how long does it take to charge lawn mower battery

How Long Does It Take To Charge A Lawn Mower Battery?

Cordless lawn mowers are one of the most convenient garden tools out there but if you want yours to run smoothly, the battery needs to be charged. For users of riding mowers, there is also a need to stay on top of charging your mower battery but a lot of people don’t know how long to charge a lawn mower battery.

A lot of cordless mower batteries will take around 100 minutes to reach a full charge; they will also run for around the same length of time per charge. However, large riding mower batteries could take as long as 12 hours to recharge. There are some that benefit from fast chargers which can see them refilled with power in as little as four hours.

In any case, it’s really important to take good care of your lawn mower battery. In this guide, we will look at how long to charge a mower battery and the best way to maintain it for a longer life.

It is almost impossible to give an exact time for charging a lawn mower battery because each battery is different. That said, there is some information you can use which will allow you to work out how long to charge a mower battery.

These pieces of information relate to the battery voltage and the amperage. Depending on these two factors, the correct charging time for a lawn mower battery could vary drastically.

Start by looking at the amp hours (Ah) of your battery and then divide this by the number of amps of the battery charger. This should tell you how long to charge your battery for.

Factors Involved In Lawn Mower Battery Charge Times

As we have touched upon, there are a couple of factors that will affect how long you need to charge your lawn mower battery. There are a lot of different types of lawn mower batteries out there so it is very important to take these things into consideration.

In order to figure things out, you’re going to need to familiarize yourself with the battery voltage, the charger voltage, the charger amperage and the amperage of the battery. But this can sound a little confusing so let’s take a look in a little more detail.

Battery And Charger Voltage

As we have touched upon, there are a couple of factors that will affect how long you need to charge your lawn mower battery. There are a lot of different types of lawn mower batteries out there so it is very important to take these things into consideration.

In order to figure things out, you’re going to need to familiarize yourself with the battery voltage, the charger voltage, the charger amperage and the amperage of the battery. But this can sound a little confusing so let’s take a look in a little more detail.

Battery And Charger Amperage

As well as voltage, you need to think about the amperage of your charger and battery. If you have a 6 amp or 12 amp battery then it could have one of many amp hour ratings so make sure you look in your manual so you know what yours is.

The difference here is that the charger and the battery do not need to have the same Ah rating in order to be compatible. That said, it’s not usually recommended to have a battery charger with more than 20% of the Ah of the battery. To demonstrate this, if you are using a 40Ah battery, you wouldn’t want a charger with more than 8 amps as this could damage the battery.

Lithium Ion Battery

In modern lawn mowers, you’ll almost always find a lithium ion battery. These batteries are also used for a whole host of other applications including laptops, smartphones and much more. However, the charge times for these batteries will differ greatly and this again depends on the amps and the voltage.

Lithium ion batteries work by releasing a charge to an external circuit. When they are charging, ions are stored inside the battery while the voltage is responsible for the flow of current to the battery. When it reaches its preset voltage, it is fully charged. With your lawn mower battery, the length of time this takes will depend. However, there are now many fast chargers out there designed to boost the speed of charging.

Some lithium ion batteries, particularly larger ones, can take up to 12 hours to reach full charge. These are normally batteries found on heavy duty or large riding mowers. However there are also super fast-charging lithium ion batteries, some of which can take as little as half an hour to fully charge. You’ll normally find these on lightweight, domestic cordless lawn mowers.

lithium ion battery

Lead Acid Battery

Lead acid batteries are a much older concept but we have stopped seeing them as much in lawn mowers as they are not as efficient. The main issue is that, once a lead acid battery discharges, it cannot go back to full capacity.

What’s more, these batteries take a lot longer to fully charge with many having to charge for between 12 and 16 hours. If you’re using a larger lead acid battery then it wouldn’t be unthinkable that it could take up to 48 hours to charge!

If you have a lead acid battery then you need to stay on top of charging as these batteries cannot be allowed to fully discharge. In fact, it is usually recommended that you start charging as soon as the battery reaches 30%. Once it is on the charger, you should not remove it until it is 100% charged. As we have learned, this can take a considerable amount of time

lead acid battery

Comparing Lithium Ion Vs Lead Acid Battery

When you are buying a lawn mower, you may wonder which is the best battery for it. I think it’s pretty obvious that when it comes to charging times, the lithium ion battery always comes out on top. But let’s take a look at lithium ion vs lead acid batteries.

  • Lithium ion uses premium technology to make a more efficient and longer lasting battery.
  • Lithium ion batteries tend to cost more money than their lead acid counterparts.
  • Lead acid batteries need a lot more maintenance than lithium ion.
  • Lead acid batteries have a considerably longer charging time.
  • A lot of lithium ion batteries can be charged in as little as an hour on a fast charger.
  • Lead acid batteries release gas which can cause them to explode in some cases.
  • It is possible for a lithium ion battery to overheat and explode but modern technology means that this is very rare.

How To Keep Your Lawn Mower Battery Healthy

Making sure that your lawn mower battery is well maintained is one of the best ways to ensure it has a long life. There are several things you can do to keep it healthy.

Don’t Overcharge

When you overcharge your battery this will shorten its life as well as decreasing its ability to hold a charge. Over time and through several overcharges, you may notice that the battery starts behaving in strange ways and will eventually give up the ghost.

Use Correct Charger

Your lawn mower will come with a charger or if it is a bare tool, there will be a recommended charger. It’s important to always use this as it is optimized to work with that specific battery and keep it running as it should. Using other chargers comes with a risk of varied voltage which could affect the condition of the battery.

Read Instruction Manual

We might consider ourselves mower experts but there is nobody that knows your lawn mower as well as the people that made it. So, make sure to follow the instructions in the manual to the letter.

FAQs About Lawn Mower Battery Charge Times

Can You Overcharge A Lawn Mower Battery?

It is possible to overcharge a lawn mower battery and this can shorten its life. In order to avoid this, a lot of manufacturers use special chargers to avoid the issue.

How Long Does It Take To Charge A Dead Battery On A Lawn Mower?

If your lawn mower battery is totally dead then you may need to leave it charging for up to eight hours. However, this will vary from product to product so it’s essential to read the user manual for more precise information for your model.

How Long Should I Charge A Lawn Mower At 10 Amps?

If you have a 10 amp charger then you should be able to fully charge your mower battery within about an hour. However, if the Ah rating of the battery is higher then it’ll typically need a little more time to charge. What is great about 10 amp chargers is that there is less risk of overcharging.

How Long Should I Charge A Lawn Mower At 6 Amps?

For 6 amp chargers, it’s going to take almost double the time to achieve a full charge than when using a 10 amp charger. For most batteries, this will mean a two hour charging session.

How Long Should I Charge A Lawn Mower At 40 Amps?

If your charger is 40 amps then this is considered to be a fast charger, as is the case with anything over 20 amps. These charge batteries much more quickly and will often achieve a full charge in less than an hour.

Final Thoughts

To keep your lawn mower running, you must make sure that the battery remains charged. But this can be a pain when you’re waiting to cut the grass and leaves a lot of people wondering how long it takes to charge a lawn mower battery.

There is no cut and dry answer to this question as different batteries will have different charging times. Most modern mowers use lithium ion batteries which charge much more quickly and in some cases, can be fully charged within just one hour.

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Andrew Fisher

Andrew Fisher

Andrew is a dedicated father of three who really takes pride in his lawn and garden. You'll find Andrew behind the scenes of almost everything Edge Your Lawn produces. When he's not helping readers find all the information they need, he's in his backyard working on his lawn and garden landscaping. This year he hopes to build an outdoor deck and sort out his veg patches.