This is to give the charger something to connect to, it won’t damage anything. Using the plug that the battery would connect to, insert a couple of small nails or screws into the plug. Sometimes a battery can give you a false good reading before moving on to switches and motors unplug the battery from the vehicle. There was corrosion in one of the connectors preventing the battery from making contact. I had a customer who had a 12 volt John Deere back hole tractor, the battery and charger were both checked out good but he could not get the tractor to work. You also want to check the terminals inside the connectors battery side and vehicle side. Check 6 volt or 12 volt batteries 6 volt fully charged should read 6 plus volts 12 volt should read 12volts plus.
