You could try Connects2
I have one of their kits (part AFOIPOD005), which was discontinued but mine works OK. They may now have an alternative, and one of the above kits is available on Amazon.co.uk for £60.
- couple of seconds of interruption, with message "CDDJ low power"
- Occasional complete failure ("NO CDDJ"), that sometimes resolves itself when the car has been parked a while, or may need the connection to the battery to be interrupted somehow (e.g. disconnect/reconnect box behind head unit)