Can You Overcharge a Lawn Mower Battery? Guides 2021

Can You Overcharge A Lawn Mower Battery

How many times you put your battery-powered equipment or devices on a charge, and it overcharged throughout the night? More or less, it happens to pretty much every individual.

Today, I will talk about the consequences of overcharging lawn mower battery. As it’s powered by an acid-lead battery, it requires a long time to get fully charged. This lets us charging the battery overnight, which is responsible for overcharging.

So, can you overcharge a lawn mower battery? Should you overcharge the battery? Does it bring any benefit? Or results in dead battery? This article will give answers to these queries.

Can You Overcharge a Lawn Mower Battery?

Before beginning, let’s talk about the battery first. Most lawn mowers these days run on 12V automotive acid-lead battery. Older models have a 6V battery. Regardless of the battery size, the mower gets enough power to start the engine and roll in the yard.

You can charge the battery using a typical charger or a car charger. No matter which option you choose, the risk of overcharging is still there.

Many advanced lawn mowers these days, feature advance charging system that stops taking charge once the battery is full. But, if your one doesn’t offer such a thing, you need to do it manually.

What Happens When You Overcharge a Lead-Acid Battery?

Overcharging causes a lead-acid battery to provide less power efficiently, and in some cases where it’s extremely overcharged, it can even explode.

When you overcharge the battery, electrolyte water inside the battery breaks down and turns into hydrogen and oxygen gas. Then the gases leave through the venting system even though the battery is a sealed one.

There are some one-way vents that open to safely expel the gases only when the internal pressure abnormally increases due to overcharging.

Electrolyte level drops as more water turns into gases. It also causes sulfuric acid to concentrate, and to become stronger, which eventually damages the battery. Overcharging duration and temperature also influence the severity of the damage.

If you try to pour distilled water in the concentrated sulfuric acid, it will produce further heat. When the heat is too high, it can explode. So, when you have no option left but adding water, make sure you pour very slowly to keep the heat as low as possible.

In the normal state, the electrolyte of the battery isn’t highly concentrated that can reach to the water boiling point when you add water. It happens only when you overcharge the battery.

The mass of the metal plates contributes to absorb the heat, and manage to spread it somehow when you add water.

What to Do When You Manage to Cool Down the Battery?

Once you cool down the battery, consider performing a slow charging cycle. Then, slowly discharge, and recharge it for 3 cycles. Afterward, you can determine how much capacity and terminal voltage are left.

When all seems okay, further charge the battery slowly until it’s full. Leave the battery in an idle state for about weeks, and perform a capacity test again. If the battery can hold the charge while providing close to the rated capacity, you can continue to use it.

Consequences That Comes with Overcharging a Lawn Mower Battery

The alternator within the battery cannot handle excessive power; thus, burnout is pretty much inevitable if it gets extremely overcharged. Additionally, the components inside aren’t designed to survive high heat and pressure.

Overcharging an acid-lead battery can eventually kill it. During that state, the mixture of sulfuric acid and distilled water boil and increase the temperature of the battery.

As a result, the casing or housing melts and swells, and creates hydrogen and oxygen. All these complications make your lawn mower battery a sitting bomb, which can explode if there is an electrical spark.

The effects of overcharging an acid-lead battery are as follows –

Corrosion on Battery Plates

When the battery temperature increases, it allows hydrogen and oxygen to break out of the water. Corrosion strikes when these two gases are on any metal object. Battery plates are made of metal; thus, this part gets corroded within a short time.

When positive battery plates have corrosion on them, you will have a very tough time to cool down the battery once it’s overcharged. This can lead to an explosion due to excessive heat.

Increased Water Consumption

The battery needs to cool down when there is excessive heat, and the sulfuric acid is concentrated. To deal with the situation, you need distilled water. The increasing heat demands pouring more distilled water. Therefore, the overall consumption of water rises to a high level.

Excessive Temperature

People understand this fact the most. Whenever you overcharge an electronic device or equipment, it will increase the battery temperature. When it gets extremely high, it can explode, as well. The continuous heating can eventually destroy a battery within a few hours.

Even if the battery doesn’t explode, still there will be damages inside the battery, which will affect its lifespan as well as performance.

However, as far as sealed acid-lead batteries are concerned, their bloated housing re-combine gases. It’s a safety feature to prevent the battery from exploding due to excessive heat.

Lowers the Performance

Overcharging brings some catastrophic damages such as weakening the housing and making it vulnerable to damage, evaporating electrolyte, damaging cells, corrosion, high temperature, roll on battery plates; all these complications affect the performance of the battery.

You will not get the same battery backup from an overcharged battery. Also, it greatly reduces lifespan. Therefore, the battery cannot perform optimally.

Tips to Avoid Overcharging –

  • Consider not charging the battery full regularly. It will decrease the overall life-cycle of the battery. Once in a while, charge it fully to keep its performance to the optimal level.
  • Charge the battery to its full capacity when you will store the battery or will not use the lawn mower for a month or more.
  • You can use a trickle charger, as it charges the battery very slowly to prevent overcharge. Some charges a battery for a few days and some can take it to a few weeks.

Final Words

The risk of overcharging is higher at older model chargers, as they don’t come with any protective features. However, advanced microprocessor-controlled chargers come with safeguard features that prevent overcharging the battery.

So, after reading the entire article, can you overcharge a lawn mower battery? Technically, you can, but this is something you should restrain from for the sake of the performance and longevity of the battery itself.

Resources & References


Hi, I’m Adam Vachon, an avid learner and working in the product marketing niche for the last few years. The problem I faced when marketing products for manufacturers made me interested in starting GearsLoft.

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