LiteFCBike – Fuel Cell System for an Electric Carrier

The market for e-bikes and pedelecs as a sustainable alternative to cars for short distances has been growing for years. Their purpose ranges from everyday bikes to cargo bikes for delivery services to support for ambitious athletes.

In this project, a compact fuel cell system will be designed and developed to provide an adequate replacement for a pedelec driving battery. It is based on José Fernandez's "Conodrive" drive concept, which consists of a light and efficient electric carrier that transforms almost any bicycle into a pedelec.

We have focused the project on developing a system that is compact, lightweight and practical for the end user. The development takes place together with the Conodrive developer José Fernandez, who works on the electronics part. Although the fuel cell system was developed for the Conodrive concept, it can in principle also be used for any other pedelec, especially for cargo pedelecs with a larger hydrogen storage.

Within the framework of the system design, it quickly became apparent that a hydrogen pressure tank was less suitable for the required quantities of energy and not practicable for the private end user. Therefore metal hydride cartridges are used. They are easily available and can be filled by yourself with a suitable small electrolyzer. In order to achieve significantly greater ranges with short refueling times, it would be possible to use a pressure tank instead (in case there is more space available). Especially for use in cargo bikes this would be more advantageous.

When selecting all other components, in particular the fuel cell stacks, the main criteria were compactness and weight: Two fuel cell stacks with open cathode are used. These are extremely light and air-cooled, so that a liquid cooling circuit with pump etc. is no longer necessary. In addition, space-saving miniature valves and pressure reducers were installed as far as possible. In order to connect all components fluidly, a compact fluidics module was developed to which all components are connected and which makes pipes and connectors superfluous.

In rated operation, the fuel cells produce approx. 70W of electrical power and recharge the buffer battery in the system. Thus the usual 250W of a pedelec are available in the support phases. Ambient air required for reaction and cooling is blown through the stack with two fans. The warm and humid exhaust air flows out to the rear and warms the metal hydride storage tanks, which can thus release hydrogen more quickly. The total dimensions of the complete system with tank and control electronics are 348x153x47mm with a weight of 3.3kg incl. hydrogen tank. The net energy content of the system is approx. 270Wh with one refueling. The system can be filled with up to 30bar, all 12 cartridges are filled simultaneously.