On the subject of indicators not blinking at intersections when the car is idling, my Elan suffered with this all through my ownership. It had an 18 ACR alternator and a good correct type battery. The MOT guy would grumble every year as when brake and indicators were on together for the test the indicators would stop, I had to start the engine and hold it at 1500 rpm to get them to flash, even then they were reluctant. All the earths were spotless.
In the latter days I had several cars and got fed up with batteries needing charging all the time and dying from under use, so as they died I did not replace them. A Mustang I had came in from the US with a very high amperage Optima red top battery, I used to put this battery on any car I wanted to take out as it was the only one available. Putting this on the Elan was a revelation, it was way over the spec for the car, but the indicators blinked at idle and the electric windows flew up and down. So before doing a dynamo / alt conversion consider fitting a monster battery.