Everything that runs off a battery is DC. However, for the past 4 months, I've been charging all my devices off solar/battery (working-travel vacation in a van

Everything that runs off a battery is DC. However, for the past 4 months, I've been charging all my devices off solar/battery (working-travel vacation in a van). I have run into some issues with certain devices not accepting charge. I think it has more to do with the device charges themselves than the power source. For example, my girlfriends Motorola Droid Turbo won't charge at all anymore off the 2.1 amp usb chargers. My S7 has no problems. Her cheap windows laptop will also sometimes refuse charge temporarily. Battery voltage is reliably between 12.3-13.0, which makes me think it's an issue with the chargers themselves.