Not a UPS power source.
Probably going to return these. I bought these to supply constant power to my USB WiFi modem that supplies Internet for my Android radio. Without constant power, the modem has to reboot any time you make a quick stop for gas or something. Then you have to wait for it to reboot before the radio gets Internet connection again. I figured these would solve that issue since they have built-in batteries. Unfortunately they don't work because they lose power for about 3 seconds whenever you turn off the car and these switch to battery power. This means the modem still has to go through reboot process. Looks like I probably need a 12v UPS (uninterrupted power supply) for my problem. They probably work just fine if you just need a phone charger. Read more