Hello.
We own two veihicles. On one (the family van), the 12 volt sockets work even when the ignition is off. On the other (my truck) The keys have to be in the ignition and turned to expect power at the 12 volt sockets.
On fishing trips in my truck, I like to attach devices like a 12 volt battery jumper box and NiMH battery chargers. With this design, I know that my battery won't get drained or that there won't be short and a fire when I step out of the car overnight. In the van, I have to be real careful, as these devices will continue to drain the battery until nothing is left.
Any logic as to why auto makers design these one way versus another? Any 12 volt devices that stops draining when source is below a certain level? Any way to (simply/inexpensively) convert the van?
Finally, can somebody give me a simple primer on 12 volt current regarding the following test:
What happens if I attatch a very tiny (very low amperage) 12 volt bulb directly in parallel to my car's 12 volt battery. Will it blow up? shine really bright and soon burn out? or work just fine, lighting as bright as it can? How does the wiring in a car regulate the amount of light that this bulb might produce without costing the battery with resistance - say for example that this was a bulb in my dash for instance?
Many thanks for any help or information.