There you sit at the front of your boat. Your finger is poised on the speed control button. The wind is picking up and you need more thrust to hold your position near the structure where fish is hiding. You want extra thrust to maintain your hold on this piece of structure that the fish are sneaking around. But you also realize that spinning it up robs your battery quickly. That balance of performance versus battery life are the heart of electric trolling motors. Knowing your amp draw isn’t simply reading something from a book; it’s realizing when you’ve got enough range left to get back to the launch.
Here’s a breakdown of current requirements for various levels of thrust. And just as importantly, here’s how much battery drain each speed setting will cost you. The starting point for most angler is a 12-volt system. It’s cheap and easy. From smaller kayaks to lightweight fishing boats, one deep cycle battery do the trick.
How Speed Affects Your Battery Life
And there is no mistaking the trade off. At full speed, higher thrust motors pulls like crazy on 12 volts. Just getting going against a moderate breeze can draw thirty amps or more. That is a lot of electricity which will burn out your reserve fast. It’s not that your motor are broken. It’s simply physics working as designed.
Moving into the higher voltage systems of 24 or 36 volts increases the pressure instead of the flow by adding batteries in series. The effect are larger motors pushing harder but drawing fewer amps per pound of push. Less strain on your wiring and longer run times is the results. In short, your speed matters much more then most of us think it does.
You’ll notice a dramatic change if you’re cruising along at speed one and then push all the way up to speed five. While trolling away at low speeds, you might pull just six to ten amps, allowing you to troll around for hours with no worries. Increase to highest gear, however, and those numbers will triple or even quadruple immediately. That’s why veteran anglers never kick out full throttle unless they’re fighting heavy current or trying to avoid some kind of hazard. To get around, they’ll stick with the mediums while saving top gears for emergency situations. This is shown very well by the infographic; as you’ll notice, increasing speed a little bit result in an exponential jump in energy usage.
The majority of anglers blow it on battery management. When you’re out there, it’s easy to burn up juice till the engine shuts down. Don’t! Running lead-acid batteries all the way down to less than half kills them quickly. If you can get in and shut ’em down before running out of juice, do so, just make sure you’ve got enough to get back comfortabley. Lithium changes the equation as they can be discharged further without harm, but it will cost more out-of-pocket initially.
Either way, you must watch your voltage. This can either be done with an integrated display or a multimeter. In both cases, you’ll know precisely how far you are from “reserve”. Until it’s too late, many people don’t pay much attention to protection and wire gauge. Using light wiring for a high thrust motor is inefficient as well as unsafe; it will cause heat build up and voltage drop. Thicker wires will lowers resistance and make sure the motor get full power. Combine this with a proper rating circuit breaker at the battery terminal and you’ve got yourself a safe deal. Your boat is protected from overload and short circuits. It is a little part that keeps big stuff from happening.
In addition to the load placed on a trolling motor, other variables such as wind, current and boat weight can affect amp draw. Your trolling motor has to fight harder when there is a strong headwind, drawing more amps with the same setting. A heavier boat sits deeper in the water, creating more drag. This means you need more thrust just to hold your position. The bottom line is that your actual battery life will change based off the conditions every day. The charts are a starting point. What happens on the water determines what happens.
Battery capacity is also a key factor in selecting a motor that provides enough thrust without overpowering the boat. A high power unit isn’t necessary for small boats. It will waste both battery space and money. Size the thrust to your typical conditions and the boat’s weight. You can use the data to plan out your day on the water. You’ll run longer fishing instead of worrying about running dry and having to turn around. That little bit of awareness keeps you moving forward when others is stuck watching their gauges go down.