battery warning light

[adamos]

hi, please point me in the right direction,
driving along, and the battery warning light has come on,
drove couple of miles home, turned engine off, and then waited a bit, and turned the engine over , starter motor sounded a slightly laboured, so think drove the car home on remaining battery power,
the battery is as far as i can see is a porsche one and could be 9yrs old.
new battery/or alternator?
thank you for any response[8|]

 

[Richard_Hamilton]

What does the voltmeter read, engine off, and engine running? It should be 12v off, and 14v (ish) running. 14v would indicate that the alternator is charging OK.

If the battery is 9 years old, and the original Porsche one, I'd be gobsmacked! 4 years and you are on borrowed time.

 

[adamos]

thanks for response.
not sure battery 9yrs, but car had loads of bills etc when i got it, but no battery bill, so assuming,
not done volt test, going to try in the morning,
hope it battery, or alternator belt,
guess trip to main dealer

 

[adamos]

morning all, just tested battery, 11.7v , no change when idle, or slight rev,
waiting for AA to pick up and take to hatfield porsche main dealer,
hope it might be a replacement belt, but wishfull thinking![8|]

 

[adamos]

update, porsche hatfield , say new alternator..... ouch!!!!!!!!!!!![]