Instead of using an external case, I placed the battery at the back of the helmet. I used RC car JST connectors as a quick disconnect and Velcro to place the battery. The XBI seems to work. I am currently charging it with the existing unit. The battery has a PCB, so I am hoping all is well.
I have a wedding to attend in Livonia. I have a 2000mah battery installed vs a 520mah stock battery. I should be able to easily get 15-20hrs of around the clock xm music and passenger streaming. We'll see how long the wirevo lasts.