The USA leads the world in the medical device market. However, there are many that make it difficult for design engineers to choose the right battery for their portable medical devices.
Original equipment manufacturers must address issues as many rely on portable, battery-powered devices. Some of the variables include battery chemistry, long term effects of aging, and battery replacement. All are concerns that continue to perplex many medical device manufacturers.
Several medical devices, usually powered by AC power, rely occasionally on their on-board battery as back-up power. A back-up battery often only receives a shallow discharge before being charged. Back-up batteries must use the appropriate battery chemistry for this type of use.
Device manufacturers must select a battery with internal resistance that is appropriate for the load over the lifetime of the battery. If the battery has a high internal resistance, then the voltage drop can be severe causing the battery to heat up, and it can also quickly reach the device’s cut-off voltage earlier then desired. Critical medical devices, like Ventilators, can require significant amounts of power leading to a drop in voltage if the appropriate battery design and chemistry is not selected. The result of this is a reduction in total run-time, and the device not operating as originally specified.
Battery aging in medical devices is an important topic for manufacturers. Some devices are in constant use, while others are on standby, which poses a challenge for aging estimates. Additionally, batteries react differently under different conditions. Most batteries perform very well at room temperature, and batteries have a longer life if not placed under stress. Fuel gauging can be used with smart batteries to display the remaining life of the battery, but the accuracy can be a challenge. Smart batteries need calibration, through cycling, to maintain accuracy.
Medical device manufacturers need to make users aware of symptoms of an aged battery and when to replace it. Manufacturers should provide information on the point which capacity has degraded to the point that a battery should be replaced. In addition to assuring sufficient battery capacity reserve, device manufacturers must also plan for a worst-case scenario so that batteries are never depleted in critical applications. Device requirements vary per application. Therefore, tighter operational requirements may necessitate the need for the battery to be replaced sooner than would be required in less demanding applications where a potential failure can be tolerated.
Our factories in North America remain open and operational and are positioned to respond fast to OEM requirements. Excell manufacturing facilities are operating at normal production levels and will continue to operate as needed to support our customers.
Li-ion Protection Circuits also known as Battery Management System (BMS), service a vital function for the safe and efficient operation of any Li-ion, Li-Poly or Iron Phosphate battery pack. The key building blocks of a Li-ion pack are a good quality cell and a good quality BMS.
A standard BMS will protect the pack against Over Charge, Over Discharge and External Short Circuit. These board features serve the purpose of protecting the battery pack from reaching an unsafe condition, which also protects the user.
At its most basic level a protection circuit can be thought of as a fuse. This means the Discharge Profile of a device must be considered when choosing the protection circuit as well as the cell. Important load numbers to consider…
Peak Current Duration
Time Between Peak Current
Continuous Current and Peak Current can be the obvious discharge rates to factor but just as important are the Peak Current Duration and Time Between Peak Current. Understanding all four and consulting the BMS data sheet are vital steps in a battery pack design process. If Peak Current Duration and/ or Time Between Peak are beyond the ‘Over Current’ limits, the load must now be treated as Continuous Current. This may require a different BMS to be selected.
Charge and Discharge Shut Off
As BMS safety features are intended to protect the cells, the board must not be used for operational control of a device. Charge and Discharge Shut Off must be controlled by the equipment the battery pack is part of. Should the device shut off fail the battery pack BMS acts as a last line of defense.
More complex protection circuits can also be incorporated with a Fuel Gauge (FG), allowing battery life to be read either by the equipment it is used in or displayed for the user. Programming is required for Fuel Gauge boards also known as Learning Cycles. This ensures the BMS operates within the exact intended limits of the customers device. Excell creates this program based on customer supplied info and the programming is part of our assembly and QC process.
Excell Battery’s Engineering Team designed our library of stock BMS boards which allows us to cover a vast array of projects with quick turn solutions. However, we also design custom boards when required for specific projects. All our designs incorporate 10k NTC and Redundant Fuse. The latter adds an extra layer of protection but is also a requirement to pass certifications such as UL2054 and IEC62133.
The U.S. Department of Transportation, along with the International Air Transport Association (IATA) requires that all lithium cells and batteries be tested for safety prior to being offered for transportation. The test criteria are listed in the UN Manual of Tests and Criteria, Sixth Revised Edition, Sub Section 38.3. These criteria are frequently known as UN 38.3.
The test criteria specify that tests be performed on all lithium cells and battery packs, and they must be completed prior to the first shipment. These tests need only be performed once. All cell types shall be subjected to tests T.1 to T.6 and T.8. All non-rechargeable battery types shall be subjected to tests T.1 to T.5, and all rechargeable battery types shall be subjected to tests T.1 to T.5 and T.7. The test criteria specify the number of cells and batteries that must be tested.
Each tested cell or battery must contain a Lithium Battery Test Summary to be eligible for shipment. It is also required that manufactures and distributors make available the test summary using a standardized set of elements. More information about the Lithium Battery Test Summary can be found at:
When Excell Battery is involved in the design of a lithium battery, a discussion of the UN 38.3 test requirements will occur with the customer to ensure compliance with shipping regulations. In many cases, a Test Summary can be issued based on the similarity to another tested battery. UN 38.3 specifies that cells or batteries be subjected to the tests if the new design differs from a tested type by:
A change of more than 0.1 g or 20% by mass, whichever is greater, to the cathode, to the anode, or to the electrolyte;
For rechargeable cells and batteries, a change in nominal energy in Watt-hours of more than 20% or an increase in nominal voltage of more than 20%; or
A change that would materially affect the test results,
Helping to Save Testing Costs
To attempt to save design cost, Excell Battery will discuss with the customer whether a battery Test Summary can be issued for a new battery based on similarity to a previously tested type.
UN 38.3 specifies the procedures to be followed to ensure safety of lithium batteries for transport. Additional regulations by the US DOT, Transport Canada, IATA, ICAO, IMDG (and others) cover the transport of lithium cells and batteries, and specific training requirements, that must be followed by all shippers of lithium batteries.
Because Excell is a critical supplier of products to both oil and gas and medical customers, our business is considered essential during this time. Our factories in North America will remain open and operational and positioned to respond fast to OEM requirements. The following Excell manufacturing facilities are operating at normal production levels and will continue to operate as needed to support our customers.
Given the current supply chain situation, it is more important now than ever before to partner with a supplier who can provide North American manufacturing to mitigate risk. Excell will continue to provide speed and agility during these times ramping production to meet our customers requirements.
Excell Battery mitigates supply chain concerns supporting emergency battery demand for COVID-19 medical devices
Excell Battery is proud to be a valued supplier responding quickly to the needs of medical device manufacturers supporting the COVID-19 pandemic including ventilators, air purifying respirators and more. Excell provides medical device manufacturers the ability to diversify their supply chain with North American manufacturing facilities, mitigating supply chain risks.
“I am very proud of our employees across our four factories for their commitment in supporting OEMs in need of urgent supply for COVID-19. They have and will continue to work hard during this pandemic to ensure we are supporting the needs of both patients and healthcare workers,” said Ian Kane, CEO.
Our team of dedicated employees in our factory’s sites in Canada and the US are working hard to deliver on urgent requests from the medical device OEMs supporting the critical medical devices for COVID-19 patients and healthcare workers. Our employees in all factories are cross trained to assist and support each other for urgent ramps in volume.
Due to our in-depth experience and expertise in the oil and gas industry, Excell responds to urgent requests by ramping up suppliers and production capacity to fulfill customers’ requirements.
The World Health Organization (WHO) has called for uninterrupted supply chains, indicating that governments should commit to making available all necessary resources to combat COVID-19 with minimum delay and ensure that cross-border medical and other essential goods supply chains are able to function effectively and efficiently.
Excell Battery continues to play a key role in this and we are focused on ensuring we maintain a reliable supply chain. Our four factories in North America continue to operate, as we are determined to be an “essential businesses” through our supply of battery solutions.
At Excell Battery, serving our customers is part of Our DNA. Nothing is more important than protecting the safety of our employees, customers and communities.
We are closely monitoring the COVID-19 situation and taking steps to minimize risk and manage the integrity of our business.
Excell Battery has implemented a Business Continuity plan (BCP) to ensure the continuity of operations in the event of an unplanned business interruption. Most of our supply chain is located in North America and the four Excell Battery factories are located in different North America geographies thereby reducing potential risk of business interruption.
We have also deferred nonessential business travel and are enforcing a stay-at-home protocol for anyone who is ill or has been exposed to someone who is ill.
Excell Battery have a proud track record of achievement and a long history of supporting our customers through turbulent times. We remain dedicated to helping our customers, colleagues and communities where needed.
We have experienced no interruptions in any of our operations to date and are fully able to respond to all our current customer commitments and welcome the opportunity to respond to any unexpected requirement that arises.
Ian Kane CEO
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Exceptional record of quality and service for over 30 years and ISO 9001:2015 certification ensure that your battery packs are made right every time.