alternator has gone. if the battery is fully charged before a journey, would it allow progress, esp' power the headlights on dip for 45 min? please say it will with no adverse effects. thanks.

Diesel – yes.
Petrol – Should do – I snapped the alternator belt on my hire car and it drove fine for 3 days (day and night) before the battery said "no more".

If you drain the battery down to leass than 25% charge which is generally the point where the voltage drops enough to stop opperating things you can cause permenant damage to the battery.

It really depends on how good the battery is and which particular car. I would have thought 45 mins was pushing it but it depends if the alternator is completely goosed or just not quite up to the job.

I would tray and do the journey in the daylight and would pick a route where I expect to brake down at all times.

damn – that didn't work so well…..

RAC to the rescue, and no nookie for me tonight 😯

RAC men can be a bit choosy, you're right there..

the AA always put out though.

My Dad did Dover to Peterborough as the alternator wouldn't charge but a jump start and a mad dash before it got dark and he made it lol.

Back in the 80's so no power steering or very few electrics back then in his Rs turbo etc.