Cell selection depends on a number of factors including cost, weight, available volume, charge time, discharge current, environmental conditions and required service life.
Battery developers have a number of cell types available to them including Nickel Cadmium, Nickel-Metal Hydride, Lithium ion and Lithium ion Polymer. In recent years it is the Lithium ion chemistries that have dominated product development due to their high energy density and reducing cost, but the older Nickel chemistries do still offer superior performance in certain applications.
Yet when designing a customised battery, cell selection needs to be regarded holistically. This means that a decision should be based on individual cell attributes that fit the design best. It is important to remember that no single cell type offers every performance attribute that might be required – there will always have to be a compromise.
There are a number of different ways of communicating with a battery. Some manufacturers use proprietary protocols, but I believe that an open standard such as the Smart Battery System (SBS) offers the best solution for battery, charger and device manufacturers alike. Using SBS allows all of the actors to develop their own products with the knowledge that they will work seamlessly with each other. Adopting a common standard also allows for ‘chemistry independence’ where chargers that are developed now will work perfectly well with batteries that are developed in the future.
When the world demands higher energy density from its batteries, what are you doing to keep the weight of your products down?
It is a known fact that anything you add around the cells of a battery pack reduces energy density. However it is important to carefully weigh up the need for energy with the need to create a battery solution that is easy and safe to use throughout the life of the product. All components in and around the battery have to add value in some way – if this is to protect against vibration, prevent water ingress or to simply allow the battery to be latched onto the host device they must all play their part. There is little point in creating an integrated electronic protection system for the battery if this is damaged by external mechanical abuse – such a system must be protected in the same way as the cells must be protected – to ensure that safe and reliable operation is maintained under all operating conditions. The use of modern polymer materials can provide both light weight and extreme strength when used correctly. Alternatively, materials such as magnesium can provide enhanced electrical shielding for mission critical applications.
What do I need to know about battery certification?
The days in which a battery pack could be quickly assembled, reviewed by an OEM and then dropped into an application are long gone. Today, most OEM applications require their rechargeable batteries to undergo a level of regulatory testing before they can be used. IEC62133 is already a mandatory requirement of many device standards. For Lithium ion batteries there are additional testing requirements for transportation. Once testing has been done for CE marking and country or application specific testing have been completed you can see that the list of regulatory tests becomes quite long. Accutronics boasts a great deal of experience in having batteries tested to all of these standards. We manage the process seamlessly, ensuring batteries are approved on time and within budget.
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