Comparing Tesla's CTC battery vs BYD's CTB battery, what's the difference?

Battery electric vehicles (BEVs) come in various designs, and their battery packs are no exception. Different approaches are taken to integrate batteries into these vehicles, each with its own benefits and drawbacks.

In this article, we'll explore some of the battery pack designs that have evolved in the recent years.

The early battery designs utilised a conventional approach known as Cell-to-Module (CTM). In this method, individual battery cells were packaged into modules, which were then assembled into the final battery pack.

While functional, this approach required numerous parts, increasing both the cost and weight of the vehicle due to additional structural elements. It also has limitations in space utilisation and is gradually being replaced by newer integration methods.

Then came CTP (Cell-to-Pack) technology, which integrates individual battery cells directly into the battery pack, skipping the traditional module design. This approach boosts energy density, reduces the size and weight of the battery system, and is pioneered by battery supplier CATL and BYD.

BYD's Blade battery is an example of CTP, arranging individual battery cells in an array resembling a "blade" and inserting them directly into the battery pack.

Also read: BYD Atto 3's LFP Blade battery - This is what makes it superior to its rivals

Building upon the advancements of CTP, BYD introduced Cell-to-Body (CTB) technology, an approach that integrates battery cells directly into the vehicle body. This method transforms body integration into battery-body integration, further enhancing space utilisation.

BYD's CTB technology combines the body floor panel and the upper shell of the battery pack into a single unit, simplifying sealing and waterproofing requirements. This integration not only improves structural integrity but also reduces space loss. The first BEV to utilise this technology is the BYD Seal.

Meanwhile, on the other side of the world, Tesla introduced its Cell-to-Chassis (CTC) technology in 2020. At the core of Tesla's CTC technology are its 4680 battery cells, arranged with cooling ribbons for optimal thermal management and structural reinforcement.

With CTC, battery cells are installed directly into the vehicle body, connecting the front and rear body castings and replacing the cockpit floor with a battery upper cover. The result is reduced vehicle weight and a more streamlined production, which in turns lead to more efficient and cost-effective manufacturing.

Both CTB and CTC have been used interchangeably since both similar in the sense that both feature structural battery packs.

Based on our findings, the first Tesla model to incorporate the CTC battery technology is the Model Y. Reports suggest that the choice of battery cells - either Tesla's proprietary 4680 cylindrical battery or BYD's LFP battery - varies depending on the manufacturing location.

One concern often raised about structural battery packs is their repairability in case of accidents. And in many cases, even a relatively minor collision results in a complete write-off.

Sandy Munro, head of Michigan-based Munro & Associates, which tears down vehicles and advises car companies on how to improve them, said the Tesla Model Y battery pack has "zero repairability," and that it would likely be discarded rather than repaired. However, Tesla's service manual states that the battery pack is removable.

The argument is that structural packs aren't repaired; instead, they undergo grinding into dust, and their chemical components are recycled into a new pack. But that doesn’t stop insurance companies from rising the premiums on BEVs, as reported previously.

Also read: EV battery scratched during accident? Insurance may consider it a total loss

So while CTC and CTB offer significant benefits in terms of space utilisation, structural integrity, and cost-effectiveness, the downside is the lack of repairability. Nonetheless, it appears that these two BEV powerhouses are forging ahead with this technology, and it remains to be seen if others will follow suit.

Also read: Despite poor quality, Toyota admits there is value in learning from Tesla's manufacturing know-how