The specialist for measurement technology and test systems Smart Testsolutions has developed a cell contact-making unit for the voltage tap on fuel cells, which has a height of only five millimeters. Previous solutions needed space between 35 and 250 millimeters. In addition, the new unit makes complex positioning work on the contacts unnecessary. The unit can be used in stationary test equipment as well as in fuel cell vehicles.
With regard to cell spacing of just about 1 millimeter in modern fuel cell stacks, the voltage tapping at the bipolar plates between the individual cells presents a great challenge. So far, spring contacts have generally been used, which need to be extensively adjusted and built up high.
The CVP (Cell Voltage Pickup) from Smart Testsolutions ensures reliable voltage tapping without manual adjustment. The contacts center themselves in the cell pockets. This guarantees short assembly times. At the same time, the contacting unit has a height of only five millimeters, while conventional solutions have heights of between 35 and 250 millimeters.
Thanks to their compact design, the CVP contact unit can be used both stationary on test stands and mobile in fuel cell vehicles. By using 3D printing processes, the design is adapted in such a way that Smart customers can integrate the system into a space-neutral configuration in existing serial design signals.
The contacting unit consists of gold-plated copper-beryllium wires which are spring-mounted in modular holders. This ensures that production tolerances of the stack as well as impact and vibration loads in the vertical direction are compensated. The holders are threaded onto profiles and stored in a floating position. Thus, the system can also compensate for changes in length of the stack in the horizontal direction.
The entire contacting unit is attached to the end plates and, if present, to a center plate. In this pretensioned state, a simple and rapid introduction of the contacts into the cell pockets is possible. In doing so, most of the contacts center themselves. If smaller corrections are required, these can be carried out without problems due to the clear structure and good accessibility. Hours of laborious positioning work are no longer required. The final positioning and fixing of the system is carried out by a hood, which presses the copper-beryllium wires into the cell pockets, thus ensuring a constant contact pressure and a reliable voltage tap.
The design of the cell contacting unit CVP was carried out in accordance with the test standard LV 123, in which German automotive manufacturers define test conditions for the test of high-voltage components for electric and hybrid vehicles. The cell contacting unit is vibration and temperature insensitive and can be used flexibly. This is the ideal addition to the Smart systems for cell voltage measurement on batteries and fuel cells.