Top 5 reasons why Lithium Iron Phosphate (LiFePo4) is the best battery for your electric boat
Choosing the right electric boat battery is crucial as it is a costly and critical component that will impact your boat's performance. However, it can be an overwhelming decision since electric boats on the market employ a wide variety of rechargeable batteries. In this article we cover the different types of batteries which are available, and explain why Lithium Iron Phosphate (LiFePO4) batteries are the recommended choice for electric boats.
Types of rechargeable batteries for electric boats:
There are three main types of rechargeable batteries which can be used in electric boats:
Lead-acid batteries
The most common types of Lead-acid battery are Flooded lead-acid (FLA), Absorbent Glass Mat (AGM) batteries Gel batteries, and Valve-regulated lead-acid (VRLA) batteries.
Nickel-based batteries
Nickel-cadmium (Ni-Cd) and Nickel-metal hydride (NiMH) are the most common types of Nickel-based batteries.
Lithium-ion batteries
Lithium-ion batteries are a battery technology that uses Lithium-ion as the critical element of their electrochemistry. They are the most popular rechargeable battery in the world today, used in many applications from laptops, mobile phones, EVs, and small watercraft.
There are many types of Lithium ion batteries but the most common are Lithium Nickel Manganese Cobalt Oxide (NMC), Lithium Cobalt Oxide (LCO), Lithium Manganese Oxide (LMO), Lithium Nickel Cobalt Aluminum Oxide (NCA), and Lithium Iron Phosphate (LiFePO4).
48 V Lithium ion battery
The voltage of an electric boat’s system, measured by the unit V (Volts), is a critical component of any electric boat because it directly affects the power available for the propulsion. A system’s voltage should strike a balance between power and safety as a voltage that is too high can be unsafe, while a voltage that is too low can result in impractical acceleration and speed. For 3-5m tenders and RIBS, a 48 V Lithium Iron Phosphate battery strikes this balance perfectly (assuming the manufacturer has maximised the system’s potential). ZeroJet, for instance, has developed a revolutionary 48 V system that delivers significant power despite the relatively safe voltage level.
What is a LifePO4 battery?
A LiFePO4 battery (also known as an LFP battery) is a type of Lithium ion battery with its own unique chemistry- the materials involved in the chemical reaction that produces the electric charge. These use different cathode materials from other lithium-based compounds, nickel or lead:
Solid but thin and porous electrodes and non-aqueous electrolytes with a higher packing density of active materials, unlike lead-acid and nickel-based batteries which use thicker electrode plates made of lead or nickel-based alloys and have a lower surface area per unit volume of active material.
Graphite and carbon as the anode material, instead of nickel and lead.
An inorganic, non-flammable electrolyte instead of a flammable, organic electrolyte.
This unique chemistry leads to a battery with a lower operating voltage, a stable and flat voltage profile and one with very low internal resistance. LiFePO4’s combination of Lithium ion battery technology and Lithium-iron phosphate chemistry makes them significantly lower maintenance, very energy dense, fast to charge, long lasting and safer than all other batteries on the market—overall the superior battery solution for a small electric boat.
Why choose LiFePO4 batteries for electric boats?
1. LiFePO4 batteries can store more power in less weight and they can release it quickly
Higher discharge rate than other Lithium-ion batteries
LiFePO4 batteries are capable of delivering a higher power output than other Li-ion batteries because they have a higher discharge rate- the rate at which a battery can release its stored energy when in use. Plus, they are able to do this consistently over their lifetime without experiencing voltage drops or reduced power output. This means your electric boat will deliver energy quickly and efficiently, helping you to achieve higher speeds and faster acceleration.
Higher energy density than Nickel and Lead-based batteries
As a type of Lithium-ion battery, LiFePO4 batteries can pack the same power in half the weight of Nickel-based and Lead-acid batteries because they have a high energy density - the amount of energy that can be stored in a battery per unit of volume or mass. This makes them ideal for small watercraft where low weight is crucial for achieving fast acceleration, high speeds, and getting up onto the plane easily. The compactness of LiFePO4 batteries also provides more on-board space compared to other batteries. For example, the use of LiFePO4 batteries in the ZeroJet-powered OC 350 has enabled it to boast a superior speed-to-weight ratio and weigh just 130kg yet seat up to 6 people.
2. LiFePO4 batteries are the longest lasting batteries on the market
LiFePO4 batteries have a very long cycle life - the amount of times the battery can be charged and discharged before its performance starts to degrade. In fact, they can be charged around 3,000-5,000 cycles at 80% Depth of Charge (meaning you can recharge this many cycles as long as you charge before battery energy goes lower than 20% total energy). While other lithium ion batteries, nickel-based batteries and lead-acid batteries typically last just 500-1000 cycles. So, if you choose LiFePO4 batteries, you’ll get up to three times as much use out of your electric boat battery before you have to face the expense and down-time of replacing them.
3. LiFePO4 batteries are more environmentally friendly than other battery types
LiFePO4 batteries are better for the environment than nickel and lead based batteries. This is because Lithium ion batteries do not contain hazardous materials such as cobalt and nickel. As explained throughout this article, they also last longer, are lower maintenance and deliver a greater range and runtime, meaning less replacements, waste and electricity used over time.
Questions have been raised about whether electric boating really is better for the environment since the mining and extracting of Lithium ion batteries indeed produces emissions. Calculations however show that electric boats are indeed better for the environment, even when taking into account the emissions produced during the production of the batteries. Please see our article ‘Electric boat or combustion motor-which to choose?’ for more details on this.
4. LiFePO4 batteries are safer
LiFePO4 batteries are incombustible as they have a very low risk of thermal runaway- a phenomenon that occurs in batteries when the temperature rises to a certain point, causing a chain reaction that can lead to fire or explosion. They also do not contain any flammable electrolytes, instead using a non-flammable, non-toxic electrolyte that is much less likely to ignite under extreme conditions even if damaged or punctured. So you can be confident your friends, family and mothership are protected when using your electric boat and storing it on your home on the water.
5. LiFePO4 batteries are lower maintenance and more resilient
LiFePO4 batteries require significantly less maintenance than all other batteries on the market which means less time spent up-keeping the boat and more time enjoying it! This is of particular benefit to those boat buyers who value time and convenience. There are five main reasons for this:
Lowest self-discharge rate of all battery types
LiFePO4 batteries can sit empty for longer periods of time without experiencing irreversible damage such as losing their charge or affecting their lifespan, unlike other battery types which can lose charge more quickly and which require more frequent charging to maintain performance (capacity and voltage). This is because LiFePO4 batteries have a low self-discharge rate - the percentage rate at which a battery loses its charge when it is not being used or recharged. This means you can leave them stored for longer periods of time before needing to charge just to keep them properly maintained.
It’s worth noting that different brands of LiFePO4 batteries have a higher self-discharge rate than others. For example, Super B LiFePO4 batteries are designed to have an extremely low self-discharge rate of less than 3% per month.
The self-discharge rate of a battery can also be affected by other factors, such as temperature and storage conditions, so it is important to follow the manufacturer's guidelines for storing and using LiFePO4 batteries to ensure optimal performance and longevity.
No Memory Effect unlike Nickel and Lead-based batteries
LiFePO4 batteries will not lose their ability to hold a full charge over time regardless of when they are recharged in their discharge cycle or how frequently they’re charged. This is because they do not suffer from a memory effect where the battery develops a "memory" of its previous charge cycles and limits the amount of charge it can accept, unlike other batteries such as Nickel-Cadmium which require periodic deep cycling to maintain their overall capacity and lifespan.
Highest tolerance for deep discharge of all battery types
LiFePO4 batteries can handle deep discharges on a regular basis without suffering a drop in voltage, degradation of the battery or irreversible damage. This is because LiFePO4 batteries have a high tolerance for a deep discharge- when a battery’s charge is below 30% of total charge.
To maximize the performance and lifespan of a battery, it's generally recommended to avoid deep discharges whenever possible and to recharge the battery before it reaches a low level of charge. For example, for optimal results, ZeroJet recommends recharging batteries used for their electric jet system before they reach a 20% discharge level.
Higher Charge Acceptance than other Li-ion batteries
LiFePO4 batteries can accept higher charging currents, meaning they can be charged faster than comparative batteries without overheating and without experiencing significant voltage drop. This is because they lose a much lower percentage of total energy input as heat during the charging process. In fact, their charging efficiency is 96-99%. On a related note, LiFePO4 batteries can also be charged to a higher voltage than all other battery types, meaning if you accidentally overcharge them, they are far less likely to experience damage.
Highest tolerance to temperature of all battery types
LiFePO4 batteries can operate at a much higher tolerance to extreme temperatures than all other battery types—meaning they can operate in a wide range of environments without risk of safety hazard or performance decline so you have more flexibility to take your boat out in certain locations or under certain weather locations.
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