On an electric-only lake, your trolling motor battery is your only way back to the ramp. Size it for the whole day plus a reserve. For a 55 lb, 12V motor averaging half speed, a 6-hour day takes about 130 Ah of lithium, or roughly 270 Ah of AGM. A single 100Ah lithium battery covers about 4½ hours at that pace.
Why electric-only lakes change the math
On a lake that allows gas, a dead trolling-motor battery is an inconvenience: you drop the outboard and run home. On an electric-only lake, even if the rules let you keep a gas outboard on the boat, you can't start it. So the battery has to cover three things:
- Fishing time at your normal trolling speed
- Running time across the lake to your spots and back, often at full throttle
- A reserve for a headwind on the way home
The running part is easy to underestimate. Draw climbs steeply with speed: our calculator estimates a 55 lb motor at about 18 A at 50% speed, but 52 A at 100%. Thirty minutes at full throttle uses about as much battery as an hour and a half at half speed.
How long a 100Ah lithium battery lasts
Estimated hours of continuous running on one 100Ah lithium battery (or a 100Ah 24V or 36V pack), by motor and speed setting:
| Motor | Max draw | 30% | 50% | 70% | 100% |
|---|---|---|---|---|---|
| 30 lb, 12V (kayak/jon boat) | 30 A | 18.2 h | 8.1 h | 4.8 h | 2.7 h |
| 55 lb, 12V | 52 A | 10.2 h | 4.6 h | 2.7 h | 1.5 h |
| Minn Kota Endura Max 55, 12V | 50 A | 10.6 h | 4.8 h | 2.8 h | 1.6 h |
| Minn Kota PowerDrive 70, 24V | 42 A | 12.8 h | 5.7 h | 3.4 h | 1.9 h |
| Minn Kota Terrova 80, 24V | 56 A | 9.4 h | 4.2 h | 2.5 h | 1.4 h |
| Minn Kota Terrova 112, 36V | 52 A | 10.2 h | 4.6 h | 2.7 h | 1.5 h |
| Minn Kota QUEST, 24V or 36V | 60 A | 8.8 h | 3.9 h | 2.3 h | 1.3 h |
Minn Kota says its brushless QUEST motors give up to 30% more runtime than its 24V brushed motors at max speed, so a QUEST may well beat these estimates. We use the same formula for every motor so the numbers stay comparable.
How much capacity you need for a day
Estimated amp-hours needed to run continuously at 50% speed. For 24V and 36V systems, the figure is per 12V battery in series, or the Ah rating of a single 24V or 36V lithium pack.
| Motor | 4 h lithium | 6 h lithium | 8 h lithium | 6 h AGM |
|---|---|---|---|---|
| 30 lb, 12V | 51 Ah | 75 Ah | 99 Ah | 156 Ah |
| 55 lb, 12V | 89 Ah | 130 Ah | 171 Ah | 270 Ah |
| Endura Max 55, 12V | 85 Ah | 125 Ah | 165 Ah | 260 Ah |
| PowerDrive 70, 24V | 72 Ah | 105 Ah | 138 Ah | 218 Ah |
| Terrova 80, 24V | 96 Ah | 140 Ah | 184 Ah | 291 Ah |
| Terrova 112, 36V | 89 Ah | 130 Ah | 171 Ah | 270 Ah |
| QUEST, 24V or 36V | 102 Ah | 150 Ah | 197 Ah | 312 Ah |
Most anglers don't run the motor nonstop at 50%. If you average 40% instead, a 55 lb motor needs about 93 Ah of lithium for 6 hours rather than 130 Ah. Put your own speed and trip length into the calculator.
Build in a reserve
A simple way to plan: work out the capacity for your fishing hours, then add the run back to the ramp at full throttle. On a 55 lb, 12V motor that pulls 52 A flat out, every 15 minutes of full-throttle running costs about 13 Ah. If your best water is 20 minutes from the ramp, that's roughly 35 Ah for the round trip, before Peukert losses and before any wind.
Two habits help on electric-only water:
- Fish the far end first. Run out while the battery is full, then work your way back toward the ramp.
- Watch state of charge, not hours. A battery with Bluetooth monitoring or a battery meter tells you when it's time to head in, whatever the wind did to your plan.
Lithium or AGM for electric-only lakes
Lithium (LiFePO4) usually wins here. It gives you about 90% of its rated capacity against about 50% for AGM, so a 100Ah lithium does roughly the work of a 200Ah AGM bank. It also weighs about a third as much. Many electric-only lakes are small reservoirs with car-top or carry-in launches, where a 25 lb battery is a lot easier to haul than a 65 lb one.
AGM still makes sense if you fish these lakes only a few times a season, if your budget is tight, or if the lake's rules call for a specific battery type. Ask the manager if you're unsure.
Check the lake's own limits first
Some electric-only lakes regulate the motor or battery, not just the fuel:
- Voltage: the Cambria Somerset Authority's Pennsylvania reservoirs cap motor voltage at 24 volts, which rules out a 36V system.
- Thrust and battery count: Lake Carmel in Kent, New York allows removable motors up to 55 lb thrust and at most two sealed 12-volt marine batteries per boat.
- Horsepower: Lady Bird Lake in Austin allows electric motors up to 5 hp. For a sense of scale, a motor drawing 60 A at 36V uses about 2,160 watts, or roughly 2.9 hp of electrical input. Ask the lake how it measures horsepower if you're close to a limit.
- Speed: Pennsylvania's Fish & Boat Commission and state park lakes hold electric boats to slow, no-wake speed. That helps your battery last.
Each lake in our electric-only lake finder lists any extra rules we found and links to the official page.
Match the BMS to your motor
A lithium battery's BMS shuts it off if your motor pulls more than its rating, and on an electric-only lake that leaves you paddling. We recommend a continuous BMS rating of at least your motor's max draw plus 10%, rounded up to the next 10 A:
| Motor | Max draw | Minimum BMS | Our picks |
|---|---|---|---|
| 30 lb, 12V | 30 A | 40 A | Best 12V batteries |
| 55 lb, 12V / Endura Max 55 | 50–52 A | 60 A | Best 12V batteries |
| PowerDrive 70, 24V | 42 A | 50 A | Best 24V batteries |
| Terrova 80, 24V | 56 A | 70 A | Best 24V batteries |
| Terrova 112, 36V | 52 A | 60 A | Best 36V batteries |
| QUEST, 24V or 36V | 60 A | 70 A | 24V or 36V picks |
Not sure what your Minn Kota needs? See what battery your Minn Kota needs.
FAQ
Is one 100Ah lithium battery enough for an electric-only lake?
For a kayak or small boat with a 30 lb motor, usually yes: about 8 hours at half speed. For a 55 lb motor, it's about 4½ hours at half speed, which covers a morning but not a full day of steady running.
Should I bring a spare battery?
If your boat can carry it, a second battery is cheap insurance on electric-only water. Wire it in parallel for more capacity on a 12V system, or carry it as a swap. Use the same type and capacity, and follow your motor maker's wiring instructions.
Can I charge on the water?
Few electric-only lakes have shore power. Plan to charge at home before each trip, and charge lithium with a charger that has a lithium profile.
Does cold weather change things?
Lithium can be discharged in the cold but shouldn't be charged below freezing unless it has a heater or low-temperature charge protection. Cold also cuts usable capacity, so allow extra reserve on winter trips.
Sources (checked October 2026): runtimes and capacities from our runtime calculator (method on how we pick batteries); Minn Kota published max-draw and QUEST runtime figures (see our Minn Kota lineup comparison); lake limits from Cambria Somerset Authority, Town of Kent, NY, Austin Parks and Recreation and 58 Pa. Code § 107.2.