Hi all , hope your well, Thursday the sport broke down ( Surprise, surprise). Altenator packed in, AA arrived, the car wouldn't start unless jumped started, battery showing 3 volts.
The RRS was repaired new alternator belt and pulley, But when driving with lights heater and wipers, the Battery light comes on, then after a minute or two goes out, I've checked connections all fine.
Could it be the battery?

If the battery was that low then it's knackered. Normal car batteries do not take kindly to being deep discharged in that way.

Get a new battery ASAP before you up the new alternator. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed