As most of the Amazon Vine reviewers has pointed out this product's Build quality is very good and I fully agree with them. The product also works as advertised. I tried it using on a old Ford Focus 2001 car that I seldom use and sits in the garage most of the time and connected this 5W Solar Battery charger and Maintainer via the cigarette port for several days.  The battery did seem to charge adequately. I did monitor the battery voltage from time to time using both aFluke 87-V Digital Multimeterwhich I own and also used aScanGauge II Automotive Computerand it maintained 13.8v which is considered nominal for that battery in the focus.This obviously is not designed to fully charge a dead battery but merely trickle charge the battery when you do not use your vehicle for couple of weeks and it perfectly works for those situations.Having said, One of the user reported on Amazon concerning about the panel's high voltage output in direct sunlight and the possibility of overcharging small batteries. I must admit it is quite possible if this 5W panel is left alone with a small size battery for extended period of time and I fully agree with that reviewers concerns.That approximately 24 vDC - 25.1 vDC output from the panel indicates the Open Circuit Voltage (Voc) most panels of this type do always output similar voltage characteristics and as long as they are installed properly do not pose any sorts of risk damaging a huge car battery for example as it will take considerable amount of Amps to ruin a standard car battery which this panel can never provide as it max out at about 400 ma under full sunlight and cannot overcharge it.If you are paranoid about the Open Circuit Voltage (Voc) you can always install aZENER DIODE 1 WATT 14V 5% DO-41diode which falls in that range of voltage which you feel safe for the battery (Cheap option) along with aSchottky Blocking Diodesor better install aCharge Controllerbetween the panel and your car battery just to be safe.Hope this proves useful to others.Happy Shopping here on Amazon.