Stupid question maybe: The Indycar hybrid system uses supercapacitors, which – unless I'm mistaken – is not the same as a battery? So even if the cause of the electrical issue may have been related to the hybrid system, I guess the battery that they talk about has nothing to do with the hybrid system? Right?
If it’s anything like my car, then there’s a 12V battery which does the ancillary stuff you’d expect as on any car, and then the hybrid system is separate and used only for propulsion. Racing cars typically don’t have the weight of an alternator, so all the electrical systems still have to run off the battery even when the engine is running.
Hybrid systems tend to charge and discharge from the drivetrain, and a capacitor based system probably has very limited connection, if any, to the cars electricals.