Can a Lawn Mower Be Jumpstarted by a Car Battery?


Like a car, the life of a lawn mower battery is not infinite. They die and usually at the most inopportune times. Although frustrating, there are some options to remedy the situation to get back on the lawn and get it looking nice again. One alternative is jumping the battery like you would a car.  

You can jump the battery as if you were jumping a car. Car batteries typically are 12-volt batteries. A lot of batteries used on a lawn mower are also 12-volt batteries. Do not attempt to jump the battery if the two batteries are not compatible because this can cause a battery explosion and potential injury.

You also must make sure that your car is turned off. The amperage that your alternator generates is too much for your lawn mower and again has the potential to explode. It is not hard to jump the battery, you just need to be safe during the process. Here are some ways to jump-start your battery.  

How Do You Start a Lawn Mower with a Dead Battery?

You can jump start a lawn mower using a car battery, but you need to do it carefully, taking all the necessary precautions.

It is advisable to follow this step-by-step process below. Doing things in order will reduce the likelihood of safety issues occurring, including accidental battery explosions and potential injury to yourself and anyone who may be helping you. 

Inspection of Your Batteries

The first thing is safety. Whenever you jump-start anything you want to make sure your equipment is in good condition. Inspect your jumper cables and ensure that: 

  • There are no frays
  • The jumper cable clamps are firmly attached to the cable
  • There are no breaks in the cable

Next, you want to make sure that the battery in your car and the battery in your lawn mower are rated at the same voltage. Do not attempt to jump the battery if the voltage rating is not the same, the battery may explode and cause injury. While most cars and lawn mower have 12-volt batteries, it is not always the case, so double check before moving ahead. 

You also want to inspect the battery of both your car and the lawn mower. Check for immediate signs of leaking of battery acid or severe corrosion on the battery terminals. If this is observed, it is better to replace the battery. Do not ever open the casing of a battery because there is hazardous material inside that can cause injury. 

You also want to inspect the cables that are connected to the battery. Make sure that:

  • The cables are tight
  • There is no fraying or damage
  • That the battery is mounted securely in place

Wipe away any dust build-up, be very careful around the battery terminals as there is live voltage and potential for injury. 

Set-up Your Cables

If your battery looks good on both your car and lawn mower, then it is time to move on to jumping the battery. To set up, you will need your jumper cables and access to your batteries. You want to position the car and lawn mower in a manner that the cables will reach comfortably with little tension. Make sure neither vehicle is touching as this can complete a circuit and you could have live electricity flowing from chassis to chassis.

You want to identify the positive and negative terminals on both batteries. Then:

  • Connect the red cable, which is positive, to the positive terminal on the dead battery
  • Connect the other end of the red cable to the positive terminal on your car

Make sure the cable clamps are secure and not touching any other exposed metal of the vehicle. 

Next, you will want to:

  • Connect the black cable, which is negative, to the negative terminal on the live battery (yes, the live battery first)
  • Connect the other end of the negative cable to an exposed, unpainted metal object on the dead vehicle, such as a bolt or part of the chassis (again, make sure that the cable is not touching any exposed metal on your car)

This may seem a bit counter-intuitive but it is for safety, it reduces the chance of explosion. Try to find a spot away from the battery if possible. If there is no space to do this, you can use the negative terminal on the dead battery, just be cautious. If you see a spark, be ready to react. 

Jump the Lawn Mower

Now that everything is set up and safe, turn the key on the lawn mower. Remember, do not turn your car on, the alternator from your car provides too much amperage.

You may need to turn the key on your car enough to initiate the electrical power, but do not turn the engine over. This can cause an explosion. The generator on your lawn mower will charge the battery. You are just giving in the juice it needs to start. 

Once the mower is running you can disconnect the cables and close everything up. If the mower is not running, double-check your setup and connections. You also may have a problem somewhere else, or the battery may be so dead that it is time to replace it. 

Disconnect the Cables

The safest way to disconnect the cables is in the reverse order that you connected them originally.

  • Remove the negative cable from your lawn mower
  • Then remove the negative cable from your car battery terminal

Be careful, as there is still live voltage, do not accidentally touch metal or you may get a shock. 

Once you have removed the negative cable, then:

  • Remove the positive cable from your car first
  • Then remove the positive cable from your lawn mower.

Again, practice safety. it is unlikely that you have live voltages on the jumper cables at this point, but you still have an actively running engine and exposure to the batteries. 

It is advisable to let the lawn mower run for a while. This will give the generator on the lawn mower a chance to charge the battery on the lawn mower. While you let it run, you can pack up your jumper cables and move your car to a safe location.

Whenever working on a motor vehicle, whether it is a lawn mower or car, it is very important that you practice safety. When jumping a battery in a lawn mower you are involved with electricity as well as moving motor parts. Safety should be your number one priority so let us take a look at some safety precautions. 

Safety Tips For Jumping Your Lawn Mower

When jumping your lawn mower from your car battery, there are safety precautions that should be observed.

Not only is there an electrical component but also moving motor parts like the blade of the lawn mower, all of which can bring severe injury to you or those around you. Read on to take a look at electrical and mechanical safety. 

Electrical Safety

Getting electrocuted is not fun and it is very dangerous. It takes a trace amount of amperage in a circuit to potentially kill someone. A 10-milliamp shock has the potential to kill someone because our hearts just do not have much resistance. Most lawn mower have 12-amp engines, and the cold crank amps at the start can be much higher.

When working around electricity, make sure the power to the mower is off. It is a very good practice to just remove the keys from the ignition altogether. This way you know for sure that the mower is off. If you have someone helping you, make sure that you communicate with them about what state the mower should be in to prevent accidents. 

Whenever working with electricity, you should always try to work with one hand. If you need to take a cable off or put one on the battery, do this one-handed, and make sure that your other hand is not touching the vehicle chassis or exposed metal. If you do use both your hands, try to use gloves that have rubber insulation. You do not want to create an accidental circuit across your heart. 

As an added precaution, remove:

  • All metal jewelry
  • Wedding rings
  • Accessory rings
  • Even necklaces that can potentially hang low enough to touch electrical components

Always practice safety around electricity. Now on to mechanical safety. 

Mechanical Safety

Working around the engine and blade of a lawn mower means you are around mechanical moving parts. The blade itself is very dangerous. It is always better to be safe, rather than put yourself or someone else at risk, so:

  • Limit the number of people around you
  • Remove small children from the area
  • Make sure the people helping you stand away from the mower when you jump-start it

If the lawn mower has the ability to disengage the blade, that is the best practice. Most mowers have that ability. You do not want the blade to accidentally start moving on you when you jump-start the battery.

Moving motor parts, both on the lawn mower and your car can be dangerous. Try to wear tighter clothing or short sleeves. You don’t want your clothing to get caught up in any moving part of a motor. Also, try to wear safety glasses in case of catastrophic failures. If your battery explodes or a belt snaps, this may be your only protection for your eyes. 

Always use safe practices around your lawn mower. While using your car is one way to jump-start your lawn mower, there are other options available. Some of these options are easier and can be considered a little safer when you do not have to get a second vehicle involved. Consider these options before deciding on what works best for your situation. 

Alternative Options

In some situations, you may not be able to get a vehicle to where your lawn mower is located. Or your vehicle has a battery rating that does not match what your lawn mower uses. In these situations, having a couple of options is good alternatives to a standard jump start:

  • New battery
  • Portable jump starter
  • Trickle charger
  • Combination jump starter

These options, if you do not already have them, will cost a little money, but they are good to have if your dead battery situation happens again and can be used not just for your lawn mower, but other vehicles as well. These options can get you on your way. 

New Battery

A new battery is sometimes the only option you have. If the dead battery may not be recoverable if it has signs of:

  • Leaking
  • Severe corrosion

If these things are the case, then your battery is a safety hazard, and it is dead. It would be a high risk to try to jump it and may cause injury. 

Spending money on a new battery is not always what anyone wants to do, but it is the safest option when dealing with a questionable battery. Also, you know you are going to get some life out of the new battery, and will not have to worry about jumping it anytime soon. 

Portable Jump Starter

If you already have one, then it is no cost to you. Many people carry these in their vehicles as part of their road kits. If you do not have one, they are fairly inexpensive and can be found in:

  • Your local auto parts store
  • Big box stores
  • Online

These devices are so convenient, and are a huge help, especially if you leave your car parked for some lengthy period without starting it. 

The portable jump starter is basically a battery with jumper cables already connected to it. You charge it before you use it using the manufacturer guidelines. Once charged it can hold the charge for quite some time until you are ready to use it. These are great for taking on a long road trip, or if you park your car for an extended time at the airport. You never know when your battery is going to need a jump. 

To use it, the process is simple. You are not using another vehicle, so all you need to do is hook up the cables from the jump starter, positive and negative to the proper terminals on your dead battery. Follow the manufacturer instructions for the unit that you have, as each manufacturer or model operates differently. Once you jump your battery, pack it away, and be sure to charge it again for the next time you might need it. 

The advantage of one of these devices is that they are portable. They are a little heavy but you can carry them to where your battery is. It does not require another vehicle, so the space needed to jump is reduced drastically. Although they are great, they are not the only option.

Trickle Charger

A trickle charger is a device that basically charges your dead battery over an extended period. This option is not the quick fix, but if you know in advance that the battery is dead, you can hook up one of these devices to your battery to get the charge you need to be able to start your vehicle. 

Similar to the portable jump starter, the trickle charger has an enclosed battery with jumper cables already hooked to it. To use it, you hook it up the same way you would the portable jump starter:

  • Positive cable to the positive terminal
  • Negative cable to the negative terminal. 

Trickle chargers also come adaptable, meaning you can change the battery voltage and amperage of the unit, to match the battery rating of your dead battery. For instance, if you have a 12-volt lawn tractor battery that needs a charge you can adjust the device for that, if your car or truck has a 24-volt battery, you can adjust the trickle charger for that as well. Allowing you to use this device for multiple types of batteries. 

The only difference between the portable jump starter and the trickle charger is that the jump starter is ready to jump your battery now. The trickle charger will charge the battery, like when you charge your phone battery. So, it will take some time and that will depend on the manufacturer and model you have. We have one other option to look at. 

Combination Jump Starter

The last option is combination, and that is exactly what it is. It is the combination of a portable jump starter and trickle charger all rolled into a single package. Some even come with built-in air compressors to serve multiple needs. Although, they are a little more expensive because of these extra options. 

These are great devices because it gives you a lot more for your dollar, and is fairly inexpensive, you can find them for less than $100 in stores and online. The option to fix multiple problems is great, especially when you are on the road. Like the others

  • They are portable
  • Operate similarly to the other machines

Just follow the manufacturer’s instructions. 

Conclusion

Lawn mower batteries function very closely to that of a car battery and can be jumped using car batteries. Taking care of them is similar as well. You always want to practice safety first. Jumping a battery is not hard, but it does involve electricity, and you can be near-moving parts of an engine at times. Practicing safety should be your number one concern. 

Using alternative devices to jump your car battery is the best option for you when it comes to portability and safety. Often, they have built-in safety indicators that will tell you if your cables are not hooked upright. These features can prevent damage to the battery and to you as well. Always use safe practices when working on any vehicle whether it is your lawn mower or vehicle. 

Powered Equipment Team

We're just a guy and a girl obsessed with outdoor power equipment! We are excited to share the knowledge and tips we have learned over our combined 55 years in the power equipment industry. We have both ran equipment dealerships and took pleasure in helping our customers everyday providing equipment repair, parts, purchasing, and business tips to our residential and commercial clients. We hope our blog will help you with your next purchase, repair, or project.

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