When my backup generator failed to start during a recent power outage, I found that the starter battery was dead, most likely due to age. I bought and installed a new 12v battery and checked its voltage. When the generator was run on a weekly 20-minute exercise cycle, the voltage rose to about 13.6 volts as it was "charged" by the generator. At night (when the temperature has dropped to almost freezing) the voltage has dropped below 12V, which is not very good for maintaining a healthy battery. So I had to come up with a better way to keep the battery fully charged than being recharged by a generator once a week. I chose this unit for its many battery and charging options, including the ability to charge a lithium-ion battery that I have in my RV, and it's a "smart" technology that I've learned from it is very important after how many batteries have deteriorated due to my carelessness in maintenance. I liked that it comes with additional connection types and "Quick Connect". ' keep your mouth shut. TIP: Set the battery type/charging mode after you connect the device to the mains power but before you connect it to the battery. As explained in the manual, the battery voltage reached and stayed at around 14.3V (absorption phase) for a few days and has since stayed at around 13.4V in the float phase. I may or may not leave the charger plugged in at all times as I monitor how well it holds a full charge when charged by the generator once a week in the summer when it's hotter and the battery loses less voltage overnight.