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What happens when you overcharge a battery?

What happens when you overcharge a batteryOvercharging means charging a battery more than its designed capacity. This process can lead to leaks or irreversible damage and may even cause the explosion of the battery in extreme situations. Overcharged batteries can even cause damage to devices that are connected to them.

What happens inside a battery when it’s overcharged?

As the battery is overcharged, a “gas” gets created inside the starter battery. This gas is formed by the decomposition of the electrolytic water contained in the diluted sulphuric acid. The formation of oxygen and hydrogen leads to explosive gas formation, which is why you should not have sparks, open fires, or hot and glowing objects near the battery.

Here the process in a more detailed form:
An overloaded battery boils the mixture of sulfuric acid and distilled water. The battery compartment may feel hot and begin to melt or get bloated. In the battery, combustible hydrogen can accumulate, which expands the housing under pressure and seeps through the small holes. Once hydrogen is added to oxygen, it becomes a time bomb. Even a small number of electric sparks can ignite the gas and cause the battery to explode. In addition to the corrosive sulphuric acid spray, plastic and lead bombs can also fly.

Here’s what overcharging a battery looks like:

Symptoms of overcharged batteries

When the battery is overcharged, it starts to boil. Then bubbles rise in the cells. You should be able to see and hear that. The overcharging process is also commonly associated with other tell-tale-signs:

  • Acidic smell
  • Battery bloating
  • Increased heat
  • Visible smoke
  • Electrical burn smell

Whenever you see a battery displaying one or more of the above signs, you need to be extra careful. It’s possible that acid spays to be released from the battery. These sprays can cause damage to your eyes, asking, and/or clothes. Contact with overloaded batteries should be avoided as much as possible and they should be approached with great caution.

How much damage can overcharging cause to a battery?

Overcharging is not an ON/OFF process. Instead, it’s like a spectrum of intensity that can have various degrees in terms of consequences. It of course depends on how long and how hard the battery gets overcharged. That means that overcharging can cause just a bit of damage, for example, a loss of capacity, which might even go unnoticed. On the other side, extreme overcharging can lead to complete destruction of the battery, even to fire and explosion.

Can you repair an overcharged battery?

No, overcharged batteries are not repairable and should be immediately replaced. In overcharged batteries, sulfur compounds get released, which causes irreversible damage to the battery. The release of the sulfur has got a very strong smell.

What should you do in case of an overcharged battery?

First of all, try to prevent an overcharge happening. Always have a look at the charger you are using and at the battery. Make sure to use the correct voltage when recharging your battery and not to leave it on for long periods of time.

However, if you do manage to get a battery to overcharge try to immediately replace the battery as soon as possible. There is not really a thing you can do. Ideally, dispose of the overcharged battery at designated collection points. Under no circumstances should you dispose of the battery in a regular trash bin as it could generate fires and also because it’s very bad for the environment.

Why rechargeable batteries should be constantly recharged

Brand new batteries sold on the shelves come fully charged but they are slowly discharging. Lead sulfate has already started to precipitate on the lead plates of the internal battery. Given enough time, all batteries will deplete completely if not recharged.

So overall, any battery requires two cycles to ensure a long service life: charging, and discharging. If the battery is left for too long without any of these two processes, the sulfate inside begins to crystallize and harden.

Charging an empty battery can reduce sulfate production by converting sulfate particles adhering to the discharge area of the battery back into usable leaf material. This is why, for long battery life, it’s advisable to regularly charge and discharge it.

Have you ever encountered an overcharged battery? Let us know in the comments!