ATV Battery Guide: Types, Sizes, Charging, Storage and When to Replace

Nearly every ATV runs on a small 12-volt battery, and most current models use a sealed AGM (absorbed glass mat) battery that never needs water. Conventional flooded batteries and lightweight lithium (LiFePO4) batteries are the other options. The right one is the part number listed in your owner’s manual, such as YTX20L-BS for a 2016 to 2020 Yamaha Grizzly 700 or Kodiak 700, because that number fixes the case size, terminal layout, polarity and cranking power.

Charging is where most ATV batteries are ruined. Yuasa, one of the largest powersports battery makers, says to charge at about the battery’s amp-hour rating divided by 10 and never above 3 amps, which rules out most car battery chargers. A fully charged conventional battery should read 12.6 volts or more after resting, and an AGM slightly higher.

ATV battery types compared

Yuasa explains that a dry “BS” AGM battery has a shelf life of 5 years as long as its foil seal is intact, while a factory activated battery is already filled and charged and “cannot be stored indefinitely.” A sealed, unfilled conventional battery has a 2-year shelf life at room temperature. Once a dry battery is unsealed, the plates start to oxidize, so it should be activated, charged and installed straight away.

How to read an ATV battery part number

Powersports battery numbers look cryptic, but each part tells you something. Using Yuasa’s system as the example, which most other brands copy for cross-reference:

• YTX, YTZ, YIX, YT, GYZ: AGM battery families. GYZ is Yuasa’s higher-output AGM line.
• YB: a high-performance conventional (flooded) battery. 12N numbers are standard conventional batteries.
• The number (14, 20 and so on): the case size, not the exact amp-hours.
• H: higher cold cranking amps than the standard version of the same size.
• L: reversed terminal polarity. A YTX20L-BS and a YTX20-BS have the same case but the positive and negative terminals swap sides, so cables may not reach.
• BS: bottle supplied, meaning the acid comes in a separate pack. FA means factory activated.

Polarity is the most common mistake when buying online. A battery that “fits the box” but has its terminals on the wrong side can stretch cables against the frame or reach the wrong lead, and connecting it backward can damage the electrical system.

Common ATV batteries by model

Yuasa’s application guide lists which batteries fit which ATVs. A few Yamaha examples, plus the specs for each battery, from the guide’s 2021 edition (it covers model years through 2020):

The pattern holds across brands: big utility quads with winches, lights and power steering carry an 18 to 20 Ah battery, while sport quads such as the Raptor 700 and YFZ450R use much smaller ones to save weight. For a 2021 or newer ATV, confirm the part number in your owner’s manual or the maker’s current fitment lookup. Our guides to the Yamaha Grizzly 700 and Yamaha Kodiak 700 cover the rest of their specs.

Moving up from a standard AGM to a high-output version of the same size (YTX20L-BS to YTX20HL-BS, for example) adds cranking amps for cold starts and winching. Check the polarity letter matches, and note the high-output battery weighs a little more: 15.1 lb versus 13.9 lb in Yuasa’s figures.

How to charge an ATV battery safely

Yuasa’s guidance on charging small batteries is specific:

1. Check the voltage first. Measure the open-circuit voltage with the battery at rest, before charging.
2. Use the right charger. Never exceed 3 amps on a powersports battery. Most automotive chargers put out more than that and are not suitable. An automatic maintainer made for small batteries is the safest choice because it stops at full charge.
3. Set the rate. Divide the amp-hour rating by 10. A 14 Ah battery charges at 1.4 amps; an 18 Ah YTX20L-BS at 1.8 amps. Many batteries print the charge rate on the label.
4. Connect with the charger off. Charging produces hydrogen gas, which is explosive. Turn the charger off before connecting or disconnecting the clamps, wear safety glasses, and charge in a ventilated space.
5. Watch the temperature. Stop if the case becomes too hot to touch, let it cool for 6 to 12 hours, then resume.
6. Check again. Verify the state of charge about 30 minutes after charging, and do the definitive resting-voltage check after the battery has sat off the charger for one to two hours.

Overcharging an AGM is permanent damage. Yuasa notes that too much boost charging drives off electrolyte that cannot be replaced in a sealed battery, and the battery loses starting power for good.

A brand-new AGM or conventional battery also needs an initial charge. After filling with acid, it is only about 75 to 80 percent charged, so charge it fully before installing, even if the ATV starts on it.

Testing an ATV battery with a multimeter

A basic digital multimeter tells you most of what you need. Set it to DC volts, put red on positive and black on negative, and read the battery after it has rested off the charger and off the ATV’s electrical load.

The 12.6-volt full-charge figure, the slightly higher AGM reading and the 11.5-volt threshold come from Yuasa; the middle rows are general guidance for 12-volt lead-acid batteries. Yuasa stresses that voltage alone is not conclusive. A battery can show good voltage and still collapse under load, so if a fully charged battery cranks weakly, a load test (many parts stores and dealers will do one) is the real answer. With the engine running at a fast idle, a working charging system should push the voltage above the battery’s resting value. If it does not, the stator, regulator or wiring may be the problem rather than the battery, and that is a job for a shop if you do not have the service manual’s test values.

Winter storage and keeping an ATV battery alive

Batteries mostly die from sitting. Yuasa names two main killers: sulfation, which builds when a battery stays discharged, and freezing, which only happens to a discharged battery. A fully charged battery’s electrolyte does not freeze until about -75°F, while a badly discharged one can freeze at about +18°F to +27°F.

• Disconnect or maintain. If the ATV will sit, disconnect the battery cable to stop small drains from clocks, GPS units and accessories, or leave it on an automatic maintainer.
• Check on a schedule. Yuasa says to check conventional batteries every month and AGM batteries every three months in storage, and more often below 60°F or above 80°F.
• Keep it cool, not hot. High storage temperatures speed up self-discharge and damage batteries.
• Conventional batteries only: keep the electrolyte between the lines with distilled water, keep the vent tube free of kinks, and finger-tighten the caps.
• Short rides are not enough. A few minutes of riding with lights and a winch does not replace what starting used. A maintainer between rides helps.

If access to the battery is awkward, a pigtail lead with a quick connector, run to an easy spot, lets you plug in a maintainer without removing seats or panels.

Lithium ATV batteries: what changes

Lithium iron phosphate (LiFePO4) is the lithium chemistry used in most powersports batteries in North America. Its appeal is weight: a lithium starter battery is much lighter than an AGM, which matters most on sport quads where every pound counts. It also does not sulfate.

The rules are different, though:

• Charger. Use a charger with a lithium or LiFePO4 mode. Lithium battery makers warn against chargers with an automatic desulfation mode that cannot be switched off, because that mode is meant for lead-acid and can harm lithium cells.
• Deep discharge. Clore Automotive, which makes powersports chargers, notes that most lithium batteries have a management circuit that blocks charging once the cells are over-discharged. Do not leave a lithium battery connected to a drain all winter.
• Cranking spec. Lithium batteries are often rated differently from AGM, so compare the maker’s recommended replacement for your ATV rather than matching the amp-hour number alone.
• Cold. Read the manufacturer’s cold-weather instructions if you ride or park below freezing.

ATV battery prices and when to replace

As of 2026, typical retail prices for an ATV battery run roughly $30 to $80 for a small sport-quad AGM such as a YTZ7S-size battery, about $60 to $150 for an 18 to 20 Ah utility AGM, and about $100 to $300 for a lithium replacement. Prices vary with brand, high-output versions, whether acid is included, and core charges in states that require battery recycling deposits. Big-box stores, auto parts stores and powersports dealers all stock the common sizes, so compare by exact part number.

Replace the battery when it will not hold a charge after a full charge, fails a load test, has a cracked or swollen case, or keeps dropping below 12 volts within days of charging with nothing connected. For a battery that is only a season or two old, rule out the charging system and parasitic drains first, because a new battery will die the same way. Dispose of the old one at a retailer that takes back lead-acid batteries; never put it in household trash.

Weight counts when you move or load the quad, too. Our guide to how much an ATV weighs lists wet weights by model. Before your next ride, check that your ATV helmet is up to date as well.

The single habit that saves the most batteries: plug a powersports maintainer in whenever the ATV is parked for more than a couple of weeks.