Replacing the battery on a Sphero SPRK+

I have a set of Spheros that have all come to the end of their battery lives. The batteries have visibly swollen and they either won't operate off the cradle at all or give less than a minute before disconnecting. In this video I cut a sphero in half and replace the two batteries inside with Hubsan H107c batteries which have the same physical size but slightly less mAh (240) . The original battery is 3.7v 350mAh 1.3Wh 702035 151226-03S. While batteries are available from a variety of sources internationally, they are often prohibited from air transportation so you need to careful about what can be delivered! The shell is destroyed in the process, and replaced with a flimsy Xmas bauble which is sufficient for general use but won't sustain the regular beating that the original can. Don't drop it or you'll be replacing the shell over again. Note, the silent sequences in the video are where it has been sped up. Here is the site that I eventually succeeded in getting 30 batteries from https://www.alibaba.com/product-detai...