On Fri, 08 Jan 2010 19:27:47 -0800, TedVerizon wrote:

I would appreciate some basic info about using a 12VDC "wall wart" to
power or charge a device using a car cig lighter attachment.

In other words, I'd like to take the power cord that normally plugs into a
car cigarette lighter power source and connect it to a power supply I plug
into a wall outlet.

I know a little about electricity so I know the amp rating of the power
block must be sufficient. I can figure out the correct polarity.

What I AM confused about is why I plug a 12VDC power brick in and measure
it with my tester to find they read about 15 or 16 VDC with no load. I
know cars supply about 12V when off and perhaps 13-14V when running. I do
NOT want to damage anything and am concerned that 16V is too high unless
this is normal and it will be less when it is actually powering something.

Any comments or things to watch out for would be appreciated. I was
thinking of charging my GPS for which I do not have a house charger for
and things like that.

Thanks very much!

You are correct about the voltages a discharged car battery will measure
up to 14-15 volts when the car is started and usually shows 14v when fully
charged.

Unregulated wall warts are able to produce higher voltages depending on
how much current they were rated at for that output voltage.

But there are plenty of switching regulated wall warts avialable that will
prduce a steady 12v output at all times and should be perfectly safe for
charging your GPS

This site has a very good assortment of power adapters at reasonable
prices.

http://www.allelectronics.com/make-a...upplies/1.html


They even have this one that plugs in and provides a cigarette lighter
socket at 1 amp.

ttp://www.allelectronics.com/make-a-store/item/PS-1201/12V-1000MA-CHARGER-W/CIG-LIGHTER-SOCKET/1.html


I doubt that you will need anything heavier than 1-2 amps for charging
that unit.


Gnack