Originally Posted by BubbaATL
Is there any downside to keeping a charger (just the charger, not the phone) plugged into an always-on 12V outlet like that? I notice the ones with lights stay lit, so they're drawing at least some minimal amount of power even when the phone is not connected.
I just did tests on some 12v USB chargers (single and double). They seem to draw minimal or no current. The double (no LED) had NO current draw when no USB is connected. A single (with LED) was drawing 14mA, which is mostly the LED current. Another single (with LED) showed 12mA. This minimal current may drain your battery after a year or 2 of not running (drainage will not be an issue).
Ideally it would be best to have them unplugged in case the unit goes faulty whilst plugged in, although this would be rare.