Once restricted to larger vessels, fishfinders and trolling motors are no longer unusual to find on well-equipped kayaks. Of course, these accessories need power to function, and finding the right battery is not as easy as it might sound.
For kayakers, weight and size matter as much as battery life, and unlike bass boats, we just can’t afford 150 pounds of batteries! And that means we ask a lot from a single 12v unit, making the choice of a power source pretty complicated.
To help, we’re offering a buying guide that covers the basics you need to know, along with the following reviews to help narrow your search.
Best Battery For Fish Finders
Best Battery For Kayak Trolling Motors
Interstate Batteries Sealed Lead Acid (AGM) Deep Cycle Battery - DCM0035 replacement battery - Editors Choice
Battery School: What You Need to Know when Choosing a Kayak Battery
When most people think about batteries, they either imagine a typical car battery or the Duracells that you buy at the checkout in a grocery store. There’s a lot more to it than that, and though you don’t care about the chemistry that makes them work, you do care about the important differences.
- Deep cycle - Deep cycle batteries use solid plates to create the chemical reaction that allows them to store and discharge power. This makes them very heavy for their size, but gives them one incredible advantage. Unlike conventional batteries, they can be discharged down to 20 percent of their capacity again and again, without suffering damage.
- Starter batteries - Starter batteries use lighter, spongy plates. While still heavy--go lift your car battery and see!--they’re lighter than deep cycle batteries. But instead of deep discharge cycles, they’re designed to provide a sudden, powerful burst of electricity to start a motor. These are exactly what you don’t need, so be careful!
- Dual use batteries - Dual use batteries are the sweet spot between these two types. You’ll find them on larger boats where they can start the engine and run electronics.
- Marine batteries - Sometimes used as a synonym for ‘deep cycle,’ marine batteries can consist of any of the other types, depending on their purpose.
- External battery packs - These are the small batteries you can use as backups for laptops and other devices. Essentially the same type of battery you have in your smartphone, they can run small devices for quite some time. They’re rechargeable hundreds of times, and if equipped with a 12v output, can be an awesome option for the kayak angler who only runs a fish finder.
SLA/VRLA/AGM vs Lithium-Ion vs Lithium polymer
There are two basic battery types for trolling motors, each with advantages and disadvantages. But if you’re running only a fishfinder--no trolling motor--you’ve got a third, awesome choice for your ‘yak.
- Sealed Lead-Acid (SLA), Valve-Regulated Lead-Acid (VRLA), and Absorbed Glass Mat (AGM) - Essentially three terms for the same chemical system, SLA/VRLA batteries use lead plates and jellied acid as their basic components. AGM batteries add one additional chemical trick. The result of this tech is that they’re all heavy, big, and safe--and they don’t require the maintenance of traditional wet cell batteries. On big boats, that weight and size may not matter; on a kayak, they most certainly will.
- Lithium-Ion (Li-ion) - These batteries use some pretty complex chemistry to charge and deliver power. The result is that they’re easily rechargeable and generally smaller and lighter than the SLA or AGM batteries of the same power. They’re simply better battery tech. The downside? They can be insanely expensive, and 12v systems designed for marine use can be as much as $1,000! But they can also be found in the form of tiny external power packs, like their polymer cousins.
- Lithium Polymer (LiPo) - Basically a twist on a lithium-ion battery, these tiny powerpacks are usually used to augment the batteries on a laptop. But if they offer a DC 12v output, they can power your fishfinder with ease. Cheap, small, and light, if you’re not running a trolling motor, these battery packs are the way to go!
Weight and Size
Powerboats don’t face these problems, and it’s not unusual to see them sporting three 12v batteries to start their outboard, run their fishfinder, and power their trolling motor. But keep in mind that a typical SLA battery can weigh between 50 and 75 pounds--you can see the problem for your kayak immediately!
If you need to run a conventional battery, look carefully at your kayak’s maximum capacity, the space you’ve got, and assess what the added weight will do to the trim of your ‘yak when everything’s in place.
That’s why we so strongly recommend using an external power pack if you’re not running a trolling motor. They can be as small as three or four smartphones stacked on top of one another, and just as light. On a kayak with limited space and capacity, that’s a deal-making advantage.
Power and Battery Life
This is where things can get tricky. Battery power over time is reckoned in amp-hours (and milliamp-hours on smaller batteries). You’ll see the abbreviations Ah and mAh in battery descriptions, and you need to pay close attention to these. You’ll also need to look at how many Watts or milliamps (mA) your accessories draw. With those numbers, you can get a sense of theoretical battery life.
To help you out, there are online calculators like this one. It’s pretty simple math--once you figure out the conversions!
Of course, my conclusions in the reviews aren’t real-world numbers, and actual run-times will vary. And obviously, continuous use drains batteries faster than intermittent consumption. But to offer you an apples-to-apples comparison, I’ll use our top pick fish finder and trolling motor as standards, giving you a rough sense of how each battery compares to its competitors.
Recharging, Storing, and Service Life
Whatever choice you make, you need to treat your battery right if you want it to work well and last.
- Temperature - No battery likes to be hot or cold, and temperature extremes affect performance and storage life. You probably already know this if you’ve tried to start your car when it was really freezing outside, but be aware that extreme heat is a problem, too.
- Storage - When you’re not using your battery, you need to keep it cool and dry. You’ll also want it to be charged rather than depleted when you store it, so before you put it away, be sure to top it off.
- Recharging - Unless you choose a battery pack which plugs into a standard outlet, you’ll need to invest in a battery charger. Slow charging is always better than fast, and it’s important to ensure that you never overcharge your battery. Most batteries can be recharged overnight, and smaller batteries may recharge in a few hours.
- Service life - Most deep cycle batteries can be discharged and recharged hundreds of times. Expensive lithium batteries offer thousands of cycles, eventually breaking even with cheaper SLA and AGM alternatives--if you take care of them. Try to avoid completely draining your battery; it’s best to stay above 50 percent charge if you want to get the longest service life from it.
Reviews of the Best Kayak Batteries
For each battery, we’ll be commenting on theoretical battery life with these accessories:
TalentCell’s ‘large’ battery pack offers an impressive 8300 mAh in a small, dense package. While nearly as tiny as the Rexuav, this lithium-ion battery is about three times heavier, weighing in at just over a pound. That’s still nothing in real-life applications, and given that it nearly doubles the power of the Rexuav, that’s not a bad trade-off.
Sporting LED lights to keep you in the know about its current charge, this battery has the juice to keep the Helix 5 running for more than nine hours. It’s reasonably priced as well, and if you’re looking for a single lithium battery pack to run your fishfinder all day, this may be the best choice for you.
The downside is that this battery pack may have quality control issues that appear during recharging, including excessive heat. The good news is that users report excellent customer service from TalentCell.
Rexuav’s 4800 mAh 12v battery pack is impressively small and light--you’ll have a hard time finding anything slimmer or trimmer than can run a 12v device. It’s not cheap, though, and it’ll run you nearly what a standard battery might.
It’s also pretty basic, offering just an input, output, and on/off switch. In fact, its very basic appearance has no features to let you know about its current power level. But what it does provide is power for size and weight.
At 4800 mAh, this tiny pack can deliver power to a Helix 5 for 5.5 hours! The downside is that since these aren’t cheap, buying more than one is probably not in the cards if you’re on a budget.
TalentCell’s small external battery pack is in many ways an ideal choice for a kayak angler who doesn’t use a trolling motor. It’s tiny and incredibly light--just 6.53 ounces!--and that combination makes it easy to adapt to life on an angling ‘yak.
It features LED lights to keep you informed about battery life, which is a nice touch and something to consider.
Offering 3000 mAh of electricity as 12v, it can keep the Helix 5 running for roughly 3.5 hours.
And since they’re inexpensive, more than one in a modified clear plastic storage box can give you a full day of juice at a reasonable cost.
Unfortunately, some users complain about these packs failing to charge soon after purchase. That said, customer service from TalentCell is excellent, so this is a risk you may want to take.
Best Batteries for Trolling Motors and FishFinder Combos
Best Batteries for Trolling Motors and FishFinder Combos
Type: Deep Cycle
Weight: 23.1 lbs.
Size: 7.68" x 5.16" x 6.14”
Capacity: 35 Ah
Interstate Batteries’ Deep Cycle model was designed to power wheelchairs, but its light weight and small size have made it a popular choice to run trolling motors and fishfinders on small boats. At just 23.1 pounds, you’ll have a hard time finding anything lighter. It’s pretty small, too, and if you’re handy, you might be able to modify a tough plastic bin instead of opting for a larger battery box. For kayakers, that’s a combination to take seriously.
Offering 35 Ah, it can run the Newport Vessels 55 for roughly half an hour at 100 percent. But customers report four to five hours of battery life when operating similar trolling motors and the Helix 5 simultaneously.
For budget-minded anglers, this is a great choice.
VMAX’s deep cycle AGM battery is built tough to take the abuse of the outdoors, and if you need a battery that can take a beating, this is a good place to start your search.
At 67 pounds, it’s no lightweight, and you’ll need to think carefully about how it’ll affect your ‘yak’s trim. It isn’t small, either, and in a battery box, you can pretty much guarantee that it’s going to end up in the stern well.
The good news? It provides 100 Ah of power, which is enough electricity to run the Newport Vessels 55 for 1.6 hours at 100 percent. If you can keep the throttle at a lower setting, you’ll get even more battery life--something in the order of three to four hours at 50 percent. It won’t even notice the draw of a fishfinder, so no worries there!
These also don’t come cheap, so if you need a budget option, you’ll want to look elsewhere.
Optima Batteries’ Blue Top is well-known in the boating world, and it’s a reliable, dual use battery that you’ll find on plenty of bass boats. For kayakers, its ability to double as a starting motor doesn’t come into play, but its light weight does.
At just 43.5 pounds, this is a trim choice, offering 55 Ah, or about an hour at 100 percent throttle on the Newport Vessels 55. If you’re not running long distances on your ‘yak, or you can take your time in a lower throttle setting, this battery may offer the life you need at a weight you can manage. But be warned, the Blue Top isn’t a budget-friendly option.
Another downside is that some customers report short service life for this battery, though that may be due to improper charging.
If money is no object, Renogy’s lithium marine battery might be the best choice. At just 28.1 pounds, it delivers the same power as the VMAX at roughly one-third of the weight. For kayak anglers, that nothing to sneeze at.
If treated well, this battery can provide an incredible 7,000 recharge cycles, far more than any conventional deep cycle competitor.
Like the VMAX, you can expect about 1.6 hours at 100 percent throttle running a Newport Vessels 55. Expect longer battery life at lower output.
Be warned--this battery is a premium option at a premium price!
Our Pick - The TalentCell Rechargeable 12V/8300mAh DC Output Lithium Ion Battery Pack and the Interstate Batteries Sealed Lead Acid (AGM) Deep Cycle Battery - DCM0035 replacement battery
For kayakers, size and weight are critical considerations, and while all of these batteries can be good choices depending on your needs, these two really stand out to me.
TalentCell’s 8300 mAh battery pack is ideal for anglers who run a fishfinder but still prefer to paddle. Tiny, lightweight, and powerful, it has the juice you need for all-day adventures on the water. With LED lights to keep you aware of its power level, this is a fantastic option since its price, size, weight, and battery life are hard to beat.
But if you run a trolling motor, external battery packs can’t get the job done. Instead, you’ll need to turn to their larger, heavier rivals. And while there are a lot of great options when size and weight don’t matter, on a ‘yak, that’s never the case. This is where the Interstate Batteries Deep Cycle really shines. Lighter and smaller than its competitors, it has the power to keep your motor and fishfinder running, as long as you’re conservative with the throttle. Best yet, it’s budget-friendly, too!
While none of these batteries are a bad choice, I’m confident that these two deliver the best performance in the smallest, lightest package.