Definately sounds like low voltage..........

Check that with all the heavy-current stuff on ( HRW, A/C, headlights, heater blower etc, etc) there is still more than 12Volts at tickover.

If you haven't got a meter, treat yourself to one, it's the cheapest/most useful tool this side of a spanner.........

When turning at anything above tickover you should have a good 13-14V. Any less, the voltage regulator needs looking at.

It may not have been changed with the Alternator, depending on the design, it may be remotely mounted.

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Paul Gibbons
'93 320CE
'73 Jensen Interceptor (Resting)
Giant Full Sus Mountain Bike