The great number of existing trolling motor batteries includes products for all tastes but simultaneously makes it more difficult to find the one you really need. Before buying a battery, you have to consider its purposes, type, the manner of use, size, durability, weight, required maintenance conditions – all the factors that define the product that really suits you.
So, what features are more significant and what factors could be put at the end of the checklist? This buyer’s guide will help you figure it out.
Three Different Types of Batteries
These traditional batteries (sometimes called flooded cells) are expected to withstand frequent chargings and rechargings. You’ve seen them countless times in everyday life: they are used in all types of cars.
These batteries deal pretty well with frequent recharging, have lower prices than lithium and AGM ones, and are relatively overcharge-resistant. While they often show slick performance, their main flaws mostly relate to the specific working conditions. Wet-cell batteries are not sealed, and therefore do not exclude the risk of acid leaks and resulting corrosion. Installed in rooms/closed premises, wet-cell units require ventilation to not put you in danger of flammable hydrogen gas accumulation.
Absorbed Glass Mat or AGM batteries
Unlike the wet-cell sets, AGMs are tightly sealed. As a result, they release no hazardous gas, require no extra ventilation, and can be mounted in many different ways.
AGM batteries are at least twice as expensive as flooded-cell units, yet they charge faster and tend to last two times longer. Here, the disadvantage of higher prices may be balanced by extra durability and cycle life. Lesser weight and smaller size may also be a top-one priority for light-sized boats.
Because of their tightly-sealed design, modern AGM units are more vibration-resistant and invulnerable to potential leaks of sulfuric acid.
Normally, these accumulators have no problems with temperatures below zero. On the bad side, their use in high temperatures is limited. Also, their performance and durability parameters significantly decrease after overcharge.
These storage cells are designed to operate in a charge-depleting mode regardless of the charge level. AGM and wet-cell products usually provide a more powerful start; however, their ability to maintain a stable performance is significantly lower. If multitasking means a lot to you, then maybe it’s high time to give lithium a try.
Lithium cells are also lighter in weight and have a noticeably longer cycle life. Their main flaw is the price. In fact, it is hard to tell which variant is more reliable and money saving: lithium-ion with higher capacity or a pair of wet-cells as a reserve. In this case, the required size, capacity and maximal life of the product should be determined by your preferences.
Dual Purpose Batteries vs Deep Cycle
First and foremost, you should not use a starting battery as a power source on a regular basis.
Here, gradual and steady discharging is what you want to opt for, whereas starting cells are constructed to discharge a large percentage of the accumulated power in one impulse and, consequently, start the engine. Yes, you can use a starting battery in a critical situation; no, it will not last for long if this repeats too often.
There are two alternatives to choose from:
- Dual purpose batteries, which are capable of starting the engine and supplying the boat with a consistent flow of electrical power. They are designed as a universal solution, which means that they are good but not perfect for both of said purposes.
- Deep cycle batteries involve near-full discharging of its capacity in the process of constant energy supply. Single-purpose accumulator units provide a higher performance rate, last longer and have an increased battery cycle life with an added benefit of shorter charging time.
Anticipated Conditions of Service
Anticipated working conditions are your ground for the selection of a certain battery type. Ideally, you should be able to install two batteries to combine starting and deep cycle accumulator units. However, if the price and/or free space on the boat proves to be limiting factors, then a dual purpose cell will surely do – this is then your silver bullet for igniting the engine and providing energy for the motor power center.
Amp Hours (Ah)
This parameter describes the durability: an amount of time during which the energy storage device may power up an engine. It is measured in amperes per hours – for example, it the trolling motor uses 5.0 Ah and the capacity of the battery is 50 Ah, then it would be able to work for approximately 10 hours. This parameter is always indicated in the labels of deep cycle batteries but often absent in the dual-purpose cells.
Obviously, you should give precedence to the batteries with larger capacity because this one specification determines both a maximal speed and an average traveling distance. However, the capacity parameter provides only approximate values because of what cuts down the productivity index, namely:
- the size of the boat (bigger boat needs more power);
- the initial charge state (accumulator has more juice when it is freshly charged);
- all the other devices and onboard electronics that use the same 12 DC battery as a source of energy.
In order to maintain speed, the boat needs a certain thrust. It is a multivariable index that is calculated depending on the boat’s size and form, trolling motor performance and power supply. Bigger boats have to develop more thrust levels and, as a result, require batteries with higher Ah parameters.
Approximate Trolling Motor Battery Run Time
|Trolling motor trust (lbs)
||Amps Drawn at Various Speeds (amps)
||Run Time (hours)
The voltage of the battery should correspond to the demands of the power system – a weak charge will not drive the engine. For example, 24 DC power system requires a battery with equivalent parameters. It is nevertheless possible to install several weaker cells to achieve desirable electrical voltage, such as three 12 DC batteries for a 36 DC power system and so on.
It’s better to avoid wild improvisations here; the battery’s size should match the size of the motor power center with few to no exceptions. You can do without boring yourself out of your skull with measuring tape and simply find the measurements on the label right on the motor center. They are designated as BCI group size – these are the physical dimensions of the box size according to Battery Council International. When choosing a battery holder it is advisable to look for one with “M” in the BCI group size, which is the designation for “marine”.
Today, there are many different trolling battery motor centers provided by an array of manufacturers, including Newport Vessels, Minn Kota, and few others, which means finding a fitting accumulator cell isn’t necessarily going to become a difficult task.
Reverse capacity indicates how long it takes for the battery to achieve 100% charge status. The higher this parameter the less time it takes to replenish an unloaded cell. However, being not a universal parameter, it quite often shows an inverse correlation with the durability index. Thus you should decide what matters more: quick and prompt charging or potentially longer lifespan when dealing with two products with different reverse capacity values. In general, lithium batteries demonstrate great results at the intersection point of the charging duration and optimal lifespan.
Deep cycle batteries usually last longer than the all-around types, while lithium cells tend to live longer than wet-cells. A bottom line for a good quality battery starts from approximately 150 deep discharge cycles and gradually raises in relation to average prices and quality.
Not all batteries survive the storage well. Some of them may not keep their operational abilities or get a cycle life significantly decreased. This is why, when deciding between power and reliability, likewise consider the storage conditions of your battery. Make sure that the battery is newly made or at least check that its parameters are within acceptable limits.
In fact, when it comes to lead wet-cell accumulators, it is recommended to avoid those that are more than hundred days old because wet-cells require periodical charges in order to prevent the process of inner sulfurization. AGM and lithium-ion batteries may be stored up to a year without significant losses in power capacity and durability.
Since the battery is by design always located in a place exposed to mechanical vibrations, you should look for the container with significant shock and vibration-resistant properties. Such products are always tightly-sealed and covered with thick non-hazardous plastic panels designed to preserve the cells and prevent the possibility of leaks. Such features greatly extend the lifespan of dual purpose or deep cycle batteries, allowing you to minimize maintenance routine and conduct regular checks less often.
Some manufacturers protect the batteries with thick metal plates. The plastic bodies, though, are just a little bit less durable while remarkably more lightweight. Both materials are corrosion-resistant and provide good shock and waterproof protection.
In case of wet-cell accumulators, the cells are usually inserted into a hard rubber case or a high-density tough polypropylene, allowing them to withstand mechanical shock. However, from this point of view, Absorbed Glass Mat cells seem more protected.
All types of trolling motor batteries are able to recharge from various sources given correct current parameters and a reliable charger. This gives an opportunity for new charging combos, for example, it is possible to connect a battery to a solar panel through a solar battery charger, which compensates for the differences in voltage. You can now gradually recharge while actively using the boat, consequently increasing the available distance as well as a power reserve.
Design & Special Features
In addition to the maintenance-free cycle of work, modern AGM batteries do not require special orientation towards the central axis of the boat, since they are sealed with thick plastic plates against all types of leaks. Therefore, they can be installed not only in one position but also on one of the sides or even upside down.
Weight of Batteries
Take the battery weight into account only if it affects the manner in which the battery will be used. If you plan to transport your accumulator unit a lot, then you may look for a portable lite battery, possibly a lithium, which weighs below 50 pounds.
Otherwise, a heavier AGM battery (from 50 to 100 pounds) will also get the job done.
All branded batteries come with a warranty. It usually ranges from one to three years with a chance of full replacement. In rare cases, you may get lucky with up to 5 years of prorated service maintenance. The terms are not identical for each product, so keep in mind to double-check the conditions when purchasing a battery.
Frequently Asked Questions & Answers
How to Connect a Newly Purchased Battery?
- Turn off all the switches and shut off the ignition switch.
- Remove the cables starting with the negative ones.
- Remove the wasted old battery.
- Double-check all the connections to avoid the risk of short circuit and corrosion. Clean or replace the damaged connections.
- Connect the negative cables, then the positive ones. Scrupulously check all the connections before turning the power on – reversed polarity immediately destroys the accumulator cells and may cause explosion and fire.
- Check the levels of the electrolyte and the charge status.
Maintenance and Nuances of Battery Care
When properly designed and constructed, a battery is capable to withstand even pretty harsh conditions without malfunctions. From a user’s perspective, the battery is an all-in-one unit and it should remain to be so. AGM and lithium-ions require no special maintenance; wet-cells should be checked for sufficient levels of electrolyte.
Below are pretty much all the care tips that may ever come in handy:
- Avoid hitting your newly purchased batteries;
- Use breakers to turn off the power during the inactive period;
- Recharge them after every trip;
- Store the units in a battery box;
- Regularly check the fuses to make sure everything is protected in case the battery decides to short-circuit.
Finally, keep your boat in a flawless condition; as long as you take care of your watercraft, normally operating batteries can be left unattended.
Do I Really Need to Purchase a Specific Battery Instead of a Multipurpose One?
In fact, yes, staying specific is the most recommended. The secret to efficient energy supply lies in dividing the functions between to completely different battery sets. In this way you will increase the reliability of the whole system, making it possible to interchange the batteries more quickly, and even buy yourself a chance to use a starting pack in case of emergency or major malfunction. All-around accumulator units may seem promising, yet they give up their advantages over the long term.
How to Check the State of Charge?
In order to prolong the battery’s lifecycle, you may use additional hardware designed to detect malfunctions, monitor the charge and maintain a proper charging schedule. Important! Overcharging significantly reduces the durability of Absorbed Glass Matt batteries and wet-cells. Digital portable modules provide a possibility to control voltage and current inputs, check the charge level before and after charging and detect possible malfunctions. Since the monitor devices have a memory cell, it is also possible to analyze the performance rate by comparing test results at various stages (the majority of market-available devices allow to save results of several tests).
What Charger to Use?
To charge the battery properly, it is necessary to get at least one reliable 12/24 DC charger with built-in protection. In this way, you will be able to maintain the batteries’ good health and recondition them in order to achieve maximal performance. Regular and careful recharging will help prolong the battery’s life and keep your accumulator ready for use. By distributing the charge among all batteries in the pack, the charger allows you to minimize fuss with the charging routine and avoid premature deterioration of the actively used cell.
A good idea would be to get a reserve 12/36 DC charger with shorter charging period and higher efficiency if you find yourself short on time once too often.
Can I Use a Car Battery Instead?
Car accumulators belong to the category of starting batteries designed to provide a single powerful impulse instead of keeping high current for a long time. Even half a dozen car batteries would never replace a specialized trolling motor cell neither in durability nor in thrust. It could be used in dire need at most.as an exception rather than a day-to-day substitution.
Do I Need to Keep a Reserve Battery?
A reserve power source is one of those things that fall into a “must-have” category. Since the main battery is pretty much your one and only source of energy, a reserve would be a nice thing to have in an emergency. It does not have to be the exact same type of battery: for example, you may use a longer-lasting lightweight lithium or an all-around battery to secure the energy needs of the onboard electronics and communication equipment. Ultimately, you can even use a cell with lesser voltage as a temporary energy source.
In general, a trolling motor battery must provide enough power for your boat, an optimal duration of recharging and hold a charge as long as possible without noticeable power losses. In order to get a well-designed and full-scale functional trolling motor battery, you have to go through a couple of reviews and understand what features are of most value to you.
First, choose the right type. Next, learn more about all the nuances of maintaining and cleaning your battery to prolong its lifespan. Extra operational hours are never redundant, especially when dealing with such a vital factor as the powering of your boat. So, make sure you know what to do with the chosen battery and how to keep it in prime condition before you purchase it.
Take care of reserve batteries in order to eliminate even the slightest possibility of critical power loss. Equally important criteria include motor voltage, lifespan and BCI group size. Make sure the battery will fit said parameters of your power system.