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How Do I Charge a Lawn Mower Battery?

We had an old ride-on lawn mower once that had a dead battery. I tried to recharge it but the battery had been damaged over the winter and couldn’t hold a charge, so we ended up buying a new one (battery not mower!). So how do you test and charge a lawn mower battery so your ride-on starts first time every time?

Wearing gloves and goggles, connect your battery charger’s red cable to the positive terminal and the black cable to the negative terminal on your lawn mower battery. Set the voltage and amp level, ensuring they match the battery’s. Switch on then disconnect the charger when the battery is full.

Let’s explore the subject of charging your lawn mower battery in more detail, and discover the exact steps to do it safely, how to jump-start a mower, and how to winterize your battery so it’s not damaged during the colder months…

Can You Recharge a Dead Lawn Mower Battery?

Yes, you can recharge a dead lawn mower battery – which is just as well, as many die over the long winter period! Many gardeners unlock their sheds in the spring, go to turn the key in their ride-on mower, and… the sound of silence

Luckily, with a bit of know-how, you can get that mower battery going again. We’ll take a look at how you recharge your ride-on mower battery.

How Do I Charge My Dead Lawnmower Battery?

It’s a simple process to charge a dead mower battery, provided you know what you’re doing. Here’s how:

  1. Put on your gloves and safety goggles, just in case any sparks fly
  2. Find the battery. It’s usually under the mower’s seat, and it can stay in place during the charging process
  3. Connect the battery charger’s red cable to the positive battery terminal and the black cable to the negative terminal
  4. Set the voltage and amp level, making sure that the voltage matches your battery’s voltage (most modern mower batteries are 12 volts)
  5. Plug the charger into a wall socket, ideally in a ventilated space
  6. Disconnect the charger when the battery is full

How Long Does It Take to Charge a Mower Battery?

It generally takes about an hour to fully charge a lawn mower battery. This timing is based on a standard, 10-amp charger. Add on extra time for a lower-amp charger: for example, a 5-amp charger will take around 2 hours to do the same job.

If you’ve been charging for hours, and there’s still no life, it’s time to go get a new battery.

Can You Charge a Lawn Mower Battery With a Car?

Yes, you can, and here’s how you do it:

  1. Move the car and mower next to each other on a flat surface like the driveway. Put both into park, and turn off the car engine
  2. Put on those safety goggles and gloves
  3. Open the car hood, and locate the battery. Also locate the mower’s battery (usually under the seat)
  4. Check the voltage of both batteries, because this has to be equal. If it’s not, quit now, as it’s not safe to charge the battery using your car
  5. If it’s equal, go ahead. Disconnect the car battery
  6. Connect the batteries using charging cables. Connect the positive red terminal of the mower battery with the positive red terminal of the car battery. Connect the negative black terminal of the mower battery with the negative black terminal of the car battery
  7. Make sure it’s worked by turning on the mower. Nothing? Charge it a while longer. Working? Excellent. Disconnect it carefully 

Can You Jump Start a Lawn Mower With a Battery Charger?

What if you can’t get to a flat driveway and a power socket, and your mower runs out of juice? You can jump-start it using a battery charger. 

Landscaping with Zach takes you through how to get the battery going using a portable charger. Watch this short film to see how to jump-start your ride-on mower with a charger.

Can You Jump a Lawn Mower Battery With a Car?

Yes, you can, provided the mower has a 12-volt battery. If it hasn’t, there’s a danger that this method will overload it. 

Overloading happens easily: just think how much more powerful a car battery is than a mower battery. If you’re using this method of jump starting, always switch the car engine off before turning on the mower, or prevent the alternator from overloading the mower battery. 

Can You Charge a Lawn Mower Battery Still Inside the Mower?

Yes, generally speaking, it’s safe to leave the mower battery inside the ride-on mower while you’re charging it. 

Make sure the mower is in a safe, flat location with plenty of ventilation, and wear safety goggles and gloves in case there are any sparks.

How Do I Know if My Lawn Mower Battery Is Bad?

Aside from the motor not coming on when you turn the key, there are other ways of telling if your ride-on lawn mower battery is bad. Firstly, have a quick (and careful) visual inspection. Signs to look for include corrosion, cracks, and bulges. If you see these, it’s time for a new battery.

You can also use a multimeter to test the battery. These handy devices connect onto the battery and give a reading of its voltage. Charge the battery first, otherwise, you won’t get an accurate reading.

Lawn mower battery charging

How Often Should You Charge a Lawn Mower Battery?

Lawn mower batteries don’t need charging very often. There are three main occasions when you need to charge the mower’s battery: after the winter, if you’ve completed a large mowing job; if you’ve left the keys in the ignition (and yes, we’ve all done that…)

How Long Does a Lawn Mower Battery Usually Last?

Generally speaking, a lawn mower battery has a working life of between three and five years. Obviously, the better care you take of it, the longer it should last. If it goes bad within a year, then it’s back to the manufacturer or store.

What Keeps Draining My Lawn Mower Battery?

There are several things that can cause a battery to lose charge, such as poor or corroded connectors or a loose connector.

If you’ve tried to charge it for several hours and nothing is happening, then it’s dead and beyond recharging. (We’re assuming, of course, that you’ve remembered to remove the keys from the ignition…)

How Do You Charge a Lawn Mower Battery Over Winter?

Are you putting your mower into storage over the winter? Ideally, you want to rest the battery as well, rather than leave it on charge when it’s not needed. If you leave the battery on charge, you risk overcharging it, which will cause a lot more problems than the battery simply running out of juice.

The easiest way to take care of your mower battery during this period is to start by charging it fully. Once it’s charged, disconnect the negative terminal. It’s now ready for winterizing.

Some folks completely remove the battery over winter, storing it in a safe, dry place away from any flammable or combustible materials. This gives you a great opportunity to give the mower a good old clean.

However, in some circumstances, you might decide to keep your mower battery on a really low trickle charge over the winter. This is a different process to a standard battery charge, and we’ll take a closer look at this in just a moment.

Should I Put My Lawn Mower Battery on Trickle Charger?

The main use for a trickle charger is to keep a little-used vehicle ticking over, so that it’s ready to use in an emergency. As there are very few emergencies that involve mowing a lawn in the winter, it’s arguable whether this is a good use of your resources.

Most gardeners will disconnect the battery in November, then give it a good charge again once the grass begins to grow.

However, in some climates, trickle chargers have an important function: taking care of the lawn mower battery in freezing weather conditions.  

Trickle chargers work by delivering a very low and slow charge to a battery. This prevents the battery from becoming cold as well as completely running out of power. So, if you live in a region that gets very cold winters, a trickle charger can be a really good idea, preventing the battery from freezing or cracking.

These chargers work like normal battery chargers, except that they deliver a constantly low charge. Were you to leave your mower battery on a conventional charger for an extended period, the battery could become “overcharged” and damaged. However, this extremely low current (usually between one and three amps) doesn’t cause this problem.

Final Words

Ultimately, if you’ve tested your lawn mower battery and it’s capable of holding a charge, then following the simple steps above will get you up and running again in no time.

Make sure you then winterize and care for your battery properly so you don’t have recurring problems when mowing weather returns again.

However, if your battery is completely spent like ours was, then buying a brand new one is relatively cheap and could be your best option if you’ve tried everything else. Happy mowing! 🙂

Mark H.

Homeowner and property investor Mark H. aspires to bring you the very best outdoor living content, based on his years of experience managing outside spaces. Read more >