Critical equipment and applications that need to run continuously can’t rely solely on mains supply; additional energy solutions in the form of battery backup are also required. The high energy density of Lithium-Ion battery technology is an ideal solution for applications where energy reliability, flexibility and safety are paramount. Here, Neil Oliver, technical marketing manager at Accutronics explains how these energy solutions can be the future of applications in sectors such as medical and healthcare, defence, security, industrial and backup electronics
When planning to build an off the shelf battery, manufacturers need to consider a few key points. Quality, availability and the level of customisation that might be required by the end user should all be addressed.
Developing intelligent batteries
Many OEM (original equipment manufacturer) designers want to be able to integrate a battery that suits their application, without going through the time and expense of developing a new energy solution for every product. However, finding a product that meets their quality expectations and that comes with the right level of functionality and regulatory compliance is no mean feat.
It was to meet this demand that the range of credit card batteries was born. The series has been designed as a standard, readily available product which lends itself to customisation in a timely and cost effective manner. The credit card sized batteries are pre-engineered, tooled and qualified before it reaches the end user.
The rationale for developing the new range of smart batteries came from the fact that electronic device OEMs in professional markets find it difficult to access smaller high quality rechargeable Lithium Ion battery packs for their portable devices. This might seem surprising, given the success of Lithium ion batteries in consumer electronic devices such as mobile phones and laptop computers.
However, the requirements of OEMs in professional markets are very different from those in the consumer sector, and there is often disconnect between managing expectations and what the battery industry is willing or able to provide.
For instance, the lifecycle of an average consumer battery is 18 months. In contrast, specialist OEM devices have a lifespan of 15 or more years, which makes the risk of obsolescence very high. This means embedding a consumer battery, which will become obsolete in just a couple of years, is not a viable solution for manufacturers.
Regardless, OEMs often have to buy a battery which was designed for a mobile phone or portable camcorder. However, such products don't come with the technical backup required and the OEM is at the mercy of the product life cycle of the consumer device for which the battery was originally intended.
Lithium-Ion battery technology
Traditionally, lead acid battery systems have proven to be both heavy and associated with low volumetric energy density. This means that despite their large dimensions, the power they hold may not be enough to support some applications, such as medical devices, for the length of time required.
With its higher gravimetric and volumetric energy density Lithium-Ion battery technology provides a longer runtime and reduced weight in comparison with older chemistries such as nickel-cadmium, nickel-metal-hydride and lead acid. As with other battery technologies, Lithium-Ion is perfectly safe and it can be used in any orientation. From an environmental perspective, Lithium-Ion batteries contain no heavy metals, they can be easily recycled and there are no restrictions on their disposal.
However, the transportation of Lithium-Ion batteries by air, sea and road is regulated and Lithium-Ion cells and batteries must pass mandatory UN (United Nations) transportation tests, called the UN 38.3 T1 – T8 tests. Batteries with energy in excess of 100Wh must be transported as class nine dangerous goods - which is not only costly - but it also increases time to market, which in turn affects delivery to the end user.
Listening to the requirements from OEMs (Original Equipment Manufacturers) and responding to their demand for a short lead time, Accutronics created an off the shelf, modular battery system that draws energy from removable, Sub 100Wh Lithium Ion smart batteries and feeds them through a central controller, allowing a >100Wh energy system to be manufactured whilst still complying with transportation regulations. Up to eight batteries can be built into one system, providing in excess of 700Wh.
Intelligent Power Vault is a power management device that uses multiple Lithium-Ion smart batteries to provide rechargeable battery power to a wide range of medical and industrial devices. The swappable smart battery technology represents a revolutionary way of storing energy for critical applications. Modularisation offers the high energy density and flexibility of smart Lithium-Ion battery technology without shipping limitations.
The Intelligent Power Vault consists of a control module on the exterior and slots for up to eight battery modules. Special brackets for mounting in a 19 inch rack are available for units configured with eight.
The loading system allows batteries to be easily removed for transportation without the need for tools. Once taken out of the rack, the individual batteries are excepted from shipping regulations and can be shipped with the power management device under a UN packing instruction that allows the shipment of 100Wh with equipment. As a result, the device can be transported anywhere by air, sea or road without the cost and complexity associated with dangerous goods shipping directives.
Each of the individual modules contained in the Intelligent Power Vault is a compact 86.4Wh rechargeable Lithium-ion battery. Called the VR420A, the battery has been specifically designed with energy density, functionality and safety in mind. Internal smart battery electronics allow the VR420A to communicate with the power management device, ensuring efficient operation is maintained at all times.
While the individual VR420A batteries are being charged, they communicate their charging requirements back to the IPV controller so they are only fuelled when needed. During the discharge stage, the batteries also provide information on their energy levels; all of this data is collated and transmitted to the host equipment. Then the user can make an informed decision on how to use the application and for how long. Furthermore, the intelligent fuel gauging tells the user when individual batteries need to be replaced, which in the long run, allows the end user to make the most of the lifespan of the battery.
Systems can be configured to provide between 178Wh and 714Wh, depending on the requirements of the application. This can be achieved either in the form of an unregulated battery voltage (between 17.4V and 12.0V), as a fixed voltage (between 5V and 28V) or a combination of both.
In addition, a regulated 5V 500mA output is available on the data connector – this can be used to allow software start-up of host equipment.
The VR420A Lithium-Ion smart battery is at the core of the system, powering it and providing charge/discharge information when required. Each of these batteries normally contains eight Lithium-Ion cells connected in a 4-Series, 2-Parallel Configuration, providing 14.4V, 6.2Ah and 89.3Wh each. The fuel gauge and the active protection system ensure safe operation and charging/discharging. The entire system is protected by a robust, flame resistant UL94V-0 plastic casing with rail system.
The Intelligent Power Vault has been employed in a variety of high tech applications. For instance, medical carts carrying diagnostic equipment, monitors and life support devices benefit from this small, reliable energy source. Weighing less than 8kg, with eight batteries it is two and a half times lighter than an equivalent lead acid battery, making it easy for the integrator to build it into the base of the trolley or cart.
Minimal strength is required to push the cart and medical personnel can just plug the device into the mains and then use it at patient’s bedside when stationary. If the cart is needed in transit or to move patients from one ward to another, the user can check the battery energy level and confirm how long the battery’s charge will last. The device offers extremely accurate fuel gauging and flexibility of use, which is paramount for life support equipment. It is also used in high-end automated laboratory equipment where power failure cannot be tolerated. Other applications include 3D dental scanners, communications equipment and embedded computing devices - mainly industrial PCs and robotic backup.
Battery backup can be portable, cost effective and reliable, provided the right technologies are used. Unsurprisingly, consumer style energy solutions are not the best way of achieving this and they can’t be relied upon to support critical applications. Lithium-Ion battery technology allows OEMs to guarantee the safety and reliability of the end product, with flexibility and ease of use in mind. And, unlike other similar energy solutions, the Intelligent Power Vault can be easily shipped, without any transportation complications or delays.