Designing extra features into battery packs

The usual and more unusual features of a rechargeable battery pack

Rechargeable batteries, or secondary type are becoming more advanced through safety innovation as well as incorporating simple features within the pack that were more commonly external. In particular, lithium-ion chemistry battery packs (as found in mobile phones, laptops, high power tools etc) require electronic circuits built into the battery to offer safety and functionality.

Creasefield will usually build a lithium ion (li-ion) battery with a protection circuit module (PCM) as a bare minimum in order to provide basic safety features. This will protect the user and equipment from the battery if it fails or is inadvertently abused which might cause it to fail dramatically. Visit this section of our website (link) for more details.

Extra Features

In addition to the basic PCM, Creasefield offers other functionality that is increasingly required by our customers. Gas gauging is the next more commonly requested feature, and is the battery geek speak for indicating the amount of capacity left in a battery at an instant in time. This can be as basic as providing a visual indication using a series of coloured LEDs, or might be provided via a databus connection – often I2C or SMBus to the host equipment. Sometimes both are required, this can be catered for. We are continually seeking new and innovative ways of designing extra features into battery packs produced in our UK facility.

The next functionality sometimes required is a smart battery system or SBS. This means the integrated circuit on the battery PCB is capable of communicating with the host equipment and sometimes external charging equipment. This allows the battery to manage itself, to define charge parameters (how much power for a given temperature) of the charging device, and to have much more granular control of the packs operating limits. A basic PCM will protect a battery using the batteries maximum limits as the safety thresholds. A smart battery system may put stops in place such that the battery will play a part in protecting the equipment it powers against overcurrent or voltage limits that the equipment should not exceed. The battery is programmed to stop working much earlier than it would normally, or perhaps to power off in a high temperature condition.

Increasingly equipment suppliers are incorporating charge circuitry into the battery itself rather than the equipment. All the equipment design needs do is feed a suitable DC supply to the battery, it will take care of charging itself safely. Linear chargers for small batteries are small and inexpensive and can be combined with the protection circuitry.

Batteries that need to operate in cold environments cannot be charged below 0degC. Creasefield has made batteries with built-in heating functionality to allow the pack to be gently warmed by the charging power source, heating it above freezing temperatures and then charging carried out.

Our engineering team are familiar with all of these electronic features, boards are designed and tested in house and manufactured with our UK partner suppliers. Boards requiring microcontrollers and bespoke software are also developed in house.