BorgWarner, the focus is on scalable LFP battery architecture aimed at underfloor integration in electric buses. Our interview

During Busworld Europe 2025, BorgWarner outlined the structure and industrial rationale behind its current and next-generation battery offering.

Martin Busche, Vice President Battery R&D, Product Strategy and Program Management, described a family of LFP and NMC battery packs built on shared hardware, software and cell architecture, designed to support different installation concepts in buses and commercial vehicles.

The strategy reflects a focus on manufacturing efficiency, scalability and flexibility at a time when battery cost pressure and platform diversification are shaping the electric bus market.

Martin Busche, in October 2025 you have been presenting several new solutions at Busworld. What exactly did you showcase?

Martin Busche: What you saw in our booth is essentially our complete product range. Beyond what’s displayed, we have further diversifications, but here you saw the full LFP battery pack family — a four-member family — and one of the NMC pack variants, the 6 AKM version. Our NMC family also includes a 1.80-meter 9 AKM pack and a 5 AKM pack, all featuring cylindrical-cell NMC modules.

And with LFP?

M.B.: With LFP, the family consists of four packs built around blade cells. The ~50 kWh flat pack — two metres long, 14 cm high (required for ground clearance), 66 cm wide — is designed for underbody installation in buses, where height is restricted i.e. due to wheelchair accessibility requirements. The compact pack (same energy) is a shorter dual-layer version suitable for many applications: Space restricted bus engine compartments, medium duty trucks, small excavators or marine applications. In four layers, the same architecture becomes the 100 kWh cubic pack for heavy-duty truck applications. Finally, the high pack – a 100 kWh double layer version of the flatpack is tailored for rooftop installation on city buses or coaches.

BorgWarner: parts communalities is key

Where do you expect most of the demand to come from?

M.B.: For purpose-built electric bus architectures, the flat pack will be essential. Mounting packs under the floor instead of on the roof reduces structural requirements and therefore cost and weight. But from our side, we are not overly concerned about which specific pack type dominates. 

Why?

M.B.: Because we found a way to place a lot of synergies in this family so that, apart from the individual homologation, we have the maximum common parts possible.

Every pack has the same hardware and software — we call that our “Software Foundation”. We always feature the same cells. So, no matter if you have the flat pack, the compact pack, the cubic pack or the high pack, you always have the FinDreams Battery blade cells.

We even have a common substack: 52 of these 104 cells build one substack, and that is the major building block. If you take the substack and put two behind each other, you have the flat pack. Put two on top of each other, you have the compact pack. Put four on top of each other, you have the cubic pack, as we mentioned before. That’s our design language being flexible, modular, scalable and multigenerational.

The reason for that is pretty simple. We try to be as lean as possible in production, and we try to leverage maximum economies of scale — because we know we have to compete against Chinese price tags. Through the partnership with FinDreams, and through this design approach, we are able to do exactly that.

We even share the same hardware & software platorm across the different cell technologies: from the next-generation Gen.3.3 of our NMC range onwards, the NMC packs will use the same hard- and software as well. 

Can you share your annual production capacity?

M.B.: For NMC, our annual capacity is about 5 GWh. Using a 100 kWh battery as a baseline, that equals roughly 50,000 packs per year. LFP is currently in the B-sample phase, but we expect a comparable order of magnitude.

LFP scaling much faster than expected

A new trend in the e-bus industry, presented on the most advanced products, is using batteries as a structural part of the vehicle…

M.B.: That’s the cell-to-frame approach. We know it well: FinDreams, BYD’s cell manufacturer, is our bilaterally exclusive partner. But cell-to-frame only works when you build the vehicle yourself, meaning, you own the integration responsibility on the vehicle level. Our strategy is to make packs as lean and easy to integrate as possible, enabling us to serve multiple customers and retain economies of scale.

Customers can also mix and match pack types within one vehicle — for example, four flat packs under the floor plus two compact packs where space dictates. This gets us as close as possible to optimization without locking into a single bespoke vehicle platform.

On the innovation front: where is your R&D focused? Materials? Efficiency? New chemistries? 

M.B.: Currently the focus is LFP, because that’s the chemistry scaling fastest. Thanks to our partnership with FinDreams, we can adopt iterative improvements — for instance LMFP, once the cycle life is sufficient.

Five years ago the industry focus was almost entirely NMC; LFP was often dismissed as a ‘Chinese’ technology.

M.B.: NMC still has its place. Either due to geopolitics or due to physical requirements: some bus and truck applications are extremely weight-sensitive and need the higher energy density of NMC.

However, on our side, BorgWarner has its own electrochemistry team in Darmstadt continuously screening new technologies. Our hardware and software are chemistry-agnostic, like our capability to package any relevant cell form factor. When a new cell generation arrives, we can package it and adjust only the algorithm module. So we are future-proof.

What about solid-state?

M.B.: As for solid-state: I’ve worked in electrochemistry for many years. Solid-state has always been “ten years away.” It exists at lab scale, including first attempts to scale the production. The question is when will it be possible to produce it for a competitive price compared to LFP. And I think this will take another couple of years.

Back to LFP, the state-of-charge estimation is more difficult due to the flat voltage curve, isn’t it? How do you address this?

M.B.: It’s a matter of SOC algorithm. NMC has a nicely sloped voltage curve, so SOC is easy to estimate. LFP is flat. However we have very accurate proprietary LFP algorithms. Due to the modular setup of our software, we are also open to 3rd party modules: if customers want to use their own algorithms, we can integrate those as well. The system is anyway prepared for both BorgWarner and FinDreams algorithm modules.