86 Battery Problem?

[jondee86]

Best advice.... get the car to an auto electrician, and ask him to check
for parasitic current draw. A bad diode in the alternator rectifier is one
quite common cause for "battery always flat" syndrome.

Cheers... jondee86

[totta Crolla]

Earth problem maybe ?
Check especially the earth to the engine.

[NoHachi]

Or just a tired starter motor.. or a combination of both.
If the starter has worn bushes it will only tick over at full charge..and then only when it feels like doing so. But easy to check the current over the battery with a multimeter.