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?

--
The Frosted Flake
+------------------------ SPAM is for eating ------------------------+

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.

On Fri, 25 Oct 2013 04:49:03 +0000 (UTC), 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?

Unless you are in a very cold climate (say -10°C or below), 16V is
wa-a-a-ay too high with the engine running.

First order of business would be to check your alternator regulator.

With engine running, cold: 15.1V, hot: 13.3V

As for your "device", automotive transients will kill it.

Buy something like these to solve your problem...

http://tinyurl.com/km4jqre

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On Fri, 25 Oct 2013 08:00:03 -0700, Jim Thompson
wrote:

On Fri, 25 Oct 2013 04:49:03 +0000 (UTC), 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?

Unless you are in a very cold climate (say -10°C or below), 16V is
wa-a-a-ay too high with the engine running.

First order of business would be to check your alternator regulator.

With engine running, cold: 15.1V, hot: 13.3V

As for your "device", automotive transients will kill it.

Buy something like these to solve your problem...

http://tinyurl.com/km4jqre

...Jim Thompson

In addition, I would be very inclined to doubt the accuracy of the
voltmeter used, and would strongly advise checking with another
instrument to confirm the readings.

peter

On Fri, 25 Oct 2013 08:00:03 -0700, Jim Thompson
wrote:

On Fri, 25 Oct 2013 04:49:03 +0000 (UTC), 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?

Unless you are in a very cold climate (say -10°C or below), 16V is
wa-a-a-ay too high with the engine running.

First order of business would be to check your alternator regulator.

With engine running, cold: 15.1V, hot: 13.3V

As for your "device", automotive transients will kill it.

Buy something like these to solve your problem...

http://tinyurl.com/km4jqre

...Jim Thompson

---
I like this clever no-brainer:

http://www.amazon.com/ENERGIZER-Inve...dapter+for+car

On Fri, 25 Oct 2013 22:19:10 -0500, John Fields
wrote:

On Fri, 25 Oct 2013 08:00:03 -0700, Jim Thompson
wrote:

On Fri, 25 Oct 2013 04:49:03 +0000 (UTC), 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?

Unless you are in a very cold climate (say -10°C or below), 16V is
wa-a-a-ay too high with the engine running.

First order of business would be to check your alternator regulator.

With engine running, cold: 15.1V, hot: 13.3V

As for your "device", automotive transients will kill it.

Buy something like these to solve your problem...

http://tinyurl.com/km4jqre

...Jim Thompson

---
I like this clever no-brainer:

http://www.amazon.com/ENERGIZER-Inve...dapter+for+car

But, he needs 12vdc regulated, something like a sepic converter would
work with the 10v-15.5v input.

or maybe this ( cant seem to find the spec s)

http://www.amazon.com/Parts-Express-12V-2A-Converter/dp/B000KGKFA4

cheers

On Fri, 25 Oct 2013 22:19:10 -0500, John Fields
wrote:

On Fri, 25 Oct 2013 08:00:03 -0700, Jim Thompson
wrote:

On Fri, 25 Oct 2013 04:49:03 +0000 (UTC), 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?

Unless you are in a very cold climate (say -10°C or below), 16V is
wa-a-a-ay too high with the engine running.

First order of business would be to check your alternator regulator.

With engine running, cold: 15.1V, hot: 13.3V

As for your "device", automotive transients will kill it.

Buy something like these to solve your problem...

http://tinyurl.com/km4jqre

...Jim Thompson

---
I like this clever no-brainer:

http://www.amazon.com/ENERGIZER-Inve...dapter+for+car

And double conversion... up to 120 VAC, then down thru the appliance
adapter... ought to keep the greenies happy :-}

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

On Sat, 26 Oct 2013 10:51:48 -0400, Martin Riddle
wrote:

On Fri, 25 Oct 2013 22:19:10 -0500, John Fields
wrote:

On Fri, 25 Oct 2013 08:00:03 -0700, Jim Thompson
wrote:

On Fri, 25 Oct 2013 04:49:03 +0000 (UTC), 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?

Unless you are in a very cold climate (say -10°C or below), 16V is
wa-a-a-ay too high with the engine running.

First order of business would be to check your alternator regulator.

With engine running, cold: 15.1V, hot: 13.3V

As for your "device", automotive transients will kill it.

Buy something like these to solve your problem...

http://tinyurl.com/km4jqre

...Jim Thompson

---
I like this clever no-brainer:

http://www.amazon.com/ENERGIZER-Inve...dapter+for+car

But, he needs 12vdc regulated, something like a sepic converter would
work with the 10v-15.5v input.

or maybe this ( cant seem to find the spec s)

http://www.amazon.com/Parts-Express-12V-2A-Converter/dp/B000KGKFA4

cheers

I have something similar that has adapter plugs for various brands of
laptop. (The plugs contain a resistor that sets the voltage :-)

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

In article ,
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?

Your volt meter or alternator is busted. Older cars should read about
14.4V at normal temperatures. New cars may vary it from 12.6V to 14.5V
due to various tricks to save gas. 16V at normal temperatures will turn
your battery into a bucket of lead paste.

The problem with automotive power is usually very high power surges.
Cranking the car can make a 40V spike, brake lights 10V, and there's a
constant 0.5V of background noise. Devices meant for a wall wart will
need protection or their power supply filter capacitor will eventually
explode from too much current.

A very simple resistor can do the trick. The inverse of the maximum
current draw will be in the right area. 2 Ohms for 0.5 amps, 10 Ohms
for 0.1 Amps, etc. You can also buy a noise reduction filter meant for
running an old base station CB/ham radio in a car. The base station CBs
had similar circuits to car CBs but without surge protection. As others
have suggested, there are also small DC-DC inverters that can output 12V
regulated.

Don't run a battery charger off 12V unregulated from your car unless it
was meant for that. So much electrical noise can confuse it and cause
damage to the batteries you're charging.

Martin Riddle wrote in
:

But, he needs 12vdc regulated, something like a sepic converter
would work with the 10v-15.5v input.

or maybe this ( cant seem to find the spec s)

http://www.amazon.com/Parts-Express-.../dp/B000KGKFA4

Got one of those, never thought to try it.

--
The Frosted Flake
+------------------------ SPAM is for eating ------------------------+