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Boat battery types are created to serve different purposes. If you’re a new boat owner or don’t know much about batteries, you could easily invest significant money in the wrong battery that can’t meet your needs.
Understanding the types of marine batteries, based on their chemistry, and the factors to look for when choosing a boat battery will ensure you make an informed decision that allows your boat to operate effectively.
What Are the Different Marine Battery Types by Chemistry?
You can use a few different battery chemistries to power a boat. The most popular are flooded lead-acid, AGM, and lithium batteries, but lead-carbon batteries are also a potential option. Here’s what you need to know about the differences that set each chemistry apart.
Flooded Lead Acid / Wet Batteries
Wet or flooded lead-acid batteries get their name from the liquid electrolyte in the battery cell. These traditional marine batteries combine distilled water, sulfuric acid, and lead plates to power a boat. These models are quite large and heavy, weighing around 80 pounds each.
Such mass is not ideal for a boat, and since more than one of these batteries is often needed, it can quickly add up to an equivalent body weight of 2-3 extra people onboard.
Combined with the fact that wet batteries can take the longest to charge of all options on the market, it can make you wonder why boaters choose flooded lead-acid batteries for marine power.
These batteries became popular because of their low initial cost. Still, when boat owners began understanding the hidden costs of constant replacement and additional weight, they sought better options, like AGM or lithium marine battery cells.
AGM (Absorbed Glass Mat) Batteries
Sealed lead-acid batteries, also known as gel or absorbed glass mat (AGM) batteries, provide additional durability at an extra cost. Sealed cell types remove the need for additional maintenance and protect the plates and electrolyte mixture, creating a leak-proof option and a much longer lifespan (2-3x) than wet lead-acid models.
AGM batteries are more expensive than flooded batteries, but they also charge up to five times faster, weigh less, and can better withstand vibrations and extreme temperatures, making them an option well-suited for boating applications.
Lithium Batteries
Lithium batteries refer to a wide range of chemistries, but here, we’re referring to LiFePO4 (lithium iron phosphate) cells. LiFePO4 batteries have gained massive popularity recently, finding well-suited applications in portable power stations like the EcoFlow DELTA Pro 3 PPS, electric vehicles, and boats.
This cell chemistry can withstand far more cycles than most other deep-cycle options (4-5x the amount), discharge to a much lower state, and maintain a reasonable charge level for an entire year. It can discharge a whopping 70-80% of its rated capacity, whereas lead-acid batteries only allow around 30% of their capacity.
With this chemistry, keep in mind the risks of fluctuating voltage. While lead-acid batteries can be charged directly from an alternator using the EcoFlow DELTA 2 Max + 800W Alternator Charger, lithium batteries cannot because voltage spikes can become incredibly damaging.
To avoid unnecessary damage to these cells, you’ll need a dedicated charger with a built-in battery management system, such as the EcoFlow DELTA 3 Plus or the EcoFlow DELTA Pro 3 Solar Generator (PV400W), which can power boats or houseboats.
That being said, they’re still arguably the best option available today. They’re portable, lightweight, quick to recharge, secure, leakproof, maintenance-free, and durable. And, if you choose a solar generator instead of just a battery, you can recharge as needed while you’re still fishing. They’ll give you more time to spend on boating and fishing, not managing your battery.
These cells do a great job of combining the benefits of different battery types and minimizing many of the downsides.
Lead Carbon Batteries
Lead carbon batteries aren’t widely used for boats, but they can work quite well. Some boaters choose this type for their minimal maintenance, extended lifecycle (3000+ cycles), affordability, depth of discharge, and durability for year-round usage.
Lead carbon batteries use an advanced VRLA (valve-regulated lead acid) cell, using a positive anode plate made of lead and a negative cathode plate made of composite carbon. As a result, you get less sulfation, less corrosion on the positive plate, and an overall improved cycle life.
They’re still quite large and heavy, though, so they may be best suited for boats of significant stature.
What To Consider When Choosing a Battery for Your Boat
Your boat battery choice can distinguish between a long, fun-filled day on the water, an unexpected return to shore, or even an emergency rescue. Here’s what to evaluate as you select the correct battery for your boat.
Battery Chemistry
Lithium-ion batteries, such as LiFePO4 cells, are an excellent boating option. They provide superior performance at a lighter weight, smaller size, and longer lifespan than traditional lead-acid types. LiFePO4 batteries are well-suited for marine use due to their safety features and durability, even in harsh weather conditions such as wind, rain, heat, or cold.
Battery Size
Your battery size is also essential, as an insignificant capacity could render your boat unstartable. Calculate your boat’s total energy needs, adding up the capacity for the boat battery plus all electronics and their usage hours. Don’t forget essential systems like navigation equipment. Ensure your chosen battery provides 20% more capacity than your total energy requirement as a safe buffer for future expansion or surge power.
Durability
Durability is vital for a marine battery, as it will experience constant temperature fluctuations, vibrations, and potential exposure to water. Look for a battery with robust casings, sealed construction, and marine-grade terminals. Additional premium options, such as reinforced internal components for rough water conditions, may also benefit you.
Battery Type – Starting, Deep Cycle, or Dual Purpose
Starting batteries deliver short-lived, high-cranking power to turn on the engine, but they’re not made for sustained use. On the other hand, deep-cycle batteries provide long-term steady power for trolling motors and other electronics. A dual-purpose battery like a LiFePO4 battery or solar generator for boats can meet all your needs, including strong starts and extended use.
Frequently Asked Questions
LiFePO4 batteries are an excellent option for marine use. They combine some of the best features of wet lead-acid and sealed lead-acid battery cells. They’re durable and lightweight, provide a high depth of discharge, require minimal maintenance, and can power other items like electronics or GPS systems.
A lithium battery is better than an AGM cell for a boat because it provides superior power output, lighter weight, longer lifespan, and consistent voltage. AGM cells would only be a better choice if you only use your boat occasionally, as they’re initially cheaper and hold a charge better over time.
A deep-cycle battery powers systems like radios, GPS navigators, trolling motors, and more on a boat. It ensures boaters can enjoy their days on the water without interruptions or concerns about power.
Final Thoughts
While there are several marine battery types to choose from, the best option in today’s market is lithium-ion chemistry, especially LiFepO4. Not only are they durable, lightweight, and long-lasting, but they also give you peace of mind in safety and longevity.
Many devices rely on these modern batteries, and when your boat battery needs recharging, you can use another LFP-powered solution, such as the EcoFlow DELTA Pro 3 Portable Power Station.
Happy boating!