When you’re getting a new battery for your ATV, it may not seem like a big deal which one you choose. After all, many of them look almost identical at a glance, right? Unfortunately, you can’t just pick one randomly and expect optimal results. 

ATV batteries are not all the same and differ in battery technology used, rated capacity, physical dimensions, weight, and terminal style. Key properties such as price, maintenance requirements, life expectancy, mounting orientation, and self-discharge rate vary depending on battery type.

Having basic knowledge about what properties and features differentiate the various battery types and designs is crucial. Otherwise, you may well end up with a battery that doesn’t fit properly in the ATV, does not provide adequate performance, or isn’t the best choice for your riding needs.

What Are the Most Common ATV Battery Types?

ATV batteries, just like car batteries, are offered in various battery types, determined by what battery design and electrochemistry are used. 

Some of the battery types commonly used in ATVs include:

  • Conventional Flooded Lead-Acid (FLA)
  • Absorbed Glass Matt (AGM)
  • Gel-Cell (GEL)
  • Lithium-Ion (Li-Ion)

FLA, AGM, and GEL batteries are all based on a lead-acid base design. But only FLA batteries are flooded (or non-sealed), whereas AGM and GEL batteries feature a valve-regulated, sealed construction. AGM and GEL batteries commonly go by the terms Valve Regulated Lead Acid (VLRA) or Sealed Lead-Acid (SLA).

On the other hand, Li-Ion batteries do not use lead but rather lithium in their electrochemical process, enabling a range of unique features for this type of battery.

1. Conventional Flooded Lead-Acid (FLA)

Conventional Flooded lead-acid batteries, also referred to as wet-cell or vented lead-acid batteries, have been around well over 150 years and are widely considered the benchmark in battery design for any vehicle use. 

Their pros and cons are well known, and even tho newer and more modern battery types have become available throughout the years, FLA batteries are still one of the preferred choices for ATVs due to their low purchase price. 

No other battery type is more widely used, and for some ATVs, they might be the only alternative. 

FLA battery benefits

  • The cheapest alternative
  • Can be charged with a basic manual charger 
  • Are not as susceptible to damage from overcharging
  • Reliable in most riding conditions
  • Offers adequate performance and acceptable service life

FLA battery disadvantages

  • Requires maintenance (topping off with water)
  • Poor maintenance will drastically reduce life expectancy and performance
  • Can only be installed in an upright position
  • Not as energy-dense as the alternatives
  • Limited cycling capacity

2. Absorbed Glass Matt (AGM)

AGM batteries are a more modern alternative to conventional FLA batteries. To many ATV owners they offer the ideal balance between performance, durability, maintenance, and price. AGM batteries are commonly used in mid to high-spec ATVs.

The AGM technology was developed to enhance the FLA base design for increased performance, simplified maintenance, and longer service life.  

AGM battery benefits

  • Can be installed in any orientation and any location
  • More energy-dense than an FLA battery
  • Maintenance-free
  • Shock- and vibration resistant
  • Won’t spill
  • Low self-discharge rate
  • Long service life
  • More cost-effective than GEL and Li-Ion

AGM battery disadvantages

  • Cost more than FLA batteries
  • Overcharging may cause irreversible damage
  • Still relatively heavy compared to a Lithium-Ion battery

3. Gel-Cell (GEL)

GEL batteries have similar core attributes to AGM batteries and are often considered the same. But some of the unique features offered by AGM batteries, combined with some of the disadvantages with GEL batteries, make AGM the more popular alternative. AGM outsells GEL by a ratio of about 100 to 1.

GEL battery advantages

  • Can be installed in almost any orientation and any location (upside down not recommended)
  • Lighter and smaller
  • Maintenance-free
  • Won’t spill unless damaged

GEL battery disadvantages

  • Cost more than FLA and AGM batteries
  • Overcharging may cause irreversible damage
  • Shorter service life
  • Less robust internals

4. Lithium-Ion (Li-Ion)

Lithium-Ion batteries, or Li-Ion for short, are not commonly used in stock ATVs due to their high price but are often the preferred upgrade option by riders who do not compromise on performance. 

Lithium-Ion battery advantages

  • Can be installed in any orientation and any location
  • High energy density
  • Small size and lightweight compared to the other types
  • Maintenance-free – no liquid inside
  • Excellent service life
  • Very slow self-discharge rate

Lithium-Ion battery disadvantages

  • The most expensive alternative
  • Require a lithium specific battery charger

Comparing the Most Common ATV Battery Types

Let’s look at what features and properties separate the various types, hopefully without getting too technical. We’ll begin with an overview, for those that don’t care too much about the specifics:

FLA
(Flooded Lead-Acid)
AGM
(Absorbed Glass Mat)
GEL
(Gel Cell)
Li-Ion
(Lithium-Ion)
Price (Cost Per Watt-Hour)$$$$$$$$$$$$$
Maintenance Free (Sealed)NoYesYesYes
Can be installed sidewaysNoYesYesYes
Can be installed upside-downNoYesNoYes
Spill-ProofNoYesYesYes
Energy DensityLowMediumMediumHigh
Life ExpectancyMediumLongMediumVery Long
Self-Discharge Rate4-6%/month 1-2% / month2-3% / month1-2% / month
Deep Discharge ToleranceLowHighHighHigh
Charge / Discharge Acceptance RateSlowFastFastVery Fast
Sensitive to OverchargingNoYesYesYes
RobustnessMediumHighLowExcellent
Extreme Weather ToleranceGoodVery GoodVery GoodGood
WeightHeavyMediumMediumLight
Comparison of key properties in the most common ATV battery types.

Now, let’s dive a bit deeper and look at how and why the various battery types are not all the same.

Wet-Cell vs. Dry-Cell vs. Gel-Cell

While many ATV batteries may look similar on the outside, the internal workings vary considerably, depending on the battery technology used.

FLA batteries are based on what is referred to as wet-cell technology. Lead plates are placed in 6 separate cells and wholly immersed in a liquid electrolyte to aid the electrochemical process. The electrolyte is typically 30-35% sulphuric acid and 70-65% water.

FLA batteries come factory-activated with the electrolyte (battery acid) already injected into the battery or with a separate acid pack with a premeasured amount of battery acid for activating the battery.

Lithium-ion batteries, on the other hand, are so-called dry-cell. As the name implies, a dry-cell battery does not use a liquid electrolyte. 

Instead, they use separator sheets covered with a thin layer of aqueous lithium salt solution sandwiched between sheets of cathode and anode materials. Stacks of sandwiched sheets are then rolled into cylindrical battery cells connected to form a complete battery. 

AGM batteries are also often referred to as dry-cell batteries, but this can be a bit misleading. In reality, they fall somewhere in between wet-cell and dry-cell.

Like FLA batteries, AGM batteries use lead plates with an electrolyte between them. The electrochemical process is essentially the same between the two, but there is one significant difference: The electrolyte in an AGM battery is not liquid; it is wholly absorbed in layers of glass fibers placed between each lead plate. 

The primary purpose behind this design is to immobilize the electrolyte so that less electrolyte is set free. Hydrogen and oxygen created from the charging process get recombined back into water and do not need to vent out of the battery casing.

The term “Dry-cell” is used as an acronym for the wet cell technology used in conventional lead-acid batteries. Still, in reality, the electrolyte inside an AGM battery is just as wet, just that it is fully absorbed in the glass fiber mat. 

GEL batteries are commonly referred to as GEL-cell. The electrochemical process in a GEL battery is also almost identical to FLA. Except the lead plates are built slightly differently, allowing gasses created from the charging proceeds to recombine with the metals. 

The main difference between an FLA and a GEL battery is that the electrolyte of the latter is mixed with fumed silica dust to form an immobile putty-like gel to provide some benefits over a conventional wet-cel battery. 

Vented vs. Valve Regulated Battery Case

FLA batteries are vented: When charging a flooded or wet-cell battery, it develops oxygen and hydrogen gasses inside the battery casing that need to be vented to prevent pressure buildup. 

A vent on top of the battery, typically designed to connect to a vent tube, allows the gasses to escape into the air. 

The gasses created from charging a flooded or wet-cell battery present an explosion hazard. That is why this type of battery needs to be placed in a well-vented area during charging.

AGM, GEL, and Li-Ion batteries are valve-regulated: The casing on these batty types does not have a vent but rather a safety valve to let out any gasses created from accidentally overcharging the battery.

The spill-proof, pressure-regulated valve is sealed under normal running conditions and will only open from excessive internal pressure buildup.

Serviceable vs. Maintenance-Free

FLA batteries are serviceable, meaning you need to monitor the electrolyte level regularly and top off with battery acid or distilled water when required. This only applies to batteries with removable plastic caps on top, one for each cell.  

The two main components of water or H2O are hydrogen and oxygen. When the charging process creates hydrogen and oxygen molecules that get vented out into the air, the water level inside the battery decreases. Overcharging further speeds up the evaporation rate.

The lead plates inside each battery cell need to be covered entirely with battery acid as rapid sulfation occurs if the plates get exposed to air. The electrolyte levels need to maintain within the specified range at all times to prevent sulfation and the associated reduction in battery capacity.

Removing the plastic caps on top of the casing, usually one for each cell allows adding more water to compensate for lost oxygen and hydrogen.

The caps are usually threaded for easy removal by hand, but some require a large screwdriver. If the caps are installed too tight, you may need to use pliers to get them turning. Do not apply excessive force as this may cause the caps or battery casing to crack. 

Some serviceable FLA batteries use multi-cell push caps where each cap typically covers three cells. However, this style of caps is more commonly found in larger car batteries and is not as common in ATV batteries.

AGM, GEL, and Li-Ion are maintenance-free (non-serviceable): Since almost no water is lost during the charging process, AGM and GEL batteries do not require regular topping off with distilled water or battery acid as an FLA battery does.

As long as you use and charge these battery types correctly, monitoring and regulating the electrolyte level is not required. Therefore, there are no openings in the battery casing. This is why sealed batteries are referred to as “maintenance-free.” The same applies to Li-Ion batteries which are completely dry.

Caution: NEVER try to pry open a sealed, non-serviceable battery. There is a risk of getting injured in the process, and there is no way of properly sealing it back up again.

PS: While ATV batteries are categorized as either serviceable or maintenance-free, these terms can be misleading. Ordinary maintenance such as making sure the cables are properly connected, the battery poles are free of corrosion, and there isn’t any visible deformation or cracks in the casing still applies regardless. 

Battery Casing Appearance

See-through battery case: The casing in an FLA battery is typically semi-transparent to read the electrolyte level inside each cell without opening the battery caps. Markings on the case indicate a minimum and maximum level of battery acid.

Non-see-through battery case: The casings on AGM, GEL, and Lithium-Ion batteries are typically single color (typically black or grey), non-see-through with a flush top without any filling ports, caps, or openings. Also, no max/min markings need to be monitored.

Mounting Flexibility and Options

FLA batteries are position sensitive: A non-sealed FLA battery needs to be installed in an upright position to prevent spills and to keep the lead plates inside covered with battery acid at all times. This dramatically limits the mounting options and may lead to installing the battery in a less desirable and more exposed position. 

An FLA battery can handle aggressive riding styles such as jumping, fast cornering, or climbing steep hills well. However, the open serviceable and vented design may cause a leak if permanently installed upside down, in a horizontal position, or even at an angle. The highly corrosive liquid electrolyte could cause damage to the ATV or rider if spilled.

AGM and Lithium-Ion batteries are position insensitive: The sealed, non-vented, non-serviceable dry-cell design allows them to be mounted in any orientation without risk of internal damage or leakage. 

The ability to install the battery at an odd angle offers excellent mounting flexibility. It enables the possibility to install the battery in an ideal location where it’s less exposed to impact damage.

GEL batteries are partially positioned insensitive. They can be mounted upright and on the side, but upside-down installation is not recommended.

Self-Discharge Rate

Any battery will self-discharge over time, meaning it will lose some charge even when not used. This happens regardless of battery type and chemistry. 

The self-discharge rate depends on factors such as storage or operating temperature, state of charge, and battery type.

A low discharge rate is critical in ATV batteries, where the vehicle typically sits for more extended periods without being used.

  • FLA batteries offer a decent self-discharge rate ranging from 4% to 6% or more per month.
  • AGM batteries self-discharge much slower, at a rate of only 1% to 2% a month.
  • Gel batteries self-discharge at a rate of about 2% to 3% per month.
  • Li-Ion batteries will keep their charge for the longes, with only a 1% to 2% self-discharge rate. This number lowers from year to year as technology advances further. 

Related: How to Charge a Dead ATV Battery

Cycle Life

Discharging a battery from 100% down to 0% capacity and charging it back up to 100% is referred to as one battery cycle.

For each battery cycle, the battery loses some of its capacity. A battery’s cycle life is defined as the number of cycles a battery can complete before its capacity drops to 80% of its specified capacity when new. At this point, you’ll begin to notice a visible reduction in performance.

The specified cycle life of the battery will vary between different brands and models, but here are some general guidelines on what to expect: 

  • FLA: 500 to 800 cycles
  • AGM: 1000 to 1500 cycles
  • GEL: 1000 to 2000 cycles
  • Li-Ion: 2000 to 3000 cycles

Note that the specified cycle life of a battery is only theoretical and can only be achieved under ideal conditions.

Factors such as temperature, time, depth of discharge, proper charging, frequency of use, and quality of maintenance can significantly impact the number of cycles a battery can provide before becoming unusable. More on that further down the post.

Deep Discharge Tolerance – Usable Capacity

While one complete charge cycle is counted from 100% – 0% – 100% capacity, not all battery types can be discharged all the way down to 0% without permanently damaging the battery.

  • FLA batteries should never be discharged below 50% capacity.
  • AGM and GEL batteries tolerate being occasionally discharged down to 20% to 30% capacity but should not regularly be discharged below 50% for optimal service life.
  • Li-Ion batties can tolerate a discharge down to 0% to 20% capacity.

This means you can utilize less of the theoretical capacity of an FLA battery, effectively making it much less efficient than the other battery types. Li-Ion batteries are the most effective, with up to 100% efficiency. 

Robustness and Life Expectancy

All ATV battery types feature a robust, durable, non-conductive casing, typically made from ABS or polypropylene (PP) plastic. The case must remain impact- and crack-resistant in arctic-cold to desert-warm temperatures. 

Unless exposed to a fire or a high impact force from a collision, the casing typically outlasts the battery’s life expectancy and should handle regular abuse from jumps and vibration.

However, the battery internals is a different story. Abuse from vibration, impacts, overcharging, deep discharges, and storage at a partial discharge will significantly negatively impact some battery types’ life expectancy and performance. 

FLA batteries do not withstand vibration very well and do not handle deep discharges. However, they are less prone to damage from overcharging. An FLA battery will last for many years if maintained and looked after properly. However, if neglected, it may only last a few months. 

An FLA battery left sitting at a low charge or with electrolyte levels too low for more than a few days will begin to lose its capacity gradually due to internal sulfation. When internal sulfation reaches a certain level, the battery is no longer salvageable and needs to be replaced.

Another common cause of reduced service life in flooded lead-acid batteries is a phenomenon known as stratification. 

Battery fluid, or liquid electrolyte, consists of sulfuric acid and water mixture. Stratification is when the heavier sulfuric acid molecules settle at the bottom of the battery leaving a less acid water mixture at the top.

This imbalance causes premature sulfation at the bottom of the plates, where the concentration of sulfuric acid is the highest, and corrosion at the top, where the water now makes up a more significant proportion of the mixture.

Typical conditions that cause battery stratification:

  • The battery is stored or not used for a more extended period.
  • The battery is regularly left at a state of charge around 80 to 85%.
  • The battery is charged using a constant voltage or a fixed charge algorithm.

The best way to prevent battery stratification is regular and proper charging.

AGM batteries were designed to offer a more robust alternative to FLA batteries. The added glass fibers placed between the lead plates of an AGM battery make it less prone to durability issues or reduced battery life from vibrations and impacts. This feature makes AGM batteries well suited for ATVs that frequently ride in rough terrain. An AGM battery typically lasts about twice as long as an FLA battery. 

GEL batteries use thinner lead plates with tight spacing, making them more applicable to damage from vibration or impacts, thereby reducing life expectancy. The gel is fragile and may burn from a high current draw, such as winching. Also, a GEL battery can easily get ruined from charging at a too high current.

Li-Ion batteries are the most robust ATV battery. They can typically handle very fast charging or discharging and don’t require a full charge before storage or use. Actually, you are better off not fully charging the battery, as high voltage may stress the battery. A Li-Ion typically løasts 4 to 5 times as long as an FLA battery, depending on how it’s used. 

Related: How Long Do ATV Batteries Last in Real-World Conditions?

Charge and Discharge Acceptance Rate

The charge and discharge acceptance rate tell you how fast a battery can be charged or discharged.

Benefits of a fast charge acceptance rate:

  • Reaching a full charge faster lowers the risk of the battery being stored at only a partial charge, negatively impacting performance and service life.
  • Topping off the battery with an external charger when required is faster. 

Benefits of a fast discharge acceptance rate:

  • Allows for high current applications such as using a powerful winch.

FLA batteries offer the slowest charge and discharge acceptance rate due to their thick lead plates and liquid electrolyte.

AGM batteries charge up to 5 times faster than an FLA battery and handle rapid discharges well.

GEL batteries offer a relatively fast charge and discharge acceptance rate but are prone to damage from charging too hard or drawing too high of a current. 

Li-Ion batteries will handle much faster charging or discharging than FLA batteries. The battery’s C-rating determines the charge rate. A battery rated at 1C can be charged from 0% to 100% in one hour. A battery rated at 0.5C can be charged from 0% to 100% in two hours and so on. 

Charging and Overcharging

FLA batteries are somewhat more forgiving for what type of charger you use than a sealed battery, as it’s not as prone to damage from overcharging. 

Overcharging is when you charge a battery for too long or at too high a voltage, causing water in the battery fluid to evaporate. 

When using an intelligent charger, you don’t need to worry about overcharging as the charger will shut off automatically when the battery is full. 

However, a manual charger will continue charging even after the battery is full. This may lead to overcharging if you don’t monitor the charging process or forget to disconnect the charger when the battery is full. 

If you overcharge a sealed battery, there is no way of adding more battery fluid. However, on a serviceable lead-acid battery, you can top off with distilled water through the removable battery caps. Doing so may prevent battery damage or reduced service life, as long as you discover and address the issue before too much time has passed. 

To prevent stratification in a lead-acid battery, you should use an intelligent charger that applies an equalization charge at the end of the charging process. 

As the battery reaches a full charge, the charger increases the voltage to at least 14.4V for a short period. Charging at a slight overcharge promotes the creation of gasses at the bottom of the battery. As the bubbles rise to the top, it mixes or “equalize” the electrolyte back to a consistent mixture.

AGM or GEL batteries require more careful charging as there is no way of adding more electrolytes in case of overcharging or thermal runaway. Make sure to use a smart charger designed and rated for the specific battery type.

Li-Ion batteries should only be charged using a Li-Ion rated smart charger, or the battery can get damaged. As long as you use the correct type of charger set in the right setting, there is little to no risk of overcharging or otherwise damaging the battery. Charging at a higher than the specified voltage may cause the battery to become unstable. 

Battery Capacity 

The capacity of an ATV battery is measured in Ah (amp-hours) and CCA (cold-cranking amps).

The Ah rating tells you how much capacity the battery holds. The CCA rating is an essential factor indicating how much starting power the battery can provide in cold weather. 

You need to make sure the battery you choose offers a high enough capacity to run your ATV, your owner’s manual should provide this information.

Any battery type comes in almost any capacity rating, but some battery types offer a higher capacity per a given weight or volume. This is referred to as the battery’s energy density, where higher is considered better.

Related: What Do ATV Battery Numbers Mean?

Energy Density – Size and Weight

Lead-acid-based batteries (FLA, AGM, and GEL) offer a relatively low energy density of about 30 to 40 Wh/kg. Wet-cell batteries are typically even larger than sealed, dry-cell lead-acid batteries due to the amount of electrolyte required. 

This makes FLA batteries the largest and heaviest battery type on our list relative to the amount of energy they can store. 

Li-Ion batteries offer the highest energy density with 100 to 265 Wh/kg. This means the same size battery can provide a much higher capacity, or you can use a battery with lower weight and much smaller physical dimensions and still receive the same capacity as a lead-acid-based battery. A Li-Ion battery is about 60% lighter than a similar capacity lead-acid battery. 

Price: Cost per Watt-Hour

FLA batteries offer the most basic battery design with a relatively simple manufacturing process, effectively making them the cheapest battery alternative for ATVs. 

They offer the lowest cost per watt-hour and the lowest cost per charge/discharge cycle compared to any other rechargeable battery type.

AGM batteries come with an initial cost of about three times an FLA battery due to higher manufacturing costs. Despite being more energy-dense, they also cost more per watt-hour. 

However, ATV batteries are often subject to poor maintenance or long-term storage. As AGM batteries can better handle this type of abuse, the cost over time from not having to replace the battery so often may prove them the cheaper alternative in the long run. 

GEL batteries are similarly priced or slightly more expensive than AGM batteries. 

Li-Ion batteries are by far the most expensive alternative to purchase. However, a longer service life weighs up for some of the initial cost over the battery life span.

Environmental Impact

FLA and AGM batteries are almost 100% recyclable. They are the commercially available product with the highest recycling rate globally. 

Li-Ion batteries leave the highest environmental impact, with only about 5% current recycling rate.

Extreme Weather Tolerance

FLA batteries can handle most normal operating temperatures but are not as good as the other battery types. Extremely hot operating conditions may cause electrolyte evaporation and thereby reduce service life. Low temperatures, on the other hand, reduce the available capacity.

Charging an FLA battery at high temperatures requires using a lower voltage and a high voltage at low temperatures. 

AGM batteries are designed for harsh climates and operate at optimal capacity at a wide temperature range. They can operate in temperatures down to -20°C.

GEL batteries are designed to withstand extreme weather. The gel electrolyte is less prone to evaporate in high temperatures and less likely to freeze in icy weather.

Li-Ion batteries can handle a wide temperature range from about -40°C to +60°C but suffer from a noticeable performance loss in extremely cold climates. Some Li-Ion brands advertise a minimal loss of capacity, even in sub-zero temperatures. 

Safety 

All battery types are considered safe, but there are some differences between the various types to consider:

  • The liquid and highly corrosive electrolytes in an FLA battery are more likely to spill in the event of an accident.
  • GEL batteries will not leak under normal operating conditions, but the gel may spill if the casing cracks in the event of an accident. 
  • AGM batteries are truly spill-proof and will not leak, even in the event of an accident where the battery casing gets damaged.
  • The safety valve on sealed batteries will emit any excessive gas from the charging process to prevent the battery from cracking. 

Different Battery Terminal Types

Not all ATVs have the same battery terminal design. More than 14 different types are commonly used in ATV and Powersports batteries. 

So make sure the one you choose is compatible with the connectors on your ATV. Also, make sure the “+” and “-” battery terminals are located in the same position as your old battery.

Are ATV batteries standard?

ATV batteries are not standardized. They vary in size, capacity, terminal design, and technology being used.