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Trolling motor runtime calculator

How many hours before you paddle home?

Pick your motor, your speed and your battery. On the same 100Ah size, lithium gives you about twice the time on the water of AGM, because you can use all of it.

Work out my hours See the table

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The hours of a same-size AGM

Lithium runs to empty; AGM should stop at half

4 hours

55 lb motor, half speed

12V 100Ah lithium, $242.89

42 lb

Less to haul to the boat

22.05 lb lithium vs 63.9 lb AGM

Your hours on the water

1. Your trolling motor

2. How hard you run it

Moving between spots or pushing into a breeze: half of full draw (Newport's rule of thumb).

3. Your battery (12 V)

Time on the water

about 2 hours

Short of a 8-hour fishing day at this pace. The motor draws about 25 A here from a lithium you can run to empty.

50 Ah you can use from this battery (all of it)
11 lb to carry to the boat
$215.99 when we checked

Check price on Redodo

Draw at full speed is 50 A from Minn Kota's Endura C2 manual. Wind, current, boat weight and spot-lock change it; treat this as a calm-day guide.

Hours at a glance

Half speed, calm water, with the usual lead-acid setup and a 100Ah-class lithium for each motor voltage.

Trolling motor runtime by motor and battery
Motor	Max draw	AGM (run to half)	Lithium	Lithium, slow troll
30 lb, 12 V	30 A	100Ah AGM: about 3 hours	Lithium 12V 100Ah: about 7 hours	about 13 hours
45 lb, 12 V	42 A	100Ah AGM: about 2.5 hours	Lithium 12V 100Ah: about 5 hours	about 10 hours
55 lb, 12 V	50 A	100Ah AGM: about 2 hours	Lithium 12V 100Ah: about 4 hours	about 8 hours
70 lb, 24 V	42 A	2 x 100Ah AGM: about 2.5 hours	Lithium 24V 100Ah: about 5 hours	about 10 hours
80 lb, 24 V	56 A	2 x 100Ah AGM: about 2 hours	Lithium 24V 100Ah: about 4 hours	about 7 hours
101 lb, 36 V	46 A	3 x 100Ah AGM: about 2 hours	3 x lithium 12V 100Ah: about 4 hours	about 9 hours
112 lb, 36 V	52 A	3 x 100Ah AGM: about 2 hours	3 x lithium 12V 100Ah: about 4 hours	about 8 hours

Max draw from Minn Kota's Endura C2 manual. Runtime is usable amp-hours divided by amps, Newport Vessels' formula. Battery prices from Redodo and Renogy, checked October 20, 2026.

How we work it out

Hours = usable amp-hours / amps. A lithium battery gives you all of its rating; Renogy advises running its AGM no lower than half. Batteries wired in series for 24 or 36 V keep the same amp-hours, so the sum works the same way.

Speeds. Slow troll: Creeping a bank or holding position on a calm day: a quarter of full draw (our estimate). Half speed: Moving between spots or pushing into a breeze: half of full draw (Newport's rule of thumb). Full speed: Wide open into wind or current: Minn Kota's maximum draw.

Myths, answered

"A bigger AGM is just as good." A 100Ah AGM gives about 50 Ah you should use, at 63.9 lb. A 12V 50Ah lithium gives the same 50 Ah at 11.27 lb, and keeps the motor at full strength until it is empty instead of fading through the afternoon.

"Lithium dies in the cold."It runs fine on a cold morning; it just shouldn't be charged below 32°F (Battery University). Every Redodo pick here except the base 12V 100Ah pauses charging in the cold to protect itself.

Frequently asked questions

How long will a trolling motor battery last?

On a calm day, a 55 lb motor on a 12V 100Ah lithium battery runs about 4 hours at half speed and about 8 hours at a slow troll. The same motor on a 100Ah AGM, which you should only run to half, gets about 2 hours at half speed. At full speed any 100Ah battery is done in about 2 hours on lithium. Wind, current and spot-lock shorten it.

How long will a 100Ah lithium battery run a trolling motor?

Divide the amp-hours by the amps the motor draws. A 55 lb Minn Kota draws up to 50 A at full speed, so 100 Ah lasts about 2 hours flat out, about 4 at half speed and about 8 at a slow troll. A 30 lb motor (30 A max) gets about about 7 hours at half speed.

How long will a 12V battery run a trolling motor?

It depends on the battery's usable amp-hours. A 12V 50Ah lithium ($215.99 when we checked) runs a 45 lb motor about 2.5 hours at half speed; a 12V 120Ah lithium ($329.99) runs it about 6 hours.

How long does a trolling motor battery take to charge?

Divide the amp-hours you used by the charger's amps and add a little. A 10 A lithium charger refills 50 Ah in about five hours; Redodo says its 10 A charger takes a 12V 50Ah battery to half in 2.5 hours. Lithium charges at full speed almost to the top, while AGM slows down for the last part.

Why does my battery run out faster than the calculator says?

Full-speed runs into wind, current, a heavy boat, spot-lock holding against waves and an older lead-acid battery all add draw. Minn Kota says its maximum amp figures are peaks, so steady cruising usually draws less, but bad weather draws more.

A calm-water guide. Real runtime depends on wind, current, boat weight, battery age and how you fish. Prices change often; the dates are shown. Redodo links are sponsored. See our disclaimer.

Sources

Minn Kota Endura C2 owner's manual (Max Amp Draw table) — max amp draw by thrust and voltage
Newport Vessels: calculate trolling motor runtime with a battery — runtime = amp-hours / amps; halve max draw for lower speeds
Renogy Deep Cycle AGM Battery 12V 100Ah product page — run to 50% as Renogy advises
Battery University BU-410: Charging at high and low temperatures

Photo: Jackery Power Station on Unsplash (Unsplash License).