Thermal Batteries (Phase Change Material Heat Exchangers)

NASA has this device that they are testing a Phase Change Material Heat Exchanges (PCM HXs) on the International Space Station. It looks like a thermal energy storage mechanism.

Does it make sense for spacecraft in the COADE universe to use thermal energy storage to last longer while when retracting their radiators?

Or does the mass of the thermal batteries defeat the purpose of a space warship?

Then again, you could probably recapture some energy if you collect the thermal energy and use it to keep certain subsystem warm without having to run an electrical heater or maybe even regenerate some electrical energy if you collect enough heat to drive an onboard steam generator etc...