You should not obsess over things like this. It is not something that you should be concerned about.........in most "normal" situations. Finding out where the battery vent and fan is located would be much more useful information.
You can use Hybrid Assistant on an Android phone and a bluetooth OBD device. It provides that information. Typical HV battery temps are ambient at startup and then just a few degrees warmer than ambient after driving for a while. The three temp readings are usually within a few degrees of each other.
Hold your hand over it. If you can’t hold your hand over it for more than 2 seconds it’s hot enough to start barbecuing .