Well, I checked the battery this morning:
Static situation - (red isolator swtich = off, therefore nothing switched on). Battery = 12.5 volts
Isolator switch on, engine running. Battery = 14.0 volts at tickover.
Switched headlights on - all is ok, no headlight fade. Battery = 13.88 volts at tickover
Engine running switched other loads on (wipers, heater, headlights) all is still ok
Ran the engine for 15-20 mins untill the radiator fan kicked in & out a few times - rechecked lights etc. all is still ok.
The problem seems to have disappeared, still quite concerned so I'll keep checking it every so often. A complete mystery but here's hoping!
Thanks for all your suggestions
I'll repost if the situation occurs again
Geoff
