A trolling motor is only as good as its battery. Learn how to choose the very best trolling motor battery for your needs with this handy guide.
There was a time when your only option for batteries was lead-acid. They were the first rechargeable battery option.
Invented in 1859, they have dominated the automotive and marine industry. This domination is changing thanks to a new technology introduced by Sony in 1991.
Lithium-ion batteries provide a number of benefits that lead acid cannot. Which is the best trolling motor battery for your needs? Read our guide to help you decide.
Types of Batteries
There are three main types of batteries to choose from. When shopping for a new battery, you need to look for one designed for deep cycling.
These marine batteries will last longer. The deep cycling batteries trickle power over a long period of time.
This is different from a cranking battery. These batteries work best when they provide short bursts of strong power. While you can use them from trolling, it is not where they function best.
These batteries are relatively cheap and last about a year or two. They can withstand frequent use that involves draining and recharging.
You will have to perform maintenance on these batteries. You will need to top off the water in the battery.
These batteries also come with the risk of vibration and spilling. These are two things that you don't want to deal with while on a rocking boat.
The reason for maintenance and risk of spillage comes from the design of the battery. There is a mixture of battery acid and water that stores the energy in chemical form.
During operation, the battery uses the water. As the water gets used, the total liquid level drops.
You need to add water to replace what was lost. This keeps the plates in the battery fully bathed in liquid.
Absorbed Glass Mat (AGM) batteries have a longer lifespan because they are sealed. You can expect to get 3 to 4 years of life out of your AGM battery.
With the double lifespan comes double the price. Spending the extra money can be worth it though because they required no maintenance.
These completely sealed batteries have a glass plate and gel in them. This design allows them to be smaller than the wet-cell equivalent.
These batteries also hold their charge longer when they are not getting used. This is a slow self-discharge rate.
For the battery with the longest lifespan, you will want to choose a lithium-ion battery. They can last for around 10 years with proper storage.
You can find deep cycling trolling batteries in 12V, 24V, and 36V. These batteries are up to 70% lighter than the other two options.
You can install lithium batteries with ease thanks to a plug and play system. This lets them get connected to each other in a parallel or series pattern.
Most come with built-in protection. This prevents a battery accident while out on the water.
Lithium batteries use a Depth of Discharge (DOD) technology. DOD means that as the battery works it uses the full capacity of the battery. This maximizes the battery's power potential.
Most modern batteries weigh between 20 and 50 pounds. If you are putting this battery on a kayak or small Jon boat, the weight may be a concern for you.
Lithium batteries are going to be the best trolling motor batteries for this. They weight the least and have no risk of spillage.
Amperage of Trolling Motor Batteries
The amperage (Ah) lets you know how long the battery lasts while it uses a certain number of amps. A rule of thumb is to buy the highest amperage you can afford and works in your boat.
You'll want to make sure you can run your motor as long as you can. There is an easy way to calculate the amps when shopping.
Let's assume you have a battery that has an amperage rating of 100Ah. Now you run your trolling motor at a rate of 4amps.
You can expect the battery to last about 25 hours. If your motor pulls 40 amps, you can expect the battery to last 2.5 hours.
100/ 4= 25
Comparing Your Options
Many boaters go with what is familiar and cheap with the wet-cell battery. This may not be the best choice for your needs.
You may spend less money on the wet-cell, but you will pay more in time and effort later on. Your time is valuable, don't spend it checking water levels, refilling the water, cleaning up spills, and replacing the battery.
With the AGM battery, you will spend a bit more, but not have to worry about a replacement as often. You are still replacing your battery every few years though.
Don't let the price of the lithium sway you away from them. You have enough things to think about and worry about with a boat.
If you choose a battery that lasts ten years, that's one less thing to worry about. You gain that time and energy back so you spend more time out there trolling.
No matter what type of battery you choose, you need to take care of it for it to last the full cycle of life. The first thing you should do is charge them.
Don't Wait to Charge
When you get back from using your boat, put the batteries on charge. Leaving them in a state of discharge will shorten the life.
Keep it Cool
Store your batteries in a cool dry place when you are not using them. Keeping the battery cool will help preserve its life.
If you aren't going to use the battery for a long time, but a trickle charger on it. This slow and steady charge is better for your battery than a fast hard charge.
Replace Your Trolling Motor Battery
The first thing you need to look for is a deep cycle battery. These batteries will last with the long-term use of a trolling motor battery.
Wet-cell batteries are the traditional option. They are cheap, but this comes at a price of maintenance and short lifespan.
AGM batteries are a bit more expensive, but last about twice as long. They also don't need maintenance.
The longest lasting and most efficient option is the lithium-ion batteries. They may seem more expensive, but in reality, they are not.
You will make a larger initial investment, but they last for ten years. That is ten years of no maintenance or replacement tasks.
Start shopping for your next trolling motor today.