For many of us, there’s nothing worse than a battery running out of juice while on the water. Fortunately, planning is easier when you know how long your batteries last.
Typically, trolling motor batteries have a general lifespan of 2 to 3 years – with some types lasting up to 5 years of usage. For the runtime, a 24-volt. You can look up the motor battery type and specifications for a better lifespan and runtime estimate.
I’ll go into more detail below.
The Lifespan of Trolling Motor Batteries
The lifespan of trolling motor batteries depends on their type, but all batteries generally last for a couple of years.
Four types of trolling motors batteries exist, each with a life expectancy.
| Battery Type | Expected Lifespan |
|---|---|
| Absorbed Glass Mat (AGM) Batteries | 3 to 5 years |
| Lead Acid Batteries | Up to 5 years |
| Gel Cell Batteries | 2 to 3 years |
| Lithium Batteries | 5 to 10 years |
While battery type has a major impact on the lifespan, other crucial factors determine the actual lifespan of your batteries.
Bigger battery sizes typically have longer lifespans than smaller ones.
A good rule of thumb is the larger the battery, the more it can withstand wear and tear. Trolling motors typically come in 24-volt and 12-volt types; you can expect the former to have a longer lifespan since they’re more equipped to handle a trolling motor’s heavy power demands.
Charging and discharging rates are another major contributor to your battery’s lifespan.
Batteries, especially Lithium ones, slowly degrade their power cells if they’ve been discharging for a long time. Discharging doesn’t have to mean using the batteries. It can also store them for extended periods without charging – a common occurrence during colder seasons. It’s better to charge your batteries after every use or, if they’re in storage, charge them once a month.
Other factors that contribute to the expected lifespan of your batteries are usage frequency, motor power, and storage conditions. These factors are relatively minor compared to the ones mentioned before. Still, these can prolong or hasten the lifespan by several months or even a year.
Average Runtime of Trolling Motor Batteries
A 24-volt trolling motor battery has an average runtime of five to seven hours on a single charge.
Other factors like sea conditions, boat size, and maintenance frequency play an important part in the runtime of your batteries. At best, the batteries can even last for about half a day. Still, we understand the importance of an accurate runtime over an “at best” estimate for boat expeditions – especially if you’re embarking on a lengthy route.
You can calculate better estimates for the runtime by looking at the battery and motor specifications.
Calculating the Runtime of Your Trolling Motor
You’ll need to know two things to calculate the runtime of your motor batteries: the amperage hour rating and the motor amperage draw.
The amperage hour rating indicates how long the battery can consistently supply power. A larger rating means a larger battery capacity and the longer your motor will run. This value is usually found on the manufacturing details sticker, which has other information like wattage and voltage on the battery’s side.
The motor amperage draw indicates how much power the motor needs to run at a certain speed.
Many boat owners struggle to look for this value, but if you have the owner’s manual, you only need to look for the motor’s specifications. If you lost the manual or bought a second-hand motor, you could try to contact the manufacturer or look at online sources for the specifications.
Calculating the runtime of your motor is a simple process of dividing the amperage rating by the amperage draw:
Amperage Hour Rating / Motor Amperage Draw = Runtime in Hours
If you can’t find the exact motor amperage draw, you can use these average amps drawn stats to get a good estimate for the runtime:
- 30 lbs. Motor Thrust: 30 amps at max speed, 15 amps at medium speed, and five amps then slow speed.
- 40 to 70 lbs. Motor Thrust: 40 amps at max speed, 20 amps at medium speed, and then slow speed.
- 80 to 100 lbs. Motor Thrust: 50 amps at max speed, 25 amps at medium speed, and then slow speed.
You can use the motor’s amperage draw at maximum speed to get the shortest runtime of the battery.
This can be the baseline for motor runtime when planning your expeditions. For example, if you know the motor will stop running after 4 hours at top speed, you can shorten the length of your trip or adjust the speed of the motor to keep it from dying mid-trip.
Extending Your Battery’s Lifespan
Trolling motor batteries generally last a few years, but you can make them last longer with proper care and maintenance.
Keep the Batteries Safe and Dry
While marine batteries can handle a few water drops, keeping them somewhere dry is still better.
Water, especially saltwater, causes corrosion on the battery. In particular, the battery terminals are extremely susceptible to rust and corrosion. This causes the battery to malfunction and eventually become unusable.
Maintain your batteries by wiping and drying them when exposed to water. For saltwater, wipe them with a moist cloth before drying them.
Avoid fully Depleting the Battery
You are running out of power while on the water is not only a hassle but also a bad thing for your battery’s lifespan.
Regularly depleting your battery causes it to degrade faster. Avoid this as much as possible by charging them after every use or, at the very least, charging before they are completely dry.
Be Mindful During Off-Seasons
While many mariners are accustomed to storing their motor batteries during colder seasons, this wears them out quicker.
If you can, invest in a trickle charger for your batteries during the off-season. This sends small amounts of current through the batteries.
This supplies a constant amount of current through the batteries to keep the cells fresh – moreover, the current amount is small enough to keep it from overheating and overcharging while in storage. A cheaper alternative is to recharge the battery every month.
Doing either of the options above will keep the battery fresh in storage and extend its lifespan.
Maximizing Your Battery’s Runtime
Proper battery care and maintenance is the best way to maximize its runtime. So, what exactly should you do to take care of a battery?
Perform Regular Battery Maintenance
Regularly wipe down and clean debris build-up off the battery.
Debris on the battery terminals can cause accidental discharge and interrupt the charging cycle. Clean the top of your batteries with a damp rag at least once a week – do this more frequently if you’re heavily using the batteries.
Let the Battery Rest After Charging
Allow your batteries to cool off after recharging before using them.
Batteries heat up when recharging due to their internal components and chemicals. Letting them cool off before using them again is key to lessening stress on the battery’s cells. This keeps the battery from wearing out too quickly.
References
Different Types of Boat Engines & How They Work – Universal Technical Institute. https://www.uti.edu/blog/marine/boat-engine-types
What Is Battery Terminal Corrosion – Universal Technical Institute. https://www.uti.edu/blog/automotive/battery-terminal-corrosion
Video References
Fishing Expert
FishFindly
Foothills Marine