Hello I would like to know what type of battery does a focus rs mk1 fit? What size and voltage.I bought mine 4-5 months ago and the previous owner had a bigger battery in size(battery cap won't close) on the car.Went to a car electrician because my lights flicker a little at idle and told me to change the battery because the i have is not for the car.He checked the alternator and it was OK..Does anybody have any input?