Thin king of how and where to mount the battery, I found a few adapters available for bottle mounts using the front luggage bracket - or in this case completely replacing it. E.g. ...
https://dinokiddo.me/shop/mudguards-stays-and-fittings/custom-black-cnc-water-bottle-cage-adaptor/
Or this one:
http://vi.raptor.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=322070832686&category=62132&pm=1&ds=0&t=1506844718000&ver=0
Not cheap but these would allow for a range of battery types to be mounted without interfering with folding the bike. vfr400 's point is still valid re. looks but then beauty is in the eye of the beholder..
Tom - going back to your original post about compatibility, From what I can see these look compatible. One thing to check though is that the connectors all match up. If not then you may need to buy a soldering iron and get onto youtube!