Can I Charge a Lawn Mower Battery with a Car Charger?

Approx Reading Time: 7 minutes

There are only a few things that riding lawnmowers and standard vehicles have in common, one of which being the use of a battery to start up and run. So, if you happen to have a lawnmower with a dead battery and only a car battery charger nearby, can you, and should you, use it to charge it? 

Can you charge a lawnmower battery with a car charger? Yes, you can charge your lawnmower’s battery using a car battery charger; simply connect the mower’s battery to the charger using the jumper cables that are already attached to the charger. However, this process only works on 12-volt batteries. 

This is definitely a process that you can carry out within the boundaries of your own home without the need of professional help. However, there are some precautions you must take to avoid causing any damage to your lawnmower or your surroundings.

Why Do Lawn Mowers Run Out of Battery?

Everything eventually runs out of battery power. However, many cars and lawnmowers use gasoline to keep running and have a mechanism in place that will keep recharging the battery as long as it is functional. Therefore, you might be wondering: Why did my battery run out when I wasn’t even using the mower?

The answer to this question is usually cold weather. Lawnmowers use lead batteries, which are known to slowly discharge under cold temperatures. Therefore, if you are facing this problem in the spring, it was most likely the freezing temperatures of the winter that caused the problem, and this is entirely normal.

If your battery is damaged or you know that something besides the battery is wrong with your lawnmower, don’t hesitate to contact a professional; handling lead batteries can be dangerous.

Preventing Battery Drainage

One thing you could do to avoid your battery discharging during the winter would be to store your lawnmower somewhere where the temperature is not as cold during the season. Also, you could turn it on now and then during the winter months so that the battery recharges.

However, you are most likely reading this article because your battery is already discharged, and you are looking for a way to bring it back to life using your car battery charger, so let’s get right into it.

How to Recharge a Lawn Mower’s Battery Using a Car Battery Charger

Battery chargers have been around for a while now. A few years back, they had the major flaw of not being capable of detecting and avoiding overcharging a battery. However, battery charger technology has made that a problem of the past, and you can now safely use them to recharge batteries of different types, including that of a lawnmower.

If you don’t have a battery charger at home, or just want to upgrade to a newer model, you can buy one on Amazon.

The process of using a car battery charger to charge a lawnmower’s battery is simple:

  1. You must first disconnect the car battery charger from its power outlet if it was already connected to one. 
  2. Connect the charger’s red cable to the positive terminal on the mower’s battery, then the black cable to the negative terminal of the mower’s battery.
  3. Then, change the voltage setting on the charger for it to match your battery’s voltage (for modern lawnmowers, it is usually 12 volts). 
  4. Next, connect the battery charger into a power outlet once more, and then wait for your lawn mower’s battery to be charged. If you are using a standard 10-amp battery charger, it may take an hour until your mower battery is fully charged. Battery chargers with fewer amps may take longer. 
  5. Finally, you can disconnect the charger in the opposite order in which you connected it, and you’re set.

This method is a pretty good alternative for charging a dead lawnmower since it is efficient. The battery charger even has multiple fail-safes in place to protect you against any accidents that may occur due to the battery overcharging. 

A word of caution: Do not do anything outside of what is mentioned in the steps above and be careful with where you connect the jumper cables. The charger may have multiple fail-safes, but you don’t want to find out how far they will go when it comes to avoiding accidents.

Battery Charging Alternatives

If you don’t happen to have a car battery charger at your disposal or you are not able to purchase one, there is another method that you can try: using your vehicle’s battery itself. 

Note that this alternative will not effectively charge your mower’s battery to its full capacity, but should give it enough of a boost to start it up and move it where you need to. In addition, this method will only work on mowers with 12-volt batteries.

This process is pretty simple and straightforward and works similarly to how you would jump a car using jumper cables attached to another vehicle’s battery:

  1. The first step is to locate your lawn mower’s battery, which is usually found under the seat. 
  2. Then, get your car close to your lawnmower. You want the hood of the car to be facing towards the mower so that the jumper cables can reach both batteries.
  3. Make sure you turn off the car and set the brake in place, since having the engine running during the whole operation could result in either one or both batteries being damaged.
  4. Next, you should open the lawn mower’s battery compartment under the seat so that it is exposed, and remove the plastic covers protecting the battery’s terminals; do the same for your car’s hood and battery.
  5. The order in which you connect the jumper cables is crucial: The red cable goes first on the positive terminal of the lawn mower’s battery, with the other red end on the positive terminal of the car’s battery. Then, the black cable must be connected to the negative terminal of the car’s battery, and the other black end on a piece of metal on the lawnmower’s frame. Make sure that where you attach the black cable on the mower is not near its fuel tank or battery.
  6. Now that the cables are connected, try starting your lawnmower to see if it worked. If it did not work, then don’t worry, leave the batteries connected for a few minutes and later try again. Once the mower is up and running, disconnect the batteries in the opposite order in which you connected them.

Check out this video to see how it’s done: 

It is essential that you disconnect the lawnmower from the car as soon as possible rather than leaving them connected for longer than needed since this could overcharge the battery and result in an accident. 

What to Do if Your Battery Won’t Charge

If you find that your battery will not jump or charge, chances are you can still bring it back to life. Check out this website if you want to learn how!

In Summary

Charging your mower’s battery using a car battery charger is possible as long as your battery is in good shape and is 12-volts. A battery charger will make the process much more straightforward and safer for you since it is specifically designed to revive batteries.

If you do not have a car battery charger on hand, but a pair of jumper cables are available, then there is an alternative charge method that is just as efficient, which is using your car’s battery.

However, this solution only works to give your mower enough power to start up and drive it to a desired spot in the yard. It is not intended to provide your battery with a full charge, and doing so repeatedly could cause your battery to wear down faster. 

Peter Toth

Hi! I'm Peter, the owner of BackyardGadget. Working around the house has always been a big part of my life. I've created this site to share my experience, and to help people choose the right tools for the job. Thank you for stopping by!