There is a serial number on the top of the HV (traction) battery case (as well as serial numbers on each module and ECU, but that requires disassembling the battery to see). In my Gen2 Prius you can see the battery serial number it if you remove the panel above the spare. JeffD
That is one of the most expensive parts in the car. If I will take to a service shop after warranty expire in few years; it will not hurt to know the serial number of the battery just to make sure it will not get swap for an older units :-/ (no this is not a paranoia) just a precaution.
A wise precaution. I don't know how to find the serial number, but there are few things you can totally trust in life anymore and a Car Dealer sure as heck isn't one of them.
Simple solution is to drill a hole in a box where the buttery is and put a padlock :-/ (simple and effective).
