Yes, the newer white batteries (V15
) will work in the older model bags that use the silver JetPack battery (shown here).
The V39 will connect using the same plug as the JetPack, so no additional parts are necessary. The V15 requires a micro USB adapter to be plugged into the other female lead from the panels. If you don't have that lead, you can connect using the same plug as the JetPack, but in addition to the micro USB adapter, you'll also need a barrel connector, and the connection will look like this: