Electronics patent of the month: A battery management system for portable devices

This month features the challenge of a battery management system for portable devices, which comes up in PAG Limited’s GB patent. Michael Jaeger, of UK patent and trade mark attorneys Withers & Rogers LLP, writes:

GB Patent Number: GB2494187
Granted to: PAG Limited

I must admit that I am slightly puzzled by the patent, which I have chosen to write about this month, as I will explain below. Hopefully, one of you will be able to enlighten me.

Electronics patent of the month: A battery management system for portable devicesPAG Limited‘s GB patent, which was granted on 17 February 2016, deals with the daily challenge of powering portable devices. As explained on its first page:

“There is a growing need for higher capacity battery technology, particularly for powering increasingly complex electrical devices, as well as for powering larger devices conventionally powered by other energy sources, such as fuel. For instance, High Definition and Very High Definition cameras and other such equipment require much more power than older Standard Definition cameras. Similarly, there is a desire and need to power vehicles from an electrical source rather than using fossil fuels.”

The problem is embellished as follows. Very high capacity batteries exist, but these have inherent safety issues such as the possibility of rapid discharge during incorrect usage or damage. This leads to the risk of fire, this being a reason for the restriction on taking some lithium-based batteries on planes.

To address this problem, PAG has designed a battery management system, which includes a number of individual battery units. Each battery unit includes several cells, a controller, a male connector on one side of the battery unit and a female connector on the other. The connectors are designed so that the first battery is connected to an electrical device. The others can then be piggy-backed together on the first battery. The combined battery units can share the load drawn by the device. This means that either the combination can supply a greater current than that which would be available from a single battery unit, or the current drawn from each battery is reduced. Consequently, this reduces internal heat generation and increases the overall efficiency and discharge time of the batteries.

A key feature of the invention is that a controller of one of the battery units is chosen as the ‘master’. This then controls the other batteries, which are set as ‘slaves’. In this manner, the master controller receives information about the status of the cells in each of the other batteries and manages the supply of power to the device accordingly.

What is unusual about this patent is that the protection, which the patent owners have obtained only covers a situation where “the system is configured to retain some charge in the master battery to allow for powering an electrical device while any and all slave batteries are removed from the stack for replacement with charged batteries”. The benefit of this novel feature of the invention is explained as being able to “provide for substantially continuous and uninterrupted power to an electrical device by regular replacement of discharged batteries with charged batteries”.

The basic idea seems to make sense – piggyback a few battery units together and let them self-configure as a master and slaves.

However, the way that the patent has ended up totally restricts the “self-configuring” ability of the system, since to achieve the purpose of “providing substantially continuous and uninterrupted power to an electrical device”, the master controller must necessarily be the battery unit, which is closest to the electrical device. This then facilitates the powering of the electrical device while the slave batteries are removed for replacement with charged batteries. This is because if there is a slave battery unit sandwiched between the electrical device and the master battery unit, it will not be possible to replace it without also removing the master battery unit, thereby interrupting power to the electrical device.

In other words, what the patent actually protects is this: the configuration of the battery unit, which is directly attached to the electrical device as the master controller.

Having unpeeled the intricate language of the patent to reveal what it is really saying, this invention seems very obvious to me – or perhaps I have missed something?

Perhaps the lesson here is that worthwhile innovation doesn’t need complex wording to demonstrate its usefulness.

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


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