BMW wants hydrogen to be the next big alternative to battery-only EVs. But when journalists climbed into the company’s iX5 Hydrogen prototype, an X5 SUV converted into a fuel-cell testbed, one detail jumped out: the thing appears to be carrying a seriously large battery for a vehicle marketed as “hydrogen.”
That “wait, why is there a huge battery in a hydrogen car?” moment, reported by French tech outlet Frandroid, gets to the heart of what modern fuel-cell vehicles really are. They’re still electric cars. The hydrogen hardware doesn’t replace the EV drivetrain, it feeds it. And the battery, far from being an afterthought, can be central to how the vehicle feels, performs, and even how efficiently it uses hydrogen.
A hydrogen X5 is still an EV, hydrogen just makes the electricity onboard
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The iX5 Hydrogen isn’t a hydrogen-burning engine with pistons and exhaust. It’s an electric SUV where electricity is generated onboard by a fuel cell. Hydrogen stored in high-pressure tanks flows to the fuel-cell stack, which converts it into electricity to power the electric motor, just like a conventional EV, minus the plug.
That’s where the battery comes in. In a fuel-cell vehicle, the battery acts as a buffer: it stores energy when the fuel cell is producing more than the motor needs, and it delivers extra punch when the driver demands quick power, hard acceleration, passing, or long climbs.
Fuel cells don’t love rapid, constant swings in load. A battery smooths those spikes, helping the system respond instantly while keeping the fuel cell operating in a more stable, efficient range.
That “big battery” may be about power, not long-range driving
When people hear “big battery,” they usually think “big range.” But battery size can matter in two different ways: energy capacity (how far you can go) and power capability (how fast it can deliver or absorb energy). A battery can look massive, physically and in weight, while being tuned primarily to handle high power demands rather than to store enough energy for hundreds of miles of driving on battery alone.
On a prototype like the iX5 Hydrogen, BMW may be prioritizing a battery that can deliver strong bursts of power and capture lots of energy through regenerative braking. That improves responsiveness and can make the SUV feel more like the premium, effortless X5 buyers expect.
It also helps BMW test extremes. Prototypes are rolling laboratories, and oversizing components is common when engineers want flexibility, different calibrations, demanding drive cycles, and extra operating margin in heat, cold, or sustained high-speed driving.
BMW is testing more than tech, it’s testing the real-world hydrogen experience
BMW isn’t pitching the iX5 Hydrogen as an imminent mass-market launch. It’s an evaluation program designed to answer practical questions: How easy is it to find hydrogen stations? How consistent is refueling? How does the system behave in everyday driving with journalists and regular drivers behind the wheel?
On paper, hydrogen’s big selling point is familiar to Americans used to gas stations: refuel in minutes, not hours. In reality, that promise only works if the fueling network exists and is reliable, an issue in much of Europe, and also in the U.S., where public hydrogen fueling is largely concentrated in parts of California.
BMW is also weighing efficiency. The hydrogen pathway, producing hydrogen, compressing it, transporting it, dispensing it, then converting it back into electricity, loses energy at every step. Battery EVs typically win on overall efficiency because they use electricity directly. That doesn’t automatically kill hydrogen, but it pushes it toward niches where fast refueling and energy density matter most, like heavy-duty trucking, commercial fleets, or specific long-distance use cases.
Hydrogen vs. battery EVs: the fight is infrastructure, cost, and policy
Stack up a fuel-cell SUV against today’s battery-electric SUVs and the comparison quickly moves beyond the spec sheet. Total cost depends on hydrogen prices, real-world consumption, and, most importantly, whether drivers can actually fuel up without planning their day around a limited network.
Fuel-cell vehicles also carry expensive hardware: the fuel-cell stack, high-pressure tanks, safety systems, plus the full EV drivetrain and a substantial battery. That’s a lot of costly parts unless production scales dramatically. But scaling depends on demand, and demand depends on fueling infrastructure, a tough loop to break.
European emissions rules are tightening, and fuel-cell vehicles have zero tailpipe emissions, just water vapor. But the climate math depends on how the hydrogen is made. Hydrogen produced from fossil fuels without capturing carbon undercuts the environmental case; low-carbon hydrogen (from renewable-powered electrolysis or nuclear-backed grids) changes the equation, but it’s typically more expensive and requires major industrial buildout.
Frandroid’s surprise at the iX5’s battery size highlights the real takeaway: hydrogen doesn’t simplify the vehicle. It adds another layer. If that complexity delivers clear benefits, fast refueling, stable highway range, strong cold-weather performance, hydrogen could carve out a role. If not, it risks being an elegant engineering solution looking for a practical market.
