Hi all,

whilst it well understood that a bad battery and in particular a reading below 12.6 causes a large majority of the electrical issues in Jaguars, why is it that some is not many of these electrical faults appear whilst the car is being driven and when the electrical supply is being provided by the alternator (providing it is working properly) at around 14.3 volts. Is it perhaps the case that the electrical supply to many of the modules is supplied via the battery and as opposed to directly from the alternator whilst the car is running. In this instant, would a battery that is not necessarily not able to hold a higher enough voltage still not be able to receive (from the alternator) and pass on the correct voltage to the various modules.

Regards.

XKR 2007.

 

You'd think so, but also volts are not amps. Plus, with a bad battery, the alternator attempts to charge that battery. That's where a lot of alternator output goes, leaving less to power the car.