They're called temporary or emergency battery-cable ends. Be careful, they may also cause far more problems than they solve. These devices have been widely used over the years, and today we see quite a few problems.
Due to the high number of computers in use, vehicles today are extremely sensitive to voltage. Poor battery connections, like the one in the photo, can easily drop system voltage by two volts or more. While this may not seem that great, two volts represents over 16% loss of current, in a 12 volt system. Problems in the computer system can occur with less than half that amount of drop.
ABS lights, SIR lights and check engine lights are a few possibilities. The problem goes beyond being an annoyance. A great deal of damage can also be done to expensive parts of the vehicle. In the above example, the engine ground could no longer conduct the proper amperage. When this occurs, electric energy being used in the system must find another route back to the battery. The additional flow is called a transient ground. In some cases, an improperly grounded engine can result in current flow through the several expensive components. Not being designed to conduct electrical current, damage may occur.
Repeated radiator and heater core failures are common, when coolant attempts to conduct the transient current flow. In the case above, the transmission was severely damaged. Insufficient ground caused current drawn by the starter to flow through the transmission components. The resulting damage was several thousand dollars.
AGCO can properly repair your battery cables if needed. With our equipment, a new end can be crimped and sealed to the cable, like the factory joint. Such a repair can save a huge amount in unnecessary damage. Never take chances, have AGCO properly repair your battery harness.