The first and easiest thing to do is check our Battery Finder for your specific motorcycle or powersports vehicle, but it does not include Pre-1990’s models due to the fact that most pre 1990s models are not modern standardized sizes. You can contact us for help choosing the right battery for older vehicles. Give us a call if you have any questions (310 527 2330) or email us (

Antigravity Battery Size Options

We make many different battery sizes that fit Modern OEM sizes as well as some Universal Fit Options. Additionally, there are different features available such as Batteries with built in Jump-Starting and Full Battery Management Systems (BMS), or Race Batteries that don’t have the built in protections. Please review below what we offer.

Battery Sizes

The RE-START Powersport Batteries

OEM Replacement Sizes

ATX-20 Re-Start Battery by Antigravity
Direct Swap: Our Re-Start (RS) batteries are aimed at being a direct replacement for your current Lead/Acid Battery as a direct swap. They are sized almost identically to the battery that comes with your bike in most cases. They offer a Full Battery Management System (BMS) that prevents damage to the battery from Over-Discharge, Over-Charge as well as having Cell Balancing and Thermal Protections. This line of Batteries also has our RE-START Built-In Jump Starting feature so you will not be stranded by a dead-battery emergency.

Best for Most Riders: The RE-START Batteries are the best for the typical rider who wants a battery that offers them safety, exceptionally long life, and the lightweight benefits of Lithium, while providing the extra security of a battery that can RE-START the bike if they accidentally drained the battery. Best use is in stock vehicles or mildly modified vehicles. The RS batteries offer a direct OEM drop-in fitment.

Heavy Duty (HD) Option: The RE-START Battery is also offered in an HD (Heavy Duty) Version which has a bigger lithium cell pack inside the battery which provides more power and extra Amp Hour capacity. The HD versions are better for applications with more accessories, and higher demands of the battery. The larger HD sizes can also be used in Performance and Race Cars.

Small Case

Universal Size Lithium Battery for Powersports

AG-801 Antigravity Battery, Small Case Fitment
Ultra Compact: Our “Small Case” batteries come in an ultra compact format that is a “universal” fitment for most Motorcycles and Powersport Vehicles. The SMALL CASE sizes are most often used in applications such as Dirtbikes, ATVs and vehicles that do not have extra accessories. They are the #1 Battery for Racing applications due to their compact size and high power. The reason these batteries are most often used in Motorcycles without extra accessories is that they do not have the built-in BMS (Battery Management System) of the RE-START line of Batteries. Therefore they can be damaged accidentally if over-discharged by the user, but being Dirt bikes and other low accessory vehicles do not have Parasitic Drains then the SMALL CASE battery can offer exceptionally high power and weight loss and long life.

Best for Racers: These batteries are the go-to battery for Racers at all levels including the Top Teams such as Monster Energy Kawasaki, Star Racing Yamaha/Factory Yamaha, and much more. This is because they are the most compact and powerful Batteries on the Market with a reputation for durability and long life in these demanding applications of Professional Racing.

High Power: These batteries are best where the most compact yet powerful option is desired. For example our AG-801 offers TWICE the POWER of the Lithium Battery that comes in your KTM/HONDA/YAMAHA Enduro or MX bike, yet is more COMPACT. Additionally we offer the AG-401 that is HALF the size of the stock Lithium Battery in a KTM/Honda/Yamaha/Kawasaki yet has just as much power in a more compact format.

Usage Note: It should be noted that the SMALL CASE batteries have onboard “Balancing” of the Lithium Cells but do NOT have a BMS and protections against over-discharge. So they are not recommended for vehicles with extra accessories or used for the Street. Please use our RE-START Batteries, they are a better application for vehicles with extra accessories like Street Bikes or similar accessorized vehicles.

Custom Builds & Other Applications

The Small Case is a favorite of Custom Builders in the Motorcycle world, as well as in all forms of Racing… But PLEASE NOTE: It is critical that you select a Small Case battery that is large enough for your application in BOTH cranking amps AND capacity, but additionally and most importantly that your Charging System and Voltage Regulator is absolutely working correctly. Please see these considerations below.

1. The Small Case battery does NOT have built-in protections of the RE-START batteries. So it can be over discharged, which can damage the battery. It must not be allowed to over-discharge. This is a Customer Maintenance issue, NOT a defective battery issue. Make sure it does not discharge below 11v.

2. The Small Case Battery can melt-down (Thermal Runaway) if it is over-charged by a faulty/old/defective Voltage Regulator. Pre 1990s bikes and ESPECIALLY HARLEY DAVIDSON AND OLDER METRIC BIKES have 25 year old Voltage Regulators that are defective. They can spike voltage over 24v to the Lithium Battery if not operating correctly and cause a melt-down or potential for Fire! The Voltage regulator must be replaced to a modern/updated solid state unit in older bikes for safety.

3. The SMALL CASE battery cannot be put into a Custom OIL BAG (such as used on Custom Harley Davidson, or other Custom V-Twin Bikes) that surrounds the Battery with no area for heat to escape. NO battery can handle the over 200 degree temperatures and higher created by this type of installation.

4. If you over-discharge a SMALL CASE battery it should not be Jump Started or Push Started from below 10.5v. This can overheat the battery. It should be put on a Lithium Specific Charger and allowed to re-charge. The Jump Start or Push Start will allow the Vehicle’s system to start charging at a faster rate than the Battery can handle if it is over-discharged. This may create a potential for Thermal Runaway.

Lithium Pros & Cons

Advantages of Lithium compared to Lead/Acid

  • Lightweight, up to 70% lighter than Lead/Acid.
  • Better Starting, More powerful. Lithium offers a higher pulse discharge ability than lead acid. On average about 2x the Starting power.
  • Protections from over-discharge and Damage by accidental over-discharge (RE-START Models).
  • On average, if maintained, a two times longer life cycle than Lead/Acid Batteries. Lithium is rated at more than 2000 cycles… Lead is rated at 1000 cycles.
  • Safer for the environment: No Lead or Acid.

Disadvantages of Lithium compared to Lead/Acid

  • Lithium is more expensive upfront than Lead-Acid Batteries.
  • Lead/Acid has more Amp Hours in the same case format, but less power.
  • Lead/Acid is better at cold weather starting in the close to and below Freezing weather temperatures. But with a proper sized Lithium Battery this is not much of a concern at this point in time.

Common Questions

What is a BMS?

A BMS is a Battery Management System. It is a circuit-board built-into the Lithium Battery that controls many aspects of the battery in terms of preventing the battery from over-discharging, preventing over-charge for occasional spikes in voltages. It makes sure the Lithium Cells are being evenly recharged, and it has Thermal Protections to provide a higher level of safety if the battery overheats.

With a BMS the Lithium Battery can achieve an extra long life since the battery is never being put into conditions that can damage the battery such as over-discharging. Additionally the BMS creates a high level of safety and prevents accidental damage to the battery, for example if the Consumer left the light on. So overall it adds greatly to the safety and lifecycle of the battery.

Can I use a Smaller or Larger Battery for my vehicle?

It will depend on the application you use the vehicle in. For example if you ride more often on longer distance rides, like Touring or Adventure riding, you would want more AMP HOURS (Capacity), so you would want to go with the Heavy Duty (HD) Versions of the Batteries. But if you are a regular street rider not often going on longer road trips you will be fine with the regular version of the battery. But if you Race you might want to get a smaller battery for extra savings on weight since you will not have all the accessories of a regular street vehicle. The other key is you can use the largest possible battery ALWAYS, it will not hurt the vehicle. But if you use too small of a battery and it struggles this can damage the Starter Motor and Battery.

What is the smallest size battery I can use for my vehicle?

This will ultimately depend on the vehicle’s motor size, and application. There are too many factors to answer that question, such as if motor has high-performance parts and was built either “tightly” or “loosely”. So there are many variables to consider when determining the smallest size battery possible. The key is to not put too small of a battery that will be over-stressed and will not have a long life cycle.

1. In general our Re-Start batteries are recommended for direct replacements in stock and standard motorcycles as they come from the manufacturer. Our Restart batteries are intended to replace the battery in those stock vehicles and our part numbers reflect the same part numbers typically of the manufacturer’s stock battery. When using the Restart battery you should only go with the recommended stock size or our Heavy Duty (HD) version of the stock size.

2. See the FAQ above for when to choose Small Case over Restart. Generally, when using our Small Case batteries, the AG-401 can be used in motorcycles up to 450cc, the AG-801 can be used in motorcycles up to 750cc, the AG-1201 can be used in motorcycles up to 1200cc, and an AG-1601 can be used in motorcycles up to 1800cc.

But it should be noted that this depends specifically on the application in which you intend to use the battery – for example if it is a custom bike with a high performance motor you should go up one size. Also note that in race car applications you can use batteries as small as the AG-1201 depending on the motor size. Examples of best uses can be found on any battery’s page.

Contact us for more details.

Can I put too big of a battery in the bike?

As long as the battery fits into the battery tray of your bike and can be connected correctly and safely mounted, a larger size will not hurt the vehicle. There is no problem in fitting a higher specification battery within the same voltage range to a vehicle. There is a myth that a more powerful battery can damage the starter motor or that the alternator will not be able to charge the battery; these are wrong. A more powerful battery will start the vehicle over a wider range of conditions and will have a longer life as it will not be worked so hard. There are benefits to this, especially if the vehicle is subject to heavier usage or additional accessories have been fitted to the vehicle.