Breakthrough that unlocks the potential of every motor

Lower Embodied Emission

Smaller & Lighter

Less Rare Earth  Magnets

Cheaper

Unlock more  continuous power at no extra cost

More Power

Built to cool, Engineered to Lead

cost reduction

Land, Air or Sea,  One Shaft to Power  Cool Them All.

Introducing CoolShaft™ The Future of Every Electric Motor

Unlocking the Hidden Potential of Electric Motors without clean sheet design

Electric motors drive the future of mobility, but they are fundamentally constrained by heat buildup, the thermodynamic barrier. 

Rotor heating is often the fundamental bottle neck that controls the size and cost of conventional motors (95% of motors). Rotor heat control is also the key that enables the adoption of the ultra cheap, ultra clean magnet less motors. 

CoolShaft™ is a breakthrough rotor cooling system that removes this bottleneck. Designed to integrate seamlessly into existing electric motor architectures, CoolShaft™ can enable more than 50% more continuous power, which can be converted to 50% smaller and lighter motors, & unlocks the adoption of magnet less motor topologies. These are all without the need for a clean-sheet redesign.

Why Motors Are Bigger & More Expensive Than They Need to Be

Electric machines have come a long way in terms of efficiency and compactness, but one challenge persists is cooling. 
Today’s motors are sized not by their electromagnetic performance, their sizing depends on their inability to dissipate heat, where often the rotor heat is the limiting factor. This leads to oversized motors, excessive use of rare-earth magnets, and limited efficiency under real-world driving conditions. These issues persist at various degrees in all motor topologies.

Motor market & CoolShaft application

Rotor overheating limits continuous power and continuous power is the most important aspect of a motor’s performance. That is why established, leading motor manufacturers quote the performance of their motors using continuous power.

Why Continuous Power Matters

Continuous power is the real measure of a motor’s capability. It defines how much power a motor can deliver over time, during sustained highway driving and freight hauling 

Unlike peak power, which lasts seconds, continuous power defines the motor’s true utility in real-world conditions. 

This is why motors today are oversized, overbuilt, and over-dependent on expensive rare-earth magnets. It is not because they need more torque, but because they can’t stay cool enough for long enough. 

At Cooled Motors, we focused on the real problem, how to unlock continuous power by cooling the rotor. 

Delivering more continuous power requires the removal of the heat build-up, and today’s cooling strategies aren’t up to the task. While stators are commonly cooled with water jackets, rotors are left to passively shed heat through conduction and ambient airflow which is an inherently inefficient process, especially at high RPMs. This is due to the air gap between the rotor and the stator (rotor needs to be free to spin) acting like insulation.

At Cooled Motors, we believe the future isn’t about chasing attention-grabbing peak power figures it’s about delivering reliable, repeatable, high-performance continuous power. That’s why we built CoolShaft™ a rotor-first cooling system that enables smaller, more efficient, and more sustainable motors without the PR fluff.

Why Other Cooling Methods Fall Short

Liquid Jacket Approach

This is the most common thermal management method which wraps the stator in a liquid-cooled jacket. Almost all motors use this method which works well to cool the stator.

Coolant (water-ethylene glycol mix/sometimes ATF) circulates through a housing jacket
It removes copper (I²R) losses plus AC loss, & core losses from the laminated iron stack.
Stator temperatures stay within safe limits (typically Class H, 170°C max). This is higher than the limit of the magnets.

Pros: Highly effective for cooling the motor at low speeds (below the base speed), hence enhance the peak torque at low speeds. 

Cons: has negligible cooling effect on the rotor. The rotor temperature is the critical limit for continuous power, magnet grade, size and cost.

A Flawed Solution

To address rotor heat, some up and coming designs have tried to use Automatic Transmission Fluid (ATF) oil to cool the shaft or sprayed onto end windings. This improves contact and avoids electrical conductivity risks. But there are significant trade-offs:

Poor thermal performance – Oil has lower thermal performance than WEG50/50
High viscosity issues – 20x viscosity of WEG50/50, requiring large pumps to counteract the significant pressure drops.
Addition system complexity – The requirement for extra sumps, pressure pumps, and elevated oil temps (>90°C)
Integration headaches – Non-standard architecture that needs new packaging or dual cooling loops
Material concerns – Oil can absorb moisture, corrode components, and needs costly e-Fluids to mitigate.

Pros: Oil as a fluid is easy to understand and handle by the electric industry. It’s a low hanging fruit that doesn’t bare much

Cons: Oil systems are complex, expensive, & underperform, making them commercially unattractive.

Water-Based Shaft Cooling

50:50 Water-ethylene glycol (50/50WEG) is the standard cooling fluid used in all EVs. Water based shaft cooling offers dramatically better thermal performance, but only if you can contain it.

14× higher heat transfer coefficient than oil
Efficient cooling directly at the rotor via  proprietary shaft flow circuit

However, WEG’s conductivity poses a serious design challenge. If the sealing system leaks, it can lead to short circuits or insulation failure.

Coolshaft™ - Cooling What Others Can’t Reach

CoolShaft™ is the first complete water-based rotor cooling system that’s leak-proof, automotive-grade, scalable and production-ready. Unlike simplistic hollow-shaft oil-cooling attempts, CoolShaft™ is a fully engineered system combining, Advanced multi-layer sealing, leak-proof under continuous high-speed rotation, aerospace-grade CFD-optimised flow paths for maximum cooling with minimal pressure loss, cross-industry expertise from oil & gas, aerospace, & automotive

Removing rotor heat is the heart of the continuous power limitation. With CoolShaft™ you can have:

CoolShaft™ doesn’t just cool better. It solves the single biggest limitation in every electric vehicle motor today.

Measurable Gains,  Maximum Impact

We have tested the CoolShaftTM design with 20+ motor designs that are currently in vehicles in the market using industry standard multi-physics simulations with the following results:

BMW i3 with CoolShaft™

When retrofitted with CoolShaft™, the i3 motor unlocked significant extra continuous power. The increase averaged around 30% around the ‘Zone of Interest’ (3000rpm to 8000rpm) and about 240% in the high-speed region above 8000rpm.  The rotor temperature dropped from an average of 130°C to 90°C, allowing for the magnet grade to be reduced by 2 grades. This in turns reduces the reliance on , one of the rarest of the rare earths.

The BMW i3’s stator temperature limit of 170 °C became the limiting factor with the CoolShaftTM.

This demonstrates how rotor thermal limitations, not electromagnetic constraints, are the true barrier to sustained motor performance.

A real Transformation 50% Smaller Motors Vehicle  level transformation

We have tested the CoolShaftTM design with 20+ motor designs that are currently in vehicles in the market using industry standard multi-physics simulations with the following results:

This is how a 50% smaller motor translates into a vehicle-level transformation — one that improves performance, efficiency, and manufacturing flexibility all at once. CoolShaft™ makes this possible by unlocking thermal headroom and eliminating the need to over-engineer motor volume for heat.