Tl Easy Instant Car Battery & Alternator Tester - Test Battery & Alternator without Opening Hood! Get an instant reading on your car's battery & alternator condition without opening the hood! Just plug into cigarette lighter outlet - LED indicator lights show battery strength Start vehicle and 2nd LED panel shows alternator (charging) voltage output Find potential issues before they disable vehicle, avoid unnecessary & expensive repairs No batteries or wiring needed - runs off car's electrical system; compact 4" size fits in glove box