I have been prompted to write this review having seen the 1* review, as I have no idea how the purchaser comes to his conclusion. I have had the product for several years, used it several times and it has never failed me. My daughter's car failed to start this cold December morning. Simply plugged the moulded socket into the unit, connected the black and red leads to the battery and turned the ignition on. Started first time - it's that simple. The only reason I had to Google the product today is to print off the user manual for my daughter. The instructions are clear and simple to follow. You can read them for yourself - just Google "PowerPack user manual RPP110 compressor".
My only complaint is the size of the font on the instructions so I just cut and pasted into Word and printed off the relevant section in a larger font. I would have no hesitation in recommending this product to anyone. Please note that the instructions clearly say that the unit must detect some voltage in the battery. If you have had a battery in the garage for years, you need a charger, not this unit, which is designed to give your battery a boost, not replace it completely. This is the extract from the instructions:
Note: All PowerPacks are fitted with internal voltage sensitive relays that control the polarity protection on the
PowerPacks. These relays will not allow power to flow from the PowerPack to the vehicle's battery unless they detect a voltage of 1.5v +/- 0.5v.However if your vehicle battery is below this your battery may need replacing.