The first unit had an inoperative test light for the internal battery condition. Amazon was quick to send a replacement and return authorization at their expense. The second unit is in excellent condition and performs as advertised. It is carried in the trunk of my wifes car as I don't want her stranded with a weak battery problem. She has been throughly checked out as to the simple procedure to use theSchumacher IPD-1800 Instant Power Jump-Starter with Docking Stationin case of an emergency engine start need. We are very pleased with this product.