In-car battery testing is the way it is done today. Various test instruments attach to the battery themselves or to the diagnostic connector and can give you a state of charge of the vehicle, both while it is being driven and while it is sitting statically in your shop.

However, there is no battery tester in the world that can be substituted for a good visual inspection. A good visual inspection alone, however, will never tell you the capacity or current draw of a battery during the starting of the engine. Therefore, good test equipment and a commonsense visual inspection are both needed. If a customer comes into your shop and you perform a quick battery check such as that shown on the Ford vehicle in Photo 18 and the battery terminal is corroded, you could say that the battery’s health is good but the battery terminals need cleaning because they are corroded and that the corrosion will probably lead to future battery problems. It would be nice if there was a box on the thing that could be checked for battery cleaning required or visual inspection results, but because there isn’t you should include this on the actual work order or customer service advice material.