Knowledge transfer project aims to extend life of smart batteries

Based in Sheffield, Mobile Power has designed and provides pay-per-use smart batteries dubbed MOPO batteries that – at the time of writing - have been rented over 16,000,000 times by customers in in off-grid parts of Africa and parts of the continent where the grid is unstable.

The portable batteries - rented through a cloud-based platform rental system - are charged at solar charging stations before being delivered to customers, which removes the need for traditional diesel generators and reduces energy costs by up to 75 per cent.

MOPO hubs currently operate operating in eight countries, including Sierra Leone where 20 per cent of household income is spent on lighting and mobile phone charging.

Mobile Power’s solutions comprise the MOPO 50 (50Wh), which provides up to 10 phone charges and can provide power to TVs, radios and fans; and the MOPO Max (1000Wh) that is suitable for e-mobility, plus fridges and freezers - or acting as static storage - in second life applications.

“It's advantageous to make those cells last as long as possible,” said Dan Gladwin, Professor of Electronic and Electrical Engineering at Sheffield University. “If you can rent it 2000 times, then you can obviously rent it for much lower cost.”

Prof Gladwin added that the ambient temperature in countries such as Sierra Leone can improve the performance of batteries but also cause them to degrade more quickly.

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An element of the knowledge transfer project will be to manage the charging of the batteries, looking at how the cells behave and how they can be controlled to extend their life.

“If we know…we’ve got a long time, we can do a much slower charge,” he said. “If we've got [through] a fast charge, we can monitor temperature and balance out that charging rate.”

Another part of the project will look at putting off-the-shelf cells through tests that replicate the conditions they’d experience in Africa

“So far these have all been NMC [Nickel manganese cobalt]  cells but we are looking at LFP [lithium iron phosphate] and also LMFP [lithium manganese iron phosphate] that gives you a bit more capacity per cell,” said Prof Gladwin.

Another promising candidate is sodium ion which can be manufactured in-country as it does not have issues that  NMC cells do in terms of supply chain and the source of some of its materials.

“In terms of degradation of sodium ion, we looked at it from an electrical point of view,” said Prof Gladwin. “It doesn't mind being sat fully charged, and sodium ion can be fully discharged, which is unique to that chemistry, so we're only dealing with low voltage packs.”

He continued: “In terms of applications like EVs where you got high voltages, you can build these packs on the production line, completely at zero volts and it's nice and safe.”

The project will also see digital twins created for the battery packs that Mobile Power can run through their in-house systems to simulate how those cells will work in a particular application.