It finally happened to me - got a blow out just now with the Jag.

No a problem, put the spare on, but spare was low, limped the car off the freeway to a gas station. While the spare was low - and it was obviously low on air - the battery light came on. The car has a brand new battery so I don't think it's the battery.

Does the car know when your air is low and warns you with the battery light?

 

The battery light warns of low or high voltage.

Did you have the hazard lights on without the engine running whilst you were changing the wheel? This can flatten a battery quite rapidly and it takes some running time to recover.

Bet you'll be checking the pressure in the spare when you check the rest of the wheels from now on!

Graham

 

I did in fact have the hazards when the car was off while changing the tire. You've got to be kidding me - the hazards will pull that much from the battery?

 

The three big battery drainers are headlights, hazard lights and a triggered alarm.

Headlights are taken care of by going off with the ignition. Depending on battery condition, hazard lights can operate OK for about 30 mins without noticeable effects but up to an hour can start causing issues. If the alarm is triggered and not cancelled overnight, it pulls the battery right down.

Graham