Electric bus batteries in Chile: testing, refurbishment and end of life

Source: EcoBaterías test protocol · 2026-09-26.

When do you need to decide? The 2028–2029 window

Santiago’s first electric bus cohorts arrived between 2017 and 2019 under lease and maintenance contracts that included the battery. When those contracts end, the operator faces a decision that until now belonged to the supplier: what to do with a pack that no longer performs as it did on day one but is nowhere near scrap.

Our estimate, built on the publicly documented 2017–2019 cohorts, is that the first meaningful batch is around 200 buses of 324 kWh: roughly 65 MWh of lithium iron phosphate, equivalent to between 500 and 650 metric tons of packs, concentrated in 2028 and 2029. This is an EcoBaterías estimate, not a reported fleet figure: we publish it with its range because depot logistics are planned years ahead, not months.

The practical point is simple. A bus pack weighs hundreds of kilos, is handled as hazardous waste unless a characterization shows otherwise, and does not fit the household collection flow. A decision taken on the day the bus leaves service is a decision taken badly.

How is a fleet tested?

Testing is done by batch and starts at the depot, so the fleet is immobilized no longer than necessary. State of health (SOH) is the pack’s current usable energy as a percentage of what it held when new; the BMS (battery management system) estimates it, but we measure it.

1. Inventory and BMS readout. Serial number, chemistry, charge history, fault codes and recorded temperatures for each pack.
2. Electrical test. A controlled capacity cycle and internal resistance measurement to obtain the real state of health, not the one the management system declares.
3. Module spread. Measured module by module: a healthy pack with two weak modules behaves like a sick pack.
4. Thermal and cooling review. Thermography under load and inspection of the cooling circuit, the origin of a large share of field faults.
5. Classification and certificate. Each pack is assigned a route and receives a state-of-health certificate by serial number.
6. Batch plan. The full set of results becomes the plan: what returns to the fleet, what is repaired or refurbished, what moves to second life and what goes to recycling.

Swipe to see the whole table

Source: EcoBaterías test protocol · 2026-09-26. These are laboratory times, not a contractual turnaround commitment. Each test is described in lithium battery testing.

What fails in an LFP bus pack, and what gets repaired?

According to their manufacturer datasheets, the BYD K9 and Yutong E12 use lithium iron phosphate (LFP) cells, a stable chemistry that tolerates deep cycling. That is why the pack rarely dies as a whole: what shows up are unbalanced modules, degraded connections, temperature sensors out of range and cooling circuit faults.

When the fault sits in one part, the job is a repair: the module, sensor or contactor is replaced and the pack goes back to traction. When the pack has lost capacity unevenly, the job is refurbishment: every module is tested, the weak ones are replaced with matched modules and the output capacity is measured.

What changes on a bus is scale and logistics: the pack does not travel in a box, the vehicle cannot sit idle indefinitely, and any intervention has to be documented for the contracting authority. That is why we work in batches, within windows agreed in writing before we start.

The four decision routes

Each pack is assigned to one of four routes according to its measured state of health. The thresholds are EcoBaterías’ own, not a standard, and they are applied identically across our operation.

Source: EcoBaterías test protocol · 2026-09-26. Reference methods: IEC 63330-1:2024 and ANSI/CAN/UL 1974:2023, cited as reference standards and never as our own certification.

Second life for bus modules

A bus module that no longer serves traction is still a lithium iron phosphate module with thousands of cycles left in a less demanding duty. Second life is not “reusing leftovers”: it requires selecting modules by capacity and internal resistance, matching them, assembling them in a cabinet with its own management system, and testing the assembly again.

Chile’s draft battery decree also gives it regulatory weight: it proposes that at least 30% of the lithium-ion valorization target be met through preparation for reuse. It is a text under consultation, not a standing obligation, but it shows where the requirement is heading.

Recycling with a certificate

Whatever does not return to the fleet and cannot serve a second life goes to recycling. We manage its valorization with authorized receiving facilities, in Chile or in OECD countries where applicable; the authorized receiving facility closes the declaration in SIDREP (Chile’s national hazardous-waste declaration and tracking system) and issues the valorization certificate. Recycling lithium-ion batteries, managed with authorized receiving facilities, costs 22 UF per tonne + VAT (UF is Chile’s inflation-indexed unit of account); details in lithium battery recycling for companies.

EcoBaterías’ hydrometallurgical process comes from its founding partner EcoMinería (Ecoprojects): in the process EcoMinería ran in Lampa, the pack was discharged and dismantled and the active fraction was processed until the minerals were recovered. As market evidence, El Rancagüino reported in July 2024 that Codelco’s El Teniente hydrometallurgical plant successfully tested recycled cobalt sulfate, with trials from November 2023: 22% lower cost and 40% lower consumption than imported sulfate, with one daily addition instead of three. The article does not name the supplier.

When a batch closes, the authorized receiving facility issues the valorization certificate, which together with the transport traceability record is what gets reported afterwards.

What are a bus depot’s obligations?

Today a removed pack is handled as hazardous waste unless a characterization shows otherwise, under Supreme Decree (DS) 148/2003: authorized storage for six months at most, transport under a health permit with a declaration document, and an authorized receiving facility. A bus pack travels as UN 3480, class 9: if it is intact and going to recycling, under special provision 377 with packing instruction P909, which allows crates or pallets for batteries of 12 kg or more with a strong casing; if it is damaged, under special provision 376 with packing instruction P908, or P911 if it could react dangerously. We coordinate pickup with licensed hazardous-waste carriers; the step-by-step is in battery and solar panel collection and transport.

Chile’s Extended Producer Responsibility law (Ley REP, Law No. 20,920) is in force as a framework, but the decree that sets targets for batteries is still a draft. That draft, published with Resolution 821/2026 of the Ministry of the Environment, proposes three things that bear directly on a depot:

• Vehicle workshops would be required to hand removed batteries to the collective management system (Art. 29).
• Storage installations above 1 MWh would have to report every year, before May 31, through the RETC single window (Art. 40).
• Lithium-ion targets would start with no requirement for the first two years, rise to 15% in the third and reach 50% from the tenth, with at least 30% met through preparation for reuse (Art. 22).

The Ministry’s deadline to propose the decree was extended to January 29, 2027 by Resolution 4,225/2026. None of this is enforceable yet: we write it in the conditional on purpose.

Sources: DS 148/2003, BCN (opens in a new tab) · RID 2025, special provisions 376 and 377 (opens in a new tab) · draft battery decree, Chilean Ministry of the Environment (opens in a new tab) · 2026-09-26.

How do you hire the service?

The service is contracted by bus batch or by pack. Before work starts we agree in writing on scope (which testing level, how many packs, in which window), who moves the packs, what documentation is delivered at closing and the price, which is confirmed in the quote. Assessment and decision are two separate steps: first we measure, then we decide, and the report stays with the operator whether or not they continue with us.

Frequently asked questions

Sources