What is cheaper to breakdown with a faulty battery or make sure your charging system is working as per manufacturer specifications.
A charging system includes the battery or batteries depending on your car, and a alternator
The alternator should charge at 13.8 to 14.2 volts.
An older vehicle may loose some voltage from the alternator to the battery.
When checking the car charge rate at idle speed in park with the handbrake on and on a flat safe area.
A simple test is make sure you never see the charge warning light on your instrument dashboard, even if it comes on intermittently this is a warning sign to do something now.
Breaking down on the side on the road is not only unsafe but can be fatal..