About how important proper contact of battery terminals, know of any motorist. But sometimes around the lead pin of the battery cracks, through which the electrolyte or its fumes get to the terminals. This causes their rapid oxidation and contact failure. Hermetically seal the crack — a difficult task, but a small protective screen will help the cause. Take a plastic cap for milk bottles, cut in its center a hole the diameter of the pin in its lower part. Then, smeared crack modeling clay, put on top of the lid, and put a felt or a felt ring impregnated with lubricating oil. Now you can connect terminals. Behind this screen the reliable contact will continue for a long time.