Will a Lawnmower Run with a Dead Battery? [Causes + Diagnosis]

Many modern lawn mowers are wireless, which means that they have a lithium battery that needs to be charged to run the mower. Other lawnmowers, such as riding mowers, have a diesel or gas-powered engine and a battery like a car does. If the battery is flat, you won’t be able to run your lawnmower, but you may be able to jumpstart it.

Whichever type of lawnmower you have, it’s a good idea to keep the battery in good condition and fully charged so that your lawnmower works when you want to cut your grass. This article will look at whether a lawnmower can run with a dead battery.

Will a Riding Lawnmower Run with a Dead Battery?

Will a Mower Run With a Dead Battery?

Riding lawnmowers have a battery that is used to start the mower’s engine. If your battery dies, your engine won’t start unless you’re able to jumpstart it.  And, the battery needs to have enough juice to be able to provide a good spark to the spark plug. If it does not, then the engine will run really rough or not at all.

If your battery is ancient and seems to have died quickly, it may be best to replace your battery. Before replacing it, you can (and should) try to recharge your battery which is likely to take a while. If you need to mow your lawn and can’t wait for your battery to charge, you may like to try to jumpstart your lawnmower.

You can jumpstart your lawnmower battery using your car by connecting the lawnmower battery to the car’s battery using jump starter cables. Before attempting to jumpstart your lawn mower battery, it’s best to determine where it’s dead or whether your lawnmower has other issues.

If the mower is turning over fast but won’t start, it’s probably not the battery that is at fault.  Instead of continuing with this article, check out our lawnmower won’t start diagnosis section.

Follow these steps to start your lawnmower if the battery is dying:

1. Check if the battery is the problem

Before jumpstarting your lawnmower, it’s a good idea to check the battery using a multimeter to measure the battery’s voltage. If the measure is 12 Volts, this indicates that the battery’s fine. If the voltage is lower or has a zero reading, this means the battery is dead.

2. Clean the battery terminals

After determining that the battery is dead and the lawnmower needs to be jump-started, you’ll need to check the battery for signs of corrosion. Look at the batteries’ terminals and check for a white or green crust. This substance is acidic, so make sure you wear gloves while cleaning it off. Gloves will also help prevent you from getting a shock from the battery. Corrosion can be cleaned from the battery using baking soda and a wire brush.

If your battery looks in good condition and doesn’t have any corrosion, you don’t need to clean it. If your battery is very corroded or you notice that there’s acid leaking from the battery, it’s best to dispose of the battery safely and then buy a replacement.

There needs to be a tight connection between the battery terminals and the battery posts. If there is not, it can cause the mower not to charge all the way.

3. Charge the Battery

After cleaning the battery terminals, dry them thoroughly, and then jumpstart the lawnmower. You can do this by using a set of jumper cables. Be very careful when using jumper cables; don’t let them touch each other.  You can only do this if the mower has a 12-volt charging system.  If it uses a 6-volt battery, forget about it.  You’ll fry the 6v battery.

Charging the mower’s battery is preferable to trying to jumpstart it. If you have no battery charger, many parts stores will charge the battery as part of the testing process. Since you’ll need to get it tested anyway, we recommend that over jumping it.

If you have to jump it, you can connect the red jumper cable to the positive side of the lawnmower battery and the card terminal. Next, start the car and then connect the black jumper cable to the negative side. Then attempt to start your lawnmower. If you find that the lawnmower engine starts but stops soon after, you’ll need to try again. Once you’ve got the lawnmower started, leave the engine running for a while, with the jump cables attached. You can then remove the jumper cables in the reverse order. Your lawnmower should continue to run, and you can now cut your grass.

4. See if it’s charging

A lawnmower battery needs to charge in the same way that a car battery does. However, unlike a car, which uses only one type of charging system (a belt-driven alternator), there are two types of charging systems that you may find on a lawnmower.

  1. Alternator– An alternator is an engine accessory that is turned by a belt.  If you do have an alternator, it’ll be turned by a belt.  On older tractors, a failure of this belt is one of the most common reasons why a lawnmower battery dies in the first place.
  2. Stator– The stator is a hello magnetic device that is attached to the back of the flywheel. It has a round metal body and is surrounded by prongs that are wrapped in coil wires. It is hard to get to, as it is usually located behind the flywheel.

Will a wireless electric lawnmower run with a dead battery?

Will an electric mower run on a dead battery?

Wireless electric lawn mowers come with lithium batteries which need to be plugged in and charged. If your battery’s dead, you’ll need to plug it in and fully charge, which will generally take between two and three hours. You’ll then be able to cut your grass. Sometimes lithium batteries completely die and are no longer able to hold their charge; if this is the case, you may be able to buy a replacement battery for your lawnmower. Some electric lawnmower manufacturers sell replacement batteries.

Related: Electric VS Gas Lawn Mower


You may find that your lawnmower battery has died and won’t start if it hasn’t been used for a long while. Perhaps your lawnmower has been sitting in the garage all winter and fails to start again in the Spring. If your lawnmower doesn’t start, you can troubleshoot your machine, and if the problem is with the battery, you may be able to jumpstart your lawnmower.

We hope that this article helped you get your mower started.  If it has, you may want to look at our guide to the best time of day to cut grass.  Thanks for reading!