a USB charger is a 12V to 5V converter, isn't it?
Using it's own battery was an alternative I was thinking of. Then you can monitor charging state instead, wake up when charging starts, go to sleep mode when charging stops. But how long would, lets say nexus 7's 4,325 mAh battery last in sleep mode for the pine64? What happens if you leave the car for a week and it dies, how can you then turn on the pine64 with the ignition?
Using it's own battery was an alternative I was thinking of. Then you can monitor charging state instead, wake up when charging starts, go to sleep mode when charging stops. But how long would, lets say nexus 7's 4,325 mAh battery last in sleep mode for the pine64? What happens if you leave the car for a week and it dies, how can you then turn on the pine64 with the ignition?
