Cell contacting unit with a height of just 5 millimetres
by Markus Schuster
The cell spacing of less than one millimetre in modern fuel cells makes voltage tapping at the bipolar plates a real challenge when it comes to measuring individual cell voltages. For 20 years now, we at SMART TESTSOLUTIONS have been working on cell voltage monitoring for fuel cells and batteries. And this has naturally involved us putting plenty of thought into the subject of cell contacting as well. All these efforts have given rise to the new cell contacting unit CVP, which we presented to the public at the beginning of July at the 18th annual congress "Supplier Innovation 2016 – the future of the automobile" in Munich.
Tedious manual adjustment no longer necessary
Up until now, use has generally been made of spring contacts for voltage tapping at fuel cells. These not only require a lot of adjustment work, their height is also a problem. Because space is at a premium in many applications – in motor vehicles for example. Our CVP guarantees reliable voltage tapping without the need for any manual adjustment on fitting. The contacts are automatically centred in the cell pockets, thus ensuring short installation times. What's more, the height of the contacting unit is just five millimetres, as opposed to between 35 and 250 millimetres with conventional solutions.
Vibration is not an issue
Whilst not wanting to give too much away, we would like to give you a few details of the design and functionality of the solution at this point. The contacting unit consists of gold-plated copper-beryllium wires which are spring-mounted in modular holders. This enables the system to compensate for the manufacturing tolerances of the stack and to allow for vertical impact and vibration.
The holders are threaded onto sections and are flexibly mounted. The system is thus able to accommodate horizontal changes in the length of the stack.
3D printing techniques permit individual adaptation
The entire contacting unit is attached to the end plates and – if applicable – to a central plate. In this pre-tensioned state, the contacts can quickly and easily be inserted in the cell pockets. The contacts are largely self-centring. The clear-cut design and good accessibility mean that it is no problem to make any slight corrections required. There is no need for hours of tedious positioning work.
The system is secured in its final position by a hood which presses the copper-beryllium wires into the cell pockets and so ensures constant contact pressure and reliable voltage tapping. The CVP achieves all this with a maximum height of just five millimetres, thus permitting integration of the cell contacting unit into existing fuel cell packages without any extra installation space. The use of 3D printing techniques also enables us to adapt the design so that our customers can integrate the system into the installation space offered by their standard packages without having to make any modifications.
Ideal supplement to cell voltage measurement modules
Thanks to the CVP, the disadvantages of existing cell contacting methods are a thing of the past. The system is of extremely shallow design, does not require any complicated adjustment work, is insensitive to both vibration and temperature and is also highly versatile. All this makes the CVP system the ideal companion for our MCM-IntelliProbe family of cell voltage measurement modules. Please do not hesitate to contact me should you have any questions about the system.