Can you upgrade a Tesla with a more powerful used battery?
This page is translated from the original post "Peut-on upgrader une Tesla avec une batterie d’occasion plus puissante ?" in French.
- 12/08/2025 10:08
The web is starting to be flooded with used Tesla batteries. But how feasible is it to upgrade a Model 3 or Model Y?
The offer is tempting: less than 6000 euros for a Tesla Model 3 Long Range battery (75 kWh), with no further details on its age… The promise? Replace the one currently owned, damaged or tired, with a newer and more efficient model.
The rapid evolution of battery technologies is leading many Tesla owners to ask themselves: can we replace the battery of a Model 3 Standard Range with a more powerful second-hand pack, like that of a Long Range version? On paper, the idea is appealing. In practice, the project faces several technical, software, and regulatory hurdles, not to mention the labor costs.
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A physical battery replacement… technically possible
Some specialized companies, like EVShop, offer used packs from Tesla Model 3 Long Range, typically with a capacity of 75 kWh compared to about 50 to 60 kWh for older Standard Range models. The physical replacement is doable: the overall format of the packs remains similar, and the attachment points under the chassis are common across all versions.
However, two important points complicate the operation: the extra weight of a Long Range pack is about 80 to 120 kg heavier. The suspension of a Standard Range is not designed for this weight, which may require reinforcement or complete changes to the shock absorbers and springs. This will drastically increase the final cost.
Additionally, compatibility of the connections may pose a problem. Depending on the year and generation of the pack, it may be necessary to adapt the wiring harness or cooling systems.
The software obstacle: the Tesla lockout
Even if the physical battery is installed, the BMS (Battery Management System) and the ECU of the car must recognize the new pack. However, Tesla does not provide an official upgrade to “unlock” higher capacity, except for rare exceptions on older models limited by software. In the case of the Model 3, installing a Long Range pack on a Standard Range does not guarantee that the car will use the full capacity: the software may limit charging and range to the original configuration.
Independent companies can reprogram the BMS to bypass this limitation, but this involves stepping outside the official Tesla network, with consequences for warranty and future compatibility with OTA (Over The Air) updates.
And what about an intervention within the official Tesla network? Specialized forums are filled with testimonials. Some owners who had a battery replaced under warranty hoped to pay a premium to upgrade to a Long Range version. The systematic response: refusal from Tesla.
What about legality and insurance?
In France, any significant modification to the technical characteristics of a homologated vehicle – including battery capacity if it affects range and weight – requires isolated approval from the DREAL. Without this, in case of an accident, the insurance will refuse coverage, and may even initiate legal proceedings.
Ultimately, the idea of upgrading to a more powerful battery is appealing on paper, but completely unrealistic.
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