Parasitic Draw from Radio

[gooch66]

First off, I am electrically challenged. I have isolated an electrical draw from my radio. When I plug the radio back in I get a 10.00 volt draw when the battery is reading 12.52 at the posts. I have re-crimped the connections and cleaned off the ground placement. The power wire is receiving all 12.52 volts where it connects to the back of the radio harness. Is there something else I can check or is my radio bad?

 

[Viperwolf1]

You can't measure how bad a drain is with voltage. You need to measure current. The radio may have battery voltage applied and still have no current going to it.

 

[Skiddy]

You can't measure how bad a drain is with voltage. You need to measure current. The radio may have battery voltage applied and still have no current going to it.

yes, kind of like turning on a light or plugging into an electric outlet. voltage is there but no current running through it

 

[gooch66]

I removed the negative cable from the battery and tested with a volt meter and this is where I am getting the 100.00 volt reading. Am I testing this wrong? The radio works when it is connected but over a few days it has run down my battery. I re-charge the battery and disconnect the power to the radio and my battery is fine. Is there anything on the radio that I can check to see if it is the radio or something else?

 

[Broncobowsher]

Correct, tested wrong.
Use the amp scale. The draw should be way under an amp, in the neighborhood of a few milliamps (mA scale).

Word of caution when using the meter in the amp/milliamp scale, if you try to run too much current through it, even for a nanosecond, you will blow the fuse in the meter. Opening a door and the dome light coming on will pop the milliamp scale, the amp scale will probably live through that one.

 

[B RON CO]

Hi, many radios have 2 power wires. One is for the main radio power, and should be hot only when the key is turned to on or acc. The other wire feeds the clock and memory, and should be a tiny draw, as mentioned, in mili amps.
You can probably find a wiring diagram on line for your radio.
To measure amps and milli amps, your meter connects in the circuit like this: disconnect the battery. From the battery post to one meter lead, and the other meter lead to the unhooked battery cable. All the current flows through the meter
Most meters can only handle 10 amps, so don't turn on the key. My meter has a separate input for 1 test lead, for use when checking amps, and only works when the meter is switched to the amp scale.
Good luck