There is no problem using higher CURRENT. The device will only draw the current it needs. The problem comes from not having enough current available. IN other words, 9v 50 amps would be fine! 1amp may not be enough. My eken came with 9v 1.5 amp (labeled), and it's been working fine.Voltage is a different story. My understanding is using too high a voltage will can cause the device to overheat and burn out over time. It's interesting about the 12 v working, but there is a danger it will burn out with continued use. Of course, if it was designated to work with up to 12 volt, then no problem. I have some 12 volt external li-po batteries I'd love to try, but am worried about burnout. If you keep using the 12v charger, please let us know how it goes and whether it is running hot (may be hard to tell because the cpu runs very hot anyway).