The big issues with lithium ion batteries are the testing, compatibility, and the costs. Testing these batteries for wheelchairs is ongoing since medical devices, such as wheelchairs, are subjected to much higher standards than in other applications. Reliability and safety (remember when millions of laptop batteries had to be recalled back a few years ago?) are crucial so testing to ensure that these batteries will not catch fire is important.
Compatibility is also an issue with most current wheelchair electronics since they have not been designed to handle the voltage and charging characteristics of lithium ion batteries. If lithium ion batteries are simply placed in most existing power wheelchairs, issues arise, from as simple as an inaccurate battery gauge reading, to as disconcerting as overheated connections. Therefore, power wheelchair electronics aren't yet designed to accept them predictably, and simply plugging in a set of lithium ion batteries into an existing power wheelchair proves problematic. Therefore, power wheelchair electronics need to be enhanced for compatibility with lithium-derived battery technology.
The final issue is cost. A set of lithium batteries that are similar in size to standard lead-acid batteries cost about $3500. When the lead-acid sets costs about $400, consumers and insurance companies are going to go for the cheaper option, despite the advantages that lithium ion can offer. Consumers struggle to fund basic mobility products – and often have to fight insurers for it – so $3,500 for batteries is simply out of consideration for most.
At least developing and refining battery technology is one of the biggest global technology trends, where environmental concerns are pushing towards better, safer, and cheaper batteries for all sorts of applications, including wheelchairs. In time, we will have new batteries in wheelchairs that will not only be safer and environmentally friendly, but allow us greater freedom and range to get us around. It is only a matter of time.