Electronics patent of the month: Improving battery modules for hybrid vehicles

GB Patent Number: 2458942
Granted to: Amberjac Projects

One of the ‘quiet’ technological revolutions of the past ten to twenty years has been in relation to the efficiency and performance of batteries. As our world has become increasingly mobile, we rely on compact and effective portable power supplies to achieve best performance from our cameras, laptop computers, tablets, mobile phones and more recently, cars.

In general, battery-powered cars come in two varieties. There are those cars which are entirely powered by batteries and there are hybrid vehicles, which run on petrol but include an electric motor and battery. The latter are charged by operation of the petrol engine and by regenerative braking.

UK Patent Number 2458942 was granted on 3 April 2013 to Amberjac Projects Limited and relates to improvements in battery modules. Amberjac believes that the full potential of hybrid vehicles can be realised by improving the batteries used in these vehicles. In particular, they propose to replace the standard battery pack, which has a capacity of around 1.3 kWh, with a higher capacity 9 kWh battery pack.

In order to charge the larger capacity battery, Amberjac proposes to provide a charging system, similar to that used within an entirely electric vehicle, so it can be charged overnight. In doing so, this ensures that the vehicle using the larger capacity battery will benefit from providing much greater performance in terms of its miles per gallon.

As is well known, copper is an important metal in power transmission due to its high thermal and electrical conductivity. A common method of joining two metals is by welding, however because of its low melting point relative to other metals, it is difficult to weld copper with nickel or nickel-containing metals. This can present difficulties in the production of battery systems where it is required to connect a large number of battery cells in a multi-cell arrangement.

In order to achieve a high voltage, cells must be connected in series and in order to produce a battery “module” with a high capacity, these series-connected cells must also be connected in parallel.

For example, a 45 kWh battery system may comprise 106 3.2 V/1.6 AH capacity cells in parallel in each module and 84 modules in series. The best way of connecting these cells together would be by using copper.

In light of the difficulty in welding copper with nickel or nickel-containing metals, Amberjac has developed an improved method of connecting these two metals together.

According to Amberjac’s invention, ultrasonic welding is used to connect these two metals. To do this, the nickel or nickel-containing metal element is placed on to a copper element between an anvil and a ‘sonitrode’ as part of the ultrasonic welding system. The ‘sonitrode’ is forced downwards onto the area where the join is needed, effectively squeezing the two metals together and applying ultrasonic radiation in order to join them. Using this approach allows a battery module connector plate to be prepared having a series of holes, which are positioned to correspond to the upper terminals of the cells within the battery module. This further improves the efficiency of the battery modules.

Michael Jaeger is a patent attorney at leading UK patent and trade mark attorneys, Withers & Rogers LLP.

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