I’ve been in contact with Battery Specialities to order the battery. They do not list the item on their website, nor do they ship it internationally. So currently I’m looking for alternatives. I have filed a bug on the Bitbucket repository, and have gotten the following reply from Chad:
Our battery is a custom part number for them so I wouldn’t expect it to be on their website. Their sales team should be able to reference it, though. I will check with my contact there and make sure it is available. However, the battery is the easiest module to modify. It just needs to be in the 12-16Vdc range.