Are Lawn Mower Batteries 12Volts?

As an Amazon Associate, this site earns commissions from qualifying purchases. For more information click here.

If you have a rider mower, at some point you will have to replace the battery. You can only use the exact type installed on the mower, otherwise the machine won’t run. You have probably seen a lot of 12V lawn mower batteries, but are they the only ones used? After thorough research, this is what I have learned.

The majority of rider mower batteries are 12V, though some electric push behind mowers have 36 or 40V batteries. Smaller mowers may use 6V batteries.

How Do I Know if My Lawn Mower Battery is 12V?

If you look at the top of the battery you will see its size label. You will read something like “12V” or “6V”. You can also find this information on your owner’s operating manual.

A typical 12V rider mower battery is 8.3×5.1×7.2 inches (LxWxH). A 6V battery is smaller and specialized ones like a 40V have different specs.

A 12V lawn mower battery falls under the category of U1 batteries. Do not confuse U1 batteries with U1R. A U1R battery is not going to work with a rider mower because its cable is different. If you are going to replace the battery, make sure it is an exact match.

This is all less complicated than it sounds like. Your owner’s manual, the manufacturer website and the battery itself indicates the size and type.

What Battery Type Do Lawn Mowers Use?

Lawn mowers use two battery types: lithium and lead acid. There are significant differences between the two.

Lead Acid Batteries. Most lawn mowers use 12V lead acid batteries. This battery can adjust the charging voltage depending on the temperature.

Lead acid batteries are affordable which is why they are common. However, they do require maintenance.

A typical lead acid battery also has a 50% depth discharge. Meaning,, you should only use 50% of the capacity, then it has to be recharged. If you let a lead acid battery drop to 0%, it will have a negative effect and shorten the battery’s lifespan.

Lawn mower lead acid batteries have two sub types: gel and AGM. AGM in particular is becoming popular because it has a better depth discharge rate than a typical lead acid battery.

My pick is the ML18-12 as it has a solid depth discharge. It is also reliable and works well with rider mowers.

Lithium Batteries. Lithium batteries need very little maintenance and are more efficient than lead acid. The depth of discharge is 85-100%. Meaning, you can empty the battery without worrying about the effect.

The drawback is the cost. Lithium is more expensive than lead acid. But if you use your lawn mower a lot and don’t like recharging often – and the maintenance required – a lithium battery could be for you.

My choice is the NOCO Lithium NLP20 because it has a long lifespan. It is compatible with rider mowers and needs no maintenance.

How Long Does a 12V Lawn Mower Battery Last?

Lawn mower batteries are good for 3-5 years. But it can last longer with proper maintenance. Lack of maintenance and misuse also means the battery can stop working in just a few months.

The lifespan of a 12V lawn mower battery also depends on how often you use it. Most electric lawn mowers can run for 60 minutes on a full charge. Newer, more efficient models can last longer.

But a lot of factors come into play. The type of grass you mow is an obvious example. Thicker grass requires more power and will wear the battery out faster.

Even if you have same battery installed on similar lawn mowers, the one mowing thicker, tall grass will drain the battery faster.

How to Make Lawn Mower Batteries Last Longer

Read the manual. Use the lawn mower only as directed. This is one of the best ways to preserve battery life. Misuse and mishandling can ruin batteries, so follow what the manual says.

Use only needed features. If you can do without the mulch blade or self-propellant, you will save battery life. You are going to need all the juice if you have to mow a large area.

Wait for the grass to dry. Wet grass is heavier and requires more battery power to cut. Wait for the grass to dry before starting. This can save quite a bit of battery power. This will be obvious if you clean and clear a lot of grass clippings.

Mow every two weeks. This sounds counter intuitive. Why would mowing often be good for 12V batteries?

If you only mow once a month – or less frequently – the grass will grow higher and thicker. That is going to require a lot of battery power to clear up.

Lawn mowers consume less power when used regularly on light grass. In contrast, mowing thick grass irregularly uses a lot of power. So don’t wait for the grass to grow before you mow again.

Always mow with a full charge. 12V batteries are optimized to run at a full charge. This also allows you to use the lawn mower for a long time. Just make sure you don’t go beyond the battery’s recommended depth discharge rate.

Can You Charge a 12V Lawn Mower Battery?

The process for charging batteries is similar, regardless if the lawn mower blades are reverse thread. The following instructions show you how it is done.

Step 1

Rider mowers made after 1980 use a 12V battery. Just to be sure, check your owner’s manual. If it does have a 12V battery, use the 12V charger that came with it.

Some battery chargers let you switch between 6V and 12V. Set it to 12V. Make sure also the charger is set to 10 amps or lower. Anything higher than 10 amps can damage your lawn mower.

Step 2

Now that your battery and charger are set, put on safety glasses and gloves. Thick, mechanical gloves are the best for this situation.

A safety check first. Look for signs of torn cables, tears in the battery case and battery damage. Battery damage can be rust, warping, bent out of shape etc. Do not charge if any of these signs are present. Replace the battery first and have an expert examine your lawn mower.

Step 3

Look for the battery. In most rider mowers it is located under the hood or under the seat. Look it up in your manual if you are not sure. Regardless where the battery is, you do not have to remove it.

Step 4

After you find the battery, disconnect the charger from the wall socket. Connect the positive clamp onto the battery’s positive terminal. This is usually red and/or marked ‘P’, “+” or “Pos”.

Connect the negative clamp to the negative terminal on the battery. It is often black and/or marked “N”, “-” or “Neg”.

Plug the battery charger into a wall outlet. The battery will start charging.

The charging time depends on the battery capacity and how depleted it is. Modern mowers have indicators for the charging status.

Unplug the charger when the battery is fully charged. Remove the cable clamps from the battery. If you are using lead acid batteries, wait 5-7 minutes after charging before you pull out the clamps.