Do Lawn Mowers Have Alternators?

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Do lawn mowers have alternators? The answer depends on the type of lawn mower. Some mowers such as riding lawn mowers have alternators while some like push and fuel-powered mowers don’t.

In this article, you will find out why some top rated lawn mowers are equipped with this component and why some are not. 

What’s an Alternator?


An alternator is a lawn mower’s source of power that helps maintain battery power levels. When you set the ignition off, the alternator springs into action and powers the battery to keep the mower operational.

As previously mentioned, not all mowers come with an alternator. For instance, while push or petrol-powered mowers don’t have this component, riding mowers do. This is because most mowers require less energy than riding lawn mowers and can make do without the power source.

Push mowers, for example, require physical energy to move it around. Cordless electric mowers also depend on rechargeable batteries while gas-powered mowers derive their energy from the fuel. 

These mowers already have a source of energy and are okay without an alternator while a riding mower needs it to provide enough energy it requires to cover a larger area of ground while working.

Aside from that, riding mowers have some components such as starters, headlights, and electric clutches. It needs a battery to power all these components. 

The alternator charges the battery, which in turn, powers these electrical components. Without the alternator, the battery will be dead in no time.

How Does an Alternator Charge a Mower Battery?


An alternator charges a lawn mower battery using any of the two charging systems: belt-driven alternator and stator alternator.

  • Belt-driven alternator: This charging system is driven by a belt. The alternator generates the energy it needs to recharge the battery as the belt turns it.
  • Stator alternator: This is located under the flywheel, on top of the engine. It is a round, metallic system with a central hole. Some prongs that are wrapped in coil wires surround the central hole. The stator creates electricity as it turns over the stator. The generated power is forwarded to the battery to charge it.

Sometimes, though, the battery may not charge. In that case, how do you determine whether you are dealing with a dead battery or a faulty charging system?

Signs of Faulty Charging System

Like every other machine component, the charging system may be faulty and that may hamper its operation. Some of the symptoms of a faulty charging system are:  

  • Damaged wire: The charging system’s wire may be damaged due to overuse or other factors. With the cable mutilated, the alternator won’t work.  To make the system functional, replace the wire.
  • Disconnected wire. Disconnected wire means a non-functional charging system. However, unlike the damaged wire that needs replacement, connect the wire to keep the system working.
  • Broken alternator belt: The alternator belt keeps the alternator working. Without it, the charging system becomes non-functional. The broken alternator belt must be replaced for it to work.
  • Loose alternator belt: A loose alternator belt has the same effect on the charging system as a broken belt. To fix this, simply readjust the belt and the alternator is good to go.
  • Battery not charging: A good battery is expected to charge normally with a functional charging system. Thus, if a good battery isn’t charging, the charging system may be the cause.

These are some common problems with the charging system. However, before you conclude that the charging system is faulty, charge the battery with a battery charger. 

Once the battery is fully charged, test it with a digital multimeter. From the result, you can determine the source of the problem: either the battery or the alternator. 

If the multimeter readings suggest a working battery (10.5 volt and above on a 12-volt battery), the charging system is faulty. Otherwise, the battery is defective.

However, if the battery doesn’t charge, it may have gone bad. Other signs include battery not recharging or discharging at an alarming rate. 

To confirm the battery’s real condition, test it with a voltmeter. If the reading is not more than 11.5 volts, the battery has probably worn out. In that case, the battery, not the charging system, is faulty.  

How to Check Your Alternator’s Condition

  1. Turn the lawn mower’s headlight on.
  2. Turn the engine off.
  3. If the lights don’t dim, the alternator is bad. Otherwise, the alternator is good.

For a comprehensive diagnosis of the charging system, Briggs and Stratton, provides a detailed step-by step guide to help you check your alternator with ease. However, if you are unsure of your ability to personally handle the diagnosis, hire an expert to help you out. 

Your lawn mower may come with an alternator or not, depending on the type. If it doesn’t, that’s fine. If it does, it plays a crucial role in your mower. 

The mower can’t work without it. So, understanding how the alternator works and the symptoms it displays when it is faulty will help you keep the alternator in the best condition and make your lawnmower serve you long.