In addition to Li Batts’ much higher upfront cost, many of their disadvantages are rooted in the same characteristics as their advantages.
For assistive technology applications, Li Batts – both Li-NMC and LiFePO4 – are typically two-three times more expensive than traditional batteries.
Compared to traditional batteries, for optimal performance, greater care and precision must be applied to charging Li Batts. Li-NMC Batts can become dangerously unstable at the end of their useful life, if charged improperly, or if their battery management system (BMS) fails; LiFePO4 Batts are significantly less prone to these modes of failure.
In Li Batts, lithium metal (cathode) and lithium salts (electrolyte) are highly flammable, and if Li Batts are compromised, the resulting electrochemical process can lead to “thermal runaway” where the battery’s internal temperature accelerates, releasing more energy, further increasing temperature, releasing more energy, etc. in a self-perpetuating uncontrolled cycle – which can lead to very intense, hard-to-extinguish fires and/or explosions. Research and experience generally show that LiFePO4 Batts are significantly less prone to these risks.
Since they can store and deliver so much energy for their weight, when the medium-to-high-capacity Li Batts used in assistive technology applications (especially Li-NMC Batts) malfunction or fail, they have a much higher potential to do so catastrophically and dangerously compared to traditional batteries.
Currently, facilities are few for recycling Li Batts at the end of their useful lives back into constituent parts than can be used to make new Li Batts as part of a circular economy sustainability and social value plan. Specialist electrical waste management companies have to gather economically viable quantities of Li Batts and transport them to the nearest recycler – but assembling large quantities of end-of-life and/or damaged Li Batts has to be done very carefully to manage fire and explosion risks, adding significant expense and complexity to Li Batts.
Li Batts present many advantages for assistive technology, especially mobility scooters and powered wheelchairs.
Typically, Li-NMC Batts are around 1/3 the weight of traditional batteries – and LiFePO4 Batts only 20 percent heavier than Li-NMC Batts – which makes them easier for users and carers to move and reduces the overall weight of the device being powered.
Cared for properly, Li Batts may last significantly longer than traditional batteries – Li-NMC Batts up to two times longer and LiFePO4 Batts up to five-seven times longer – due in part to their higher cycle life (the number of charging and discharging cycles a battery can undergo without compromising its performance).
Whereas traditional batteries’ voltage drops significantly throughout the charge-life (experienced as weakening power output as the charge dissipates), Li Batts’ voltage remains steady throughout the charge-life, weakening only when nearly fully discharged.
Compared to traditional batteries, Li Batts are capable of storing much larger amounts of energy.
Again, compared to traditional batteries, Li Batts are capable of delivering much larger amounts of energy relative to their weight.
DoD is the maximum capacity of a fully charged battery that can be used prior to recharging without negatively affecting the battery’s overall lifecycle; traditional batteries have a c. 50 percent DoD whereas Li Batts have a c. 80-90 percent DoD – meaning, effectively, Li Batts can be used for longer without recharging.
Li Batts for assistive technology applications are typically 2-3 times more expensive than traditional batteries – however, due to longer life, Li Batts (especially LiFePO4 Batts) can, if maintained properly, reduce overall cost.
To ensure the safe handling, storage, and disposal of assistive technology products that contain Li Batts – including, but not limited to, mobility scooters, powered wheelchairs, stair-and-home lifts – BHTA is asking its members to ensure the following issues are covered during sales, orientation, and aftercare. Companies will have differing practices and processes, but the overall aim should be to promote environmental sustainability, protect customers and employees from potential hazards, and comply with relevant regulations.
De minimis, companies should take the steps below; we strongly encourage documentation of these steps as a matter of good practice and to facilitate conversations with business insurers, who are increasingly asking for this information as a condition of coverage.
All consumer advice should begin and end with a reminder to always follow the manufacturer’s stated Li Batt instructions with regard to use, charging, transport, and recycling.
Explain the proper charging procedure for the lithium battery. Advise the customer to use the provided charger and avoid using aftermarket or incompatible chargers. Emphasise the importance of not overcharging the battery to prevent damage.
Instruct the customer on how to cycle the battery before their first use. Be very clear about the safety and lifecycle implications of proper Depth of Discharge (DoD) practices with Li Batts. International shipping regulations require that any batteries – Li Batts or traditional – must be at least 25-30 percent charged when shipped; confirm your battery manufacturer’s safe initial charge level, communicate this to customers, and inform them that deviance from the safe initial charge level (especially in goods delivered by remote sale rather than physical/showroom sale) should be reported to the retailer as a possible problem before first use of the product.
Instruct the customer how to cycle the battery during ongoing use, in accordance with manufacturer’s instructions (general Li Batt good-practice is to ensure a full charge no less frequently than every 4-6 weeks; check with your manufacturer for each battery type/application you supply). Be very clear about the safety and lifecycle implications of proper Depth of Discharge (DoD) practices with Li Batts (i.e. frequency of charge).
Explain the manufacturer’s recommended practices for storing the powered device and its batteries – especially when not in use for an extended period (e.g. “hibernating” a mobility scooter during winter months).
Inform the customer about the safety and lifespan effects of extreme temperatures on Li Batts (e.g. avoiding exposing the battery to excessive heat or cold, as it can impact performance and longevity).
Discuss essential Li Batt maintenance regimes, e.g. keeping the battery and the device it powers clean; how to inspect battery terminals for any signs of corrosion; how to monitor battery performance.
Advise the customer never to leave a Li Batt device charging unattended for long periods and to avoid charging devices overnight or otherwise in periods of inattentiveness. Check your manufacturer’s recommended practices; most advise charging devices at room temperature, and many will specify whether and how to remove batteries from the powered device when charging (which be an important consideration for safe, normal operation of the battery management system (BMS), a key component for safe Li Batt use).
Under no circumstances should a Li Batt-powered assistive technology device be charged outdoors or in a space open to weather; battery chargers are not rated for outdoor use. Customers should check their local building regulations – especially tenants in group or shared accommodation – with regard to Li Batt-powered assistive technology device.
Set clear, realistic expectations about the approximate lifespan of the Li Batt and factors that can affect its longevity, such as usage patterns and charging habits.
Ensure the customer is aware of the weight capacity of the device and how exceeding it can impact battery performance and overall functionality and safety.
Explain clearly the warranty coverage for the device and its Li Batts, including any specific warranty terms related to battery replacement.
Instruct the customer to return old or damaged Li Batts to an appropriate take-back scheme or electronic waste handler retailer for proper recycling and disposal, highlighting the special concerns around proper Li Batt handling.
If using third-party transport, no Li Batt of any capacity over 100Wh/4Ah should be transported as anything other than Dangerous Goods. Other traditional batteries – e.g. spillable, sealed lead acid (SLA), absorbent glass matt (AGM), or gel – may be shipped as non-Dangerous Goods provided they are undamaged, clean, and have their terminals protected; always check with the battery manufacturer for recommended transport modes.
Show the customer the part of the device user manual that includes specific instructions for the device and its Li Batt – or, better, provide them with a stand-alone excerpt/precis of device-specific Li Batt practices – and emphasise the importance of following safety guidelines at all times. At a minimum, emphasise the following to consumers:
Inform the customer about common Li Batt-related issues they might encounter and the steps they can take to troubleshoot and resolve them, advising on how/when to seek professional assistance. At a minimum, emphasise the following to consumers:
Let the customer know all their support options – retailer, device manufacturer, battery manufacturer; including contact details – for questions, concerns, or assistance related to the device and its Li Batt.
All consumer advice should begin and end with a reminder to always follow the manufacturer’s stated Li Batt instructions with regard to use, charging, transport, and recycling.