12V in cars, or not? is it regulated?

Hi

Taking power from the battery will change as it charges while driving, as well as it depends on the speed etc. By my own experience it can be 14-16V. And should be 13.2 when idle.

I am thinking about the cigar connector - does it give regulated 12V (hence stable and no motor/charge noise)? Or is basically directly from the battery?

When I measure it it seems to regulated.

WBR Sonnich

not so

Why would anyone regulate the feed for a heating coil?

NT

My car seems to have a switcher behind the 12V socket. I can hear it scream sometimes.

--

John Larkin         Highland Technology, Inc 
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Some of the "cigar" connectors _are_ regulated and suitable only for running various power adapters... I have a unit that has a "cigar" connector plus four USB jacks. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
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| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
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I love to cook with wine.     Sometimes I even put it in the food.

Regulated, in automotive terms, might mean lots of things; the alternator is usually fitted with a 'voltage regulator' , and the battery load line (unless there's something wrong with the battery) regulates as well.

On my car the dash socket isn't electronically regulated. I suspect that's the case with most autos (and it's why you can plug in there and observe your battery charging).

Depending on how much current you draw, the voltage can easily be

11.5V when the engine is off, and with a heavy load. Much depends on the condition of the battery, terminals, fuse, switching, connectors, and wiring.

Yes, you can fit a cigar into the connector. I don't think anything else will work. It's one of the worst electrical connectors ever designed. Where else can you find a receptacle that will push the mating plug OUT of the connector?

No regulator other than the alternator regulator. It's direct to the battery, but usually goes through a fuse and some wiring. On some cars, through a relay that opens when the ignition is off. My guess(tm) is that you can safely draw about 8A from the cancer stick igniter. I've seen some vans with similar "accessory" connectors marked 20A, which I consider wishful thinking.

Lots of articles on the web on automotive transient protection: etc.

Use an oscilloscope if you want to see lots of noise, spikes, glitches, etc. Starting the car will produce the biggest spikes.

Drivel: My ham radio contrivance was temporarily installed in my Subaru on the passenger seat, with the power plug going into the cigar igniter. That was 3 years ago, and I've been too lazy to wire something more permanent. The connector doesn't like the 7A(?) draw in transmit and likes to act intermittent while trying to weld the contacts together. Fortunately, the plug is disposable and I have a fair supply. Do it the right way, not the way I'm doing it.

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Jeff Liebermann     jeffl@cruzio.com 
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Skype: JeffLiebermann     AE6KS    831-336-2558

It's not regulated unless it's a hybrid that derives 14V from the HV battery pack. The expected working voltage of automotive accessories is

10.2 to 15 volts.

Cars made in the last 10 years often do not maintain a constant charging voltage either. Turning the alternator more slowly and adjusting it's output according to driving conditions pushes up engine efficiency a very tiny bit with virtually no manufacturing cost.

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60 - 80 Volt spikes would ruin a sensitive device as a car radio. I am sure these(esp. the high-end ones) have their own voltage regulation, e.g., a crow bar circuit.

Any electronics that survives in a car will have spike protection circuits, not just the high end units. Unlike lightning protection in your home which is only needed in the unlikely event of a power surge, spike protection in an auto is needed all the time as spikes are generated all the time.

--

Rick

No. Just a mechanism to ride-out the transient... no crow-bars. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)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.

The radio power terminals will easily see 60-80V (even 150V) spikes but, yes, they do have supression circuits so that these spikes don't get to the receiver chips. What's your point?

Of course they have their own regulation (the electronics don't operate at 12V). They do not crowbar, though. They must operate during such spikes.