It's almost just a toy. I've only used it once to charge a fairly new 12v car battery that was dead. when i connected it. Nothing. No voltage reading or indication. I connected the multimeter to the battery, it showed 3.2v. Went back to my old school 6amp charger, just played with it for a few minutes and tried this unit again and it finally recognized the battery. So I left this device on to charge. Worked for 7 hours and only half charged the battery. Good enough to start the car and let the charging system do the rest. This isn't my first choice for chargers for car use or anywhere you need to rely on it to salvage a dead battery. I will keep it as a backup for my old 6 amp charger. No purchase recommendation.