Not sure if it's time for a car battery replacement? There are a number of warning signsfor which to look out, including 1. Dashboard warning lights: If either the battery warning light or the engine warning light is showing, this indicates that there is an issue – and you must get your battery tested ASAP. The engine warning. At National, our technicians can carry out a FREE battery test. This only takes a few minutes – a quick and simple health check that can diagnose any. The cost of a car battery varies depending on the type you need. At National, prices start from as little as £61. All our prices include fitting and disposal. For better idea of how much your next car. It can be so important to know which battery is right for your car. The simple answer is that it depends on your usage but, with modern cars, there's an increasing need to think about how much electrical equipment is.