The DC-UPS powers your tools from the vehicle using the vehicle electrical system, but switches to exterior battery power if the automobile's battery is taken out, stolen, or drops under a predetermined voltage, performing to be a battery backup (BBU) and power conditioner. A good quality UPS (common power supply) https://judo-history-theory-pract15825.pages10.com/getting-my-power-supply-backup-for-pc-to-work-69428748