Continuing the "tradition" of all the iBooks that have taken place so far, even the new iBook G4, oops, sorry for the slip, the new 12-inch PowerBook G4 does not keep the data content in RAM, if without power, because it does not have a battery of backup.
Like all iBook models, from the first to the last, the backup battery does not exist, if we have not so far been able to open them to check, this information can be deduced from Apple's kBase # 58445, which suggests always turning off the iBook when not connected to the power and when without battery and above all to connect the computer to the network if you change the battery and want to avoid the shutdown and loss of data.
The same also applies to the latest mini-PowerBook which would, like iBooks, have a device that collects a minimum of energy needed by the internal clock, but nothing more.
PRAM appears to have no repercussions from this lack of backup battery.
We remind you that in PowerBook Titanium models it is possible to change the battery "on the fly" while maintaining the continuity of operations for one minute without connection to the network.