It is difficult to determine if you have a poor connect between your cables and battery with a visual inspection. It generally requires a physical “hands on” inspection. Before attempting this type of inspection be sure and wear safety gloves and a pair of safety glasses. If one or both of your cables happen to be loose you will want to clean your battery terminals before tightening the cable clamps on the battery posts. Take these steps to properly clean your battery terminals to avoid getting stranded or having to pay expensive towing or repair bills.
Wear gloves resistant to acid to disconnect and remove your battery. Do not try to clean your terminals while the battery is still installed in the vehicle. Batteries contain chemical solutions that can be volatile; therefore the battery should not be left in the car while cleaning.
Wash the whole battery in a well ventilated area. Use a solution of 4 tablespoons of baking soda added to one gallon of water. (The baking soda will help neutralize the acid, if any is present on the battery.) You will want to avoid getting any water into the battery cells. If the cells are capped this will suffice. If the caps are damaged or loose, you will need to have those replaced or tightened before washing your battery. Some batteries are “sealed”. This means that you cannot remove or replace the battery cell caps or cover, whichever the case may be. If the permanent caps or the cover is loose and or damaged, you will need to replace the battery.
Rinse off the baking soda solution with plain water. Dry thoroughly with disposable towels. Take the time to clean the area where the battery rests in your car. While you’re at it, check your battery cables to make sure they’re in good shape.
Take a wire brush and clean the terminals until they are bright and shiny. This would also be a good time to wire brush the battery cable clamps as well. Place your battery back into the vehicle and secure properly. Make sure the positive and negative cables are properly re-connected to the matching posts.