I just installed an upgrade from a 90-30 to Rx3i in May. I got the new energy packs with them. The energy pack was included with the CPU module as part number IC695CPK330. The description for that part number was "Rx3i CPE330 with energy pack". There is a separate data sheet for the energy pack, but I don't have a copy of it with me.
On two occasions in 2013 or 2014 I had the energy pack fail. Even though there was an IC695ACCxxx number for the energy pack, the local distributor told me the only way to get a warranty replacement was to replace the CPU module and the energy pack as a single unit. I don't think there was any technical reason they had to be replaced together. I believe the reason was that the distributor wasn't able to obtain a stand-alone energy pack under warranty at the time. That may have changed later.
Edit:
According to the IP GFK-2940A, the IC695ACC402 energy pack is only compatible with the CPE330. For the CPE305 or CPE310 the energy pack part number is IC695ACC400.