Get the Most from Your Electric Motor
September 27, 2010
If you're like most anglers you never think about your electric motor until something goes wrong and your fishing day is ruined. Reading this article will help you keep things from going wrong.
Photo by Ron Sinfelt
By Ed Harp
The electric motor is one of the most important pieces of equipment on your boat. And yet, how much do you really know about it? How much time did you spend selecting it? How should it be maintained? How much do you know about your batteries?
The answer to those questions is probably, "not much." The answer should be, "plenty." The reason is obvious. You spend a lot of time with your electric motor. Efficient fishing is darn near impossible without one.
The first and most obvious issue you must address is: How much thrust - power - do I need?
Thrust is a measure of force. It's generally measured in pounds. How much you need depends upon a number of factors. Boat size is one. You need more thrust to pull a big center-console pontoon boat than you do to push a small lightweight canoe.
Keep in mind, however, that boat size is only one factor. Consider where and how you fish. You'll need more thrust if you frequently fish windy lakes or rivers with a moderate to high current. You'll need more thrust if you travel long distances with your electric motor or if you typically fish long days.
And what about weight load in the boat? Do you mostly fish alone or with several buddies? Do you typically carry coolers, ice and livewells filled with water? Those things matter. More weight requires more thrust.
Although not directly related to the motor's thrust, the motor's shaft length is important as well. The shaft must be long enough to keep your prop in the water, even under rough and windy conditions, but not so long as to create unnecessary drag. Most models come equipped with an easy mechanism for adjusting length - use it.
Both major electric motor manufacturers, Motor Guide (www.motorguide.com) and Minn Kota (www.minnkotamotors.com) offer many models with varying thrust capabilities and with varying shaft lengths. Carefully consider what you need and buy just that. Buying less will make you miserable. Buying more will waste money - money you could use to go fishing.
Most experienced anglers and boating experts advise selecting a motor toward the high end of the recommended thrust range for your rig. (Both manufacturers have charts you can consult for their thrust recommendations.) They draw an analogy to your combustion motor. While a smaller motor may seem to be enough at first, the lack of speed and performance will soon begin to show. It will quickly sow the seeds of discontent.
All major manufacturers offer electric motors with voltage ratings from 12 to 36 volts. In theory, the higher the voltage the more efficiently a motor runs. More efficiency means more available power. That may be true in a theoretical sense but not always in the real world. Three batteries add a lot of weight and expense to your rig, especially if it's small.
Once a decision has been made about size and power, you'll need to consider features and options. Electric motors are available with just about every feature imaginable. They include simple things such as air and water temperature gauges on up to depthfinders, sonar units, remote control capabilities, autopilots and GPS navigation systems.
These features are nice, no doubt about that. They are also expensive and require maintenance. If you need them, get them. If you don't need them, don't get them.
Maintenance on the basic motor doesn't amount to much. Depending upon your make and model there may be a few places to oil or grease occasionally, but that's about all. Check your operator's manual for details.
Selecting the right prop is important to the overall performance of your motor. A two-blade prop will give you the most speed but not the most power. A three-blade will combine speed with power and a four-blade will offer the most power. If you frequently travel long distances under electric power go for a two-blade model. If you need power to handle wind and current, consider a four-blade model.
Many props claim to be weedless. Some are and some aren't. Most truly weedless props have relatively short blades. The reason for this is that shorter blades, having a smaller diameter, are easier to turn and harder to stop.
To make your current prop more weedless keep the edges of the blades sharp. This will help them cut through vegetation. You can sharpen them with a file. There are also add-ons that can be affixed to the skag that help.
Nearly all serious anglers keep two or three props in their boat and change them as conditions require. It only takes a minute or two to do this and will make all the difference in the world in how your boat performs.
At least one prop maker, Kipawa Products (www.kipawapropellers.com), advertises their props will increase power, conserve battery life and glide through the heaviest weeds. That seems like a tall order, but the owner, David Gozdinsky Jr., makes a convincing case. Check out the Web site, give him a call, and make your own decision.
Battery selection and maintenance is critical. Next to the basic motor itself your battery is probably the most important item in the chain of equipment - and the one most likely to wear out first. After all, it's the source of power that runs the motor.
There are several types of battery construction available. They range from conventional lead acid designs to a wide variety of dry cell models. A technical discussion of battery construction is beyond the scope of this article. It is important to consider your options, however.
The most common type is lead acid. Lead acid batteries come in several designs, including those called wet cells. Some wet cells are sealed and require no internal maintenance. Others require internal maintenance, adding water. Either way, a wet cell, lead acid battery is considered to be conventional. It's the type you will most likely be using.
There are other versions of lead acid batteries. Some are known as gel cell, others are called AGM (Absorbed Glass Mat) batteries. These designs last longer and will survive more charge-discharge cycles. They are also more expensive and heavier. Some models require special chargers.
There is also a vast array of dry cell batteries on the market. Once again, they may last longer, but they aren't cheap. They may also require special chargers.
Regardless of what type of battery you select, do not run your electric motor with a cranking battery. Cranking batteries are engineered to deliver a high amount of power quickly. Deep cycle batteries, on the other hand, are engineered to deliver power at a lower rate over a long period of time. They will also withstand repeated charge-discharge cycles, something a cranking battery can't do.
Buy the biggest, most powerful battery you can afford so long as it will fit into your boat. Even deep cycle batteries are damaged by serious discharges and repeated overuse. The more powerful the battery, the less discharge it will suffer over a day's fishing.
Lead acid batteries require maintenance. There are no shortcuts, nor are there any excuses, that will paper over - or make up for - a lack of routine maintenance.
Experts recommend cleaning the battery posts and terminal connections regularly. Treat them with a corrosion-resistant compound.
If your battery is not "maintenance-free," check the water level after each use, or at least on a regular basis. Every two weeks is a good place to start. Add distilled water as necessary. Do not overfill. Never use or charge a lead acid battery that is low on water or electrolyte.
Charge your batteries immediately after use. Allowing even a day before recharging can permanently harm the battery.
And, speaking of charging your battery . . . Do not skimp on a charger. Get one of the best. Most anglers prefer onboard chargers that are mounted in the boat. They can be plugged into a standard outlet at the house, garage or dock. Follow the manufacturer's recommendations for specific charging procedures.
Select one that will charge your batteries within a reasonable length of time, say 12 to 16 hours, and that will automatically reduce the rate of charge as the battery reaches its peak. Most top chargers need not be unplugged. They will sense the state of charge in the battery and supply current as required.
These few paragraphs only scratch the surface of what you need to know about batteries. For more detailed information visit www.batterystuff.com. It's full of information that is technical, informative and practical all at the same time.