Lithium battery refurbishment: full pack rebuilds

Lithium battery refurbishment means taking the pack apart, measuring every cell or module, replacing the weak ones, balancing and rebuilding it so it goes back to the same use, with a capacity test at the end. Ecobaterías refurbishes lithium-ion packs from electric buses and cars, battery energy storage (BESS) racks, forklifts and micromobility vehicles when their measured state of health is 80% or more; below that threshold, the pack goes to second life or recycling.

SOH threshold and test times: Ecobaterías testing protocol, published in lithium battery testing · September 18, 2026.

What is lithium battery refurbishment?

A lithium battery is made of cells, the basic electrochemical unit. Cells are grouped into modules, and the modules, together with the BMS (battery management system, the electronics that control voltage, current and temperature), the wiring and the casing, make up the pack. A pack rarely fails as a whole: a few cells or modules degrade and drag the rest down.

Refurbishing means opening the pack, measuring all its cells or modules, replacing the ones that fell behind, balancing and closing it again with a capacity test. The pack returns to the same application it had: a bus pack stays in a bus and a BESS (battery energy storage system) rack stays a rack. In Spanish, Ecobaterías calls this service pack refacción. If the modules move to a different use, such as stationary storage, it is no longer refurbishment: it is second life. A refurbished lithium battery leaves with its measured capacity written into the report.

State of health (SOH) compares the battery’s current performance with its initial state; in practice it is expressed as the capacity it still holds, as a percentage of the original. Our threshold for refurbishment is a measured SOH of 80% or more. “Remanufacturing” is something else: EU Regulation 2023/1542 only recognizes it when every cell and module is assessed, the battery recovers at least 90% of its original rated capacity and the state of health of its cells differs by no more than 3%, for the same purpose. UL 1974 treats “remanufactured”, “reconditioned” and “rebuilt” batteries as equivalent: all of them return to the same application.

Measuring module by module makes economic sense: according to Autocraft EV Solutions, in 559 electric-car battery repairs carried out in 2024, 92% of the modules in the faulty packs were still fit for automotive use and an average of 1.1 modules per pack had to be replaced.

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Sources: EU Regulation 2023/1542, art. 3(28), (31) and (32) · UL Solutions, overview of ANSI/CAN/UL 1974:2023 (May 2024) · Autocraft EV Solutions, May 6, 2025 · SOH thresholds: Ecobaterías testing protocol.

How do we refurbish a pack? The 10-step protocol

The protocol follows the sequence of the standards for assessing used batteries (UL 1974 and IEC 63330-1): information and inspection first, then testing, grading and documentation. Every module stays identified from start to finish.

1. Intake and registrationWe record model, chemistry, serial number, reason and date of removal, fault history and storage conditions, and read the BMS data: cycle count, peak temperatures, insulation events and fault codes.
2. Inspection and quarantineWe inspect the pack outside and, once opened, inside. A pack with swollen cells, electrolyte or coolant leaks, burn marks or a deformed casing is not refurbished: it is isolated and sent to recycling.
3. Electrical safetyBefore opening it, we measure the insulation between the high-voltage circuit and the casing. The reference is the minimum in UN Regulation No. 100: 100 Ω per volt of working voltage on DC circuits.
4. Full teardownWe open the pack and separate modules, busbars, wiring, sensors and the BMS. Every module gets a unique code that follows it until final assembly.
5. Testing of every module or cellWe measure open-circuit voltage, capacity with a full charge and discharge cycle, DC and 1 kHz internal resistance, and self-discharge at rest.
6. Grading and matchingWe group the modules by measured capacity and internal resistance inside a narrow band. Modules outside the band are flagged for replacement.
7. Weak-module replacementEach weak module is replaced with one of the same chemistry, format and voltage, with capacity and resistance inside the pack’s band. Where the replacement module comes from (new, refurbished or from the client’s own batch) is agreed in the quote.
8. Balancing and rebuildWe bring every module to the same state of charge, replace damaged connectors, seals and busbars, and rebuild the pack. The BMS is updated or reset when the manufacturer allows it, or its board is replaced.
9. End-of-line testWe run a capacity cycle on the assembled pack and measure internal resistance, insulation and the BMS response to overcharge by voltage and by current and to overtemperature, the functions IEC 62619 requires from the BMS of an industrial battery.
10. Label, report and traceabilityThe pack leaves with a refurbished label (who did it, date, chemistry and electrical ratings), the report with its measured output capacity and a traceability record for every module. Removed modules are received for recycling with a certificate.

Testing takes from 30 minutes to 6 hours per pack, depending on its depth. The total refurbishment lead time depends on how many modules need replacing and is confirmed in the quote.

Sources: UL Solutions, overview of ANSI/CAN/UL 1974:2023 · IEC 63330-1:2024 · IEC 62619:2022 · UN Regulation No. 100 · test times: Ecobaterías testing protocol.

What do we measure on each module or cell?

Which module stays and which one is replaced is decided with these measurements, not with the serial number or the vehicle’s model year.

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Two definitions to read the table: It is the reference current of a test, equal to rated capacity divided by one hour; C is the current that fully discharges the battery in one hour, so 0.2C discharges it in five hours.

Sources: European Commission battery ecodesign preparatory study, standards annex (2019) · Battery Design, DCIR and ACIR · Zhang et al., review of diagnostic methods for retired batteries, arXiv, 2025 · UN Regulation No. 100 · EU Regulation 2023/1542, art. 14.

Why do cells need matching and balancing?

In a pack, cells and modules connected in series carry the same current. The BMS stops charging when the fullest cell reaches its maximum voltage and stops discharging when the emptiest one reaches its minimum. That is why a pack delivers the energy of its weakest module, not the average.

Matching means keeping only modules with similar capacity and internal resistance in the pack. Balancing means bringing them to the same state of charge before closing it. Without both, the pack is again limited by its weakest module. UL 1974 requires the operator to have a grading system and recommends a band of 6 sigma (six standard deviations) or tighter.

Source: UL Solutions, overview of ANSI/CAN/UL 1974:2023. Matching by capacity and internal resistance is part of the Ecobaterías protocol.

How much capacity does a refurbished pack recover?

Whatever the end-of-line test measures. We do not promise a percentage before testing: we write it into the report after measuring. Three references help read that number:

• Our entry threshold: a measured SOH of 80% or more. Below that, the cost of replacing modules stops paying off and another route makes more sense.
• Remanufacturing in the EU: at least 90% of original rated capacity, with cells whose SOH differs by no more than 3%. If the client needs this criterion, we measure and report it; we only call a pack remanufactured when it meets it.
• Electric-car retirement: electric-car batteries are usually retired at 70% to 80% of their original capacity, and manufacturers typically replace them under warranty below 70%.

Sources: EU Regulation 2023/1542, art. 3(32) · Zhang et al., arXiv, 2025 · Recurrent, November 11, 2025 · 80% threshold: Ecobaterías testing protocol.

Which batteries do we refurbish, and which do we turn away?

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IEC 63330-1:2024, which we use as a reference for assessing used batteries, is also limited to lithium-ion with data traceability and leaves out NiMH and lead-acid. If you do not know your battery’s chemistry, testing confirms it before we quote.

Source: IEC 63330-1:2024, scope · acceptance criteria: Ecobaterías testing protocol.

Which fleets and equipment is it for?

• Electric buses. Santiago runs more than 4,000 electric buses (February 2026). Their packs are refurbished module by module; fleet details are in electric bus batteries.
• Electric cars. In a sample of more than 30,000 electric cars analyzed by Recurrent, fewer than 4% needed a battery replacement outside manufacturer recalls. In the United States, replacing a full battery out of warranty costs between US$5,000 and US$16,000, and a BMW i3 module about US$3,500, according to the same source. We explain it in can an electric car battery be repaired?
• BESS racks. Chile had 8,786 MWh of battery storage in operation in May 2026, according to the National Energy Commission (CNE). A refurbished rack goes back to its system; if the whole system reaches the end of its life, start with end-of-life BESS.
• Forklifts and industrial traction. Lithium batteries for forklifts and automated guided vehicles fall within the scope of IEC 62619:2022, the safety standard for industrial batteries.
• Micromobility. E-bikes, scooters and electric motorcycles for rental, delivery or personal use. In the EU, from February 18, 2027, the cells of these batteries must be replaceable by an independent professional.

Sources: Reporte Minero, February 2026 · Recurrent, November 11, 2025 · Recurrent, battery replacement costs (December 2024) · National Energy Commission, via Reporte Minero, May 2026 · IEC 62619:2022 · EU Regulation 2023/1542, art. 11.

When is refurbishment not worth it?

• A cell that is swollen, leaking, partly melted or warm while switched off. It is a damaged battery: it is not repaired and it travels to recycling in packaging for damaged batteries.
• Burn marks or a thermal event. UL 1974 lists them as grounds for rejection at intake.
• Deep over-discharge or 0 V. Over-discharge oxidizes the anode’s copper current collector, and the EU regulation warns that even a minor over-discharge can form dendrites and end in an internal short circuit. For safety, those batteries go to recycling.
• SOH below 80%. Second life (65–80%) or recycling (below 65%) is the better route.
• When most of the modules need replacing. We say so in the proposal, with the cost compared against the other routes, so you can decide on the numbers.

If a pack is hot, smoking or swollen, do not open or handle it. Move away and isolate the area: the US National Transportation Safety Board (NTSB) recommends keeping a vehicle with a damaged battery at least 15 m (50 ft) from structures and combustible materials. Cool it with plenty of water and call the fire department (132 in Chile). An ABC extinguisher does not stop thermal runaway (uncontrolled self-heating of a cell), and a damaged battery can reignite hours or days later: the NTSB documented one case five days later.

Sources: ETH Zürich, damaged lithium-ion battery fact sheet · UL Solutions, overview of UL 1974:2023 · EU Regulation 2023/1542, Annex V, point 4 · NTSB, Safety Report SR-20/01 (2020).

Which standards do we use as references?

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We cite them as method references. They are not Ecobaterías certifications and we do not present them as such: what we deliver is the report with measured data, so that the client, its engineer or an auditor can verify it.

If the refurbished pack goes into a storage system installed in Chile, note that Technical Instruction RGR No. 06/2024 from the Superintendencia de Electricidad y Combustibles (SEC, Chile’s electricity and fuels regulator) requires lithium-ion batteries and their BMS to comply with IEC 62619 (the instruction cites the 2017 edition), UL 1973 or UL 9540, and does not mention used or refurbished batteries. The installation is declared by the licensed electrical installer; we recommend checking with the SEC before reinstalling.

Sources: ANSI/CAN/UL 1974:2023 · IEC 63330-1:2024 · IEC 62619:2022 · United Nations, sub-section 38.3 (PRBA copy) · SEC, Technical Instruction RGR No. 06/2024.

How does a refurbished battery travel?

We coordinate pickup with licensed hazardous-waste transport anywhere in Chile; packaging and documents are covered in collection and transport of batteries and panels. Do not take the pack apart before pickup: the Ministry of the Environment’s draft battery decree asks for lithium batteries to be handled and transported without dismantling them or stacking them excessively, so they do not lose their second-life potential.

On the way back, the refurbished pack travels as a product: lithium-ion, UN 3480, class 9 (miscellaneous dangerous goods). For that, its type must have passed the eight UN 38.3 tests: altitude simulation, thermal test, vibration, shock, external short circuit, impact or crush, overcharge and forced discharge.

• When UN 38.3 is repeated. A battery is a new type if its rated energy changes by more than 20%, if its rated voltage rises by more than 20% or if there is a change that could make it fail a test, such as different materials, a different number of cells, a different connection or different protective devices, software included. IATA adds that repairing or refurbishing with non-original parts or parts of another specification may require testing again.
• How we handle it. Before starting, we check whether the pack keeps its tested type (same cells, same configuration, same BMS). If the change requires a new test, we say so in the quote.
• By air. Loose lithium-ion batteries travel at 30% state of charge or less, and damaged or defective ones that could overheat, catch fire or short-circuit are forbidden.
• Removed modules. They go to recycling under special provision 377 and packing instruction P909, with no 38.3 test; damaged ones under special provision 376 and packing instruction P908, or P911 if they could react dangerously in transport.

Sources: United Nations, sub-section 38.3 and 38.3.2.2 · IATA, lithium battery guidance 2026 · OTIF, RID 2025 (harmonized with the UN Model Regulations) · Ministry of the Environment, draft battery decree (Res. Ex. 821/2026).

What warranty does a refurbished pack carry?

We do not publish a fixed term. The warranty is agreed in each contract, based on the capacity measured in the end-of-line test and on how the pack will be used.

If the buyer of a refurbished battery is a consumer, Chile’s consumer protection law (Law No. 19,496) also applies: the product must be disclosed in writing, before the sale, as refurbished or containing used parts (art. 14), and the legal warranty is 6 months (art. 21, as amended by Law No. 21,398). Between companies, the contract governs.

Sources: Law No. 19,496, Library of the National Congress of Chile · Law No. 21,398, Library of the National Congress of Chile.

Does it count toward Chile’s EPR law?

Batteries are a priority product under Chile’s Extended Producer Responsibility law (Ley REP, Law No. 20,920). If the pack has already been discarded, refurbishing it fits “preparation for reuse”: checking, cleaning or repairing a discarded product so it can be used again without any other processing. The law includes it within valorization, alongside recycling.

The draft battery decree (Res. Ex. 821/2026) proposes that at least 30% of the lithium-ion target be met through preparation for reuse. It is a text under consultation, not a rule in force: the Ministry of the Environment’s deadline to propose the decree is January 29, 2027. More context in Chile’s EPR law and batteries.

Sources: Law No. 20,920, art. 3 No. 18 and 30 and art. 10, Library of the National Congress of Chile · Ministry of the Environment, Res. Ex. 821/2026 · Ministry of the Environment, deadline extension (Res. Ex. 4,225/2026).

Refurbish, give it a second life or recycle?

Refurbishment sits in route B of the four-route scheme we use across all our battery services, so that the same pack always gets the same decision:

State-of-health thresholds: Ecobaterías testing protocol · September 18, 2026. All routes in services for lithium batteries and solar panels.

How much does refurbishing a pack cost?

It is quoted per pack or per batch, after testing. The price depends on:

• the pack’s chemistry, format and voltage;
• how many modules need replacing and where the replacements come from;
• the depth of testing and whether the BMS has to be updated or replaced;
• pickup, packaging and, if the type changes, a new UN 38.3 test.

Modules removed from the pack are received for recycling at 22 UF per tonne plus VAT (19%), with traceability and a valorization certificate for EPR reporting. The UF is Chile’s inflation-indexed accounting unit, published daily by the Central Bank (see the intake price). Lead times are confirmed in the quote.

How do you hire the service?

1. Pack detailsYou tell us model, chemistry, quantity, symptoms, location and, if you have it, the BMS data.
2. TestingWe measure the state of health and the condition of each module with our testing protocol.
3. ProposalYou receive the route for each pack, the modules to replace, the price and the lead time.
4. PickupWe coordinate pickup with licensed hazardous-waste transport.
5. RefurbishmentWe apply the 10 steps of the protocol and the end-of-line test.
6. DeliveryThe pack comes back with its label, capacity report and per-module record; whatever was removed goes to recycling with a certificate.

If the pack has a single fault and the rest is healthy, a repair is probably enough. General questions are answered in the FAQ and technical terms in the glossary.

Frequently asked questions

What is a refurbished battery?

It is a lithium battery whose pack has been taken apart, every cell or module measured, the weak ones replaced, and the pack rebuilt and balanced for the same use it had before. Unlike a used battery sold as is, it leaves with a capacity test run at the end, a report with the result and a label that identifies it as refurbished.

What is the difference between repairing, refurbishing and remanufacturing a battery?

Repair fixes a single fault, such as the BMS, a contactor or one module, without testing the whole pack. Refurbishment takes the pack apart, measures every cell or module, replaces the weak ones, balances the pack and runs an end-of-line capacity test. Under EU Regulation 2023/1542, remanufacturing also requires restoring at least 90% of the original capacity, with cells whose state of health differs by no more than 3%, for the same use.

Are refurbished batteries any good?

That depends on the testing, not on the label. A pack with modules matched by capacity and internal resistance, balanced and capacity-tested at the end can return to its original application. According to Autocraft EV Solutions, in 559 electric-car battery repairs carried out in 2024, 92% of the modules in the faulty packs were still fit for use and an average of 1.1 modules per pack had to be replaced.

How much capacity does a refurbished battery recover?

Whatever the end-of-line test measures, and that figure is written into the report. We only refurbish packs with a state of health (SOH) of 80% or more, an Ecobaterías threshold. For reference, EU Regulation 2023/1542 calls a battery remanufactured when it recovers at least 90% of its original capacity, with cells that differ by no more than 3% from each other.

Why do cells need balancing?

Because cells connected in series carry the same current, and the BMS stops charging when the fullest cell reaches its maximum voltage and stops discharging when the emptiest one reaches its minimum. If cells are left at different states of charge, the pack delivers less energy than it holds. Balancing brings them to the same level before the pack is closed.

What warranty does a refurbished battery carry?

We do not publish a fixed term: the warranty on a refurbished pack is agreed in each contract, based on the capacity measured in the end-of-line test. If the buyer is a consumer, Chile’s consumer protection law (Law No. 19,496) also applies: the product must be disclosed in writing as refurbished (art. 14) and the legal warranty is 6 months (art. 21, as amended by Law No. 21,398). Between companies, the contract governs.

Can an electric bus, forklift or BESS battery be refurbished?

Yes, if it is lithium-ion (LFP, NMC, NCA, LCO or LTO), has no mechanical damage or thermal event, and its measured state of health is 80% or more. Bus and BESS rack packs are refurbished module by module; forklift packs by module or by cell, depending on the pack design. We test first and then propose the route: repair, refurbishment, second life or recycling.

Refurbish or give it a second life?

It depends on the measured state of health and on the next use. If the pack keeps 80% or more and goes back to the same application, refurbishment makes sense. Between 65% and 80%, its modules perform better in a less demanding application such as stationary storage: that is second life. Below 65%, or with physical damage, it goes to recycling with a valorization certificate.

Sources