Portuguese 
English 
Spanish 
5 min of reading 
0 comments 
Brazilian project tests how batteries removed from electric buses can gain a new function off the streets, with use in solar energy storage, technical evaluation of reused cells, and participation of CPQD, CPFL Energia, BYD, and Unicamp in the validation stage.
Lithium-ion batteries removed from BYD electric buses have become part of a Brazilian project aimed at expanding the use of these components before final recycling.
The initiative brings together CPQD, CPFL Energia, and BYD in tests with stationary systems capable of storing solar energy and supporting other applications outside vehicles.
With the advancement of transportation electrification, there is also a growing need to define the destination of batteries that no longer deliver the autonomy required by buses, cars, and other vehicles.
-
City Hall of Belo Horizonte calls 300 homeless people for the Bolsa Moradia program
-
After fighting for 25 years to open one of the largest gold mines in Europe, a Canadian mining company loses a $4.4 billion dispute against Romania due to a historic village, environmental protests, and Roman galleries protected by UNESCO.
-
Labor shortage: even with an average salary of R$ 8,700, the profession faces a shortage of 359 workers in Brazil and helps explain why radiotherapy is still hindered in cancer treatment in the SUS.
-
Teams were excavating the port area of Rio for a modern construction when they found, under layers of landfill, a stone wharf buried for 168 years: the 1811 structure became a World Heritage Site and revealed the most important material vestige of the arrival of enslaved Africans to the Americas.
Nevertheless, some of these components may retain sufficient capacity to operate in less demanding uses, especially in fixed energy storage systems.
In this interval between automotive use and recycling, the so-called second life gains space, a stage in which reused cells are evaluated, reorganized, and integrated into new systems.
The proposal seeks to prevent still useful batteries from being immediately treated as waste, provided they exhibit performance, safety, and stability for another application.
According to CPQD, the lifespan of a lithium-ion battery in an electric vehicle is usually around 8 to 10 years, depending on usage conditions.
After this period, the gradual loss of energy storage capacity reduces the autonomy perceived by the user and limits the component’s use in automotive operations.
Outside vehicles, however, these batteries can still perform stationary functions, with less demand for weight, instant power, and dynamic response.
Among the studied applications are the storage of energy generated by photovoltaic systems, support for intermittent renewable sources, and use as backup in telecommunications stations, with an estimated additional 5 to 10 years of use.
Second life of BYD batteries in Brazil
In the initial tests, degraded batteries from electric buses provided by BYD underwent laboratory tests and measurements to verify their reuse potential.
In total, researchers analyzed about 500 cells and identified which of them still had adequate performance, safety, and reliability conditions to form a second-life battery.
This screening is necessary because a vehicle battery does not function as a single piece, even though the assembly is treated that way in daily operation.
Each pack contains several cells, and the individual behavior of each one affects the final performance, especially when the goal is to assemble a predictable system for electrical installation.
According to CPQD’s assessment, the selection of the most suitable cells depended on a specific methodology developed to separate components with greater reuse potential.
The technical stage allowed differentiation between cells that could still integrate a new system and those that no longer met the requirements for stationary use.
In addition to the physical selection of the cells, CPQD developed algorithms and a second-life battery prototype to validate the functioning of the assembly.
The solution includes hardware, mechanical structure, and a management system known as BMS, which stands for Battery Management System, responsible for monitoring essential operational parameters.
Since these batteries have already gone through previous charge and discharge cycles, electronic management becomes a central step to keep the system within safe limits.
Monitoring performance, thermal behavior, degradation, and stability helps reduce technical risks before any field application.
Solar energy at Unicamp enters the validation stage
Among the most relevant phases of the project is the use of the prototype in association with solar panels installed at the State University of Campinas.
CPFL reported that the proof of concept takes place at the Smart Electrical Grids Laboratory, the labREI, located at the School of Electrical and Computer Engineering at Unicamp.
In this environment, the system can be evaluated in conjunction with photovoltaic structures installed in the building, in conditions close to a real application.
The goal is to verify the storage performance, the quality of the energy delivered to the grid, and the battery’s response when solar generation varies throughout the day.
This use helps explain why a less efficient battery for transportation can still have value in another sector.
While an electric bus requires autonomy, power, recharge repetition, and performance compatible with urban routes, a stationary system operates with a different demand profile.
Instead of moving a heavy vehicle for hours, the battery stores electricity for later use and supports the management of locally produced energy.
The function is especially relevant for intermittent sources, like solar, whose production changes according to light incidence, cloud presence, and consumption time.
Energy Storage and Technical Standards
CPFL Energia reported that the project generated results such as the publication of three patents, the proposal of technical standards, laboratory data, and algorithms aimed at estimating and verifying battery behavior.
Economic studies, hardware and firmware development, mechanical packaging, and the use of artificial intelligence techniques were also conducted.
These steps show that repurposing is not just about removing a battery from the bus and installing it elsewhere.
To function safely, the process requires diagnosis, standardization, electronic control, and performance validation during the transition between automotive use and stationary use.
The project is part of a public call by the National Electric Energy Agency, launched in 2019, aimed at developing solutions in efficient electric mobility.
With this, the initiative brings together two expanding movements in the country: the electrification of transport and the search for storage for renewable sources.
For the electric sector, repurposed batteries can open storage alternatives with components that still have useful life.
In electric mobility, the second life helps answer an inevitable question: what to do with large packs when they no longer meet street requirements?
Repurposed Batteries Before Recycling
Although it does not replace recycling, the model delays this stage and extracts more value from components that have already consumed industrial resources to be produced.
Before becoming definitive waste, the battery can go through an intermediate phase, with an energy function and technical reuse criteria.
As more electric buses and cars enter circulation, initiatives of this type tend to gain industrial and regulatory relevance.
Every battery installed today will, at some point, have to leave automotive use, and the choice between disposal, recycling, or second life will depend on technical evaluation, safety, and economic viability.
Be the first to react!