I previously asked this question Can low battery cause car to cut out? . sorry I don't know how to link.
I have cleaned the terminals with baking soda and vinegar and initially the car ran for 1 minute and I thought it was fixed however it cut out after a minute.
Before the terminal cleaning the battery was showing 12.15v however it is now showing 11.56v. Whereas previously it would start up and cut out now the more I start it up it makes a whiny noise and hardly starts. If I leave it alone it starts and cuts out again without the whiny noise but eventually goes to that whiny noise if I keep cranking it. Might I have done something wrong(with the cleaning) which has caused the power reduction and more severe symptoms or might this suggest things improved and the battery is is being used even more now hence the reduction?
I know I will need a new or recharged battery before I can diagnose this but Im wondering if I made something worse hence the reduced voltage and behaviour? btw all lights and electronics seem to be fine even at 11.5v its just start up and cutting out thats the problem.