ATV Battery Voltage: 9 Most Important Things to Know

The primary role of an ATV battery is to power the starter and other high-energy components such as a winch, hand warmers, and power steering.

For the battery to provide sufficient electric power and maintain its capacity throughout its service life, its voltage level must be monitored and maintained regularly.

This post covers what every ATV owner should know about battery voltage to ensure optimal battery performance and longevity.

• What is ATV battery voltage?
• What voltage are ATV batteries, and how many volts should they read?
• How to check the battery voltage.
• What battery voltage is too low, and what voltage is too high?
• How many volts are needed to start an ATV?

PS: The numbers provided in this post represent an average from reading the datasheets of the most popular battery brands. Deviations may occur.

What Is ATV Battery Voltage?

ATV battery voltage is a parameter indicating the battery’s state of charge (SoC), measured as the difference in electric potential between the positive battery terminal and ground. 

There are several common ways to indicate battery voltage:

Nominal voltage. Nominal means “named.” A battery’s nominal voltage is a value assigned by the manufacturer that represents the battery’s average voltage during use (discharge). The value is a convenient way of indicating a battery’s voltage class (6V, 12V, etc.) and is printed on the battery casing. The value remains the same regardless of the battery’s charge level or operating voltage.

Open Circuit Voltage (OCV or Voc). A battery’s OCV indicates its measured resting voltage when it’s not delivering or receiving any power. There is no load connected, no current being drawn, and the battery is not connected to a charger. The OCV of a fully charged battery is typically five to seven percent higher than its nominal voltage. 

Closed Circuit Voltage (CCV) is the operating voltage and indicates a battery’s measured voltage during discharge or charging.

• Discharging is when the battery is under load and a current is drawn. CCV during discharge is lower than OCV due to internal resistance in the battery.
• Charging is when the battery receives power from an external power source such as a charger or the ATV charging system. CCV during charging is higher than OCV.

What Voltage Are ATV Batteries? (Nominal Voltage)

A conventional ATV battery has a nominal voltage of 6V or 12V, depending on the vehicle’s electrical system. 6V batteries are most common in some youth models, while 12V batteries are the most common type in adult-sized ATVs.

You must only use a battery with a rating suitable for your ATV. Using a battery with a voltage rating different from what your ATV is designed to operate in can damage its electrical components and wiring.

• If the ATV has a 6V system, you should only use a 6V-rated battery.
• If the ATV has a 12V system, you should only use a 12V-rated battery.

ATV batteries come in different types based on battery chemistry. Regarding nominal voltage, lithium-ion batteries differ from lead-based batteries such as lead-acid, AGM, and GEL batteries.

• A lead bases battery has a nominal voltage of 2.0V for each cell, giving a 6-cell battery a nominal voltage of 12V.
• On the other hand, lithium-ion batteries have a nominal voltage ranging from about 3.2 to 3.2V for each cell. That is why a 4-cell lithium-ion battery typically has a nominal voltage of 12.8 up to 14.4V. 

When upgrading from a lead-based battery to a lithium-ion battery, always ensure the battery you choose is compatible with your ATV. Most battery manufacturers provide a compatibility table. 

Related: How to Replace or Install an ATV Battery; Step-by-Step

Here are a few ways to know what voltage class your ATV is designed to run on.

• Look for labels on the existing battery. All batteries have a label indicating their nominal voltage.
• Refer to the owner’s manual. You’ll find information about battery voltage in the spec sheet or under the chapter about battery maintenance.
• Ask the dealer. If you are still unsure what battery voltage your specific ATV uses, ask the dealer rather than risk installing the wrong type of battery. 

Related: What Do ATV Battery Numbers Mean?

How Many Volts Should an ATV Battery Be? (Actual Voltage)

A battery’s actual voltage varies between battery types and is usually higher than the nominal voltage.

A fully charged 12V conventional ATV battery should read between 12.6 and 12.9V at rest, while a fully charged 6V battery should read between 6.3V to 6.45V.

Most ATV batteries are Flooded Lead Acid (FLA) or AGM. Lithium-Ion batteries are higher performance but also more expensive and operate at a higher voltage than conventional batteries.

When measured at room temperature, a battery’s voltage can be used to estimate its state of charge. The tables below give a more detailed indication of normal voltage levels for various battery types.

How Many Volts Should a 12V ATV Battery Read?

How Many Volts Should a 6V ATV Battery Read?

Typical ATV Battery Voltage When the Engine Is Running

When you start the ATV, the battery voltage increases by the charge it gets from the ATV charging system. 

ATV battery voltage when the engine is running is typically between 13.7V to 14.7V, depending on the battery type and the bike’s charging system.

Battery voltage above 14.7V measured with the engine turned on indicates overcharging, usually caused by a faulty voltage regulator. 

How to Check the Battery Voltage

You need to read the battery’s actual voltage to know whether it holds a sufficient charge or needs a proper charge.

To read the battery voltage, you can use a volt-meter or a basic multimeter.

Here is how you read the battery voltage using a multimeter.

1. Turn the ignition off. Open circuit voltage is measured when the battery is at rest with no load.
2. Locate the battery. Remove any plastic covers necessary to access the battery, usually located at the front of the ATV or below the seat. 
3. Prepare the multimeter. The Red positive lead goes to the “V” port, while the black negative lead goes to the COM port. Set the multimeter to 20 V DC (v⎓) if it’s a manual multimeter or to “V” if it’s auto-ranging. 
4. The black lead goes to ground. The black lead probe goes to the negative (-) battery terminal or ground.
5. The red lead goes to positive. The red lead probe goes to the battery positive (+) terminal.
6. Read the voltage in the multimeter display. Refer to the tables above to determine its state of charge.

• 100 %: No action required.
• 75% to 100%: It might need a slight charge.
• 50% to 75%: Needs a full charge.
• 25% to 50%: Needs a full charge.
• 0% to 25%: Needs a charge with a desulfation charger.

Note that a battery may not be in good shape even if it reads a full charge.

Related: How to Test an ATV or UTV Battery. Good, Reduced, or Bad?

What Battery Voltage Is Too Low?

A conventional lead-acid or AGM 12V ATV battery that reads below 12V at rest is too low and needs a charge. When a battery reads below 11.5V at rest, it is considered dead and needs to be replaced.

Similarly, A 6V lead-acid or AGM battery must be charged if it drops below 6V to prevent damage. When a 6V battery drops below 5.8V, it is considered dead.

Note that a 12V battery may drop below 11.5V briefly under load, such as when starting the ATV. However, a healthy battery should maintain a minimum of 9.6V even under heavy load and should jump right back up when the load shuts off.

A Lithium-Ion battery can manage the occasional drop below 12.9V, but if the voltage drops below 12.5V, this may cause permanent damage and shorten the battery life span.

What Happens When the Voltage Gets Too Low?

When the battery voltage drops too low, it doesn’t hold enough power to start or keep the ATV running and will begin losing its potential capacity due to a process known as battery sulfation. 

Sulfation is a chemical process where sulfate crystalline deposits build up on the batteries lead plates from being in a discharged condition or from being exposed to oxygen. The rate of sulfation increases as the voltage decreases.

What Voltage Should an ATV Charge At? What Is Too High?

Charging a battery with too high of a voltage may cause permanent damage to the battery and the ATVs electrical system and components.

Different battery types must be charged at different voltages to prevent overcharging. Some battery types are more prone to overcharging than others. Lithium-Ion batteries, in particular, are prone to damage from using the wrong type of charger or charging at too high of a voltage.

A high charging voltage can occur if the ATVs voltage regulator becomes defective or you charge the battery using the wrong type of charger. 

Always ensure the charger you use is compatible with your battery type and that you use the correct charging mode. Refer to the battery spec sheet for proper charging voltage.

Typical charging voltages by battery type:

How Many Volts Is Needed to Start an ATV?

An ATV typically needs a battery voltage of a minimum of 11.5V to 12V to start. Turning the engine usually requires at least 12V or more in cold weather. 

A battery that can barely start the ATV likely has a too-low voltage and needs a charge to prevent reduced battery service life. 

To Sum Things Up

As you’ve probably realized by now, no one answer fits all regarding battery voltage. Hopefully, this post gave you a better understanding of why battery voltage matters and what you can do to ensure you get the most out of your ATV battery.