How to test if enough current?

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trobins5

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Posted: December 06, 2005 at 12:40 AM / IP Logged

How do you test if a wire will support the load from the component you are trying to add to the circuit.

Example... If I want to tap into the lighter 12v wire for a 12v source for a cellular hands-free kit, how do I test to see if it will give me the extra current? Thanks!!!

dwarren

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Posted: December 06, 2005 at 12:45 AM / IP Logged

I don't know of any tests. But there are guidleines for wire size and fuse size according to amp draw. Ohms law https://www.the12volt.com/ohm/ohmslaw.asp and this https://www.the12volt.com/info/recwirsz.asp.

I can tell you that what you are suggesting has been many times with no problems.

trobins5

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Posted: December 06, 2005 at 12:49 AM / IP Logged

I know the lighter works. How about when you see 12v on a wire and you tap it and the component doesn't turn on? Not enough current?!

dwarren

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Posted: December 06, 2005 at 12:51 AM / IP Logged

Have you checked this "12v" with a meter?

trobins5

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Posted: December 06, 2005 at 12:53 AM / IP Logged

Yes, it reads 12 volts on the meter. Not a test light!

dwarren

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Posted: December 06, 2005 at 12:56 AM / IP Logged

Interesting, grab constant from the radio then?

stevdart

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Posted: December 06, 2005 at 8:13 AM / IP Logged

trobins5 wrote:

I know the lighter works. How about when you see 12v on a wire and you tap it and the component doesn't turn on? Not enough current?!

No, because the component in question would try to pull the power it wants. If it pulls too much a fuse in the source will blow; or lacking a fuse, the wire might burn up. In this scenario, given that you have tested the wire to be 12V, either the component is faulty or not sufficently grounded.

Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

DYohn

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Posted: December 06, 2005 at 9:56 AM / IP Logged

Wires don't limit current. As Stevdart said they simply burn up if you try to pull too much through them (or, if the circuit is wired correctly, a fuse blows.) Does whatever you are trying to power have a good ground to the vehicle's chassis?

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geepherder

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Posted: December 06, 2005 at 6:04 PM / IP Logged

Tell us you're not trying to get power from a/c controls, please. This will give you problems.

My ex once told me I have a perfect face for radio.

trobins5

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Posted: December 06, 2005 at 6:15 PM / IP Logged

sometimes A/C, why???

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