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Lawn Mower Battery Size Chart | A Comprehensive Guide On Lawn Mower Batteries

Mowing is a fancy word for cutting grass. As a part of maintaining the lawn, many of us spend the maximum time mowing the lawn. The purpose of mowing is to keep the grass in the lawn at a set height so that the lawn looks neat and attractive. Lawn Mowers, as the name suggests, are a piece of special equipment that helps us in mowing lawns. Today, we have cordless and electric type lawn mowers that mow using an electric motor. But if you need a heavy-duty lawn mower, then chances are you look at a gas-powered lawn mower. Earlier gas-powered lawn mowers use a pull-string to start the engine. But nowadays, you get simple electric start models. The problem with electric start lawn mowers is they need starting batteries and depending on your usage, they die and you have to replace them.

There are several important parameters and specifications that you need to be aware of while choosing a replacement. So, in this guide, we decided to make a beginner’s guide on Lawn Mower Batteries. First, we will all the essential things about lawn mower batteries and then we will move to the lawn mower battery size chart.

Using this chart, you can compare your battery with the specifications of other batteries and purchase a perfect replacement.

A Brief Note on Lawn Mowers

We have been using lawnmowers since the late 1800s. All the initial lawnmowers were completely mechanical devices. Very soon, we saw gasoline-engine-based lawnmowers that made the job of lowing a garden very fast and easy.

These types of mowers are very popular even today as they are very powerful and allow you to mow thick and tall grass very easily. Then we have the main electric-powered lawn mowers.

They are small and easy to maneuver in small to medium-sized gardens. As a result, they became very popular in the market. But the limitation is you need to drag the cable or you can reach as far as the cable allows you.

The next important type is also electric but this time it is in the form of battery-powered mowers. These are cordless devices and you can use them anywhere you want. Their ridiculous cost makes them a niche product.

Types of Lawn Mowers

The basic type of lawn mower is a Reel Mower. It is a mechanical device that runs on our muscle power. We have to push the mower and when the wheels rotate, blades mounted on a cylinder cut the grass with a scissor-like action.

Next, we have rotary mowers that are powered by electricity, a battery, or a gas engine. Of the three power sources, gas-powered rotary lawn mowers are very common and popular, especially in the North American market.

You get both push-type as well as self-propelled models in gas-powered mowers. These types of mowers are very useful for large gardens, usually up to half an acre.

If you have a relatively small lawn, then corded electric lawn mowers are ideal. They are silent (comparatively), do not pollute, and are easy to maintain. Maneuverability is the main concern with corded-electric lawn mowers. In most cases, you have to stay within 150 to 200 feet distance from an electrical outlet.

An alternative to this is battery-powered cordless electric lawn mowers. They are very easy to maneuver as you don’t have to worry about the electric cord. Cordless Lawn Mowers are heavier than their corded counterparts.

Depending on the size of the battery, these models allow you to mow continuously anywhere between 45 minutes to 2 hours. But the cost of cordless lawnmowers is very high.

All the models we discussed till now are push-type or walk-behind mowers. But there is another type in the form of ride-on or riding mowers. As the name suggests, you can sit on the mower and ride it across the lawn to mow the grass.

If you have a very large lawn, over half an acre, then it makes sense to invest in a riding lawn mower. Usually, the ride-on mowers are gas-powered with rotary-type cutting mechanisms.

You often hear the term lawn tractor when you browse for riding lawnmowers. While ride-on lawn mowers just mow the lawn, riding lawn tractors can mow the grass and much more.

With the correct attachment, you can use a lawn tractor for mowing, dethatching, aerating, fertilizing, and even plowing snow.

Understanding Lawn Mower Batteries

As we mentioned in the previous section, gas-powered lawn mowers are very popular, be it the walk-behind type or the ride-on type. Earlier models came with a pull-string to start the gasoline engine.

Depending on the age of the mower, you could start the engine with a single pull in case of a relatively new and well-maintained mower. But as it ages, the performance of this starting mechanism starts to fail and you might need to pull more than a couple of times to crank the engine.

This is where lawn mowers with starter batteries come in handy. These batteries work similarly to our car SLI batteries as they help crank the gasoline engine of the mower.

With the push of a button or twist of a key, you can start the lawn mower and don’t have to worry about any pull strings.

Comparison between Lawn Mower Batteries and Car Batteries

The moment we say lawn mower batteries are useful for easily starting the mower’s engine, we immediately start comparing them with car starter batteries. They are similar in some aspects but there are a lot of differences as well.

Let us begin with the similarities. Car batteries are usually flooded lead-acid type or sometimes maintenance-free gel-type. It is very rare to see other types of batteries as car starter batteries.

Even lawn mower batteries are lead-acid batteries and they come in both flooded as well as gel types. But surprisingly, you can also find lithium batteries for lawn mowers.

As the majority of batteries in both cases are of type lead-acid, their working remains more or less the same. The advantages and problems you have with car batteries, you also have them with lawn mower batteries.

This includes low cost, a simple charging system, the life of the battery, etc.

Does this mean can we use a car battery in a lawn mower? No. this is where the differences kick in. First thing, car batteries are much bigger than lawn mower batteries, both in terms of physical dimensions as well as capacity.

The main difference is the starting current they can provide, which we usually represent as Cold Cranking Amps or CCA. As car engines are quite large, their batteries must provide a lot of amps to crank the engine.

So, you usually see CCA ratings of 500A or more in car batteries. But lawn mower engines are small. You don’t need such large currents. That’s why you will see CCA ratings in mower batteries in the range of 130 to 150A.

Important Specifications of Lawn Mower Batteries

Continuing the previous section’s discussion, let us see some important parameters and specifications of typical lawn mower batteries.

1. Type of Battery

As we mentioned before, you can find both lead-acid and lithium batteries for lawn mowers. In the case of lead-acid type, you again have flooded, AGM (Absorbent Glass Mat), and Gel types. Each type has its advantages and disadvantages.

Lithium batteries or Lithium Iron Phosphate to be specific, are also becoming quite popular with lawnmowers.  The charging and protection methods (or lack thereof) are very different between lead-acid and lithium batteries.

Lead acid batteries are affordable, heavy, and robust to operate in all climatic conditions. But the problem is you have to take care of them and make sure they are fully charged all the time. Speaking of charging, the number of times you can charge and discharge a lead-acid battery is very less.

Lithium Batteries on the other hand are expensive and lightweight. Even though they support a good number of charge/discharge cycles, they need special circuitry in the form of a Battery Management System or BMS to protect the individual lithium cells from overcharging, deep discharging, etc.

Charging lead-acid and lithium batteries is very different. You can get chargers that support both these battery types but double-check the capabilities of the charger before using. Do not blindly use one type of charger on the other type of battery.

If the lawn mower has an alternator (which is usually the case with riding-type lawn mowers and lawn tractors), it can charge the battery once the engine is on. But for smaller mowers, this is usually not the case. You have to charge the battery externally.

2. Size and Other Physical Parameters

Physically, lawn mower batteries are smaller. In the next section Lawn Mower Battery Size Chart, we will see the dimensions of some popular types of lawn mower batteries.

Another important “physical” aspect of lawn mower batteries is the terminals and their position. Unlike car batteries, which usually have a pretty standard type of terminals, mower batteries have more than one type of terminal to connect the cables.

Also, the position of the terminals might be different between brands, manufacturers, and battery types. Usually, in a particular battery group, the type of terminals and their position (which is almost always on the top) will be common.

But we cannot say the same when you go to a different battery group.

3. Voltage

The reason why we are talking about battery voltage is in the early days of lawn mower batteries, we used to get them in 6V ratings as well. But it is safe to assume that most modern mower batteries that we get today are 12V batteries.

This applies to both lead-acid and lithium batteries. So, all the batteries we are going to discuss in the guide are 12V unless otherwise mentioned.

4. Capacity

The capacity of a starter battery is an interesting specification. It represents the amount of current in amps a fully-charged battery can deliver for 10 hours straight.

We usually see the battery capacity specification as Ampere Hour or Ah. Depending on the size of the battery, its capacity can range anywhere between 10Ah to 40Ah.

5. Cold Crank Amps (CCA)

This is one of the important specifications of a starter battery, be it for cars or lawn mowers. What does CCA mean? Cold Crank Amps or CCA represents the amount of cranking current (in amps) a fully-charged battery can deliver for a period of 30 seconds at a temperature of 0°F.

As the size of the gas engine in mowers is small, you don’t need a large cranking current to start the engine. Hence, you will see CCA ratings of mower batteries in the range of 100A to 300A. You can find batteries with CCA ratings more or less than this range. You have to check your lawn mower’s manual as it will usually recommend a specific CCA value.

6. Lawn Mower Battery Size Chart

An important thing to remember before purchasing a new mower battery is they are significantly smaller than car batteries and within lawn mower batteries we have several sizes.

A Battery Group categorizes the physical dimensions of the battery. All the batteries falling in a particular group have nearly identical shapes and sizes. If you are familiar with car and boat batteries, there are we have several battery groups.

Let us now see some popular lawn mower battery groups. The groups in this list are no way near the full possible types but these are pretty common with mowers.

The following table is a Lawn Mower Battery Size Chart consisting of the common battery groups.

Battery Group Length (inches) Width (inches) Height (inches) Voltage
U1 7.75 5.1875 7.3125 12V
YTX30L-BS 6.5625 4.9375 6.8750 12V
U1R 7.75 5.1875 7.3125 12V
YTX24HL-BS 8.0625 3.4375 6.375 12V
21 8.19 6.81 8.75 12V
YTX20L-BS 6.875 3.4375 6.375 12V
22F 9.5 6.875 7.3125 12V
YTX14-BS 5.875 3.4375 5.75 12V
22NF 9.4375 5.5 7.1875 12V
YTX12-BS 5.875 3.5 5.125 12V
24 10.25 6.81 8.87 12V
YTX9-BS 5.875 3.4375 4.125 12V
27 12.06 6.81 8.75 12V
YTX5L-BS 4.4375 2.75 4.125 12V
30H 13.5 6.81 9.25 12V
31 13 6.72 9.44 12V
45 9.4375 5.5 8.75 12V
70 9.0625 7.0375 7.8125 12V
4D 20.75 8.75 9.88 12V
8D 20.62 10.95 10.17 12V

Different manufacturers have their own set of battery sizes and they may or may not be compatible with batteries from other manufacturers. But if they come under the same battery group, then chances are they will become compatible.

How To Choose a Replacement Lawn Mower Battery?

The common thing between a gas-powered lawn mower and a car is they both have engines. But we take cars very frequently to school, work, shopping, or other commuting activities.

This is not the case with lawn mowers. We use them only when we need to mow the lawn or garden. So, for the most part of its life, a lawn mower usually sits in a garage or shed.

Here comes the problem. As we take our cars out for a spin on a regular basis, the level of discharge of the car’s starter battery won’t be that bad. But as lawn mowers are sitting idle most of the time, there is a good chance that the battery will discharge pretty quickly.

If you have an external charger, then you can extend the life of the lawn mower battery. But in case you don’t have a battery charger, then you will at a replacement in a short time.

Things to Consider for Lawn Mower Battery Replacement

The first and most important thing while choosing a new lawn mower battery is to check the physical dimensions of the battery. Lawn Mowers have a slot for the battery that fits only one type of battery.

When we say one type, we mean one size. The replacement battery must fit perfectly into that slot and it should be loose (and if it is tight, you can’t even fit the battery into the slot).

So, check the owner’s manual or maintenance guide of your lawn mower and look for battery specifications. If they mention the battery group, then you can simply browse for that particular group and purchase a replacement.

What if you can’t find the battery group information? We have to old school and measure the dimensions of your current battery. With this information, you can look up any lawn mower battery size chart and compare the dimensions with the common and popular battery groups in the list.

After the battery group size, the next important specification is the CCA rating of the battery. Once again, check the user manual if they specify the necessary CCA of the battery. If not, look at the label of the current battery and you might find the CCA ratings.

When shopping, you need to match the CCA values. It can be higher than the current value, but never lower. But if you opt for a higher CCA rating, then you have to spend more money.

Another important thing is the type of battery. We have lead acid and Lithium Iron Phosphate as the two base battery types. Further, in lead-acid, we have wet or flooded, AGM, and Gel types.

Always choose a replacement battery of the same type as your current battery. The compatibility between different battery types is, to put it in simple terms, highly questionable.


If you have a lawn or garden, then you have to invest in a decent lawn mower. It does the job of shearing or cutting the grass and maintaining it at a set level very easily.

Like many power tools, even lawnmowers come in different shapes, sizes, and power options. The most common and popular one is the gasoline engine-powered lawn mower.

Pull-starting the gas engine of the lawn mower is an old technique. Nowadays, most lawn mowers come with electric starters. When we say electric starters, it means there is a battery involved in it.

If the battery is old or dead beyond recharging capabilities, then you have to look for a replacement.

In this guide, we saw the basics of lawnmowers and their types. Then we moved to different types of lawn mower batteries and also some important specifications you need to consider while looking at mower batteries.

After that, we made a simple lawn mower battery size chart. This chart consists of some popular lawn mower battery groups with their physical dimensions.

We hope that this guide on lawn mower battery size chart could help you understand the basics of lawn mower batteries and also in making an easy purchase decision.

If you feel we missed something or want us to add anything, do let us know in the comments section below. If you want, we can add lists of possible replacements in several battery groups (for instance, all the best replacement batteries for the U1 or U1R battery group).

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