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YACT (Sort of): "Clean" 12V power from cig lighter?

J

Jzero

Lifer
I am trying to use this DC-DC PSU to power my CarPC, however it won't turn on when I plug it in to the car adapter.

I'm thinking it's b/c I'm getting +14VDC out of the cigarette lighter and the page claims that the input voltage is "strictly required between 11.4V~12.6V." Maybe there is some overload protection in the device that prevents it from running if the input voltage is too far out of spec?

Well anyway, assuming this is the issue, is there a way I can get straight 12V out of the cig lighter? I am using a cigarette plug I got from Radio Shack with a built-in fuse. Nothing special.

Maybe I need to put a resistor on the line? But I wouldn't know what kind of resistor to use....

Thanks in advance!
 
Maybe you should get an invertor and use a regular psu. Or maybe build some kind of UPS with lead acid batteries to act as a capacitor?
 
I think you're going to have to use a normal PSU and a quality inverter.

+14V is pretty normal, isnt that the regular no load charging voltage(13.8)?
 
Originally posted by: WinkOsmosis
Maybe you should get an invertor and use a regular psu.
Click to expand...

A conventional PSU + inverter is bigger and much heavier than the entire computer is including the DC-DC (7"x7"x4"). If I go that route, it's going to be a last resort.
 
the + 14 v is because you alt puts out around 14.4 volts when running.

so that could be a problem.

you could go get a thingy to keep the voltage at 12, i dont know what they are called though. keep it dropped from 14 to 12. (resistor??)

MIKE
 
Voltage Regulator. Off the top of my head I can't name you a part that can handle more then about 3 amps constant current. Look for something along the lines of a LM7812, just with a higher current rating. This will give you a clean 12 volts until you start overdrawing the regulator.

EDIT: A resistor won't work since the current won't be constant.
 
It seems unlikely that this 12V device would refuse to operate on 14V, that should be within the safe margin...

Do you get 14V from the cig lighter even when the car is off?
 
Originally posted by: NutBucket
Voltage Regulator. Off the top of my head I can't name you a part that can handle more then about 3 amps constant current. Look for something along the lines of a LM7812, just with a higher current rating. This will give you a clean 12 volts until you start overdrawing the regulator.

EDIT: A resistor won't work since the current won't be constant.
Click to expand...

Thanks for the tip. I'll see if I can find one of those! If I understand correctly, I think I need one rated to 5A. (PSU is rated at 50W peak output, 50W/12V = ~4.2A?)

I didn't test the lighter with the car off but I'm pretty sure it is only powered when the car is running.
 
Originally posted by: Jzero
I am trying to use this DC-DC PSU to power my CarPC, however it won't turn on when I plug it in to the car adapter.

I'm thinking it's b/c I'm getting +14VDC out of the cigarette lighter and the page claims that the input voltage is "strictly required between 11.4V~12.6V." Maybe there is some overload protection in the device that prevents it from running if the input voltage is too far out of spec?

Well anyway, assuming this is the issue, is there a way I can get straight 12V out of the cig lighter? I am using a cigarette plug I got from Radio Shack with a built-in fuse. Nothing special.

Maybe I need to put a resistor on the line? But I wouldn't know what kind of resistor to use....

Thanks in advance!
Click to expand...


you need to gte a voltage regulator. the power coming from the adapter is dirty, and requires filtering to get the proper 12 VDC. do as the others have recommended. voltage regulation parts' prices depend on 2 things: range of voltages at input, and wattage (or current if you will).
 
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