How to charge a lawnmower battery, this is the best way to keep your battery healthy


Most people only use their lawnmowers during the season. During the winter period, they winterize their machine and store it until springtime. But when they want to start the mower when the grass needs a cut, they find out the battery is dead. If the battery is not in good condition, you can even have a dead battery between mowing sessions. It is even possible that some chargers refuse to charge a fully dead battery. In that case, many will replace the battery, even when this is not needed.

How to charge a lawnmower battery

  • Step 1: Locate the battery and check its condition
  • Step 2: If the battery is dead, precharge with an old charger or another battery
  • Step 3: Prepare the charger
  • Step 4: Connect the charger correctly
  • Step 5: Charge the battery, and use the trickle charger functionality
  • Step 6: Check the battery
How to charge a lawnmower battery, this is the best way to keep your battery healthy 1

How to charge a lawnmower battery and keep it healthy:

Charging the battery is not a very difficult procedure. There are only a few things you need. The first step before starting to charge is to check what the battery condition is.

Equipment required:

Only a few tools are needed for this job:

• Step 1: Locate the battery and check its condition

If you measure the voltage on the battery and it is higher than 12 Volt, it means that the battery is somewhat charged. If you measure between 10 to 12, the battery is almost dead, but it will be fine to charge it. If you do not measure anything or a really low voltage, it will mean that most more modern battery chargers will not be able to charge the battery.

An alternative method to check the battery condition is to use a battery checker. This is an electronic device that you can connect to, and it will tell you what the condition of the battery is.

• Step 2: If the battery is dead, precharge with an old charger or another battery

When the battery is really dead and you do not measure something, most modern chargers will not charge. It is always good to try them first, but most often, they will give an error. This is because the charger only works when the battery has some charge in it. The solution to this is to use an old charger that does not have this kind of circuit. Connect it and charge the battery for several hours.

The other method is to use another battery and use it to charge the dead battery slightly. Connect the charged battery with the jumper cables to the dead battery. Let it charge for a few hours. Then disconnect the jumper cables. Always ensure that the battery you use has the same voltage as the dead battery.

The battery of the lawnmower supplies a specific power. Although the voltage is a constant 12 V for most of the engines, the current value might vary. The choice of charger is based on these values. It is

• Step 3: Prepare the charger

The easiest way to charge a lawnmower battery is to use a modern charger. Those chargers contain some electronics that measure the type of battery connected and the best way to charge it. When the battery is almost full, they will change the charging method to keep the battery condition optimal.

If you do not have such a charger, there are also some other methods to charge the battery:

• Step 4: Connect the charger correctly

If you use a more modern charger, connect the two cables to the battery. Set the charging option. Normally the charger has several options. Choose the one to charge a small battery, like a motorcycle battery. Or, if that option is not there, choose the car battery option. When the battery is fully charged, you will be notified on display. At this point, you can disconnect the cables. If you do not need the battery immediately, you can keep them connected. The charger should switch automatically to its trickle charge mode. This way, the battery is always full at the time you need it.

If you use another method, use the alligator clips on the jumper cable to connect the battery. Connect positive to the positive and vice-versa. Ensure the battery’s negative and live terminal do not touch each other directly, which will cause a short circuit and can ruin the battery.

• Step 5: Charge the battery, and use the trickle charger functionality

The charging time depends on the charging method and the size of the battery. It can take from an hour to several hours or a day. If you use a modern charger, it will switch to trickle charging if it is done. Using other methods, you have to check the charging yourself and stop the process. For all, it boils to some patience and until the battery is fully charged.

• Step 6: Check the battery

If the battery is charged, you can reattach it to the lawnmower and use it.

Precautions

Why is the battery important for a gas Lawnmower

Electric mowers are getting more popular these days. Their inner mechanics are a lot simpler, and they use a much bigger battery. Why the battery is important for them is logical. Without them, the motor will not work. They usually come with a specialized charger and will have to be charged before every use. Maybe you own a gas mower instead of an electric mower. But why is the battery still important?

If you have a gas lawnmower, there are 3 main functions that the battery performs:

1. The Lawnmower starting circuit:

As is evident from the name, the starting circuit is the electrical pathway that delivers the initial push to start the lawnmower. Major elements involved are:

  • Starter motor: A high torque motor that turns the engine crankshaft. It provides the force for the first intake and compression till the spark is produced and the engine generates its own power.
  • Solenoid: An electromagnet that becomes active when a current passes through it. It receives the current from the battery. It acts as a relay between the battery and the engine. It ensures that when the engine is started, the contact stops
  • Switch: The switch is like a button that turns on the starter motor and other electrical parts when the key is turned. 
  • Starter Fuse: Acts as a safety switch and protect valuable electrical parts such as the motor, the solenoid, and the switch
  • Battery: The battery provides all the power to the whole electrical subsystem of the lawnmower. The source of power is usually a 12 Volt battery. Some older lawnmowers can still use a 6 Volt battery.

2. The lawnmower ignition system:

The Ignition system consists of parts that ensure that the engine gets the spark and burns the fuel on time. For the combustion of the gas inside the cylinder, a spark is needed. Diesel engines work in a different way. They do not need a spark.

The major components involved are:

  • Ignition coil: The coil is a very tightly wound copper wire. Usually, some greasy paraffin is present inside the core of the coil. The coil acts as a step-up transformer for the voltage that is being provided by the battery. This high voltage is needed as the 12V will not be enough for the spark plugs to create a good spark.
  • Sparkplug Cable: Each sparkplug is connected to the coil using a spark plug cable. The cable is a very well insulated wire with low resistance. The wire takes care that the 22kV is sent to the spark plugs.
  • Sparkplug: The spark plug is the most important component of the ignition system. The sparkplug has a very special ceramic coating over its shaft. This coating makes sure the sparkplug is properly insulated and the high voltage does not jump back to the metal engine. On the outside part of the sparkplug, the boot wire is very tightly fitted. The part in the cylinder has two electrodes. This is the part the creates the spark.

In the lawnmowers that use a starter rope, the stater system is much simpler.

3. Powering the accessories:

You can use various accessories on a lawnmower that are powered by the battery:

  • Lights: Most riding lawn mowers have some lights in the front of the mower. They help if you are moving in a relatively low light environment. Either it is a bit cloudy, foggy, or the sun has set. Having lights on the mower can be a great help in these circumstances.
  • Safety switches and solenoids: A few safety switches present to ensure you can only start the lawnmower if certain conditions are met. For example, the seat safety switch that is on the chair ensures that you can only start the mower when you sit on it. As soon as you leave the seat, the Lawnmower engine will stop.

In an electric lawnmower, the battery has two major purposes: rotating the blade and powering the wheels.

Jump starting a gas lawnmower will work as the engine will take over, providing the energy to keep the mower working. When the engine is running, the battery is continuously charged by the alternator. In the case of an electric lawnmower, this is not possible. As soon as you remove the jump start power source, the lawnmower will stop immediately, as the primary mower battery is empty.

Related questions

1. Can a Riding Lawnmower Run Without a Battery?

As the lawnmowers do not have ECUs (electronic control units), unlike cars, the absence of a battery is not a big issue. Once the mower has started, the battery can be removed. It is not recommended, but it is possible.

2. My charger does not charge my battery

If the battery is dead, it does not have any energy. Most modern chargers will not charge as they need a minimal amount of energy in the battery to know what type it is. To make the battery charge again, you need to precharge it. This can be done with an older simple charger, or you can use another battery to charge it a little bit. See step 2 for more information on this.

3. Why should you trickle charge a battery?

Trickle charging a battery is a process where you keep the battery fully charged. When you store a battery, it will lose some of its charge over time. A modern charger with a trickle charge function will measure this and keep the battery charged and in an optimal state.

4. Do I need to disconnect the battery before charging

No. There is no need to disconnect the battery before charging. You can connect the charger and leave the battery cables connected. If the battery is really dead, would we advise you to disconnect it and charge it separately.

5. Do I need to remove the lawnmower battery during the winter

If you do not use a trickle charger during the winter to keep the battery fully charged, we would advise you to remove it from the lawnmower. To keep the battery healthy, it is good to charge a couple of times during the winter period. That way, it is in good condition when you want to start using your mower in the spring.

Final Remarks

Charging a battery seems like a simple job. In most cases, this is true. But when the battery is dead, some more modern chargers may think that the battery is malfunctioning. In this case, you need to recharge the battery to ensure that it has a minimal amount of energy. When that has been achieved, it can further be charged the usual way.

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