According to researchers at IBM India, many of the 50 million lithium-ion laptop batteries discarded every year could provide electricity storage sufficient to light homes in India and other developing countries. Research presented at a conference in San Jose, USA, analysed a sample of discarded batteries and found 70 percent had enough power to keep an LED Light on for over four hours a day for a year. The MIT Technology Review also said it is possible to combine LED lights with solar panels and rechargeable batteries, however, using discarded batteries could make the process far cheaper. Vikas Chandan, a research scientist at the lab's Smarter Energy Group who led the project said the most costly component in the system is often the battery and in this case the most expensive part of the storage solution is coming from trash. The IBM group worked with hardware R& D firm RadioStudio and opened the discarded laptop battery packaging and extracted individual storage units call cells, which they tested. They selected the good ones which they recombined to form refurbished battery packs, then added dongles and circuitry to prevent overheating and gave them to five users in Bangalore who live in slums or operated sidewalk carts. Three months later the users said the battery packs had worked well.