Selecting a Battery for your Trolling Motor
When it comes to selecting trolling motor batteries, there are a few things you will want to consider: Battery type, battery amperage hour rating and budget.
There are two specific types of deep-cycle 12-volt batteries recommended for use with trolling motors: Lead Acid Wet-Cell & AGM Batteries. Deep-cycle batteries are designed for discharging smaller amounts of current over a longer period of time and for more frequent recharging.
Lead Acid Wet-Cell – These batteries are very common, handle the frequent draining and re-charging associated with trolling motor use, and are the most affordable option. They will last between one and two and a half years, can be purchased for less than $100 and are pretty standard. The downside to these batteries is that they can require occasional maintenance – topping off the water – and they are also prone to vibration and spillage.
AGM Batteries – The other option are AGM Batteries, which stands for Absorbed Glass Mat. AGM Batteries are completely sealed, generally last longer on a charge and have a longer life-span. While a traditional deep cycle battery might last approximately two years, an AGM deep cycle battery will usually last between three to four years. AGM’s cost significantly more than standard deep cycle batteries – usually twice as much – and may not be an option for those on a tight budget. While more expensive, they are the best choice for longevity and performance out on the water. They also have the added benefit of being 100% maintenance free.
Amperage Hour Rating
You can think of a battery's amperage hour rating as being similar to the gas tank of a car. Everything else equal, a battery with a 115 amp hour rating will last longer than a 100 amp hour rated battery. In more technical terms, a 100 amp hour rated battery can deliver 100 amp hours of current to a trolling motor. So if a motor was running at low speed and pulling 4 amps, the battery should last around 25 hours. (100 amp hour rating / 4 amps = 25 hours). Similarly, if the motor was running at top speed and pulling 40 amps, the battery would last for 2.5 hours (100 amp hour rating / 40 amps = 2.5 hours). For more information on understanding battery run times, please see our guide on understanding trolling motor run time.
For trolling motors use, we recommend a battery with AT LEAST a 100 amperage hour rating or a Group 27 rating. Due to shipping restrictions, we currently do not sell marine batteries at TrollingMotors.net. However, both types listed above should be widely available in most areas.
• Never mix battery types, nor old batteries with new batteries.
• Charge batteries as soon as possible after each use – leaving batteries in a discharged state will decrease their longevity and performance.
• Periodically check wet-cell battery fluid levels and top-off as needed
• Check terminal connectors periodically for signs of corrosion – clean with a paste of baking soda and water.
• Store batteries in a cool, dry place in the off-season and maintain a trickle charge.