Electric MXer employs unique design to cool battery and motor.

By Ben Purvis  July 10, 2025

CFMoto revealed its prototype CF-X electric motocross bike at last year’s EICMA show including a handful of intriguing specifications, among them an advanced 400-volt architecture and performance that’s promised to be on a level with 450cc combustion engine competition models.

Now more details have emerged thanks to the publication of several new patent applications about the bike, giving us the first look under its skin and showing how CFMoto is making it compact, lightweight, and powerful. That’s a combination that’s normally out of bounds for electric bikes thanks to the relatively poor energy density of even the best lithium-ion batteries.

The patents all focus on one thing: temperature control. It’s not as simple as “cooling,” because both electric motors and batteries operate at their best within distinct and different temperature ranges. Getting heat into a battery can, for example, allow it charge or discharge faster than is possible when it’s cold. That’s one of the tricks to the incredible performance of some modern electric cars, with the likes of Teslas preheating their batteries before arriving at charging stations to allow faster charges, and also heating the cells to extract maximum power when required, for example in the Plaid mode of the highest-performance models.

It’s thanks to the different temperature requirements of batteries and motors that the Ducati’s V21L MotoE racebikes have separate liquid-cooling systems for each, with their own coolant pumps and radiators, to help keep the components within the ideal range. The CFMoto CF-X follows a similar path, but with just one radiator and two cooling systems that are interlinked via a thermoelectric device using the Peltier effect.

The Peltier cooler, referred to as a “refrigeration chip” in the CFMoto patents, features two thermally conductive side plates. One is exposed to the coolant flowing through the batteries, the other to the separate cooling system for the motor and control electronics. Between those plates are semiconductors connected to an electric current. Running the current in one direction will make the side of the Peltier device that corresponds to the battery’s cooling circuit colder, while the side attached to the motor warms up, and reversing the current has the opposite effect, reducing the temperature of the motor side of the cooling system and warming the battery. With no current applied, the temperatures of the two cooling systems should equalize. The patents suggest that by adding pumps for the separate battery and motor liquid-cooling systems, the temperatures can be more finely controlled by changing the coolant flow speed through each.

When we saw the CF-X at EICMA last year, we noted that it only had one visible radiator, unusually positioned underneath the rider’s seat and mounted vertically, it appeared to be fed by the openings on each side of the bike just in front of the radiator. However, the new patents show that the front side cowls—which would normally house radiators on a conventional internal combustion motocross bike—are actually used to feed a duct that runs through the “fuel tank” area of the bike and under the front section of the seat, directing air to the radiator. A second duct behind the radiator draws out hot air, which exits through vents on each side of the tail, sandwiched between the rear lower edges of the seat and the number boards.

CFMoto’s patents also concentrate on how to package the battery and motor together into a compact unit, occupying the space normally filled by a combustion engine, while preventing the temperature of each component adversely affecting the other. The battery cells are packed into a shaped pack that wraps around in front of the motor and above it, but the two sections are not in contact with each other—the patents specify a gap of 2.4mm (just under a tenth of an inch) between them, which is calculated to make the whole package as compact as possible without compromising the ability to maintain different temperatures for the battery and motor.

While some other electric motocross bikes use swappable batteries to make sure riders can maximize their time on track, the CFMoto’s battery isn’t easily removable. Instead, the ability to use the Peltier device to control the battery temperature should make faster charging possible, probably via the sort of rapid DC chargers used by electric cars.

CFMoto has a strong record of following its concept bikes with near-identical production models 12 months later, so it’s likely the finished, showroom-ready CF-X will appear at or around the EICMA show in November this year.

Source：CYCLE WORLD