This short cable that is broken off in the photo below is a battery ground cable. This cable should be connected between the negative terminal of the car battery and the body of the vehicle. Over time, if the battery is not securely tied down, the wire strands of the battery ground cable can fatigue and break due to constant movement. Rust and corrosion will accelerate this process. This can potentially be a safety issue and you might see some voltage issues as well.
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