Hi.

2004 XJR. Battery replaced 8 months ago with a Yuasa 019.

Today when driving along the battery/alternator lamp came on. On restarting it went away. Thought nothing more of it.

Tonight I got the familiar drama with loads of warning lamps and system failures that normally occur when the battery is faulty.

But then the lights on the car went out. This was very scary as it was pitch black outside on a country road with no streetlamps.

I was under the impression that when the engine is running, all power comes from the alternator. Is that wrong?

I am really really hoping it isn't an alternator fault.

What else could it be?

Halfords tested the battery this morning before the incident and said it was good as their tester measured it as 860Ah (it was a 900Ah battery originally).

Could the battery be toast already?

 

Probably the alternator unfortunately. Something similar happened to me. One day driving all the warning lights came on and I limped it home. Battery had almost no voltage left. Took the battery in and exchanged it under warranty for a new one (was only a couple years old). Drove the car another week without issue and then the battery light came on and stayed on. Tested the system and found the alternator was not charging. It was not a fun job, but it is doable. Car has been great since.