I own a previous version of this jump starter. My was made by UST and not Wagan. The exterior is identical to my unit so I assume it is made by the same manufacturer. I normally recharge it every two months even if I have not used it to maintain a full charge for when I need to jump start a car. I forgot to charge it for about 5 months and the unit is completely dead. I have try to charge it but when you press the battery status button, you can see the voltage just keep dropping. I have try to recharge it several times and I think the battery is completely dead. The charger adapter is also dead. I measure the output voltage and it measures a little over 3 volts. I take special care of my adapters so I do not damage the wires. This unit was only used several times to add air to several tires. It has not been used to jump start. Overall very bad quality.I also have a Vector unit which is now Black and Decker and it also was not charged for 5 months. This unit still had two red lights which indicate it was in good condition. I recharge it for several hours and it came back with full power. I also own Jump and Carry JNC660 jump starter. This is a professional unit with 1700 peak amps. It can hold a charge for months and still show plenty of power. This unit is the best but expensive ($130). This unit can jump start big engines and completely dead batteries.One other general comment for those people out there assessing which jump starter to buy. These lower cost, lower peak amp starters are only good for cars that has a weak battery (i.e. as engine is slow to crank over). If your battery is dead where the engine cannot even slowly crank over, these starter will not have enough power to start your car so do not blame the jump starter as low quality. I see such comments in other reviews. For a completely dead battery, you need a more powerful jump starter such as JNC660. I have the same problem with my Vector starter which has only 300 peak amps. It also would not start a completely dead battery. That was the reason I bought the JNC660 and carry it in which ever car we own that has the oldest battery. I need to buy another jump starter (I keep one in each car) and am thinking of buying JNC300XL which claims to have 900 peak amp and is about half the price of JNC660. The reviews seem very good and is made by the same company.