ATV Battery Size Guide (Physical Dimensions & Capacity)

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Selecting the correct battery for your ATV is essential for proper fitment, performance, and safe operation. Using the wrong size or capacity is asking for trouble.

This guide covers everything you need to know about ATV battery sizing and how to know what size and capacity battery your ATV needs.

How Are ATV Batteries Sized?

ATV batteries are sized by physical dimensions (L x W x H), starting power (CCA), and battery capacity, measured in amp hours (AH).

Physical Dimensions

A battery’s physical size is measured as the Length x Width x Height of the battery casing, not including the battery terminals.

ATV and Powersports batteries are available in many sizes to suit different types of vehicles and engine capacities.

Bigger engines typically need a battery with more starting power, and vehicles with power-hungry accessories like an electric winch need a battery with sufficient capacity not to run out of power too soon.

The size of a battery is often linked to its starting power and overall capacity. Therefore, ATVs with bigger engines and numerous accessories usually require larger batteries than basic models with smaller engines.

Choosing the right size battery is essential to ensure a good fit in the vehicle’s battery compartment.

The clamping mechanism may not keep the battery securely in place if the battery is too small. If the battery bounces around in the battery compartment, it is prone to cracking and other damages, and the connectors may come loose, potentially causing dangerous short circuits.

A battery that is too big may physically not fit on the ATV, depending on the design of the mounting spot.

Battery Capacity (Ah)

A battery’s capacity is how much electric charge it can deliver at its rated voltage and is typically measured in Amp Hours (Ah). Think of it as the battery’s endurance rating.

The battery Ah-rating is calculated by what current the battery can deliver constantly over a specified period (usually 20 hours), multiplied by that period. Because Ah varies with temperature, the test is done at 68 °F (20 °C) for comparable results.

For example, a battery with an 18.9 Ah (20HR) rating can continuously deliver 18.9A/20hr = 0.945A for 20 hours.

Cold Cranking Amps (CCA)

Where the Ah-rating tells you how much current the battery can provide over a long period, the Cold Cranking Amps (CCA) describe its ability to deliver a burst of power over a short time (usually 30 seconds).

When the engine runs, the ATV gets most of its power from the vehicle’s charging system; the battery only works as a buffer when you use more power than the built-in charging system can provide.

But when you start the ATV, all the electricity required to run the electric starter comes from the battery. The starter draws a lot of power from the battery over only a few seconds.

That is why the CCA rating is just as important, if not more, than the Ah rating.

A battery with a higher CCA rating delivers a higher electric current, making it more effective at starting larger engines or engines in cold weather.

There are several standards for measuring CCA, but the one below is the most common.

A battery’s CCA rating describes how much current, measured in Amp (A), a fully charged battery can deliver for 30 seconds with the voltage not dropping below 7.2V at 0°F (-18°C).

What Size Battery Does Your ATV Need?

For an ATV, you need a battery with a case that is the right size for your vehicle, has a Cold Cranking Amps (CCA) rating high enough to power the starter, and an Ampere-hour (Ah) rating sufficient to operate accessories that use a lot of power without quickly draining the battery.

There are several ways to find the right size and capacity battery for your specific make and model ATV.

Use Your Current Battery as a Reference

Checking your existing battery can be a good start. If you’re confident no one ever replaced it, you can buy a similar or compatible battery with the same battery type, physical size, CCA, Ah, and terminal layout.

However, if the battery has been previously replaced, cross-referencing against other sources is recommended.

Let’s say the existing battery was slightly too small. While it might have done a decent job, running the ATV in an underpowered state over time can harm some of its components.

A trained eye can read the size by the battery numbers, but it’s easy to read the number wrong, so that’s not an approach I recommend for most.

Refer to Your Service Manual

If you have the service manual or have access to one, you can use it to look up the stock battery specs and models.

Here is an example of what the specs may look like.

Battery	Model	Ah	CCA
YUASA	YTX20HL	18	310

Check out eManual Online to get factory workshop service and repair manuals for your ATV.

Check What Replacement Battery the Manufacturer Recommends

Some, but certainly not all, ATV manufacturers have an up-to-date online maintenance catalog with recommended spare parts, including batteries.

As you can see, Polaris keeps things simple and uses only two different battery sizes for their ATVs. The compatible ATVs are listed under each battery.

On the other hand, Can-Am seems to have a job to do. Their website contains little information about what battery their ATV models use. The owner’s manual includes information on battery type, voltage, and the required Ah rating but no information about battery model, size, or capacity.

Use an Online Compatibility/Application Guide

Many major ATV battery manufacturers and resellers have online tools designed to provide recommended batteries if you punch in what year, make, and model ATV you have.

The problem with many of them is that they are incomplete, and many recommend batteries that are not a good fit for your bike.

About 90% of stock ATVs come with a battery from the world’s leading manufacturer, Yuasa Batteries, but the battery lookup on their website lacks several newer models.

Yuasa also has a PDF version of the application guide with an overview of what ATVs are listed.

Of all the online battery lookup tools I have tested, the one I have found works the best is the one at battermart.com. Their base contains most models up to the current date and gave a hit on most of the models I searched for.

What stands out to me the most is their provision of the original equipment manufacturer (OEM) battery part number, which is helpful if you prefer to maintain the original factory setup.

Additionally, if you’re open to using non-OEM options, they offer a selection of compatible aftermarket batteries to choose from.

Measure the Battery Compartment Size

Before you order a new battery, I recommend measuring the size of your ATV’s battery compartment.

Note that some batteries are slightly larger than the spec sheet tells you, so leave room for a slight margin of error.

How Many Amps Does an ATV Need?

ATVs typically need 10Ah to 20Ah batteries, depending on equipment level and accessories. An ATV with power steering, heated grips, and an electric winch typically needs a larger AH battery than a base model that only needs to run the ignition and lights.

The battery you choose should not have an Ah rating lower than the manufacturer recommended, but you can use one with a slightly larger capacity if you want to upgrade.

How Many CCAs Does an ATV Need?

Adult-sized ATVs typically need batteries with a CCA rating of 200 to 400. ATVs with larger engines require batteries with a higher CCA rating to power the electric starter.

A modified engine with higher compression or larger displacement will benefit from a battery with even more starting capacity.

Engine Size	Typical CCA Rating
90 to 200 cc	80 to 200 CCA
400 to 600 cc	200 to 340 CCA
850 to 1000 cc	350 to 400 CCA

Typical CCA requirement by ATV engine size.

If the compatibility guide you’re using gives you several choices, choose the one that best fits your performance needs. For most users, the stock CCA rating will work just fine.

If you live in a colder climate, the extra bucks on a higher CCA battery can be well spent, as higher CCA batteries operate better in colder temperatures.

How to Choose the Correct Battery for Your ATV

Knowing what size and capacity battery you need is not enough when replacing the battery; there are several other factors you need to consider. Here is the complete list.

Size: Physical dimensions
Capacity: Amp-hours (Ah)
Starting power: Cold Cranking Amps (CCA)
Nominal voltage: 6V or 12V
Terminal type and polarity.
Battery type (chemistry and cell type)
For conventional batteries: Sensor

We’ve already covered the first three. Now, let us look at the rest.

Nominal Voltage

Most ATV batteries are rated 6V or 12V. An ATV with a 6V electrical system should only use batteries with a nominal voltage of 6V, and an ATV with a 12V electrical system should only use batteries with a rated nominal voltage of 12V.

Please refer to the owner’s manual or ask the dealer if you are unsure what voltage your ATV is operating at.

Battery Type (Cell Type and Chemistry)

Batteries can be divided by cell type and chemistry.

Most ATV batteries are based on lead-acid chemistry and come in three types: flooded cell (conventional), AGM, and GEL cell.

Out of these three, AGM is the most common in today’s ATVs. Some budget models still use conventional lead-acid batteries.

If you’re looking to upgrade to a lighter weight and higher capacity battery, you might want to consider a Lithium-based battery.

It is typically recommended not to change the battery type unless you know the ATV charging system can handle it. For instance, a lithium battery requires a different charging procedure than

Terminal Type and Location (Polarity)

In the world of power sports batteries, there are over 20 different terminal designs. It’s crucial to ensure the battery you select is compatible with the connector type of your ATV’s battery.

Another thing to consider is battery polarity. In short, the polarity tells you where the battery’s positive and negative terminals are on the battery casing. If the battery polarity is wrong, it will likely not fit the wiring on your ATV.

Battery polarity or terminal layout comes in many variants.

Sensor Design (Conventional Batteries Only)

Many conventional serviceable ATV and Powersports batteries with liquid electrolytes have sensors that monitor electrolyte levels. A warning light in the instrument ATV panel illuminates when the fluid level drops too low.

On a serviceable battery with removable caps, you can add distilled water to raise the electrolyte level where it needs to be.

Any time you replace a battery with a sensor, you must also replace the actual sensor.

The sensor plugs come in different diameters and lengths and may differ even if you choose the exact battery brand.

If the sensor diameter is incorrect, the plug will not fit.
If the sensor is too long, it may cause electrical problems.
If the sensor is too short, the electrolyte level warning light will flash even when the level is correct.

Vent Port Location

Liquid electrolyte batteries typically come with a vent port that connects to a tube inside the ATV’s battery compartment. The pipe directs any battery acid spill away from the battery compartment.

Battery acid is highly corrosive and causes much damage if spilled inside the battery compartment. So make sure the vent port on your new battery lines up with the drain pipe.

Now that you’ve decided what battery to get, I recommend you check our post on installing your new battery to the ATV.

When in Doubt – Ask an Expert

Suppose you find the variety of sizes, capacities, terminal types, and other factors confusing. In that case, it might be wise to consult an expert for battery recommendations instead of selecting one on your own.

Reliable sources for advice include your ATV dealer, a reputable battery store, or a trusted local mechanic.