty to that routine.

The motor powers down on its own after two hours stowed.

Quick answers

Does the Garmin Force Pro work with lithium batteries? Garmin’s manual neither approves nor bars lithium. It says the gauge may be inaccurate on lithium unless you set the battery type.

What breaker for a Force Pro? 60 A continuous, rated 42 VDC or greater. Not past 90 A even in heat.

Does reverse use more battery? Nearly as much current as full forward, for about half the thrust. Garmin says use it sparingly.

Which wire for a 15 ft run? 6 AWG minimum, 4 AWG optimal.

Sources

Amp Hour Supply

12V power for boats first, then vans and RVs. You can do this.

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