Electric lawnmowers come with their own set of problems. While they may be easier to fix than gas-powered lawnmowers, they have their own set of challenges. For example, if your electric lawn mower starts then dies, you have one of the more common problems electric mowers face. So, what can you do to fix your mower? First, you’ll need to diagnose the problems and understand what your lawn mower is doing, or should I say not doing. Therefore, let’s look at ten potential causes and figure out why your lawn mower is acting up.
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Electric Lawn Mower Starts Then Dies (Overview)
Electric lawnmowers generally start then die due to either a loss of power, a defective electrical component, a safety feature, or lack of servicing. Potential causes for these issues would include the following:
- Power Supply
- Power Cables
- Internal Trip Switch
- Power Switch
- Power Lever
- Carbon Brushes
- Motor
- Power Rectifier
- Thermal Cut-Off Switch
- Electrical Connections
Electric Lawn Mower Starts Then Dies (Symptoms)
Before you get into each of the potential causes, let’s first take a closer look at what’s actually going on. What do I mean by this? Well, does your mower start then die, and that’s it? Does it keep starting and dying repeatedly, or does it come back on after a while without you doing anything? These three symptoms will point you in the right direction and help you determine which of the ten issues could be the cause.
Potential Causes Why Electric Lawn Mower Starts Then Dies
Now, let’s look at the ten potential causes, understand what each means, and how the symptoms relate. Let’s dive in.
Power Supply
So, what is the power supply? This is different for battery and corded electric mowers, but the idea is the same. Is the power coming from the outlet or the battery? For corded lawnmowers, you’ll need to verify the outlet works by checking that the breakers and GFI’s aren’t tripped. For battery mowers, you need to ensure the battery is charged. As simple as this sounds, this is probably the most common cause for an electric lawn mower to stop working.
Symptom: If there is no power or the power suddenly stops, your lawn mower will stop. Your mower will shut off depending on when you lose power, say partway through mowing. If the power stops, then the mower stops. One thing to remember is that your lawn mower won’t start again until you fix the power. So if your lawn mower suddenly starts working again, then the power supply is not the problem.
Power Cables
Next on the list are power cables. Only corded lawnmowers deal with this issue. Problems such as corroded sockets on your cable or damaged/frayed wires can lead to your eclectic lawn mower stopping.
Symptoms: Depending on the extent of the cable damage, your lawn mower might stop and refuse to start up again. But tugging the cable or shaking the connection might be enough to get your mower fired up again. Sometimes, the movement of the cable is enough to restore the power.
Internal Trip Switch
Some electric lawnmowers have an internal trip switch that kicks in whenever your lawn mower draws too much current. Typically, this type of switch trips whenever your lawn mower overheats or an electrical fault forces the mower to draw too much current. For example, if there is an issue with the windings inside the electric motor or restricted ventilation, your lawn mower’s trip switch will trip.
Symptoms: If the trip switch does trip, then your lawn mower won’t start again until you reset the switch. So, with this specific problem, your electric lawn mower will start and then die.
Power Switch
The power switch is a small push-button switch inside the lever mechanism located on your lawnmower’s handlebar. This switch activates when you pull the run lever and then deactivates once you let go.
Symptoms: Now, there are a few different ways in which a faulty power switch can affect your lawn mower. For example, if the connections on the switch are corroded or loose, then the motor receives no power or intermittent power. As a result, your lawn mower may start and then die and begin working again. However, if the connections are really bad, your lawn mower will likely stop working altogether. Also, an electrical short within the power switch will stop the mower from working and more than likely trip the internal trip switch or the breaker/GFI at the outlet, depending on the power source.
Power Lever
As I mentioned, a power lever allows the power switch to activate and deactivate as you pull and release the lever. If the lever mechanism is damaged/worn out, the power switch won’t work as intended.
Symptoms: If your lawn mower is pretty old, then it’s likely that the lever is worn down on the inside. Also, if the lever is loose within its housing, it may not be able to engage the switch as intended. These two problems will either cause your electric lawn mower to work intermittently or not at all.
Carbon Brushes
Carbon brushes can be found on both corded and battery-powered electric lawnmowers. The brushes transfer power from the static part of the motor to the rotating part. These brushes wear down with every revolution of your mower’s electric motor. If the brushes wear down beyond their usable limit, they will no longer transfer power.
Symptoms: When brushes first get close to their limit, they can sometimes cause your lawnmower’s motor to start and stop intermittently. But, the usual symptom is that your electric lawn mower stops, then dies and won’t start again.
Electric Motor
There are several different problems the motor can face, from bad windings and bad bearings to too much overwork. Now, depending on the problem, your motor may be faulty or just protecting itself. So, the symptoms can vary.
Symptoms: If the motor overheats, the thermal cut-off switch will break the electrical circuit. So, your mower will start and then die, but after a while, start back up again once the motor has cooled down. If the motor has a bad connection, then it might completely stop working or work intermittently. Issues such as bad windings usually cause your lawn mower to stop completely.
Thermal Cut-off Switch
The thermal cut-off switch is designed to break the mower’s electrical circuit once the motor reaches a specific temperature. For example, Kobolt uses a thermal cut-off switch that breaks the circuit once the motor reaches 130 C / 266 F. So if the motor stops working at these temperatures, your mower is doing what it should. But, the thermal switch can stop working. For example, the thermal switch can suddenly break the circuit at lower temperatures or fail to reconnect the circuit altogether.
Symptoms: The thermal switch should break your lawnmower’s circuit once it reaches the temperature limit. Then, it restores the circuit once the motor has cooled to an acceptable temperature. So, if your mower starts then dies but starts up a while later, then this is okay. But if your lawn mower is cutting out and not starting again or is cutting out when the motor isn’t too hot, then the thermal switch is faulty.
Electrical Connections
Aside from the connection between your lawnmower’s battery or power cord, several more electrical connections are inside your lawnmower. These can include connections such as the brushes, rectifier, motor, and power switch. If any of these connections are loose or corroded, your lawn mower will have trouble working.
Symptoms: Corroded or loose electrical connections will cause your lawn mower to work intermittently or not at all. So, your mower will likely start, then stop, or not work at all.
Power Rectifier
Power rectifiers are small devices that convert AC power to DC. You will only find them in corded lawnmowers. Issues such as a short circuit or burned-out diodes inside a rectifier prevent your lawn mower’s motor from receiving power.
Symptoms: A faulty power rectifier can’t supply power to the motor. This means your lawn mower will start and then die. At no point will a burned-out power rectifier begin to work again. So when it’s bad, it’s bad. Unless, of course, it’s just a bad connection.
How to Fix a Lawn Mower that Starts then Dies
Now let’s look at what you can do once you have diagnosed what is causing your lawn mower to start then die. Here are my ten fixes to get your mower up and running again.
Restoring Your Mower’s Power Supply
To fix your lawn mower’s power supply, you’ll want to check the power outlets, breaker, and GFI and double-check that your lawn mower battery is fully charged. Once you’ve reset the breaker and GFI or charged the battery, your lawn mower should have no issues starting again.
Inspecting the Lawn Mower Power Cables
Disconnect the power cable from your lawn mower and power outlet and check for any damage. Inspect for any breaks in the plastic insulation and any bad twisting in the cable. Both of these problems can stop the power from reaching your electric mower. If you find any damage, then replace the mower power cable.
Internal Trip Switch
If your lawn mower’s trip switch has tripped, then all you need to do is reset the breaker. All you have to do is flip the switch back into the ON position.
Replacing the Power Switch
If you have a faulty power switch on your lawn mower, you’ll need to install a replacement. Usually, this is done by removing the switch cover, disconnecting the old switch, and installing a replacement. This a pretty quick and inexpensive repair that you should be able to complete in ten or so minutes once you have the replacement switch in hand.
Replacing the Power Lever
Fixing a broken or worn-down power lever is an easy repair. Even a person unfamiliar with repairing tools should be able to complete it. All you need to do is remove the power switch housing cover, remove the old lever, and install a replacement lever. With a replacement lever and a screwdriver on hand, you should complete this repair in just ten minutes.
Carbon Brushes
Replacing carbon brushes is something that every electric lawn mower owner will have to do at one point or another. Why? Well, these parts are what you call “serviceable parts.” So, they are part of regular servicing. This repair is a little trickier, but if you follow the instructions in your owner’s manual, you should have them swapped out in no time. Just remember that you need replacement brushes specific to your lawnmower make and model.
Replacing a Motor
If you diagnose that your motor is bad, you’ll need to install a replacement. This can be easier said than done, not because it’s a difficult repair, but because getting hold of a new motor can be challenging. Typically, I find that manufacturers make it difficult or nearly impossible to get a new motor. Usually, they suggest you send the mower in for repairs. For some lawnmowers, this is pretty straightforward. However, you need to be aware having the manufacturer install a replacement motor can cost more than buying a new lawn mower.
Installing a New Power Rectifier
Power rectifiers usually have two wires in and two wires out. So, installing a replacement power rectifier takes no time at all. You only need to be aware that power rectifiers are usually attached to some type of heat sink to help dissipate heat. When installing a replacement, you must apply thermal paste between your new rectifier and heat sink. If you don’t, then your new rectifier will burn out pretty much straight away.
Replacing the Thermal Cut-off Switch
Thermal cut-off switches are simple devices usually made up of two wires and the switch. So, all you need to do is remove the old switch and install your replacement. To do this, remove the motor cover to locate the thermal switch, disconnect the two connectors, and install your replacement thermal switch. Just remember to place the switch in the correct position as the switch reads ambient temperature. So, its location is important.
Repairing Electrical Connections
If your mower has faulty electrical connections, they are likely disconnected, loose, or corroded. You can clean electrical connections with sandpaper and an electrical contact cleaner. For loose connections, you should be able to crimp the connection with a pair of pliers to close the gap in the connector. As for wires that have completely fallen off, you can just go ahead and reattach them to their correct location. Repairing electrical connections takes no time at all.
