Power Tool Battery Recycling: What Actually Happens to Old Packs
A cordless drill pack that no longer holds a charge still contains a full set of electrochemical ingredients: lithium compounds in the cathode, graphite in the anode, copper and aluminium foils pressing the current out of the cell, and a flammable organic electrolyte between them. Every one of those materials has a value and a hazard. Power tool battery recycling is the industry that separates them again.
What happens to a spent pack depends on which of those materials a processor can recover economically. Lead acid set the template, because lead is easy to extract and can be reused many times. Battery University reports that more than 97 percent of lead acid batteries are recycled in the USA and that over 50 percent of the lead supply comes from recycled batteries. Lithium ion has never been that simple. It has been collected far less, and recovering the materials has historically cost more than digging fresh ones out of the ground.
That gap is closing. Here is what the process looks like from the moment a pack leaves a toolbox to the moment its materials enter a new product.
Why a pack ends up in the recycling stream
A cordless pack does not fail in one way. It reaches end of life when it can no longer deliver useful runtime, and the reasons behind that are covered in detail in the guide to testing what a pack still has left. Battery University puts the usual replacement point at roughly 80 percent of original capacity, and notes that lithium and nickel chemistries tend to deliver between 300 and 500 full discharge and charge cycles before they fall below that line.
Below the pack level there are two separate failure modes. One is capacity fade, a gradual loss driven by cycle count and age. The other is a single cell that has drifted far enough from its neighbours to drag the whole string down. A pack built from a series string stops performing when its weakest cell stops performing.
What is inside a cordless pack
Most modern 18V and 20V tool packs are assembled from cylindrical cells rather than prismatic pouches. Battery University's chemistry summary lists the 18650 format among the typical cell packagings for lithium cobalt and NMC chemistries, with power tools among the main applications for NMC. A pack also carries a battery management board with the charge and discharge protection circuitry, a plastic shell, and spot-welded nickel strip tying the cells into a string.
The composition of a lithium ion pack at the material level explains why recycling is difficult. Battery University quotes an ATZ report from 2018 stating that the 33 kWh traction battery of a BMW i3 contains 2 kg of cobalt, 6 kg of lithium, 12 kg of manganese, 12 kg of nickel and 35 kg of graphite. A drill pack holds a fraction of that, but the ratios are comparable, and cobalt and nickel are the parts a processor most wants back.
Step 1: collection and sorting
The first real step is human, and it is the step most likely to go wrong. Battery University describes a specific failure mode that appeared in late 2013, when smelters started reporting lithium ion packs mixed in with lead acid collections. A lithium ion pack reaching a lead acid process can ignite, and the article records a tenfold increase in reported incidents of that infiltration between 2010 and 2013.
The cause is incidental. Lithium ion starter batteries and lead acid ones look similar to a consumer, and the sorting has to happen at high volume. Some of the countermeasures discussed in the same source include staff training, clearer battery identification, additional labelling, and X-ray equipment that can separate chemistries automatically based on what is inside the housing rather than what the label claims.
The practical lesson for a household is straightforward: keep the chemistry streams apart when you drop packs off.
Step 2: deactivation and discharge
A pack entering a recycling line still holds energy, and a shredder full of charged cells is an uncontrolled short circuit waiting to happen. The standard first move is a controlled full discharge to strip the stored energy, and Battery University notes that the electrolyte can also be frozen to suppress electrochemical reactions during the crushing stage.
This is the thermal hazard covered from the other direction in the explanation of what an overcharged lithium battery does: the higher the state of charge, the more energy a failing cell has to release.
The regulatory side of shipping a spent pack is not the same as shipping a new one. Spent packs move under the dangerous goods framework either way, and the marks, packing instructions and state of charge limits are set out in the guide to shipping lithium batteries under UN3480 and UN3481.
Step 3: mechanical separation
Once the energy is gone, the pack is taken apart. Battery University divides the process into three treatment families: mechanical, pyrometallurgical and hydrometallurgical. Mechanical treatment crushes the cells and then sorts the output, separating copper foil, aluminium foil, separator film and the coating materials that carry the active chemistry.
The catch is that this stage does not recover everything. The same source notes that nickel, cobalt and copper can come out of the cast, while lithium and aluminium have historically been harder to recover at battery-grade quality. Material below that grade still gets used, but in less demanding applications rather than in a new cell.
Step 4: extraction
The remaining active material goes one of two ways. Pyrometallurgical treatment applies heat to smelt the metals out of the mix. Hydrometallurgical treatment uses aqueous chemistry to dissolve and then selectively recover them. Battery University flags a third route worth noticing: a process developed by Duesenfeld GmbH that evaporates and recovers the organic solvents in the electrolyte under vacuum by condensation, and which the source states uses 70 percent less energy than traditional smelting furnaces.
The trade-off between heat and chemistry comes down to what the processor is chasing. Smelting handles mixed feed well and tolerates contamination. Aqueous routes can recover more individual metals at higher purity but need a cleaner input and a tighter process. Most modern capacity is being built around the aqueous side because the cobalt and nickel in the feed justify it.
Whether a pack gets recycled at all usually comes down to economics rather than technology. Current lithium chemistries rely on far less cobalt than earlier formulations, and the chemistries with the least cobalt are also the ones that are hardest to make a margin on. That is a materials story as much as a recycling story, and it connects to how different battery chemistries compare on cost and durability.
Step 5: back into new products
Recovered material leaves the plant as metal salts, alloy or a mixed concentrate headed for a refinery. From there it re-enters cell manufacturing. Battery University notes that not all recovered material reaches battery-grade quality, and that the lower grades get absorbed into other industries: lithium is used as a lubricant additive, for example, in applications that do not need the purity a new cell demands.
The overall collection rate is the weak link. Battery University reports that only 20 to 40 percent of batteries in mobile phones and other consumer products were being recycled at the time of writing, compared with well above 97 percent for lead acid. Power tool packs sit inside that consumer category, so the gap applies to them directly.
Where to take a spent pack
The mechanism varies by country, and a national stewardship program is the fastest way to find a current drop-off point. Call2Recycle operates a collection network for rechargeable batteries in North America, and its site lists participating retail locations where a sealed or taped pack can be handed over.
Three habits make the handover safe:
- Tape the terminals with clear tape so the pack cannot short against anything on the way.
- Keep the pack in its plastic shell rather than breaking it open to pull cells out.
- Store spent packs somewhere cool and dry until the drop-off trip happens.
Never put a lithium ion pack in household rubbish. If a pack is swollen, dented or has been wet, treat it as damaged rather than as ordinary waste and ask the collection point what it accepts.
FAQ
Can a power tool battery pack be recycled at all?
Yes. Lithium ion packs enter the same collection and processing stream as other rechargeable batteries, and the recovered copper, nickel and cobalt can be returned to manufacturing.
Why is lithium ion harder to recycle than lead acid?
Battery University reports that more than 97 percent of lead acid batteries are recycled in the USA and that over 50 percent of the lead supply comes from recycled batteries, because 70 percent of a lead acid battery's weight is reusable lead. Lithium ion packs need more processing to recover comparable value, and not every recovered material reaches battery-grade quality.
What happens to a pack the moment it reaches the plant?
It is fully discharged to remove stored energy before any crushing happens. The source also notes that the electrolyte can be frozen to suppress reactions during crushing.
Can I just throw a dead drill pack in the trash?
No. A charged lithium ion pack crushed by heavy equipment in a waste stream can ignite, and landfill fires are difficult to extinguish. Tape the terminals and take it to a collection point instead.
Do I need to discharge a pack before dropping it off?
No. Household drop-off programs are set up around whatever state of charge the pack is in. The controlled discharge happens at the processing plant, not in your garage.
Is it safe to store dead packs in the garage?
Cool, dry and away from anything flammable is the short answer. A spent lithium ion pack still holds residual energy, so a garage that swings between freezing and hot is a poor storage choice.
Frequently asked questions
Can I put a power tool battery in household recycling?
No. Lithium packs go to a dedicated battery recycler or a retail drop-off that accepts lithium. Household streams cannot separate them, and a punctured pack in a collection truck is a fire risk.
How much of a lithium pack actually gets recycled?
Less than lead acid. More than 97 percent of lead acid batteries are recycled in the USA, while lithium ion has been collected far less because recovering the materials has historically cost more than mining fresh ones.
When is a pack ready for recycling?
Around 80 percent of original capacity, which lithium and nickel chemistries typically reach after 300 to 500 full cycles. Before that point a single weak cell may be the whole problem.
What inside a pack is worth recovering?
Lithium compounds in the cathode, graphite in the anode, copper and aluminium foil, and the electrolyte between them. Each material carries both a value and a hazard, which is what makes the separation step the hard part.
Why are tool packs built from 18650 cells?
The 18650 format is one of the standard cylindrical packages for lithium cobalt and NMC chemistries, and power tools are among its main applications. That common format is also what makes mechanical separation practical.