On 10/24/2013 9:49 PM, Frosted Flake wrote:
When I hook up a voltmeter to a power plug in my car, I read a bit over
13VDC without the engine running. Wit the engine running, I get
somewhere around 16VDC. I have a device that uses a wallwart rated at
12VDC out and it reads, no load, about 13VDC, like with the auto motor
off from the power plug. If I hook the device to the power plug in the
auto, should I be concerned about the 16VDC when the motor is runing?
If so, any suggestions as to how to keep the power to the device closer
to 12-13VDC?

Ditch the voltmeter and use a storage oscilloscope to look at it as you
start the engine.
The voltage measured by the voltmeter is not so much the problem.
Read this:
http://www.littelfuse.com/data/en/Ap...tes/an9312.pdf

Without knowing more about your "device" nobody can tell you much.
Safest thing might be to use a 12V to 120VAC inverter and use
the wall wart...but even that may have issues, depending on the
unspecified wall wart.