How It Works: The Step by Step of Lead-Acid Battery Recycling

September 12, 2022

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Your vehicle's battery may be on its last legs, but that doesn’t mean it should be headed for the landfill. Recycling spent car batteries is not only good for the environment, it’s also easier than you might think. Many states have laws in place that require battery retailers to accept used lead-acid batteries (the kind used in vehicles). There also are recycling centers around the country devoted to keeping batteries out of landfills. 

So what happens to your battery once it’s dropped off with a dealer or at a recycling center? Read on to find out.   

What Is a Lead-Acid Battery? 

Lead-acid batteries (often called starting batteries) are the rechargeable batteries most commonly found in cars. They power everything from the ignition system to the electrical components. 

According to the EPA, 99% of rechargeable lead-acid batteries are recycled, making them the most recycled consumer good in the United States. 

To understand how lead-acid batteries are broken down during the recycling process, it’s helpful to know what is inside. A typical 12-volt lead-acid battery is made up of five components: 

  • A positive plate covered with a paste of lead dioxide
  • A negative plate made of sponge lead
  • A separator that acts as insulating material between the two plates. It’s usually a micro-porous polyethylene synthetic material 
  • Liquid electrolyte made up of water and sulphuric acid
  • A polypropylene container

When the battery goes from a charged state to a discharged state, it’s called battery cycling. During discharge, energy is released from the battery and is recharged by the alternator. 

Many factors can reduce the lifespan of a battery, according to Popular Mechanics, but the average car battery should last about six years. That’s not the end of the road for your battery, though. 

Car Battery Recycling: Step by Step

Before starting the process of recycling a battery, fully charge the battery and perform comprehensive testing to see if it can be refurbished. Batteries that still have life left in them go through an extensive refurbishment process and return to the end user clean, pristine and ready to run. 

If the battery is deemed unusable, it begins its second life journey through the recycling process. 

Step 1: Sorting

Lead-acid batteries differ from alkaline (household) and lithium-ion (electronics) batteries in their makeup and components. Each type of battery has its own recycling process. Lithium-ion batteries are especially dangerous and pose significant fire hazards if they are not handled properly. 

Step 2: Separating Components

After sorting, the lead batteries travel into a machine where rotating hammers smash them into small pieces. A screen filters out the battery acid before the metal and plastic components continue down the line, where they are submerged in a holding tank filled with water. The lead and other metal pieces sink and the plastic floats to the top. The plastic is skimmed and separated leaving three distinct components: battery acid, metal and plastic. Every part of the battery can be recycled. 

Battery Acid


Using a chemical compound, the acid is neutralized, turning it into water. Before sending the water into the sewer system, it’s cleaned and tested to ensure it meets regulatory clean water standards. Battery acid also may be converted to sodium sulfate and used in other types of manufacturing, like glass and textile. 



The plastic is washed and dried, then sent to a plastic recycling plant where it is melted and formed into plastic pellets. 



The metal pieces make their way into a furnace for up to 10 hours where they’re melted down into a liquid. Lighter metals float to the surface of the melted lead and are siphoned off. Molten lead is purified once again and poured into bar-shaped molds.

Step 3: Back to the Start

Recycled plastic pellets and lead can be remelted to create new car batteries, starting the cycle from the beginning. A single lead bar has enough lead to make up to three new batteries. 

Not Ready to Recycle? Refurbish

A battery with life still in it is fully charged and tested to determine if it meets refurbishment standards. If it does not, clients can purchase a new battery at a reduced rate while their old one heads into recycling. 

If a battery is determined to be refurbish-ready, it’s repaired and rebuilt on site. The process ends with a thorough cleaning, which includes all terminals and casings, before being returned in pristine, working condition.