Simplest way to disconnect battery if charger is unplugged?
I have a 12V lithium battery that has a smart charger. The battery is always connected to a 5V regulator and if the power goes out, after several days that battery goes to near 0V. I need to inject a circuit between the battery and the other parts to stop the battery drain if it gets below some value ie maybe 9V so that the battery does not approach 0. Any suggestions on an off the shelf or easily hacked up method?