How Much Current Draw?
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Post Fiend
Joined: Oct 2005
Posts: 10,626
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From: Plano TX and Brentwood TN
How Much Current Draw?
I hadn't used the stock fog lights in a long long time, not since I had gotten my aftermarket volt gauge and I had them on last nite and it just seemed like they were sucking more voltage then they should have been. I started around 13.7-13.9 and then when I turned on the fog lights(didn't do this when I just turned on the headlights, just with the fogs) it went to way down to 13.2-13.3. I just saw that needle plunge down close to 13 v on the gauge when I turned the fogs on and it went shooting right back up after I turned them off(still had the headlights on though). Is this normal for the factory fogs(remember I hadn't turned them on since I had gotten the volt gauge put on there so I never had a reason to question voltage draw with those lights)?
Post Fiend
Joined: May 2006
Posts: 10,007
Likes: 4
From: Central Florida
Amps and volts are different. Draw is normally amperage, your fog lights should be about 55 watts or 4.59 amps each. You are adding just over 9 amps when they are on. So you might be stressing your alternator and drawing off the battery. The battery is a reserve system, the alternator should supply all of your current while the motor is running.
First suggestion is to try it again with no other load, meaning AC, radio, and any other electronics. If you notice a drop again, you may have a short in the system or the alternator is failing. Next, try turning on all of your accessories and watch for a spike.
If your alt test good, it might be time for an upgrade.
First suggestion is to try it again with no other load, meaning AC, radio, and any other electronics. If you notice a drop again, you may have a short in the system or the alternator is failing. Next, try turning on all of your accessories and watch for a spike.
If your alt test good, it might be time for an upgrade.
Post Fiend
Joined: May 2006
Posts: 10,007
Likes: 4
From: Central Florida
If everything is more than stock, then probably. I believe the alt is spec'd for the max stock load to be 95% of the alt's max output.
If you have extra accessories, you could be above and beyond what the alt can handle.
If you have extra accessories, you could be above and beyond what the alt can handle.
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Post Fiend
Joined: Oct 2005
Posts: 10,626
Likes: 7
From: Plano TX and Brentwood TN
Well lets see, gauges(which would be minimal I would think), touchscreen radio, I have two aftermarket mid speakers just on the driver and front passenger doors, two subs w/amp, kenwood musickeg, kenwood navigation, and sat. radio tuner that is about all above stock that I have that would be drawing any type of current, just for some reason I decided to run the fog lights(which I haven't done since the first few months that I had gotten it, they really aren't worth much in a true fog situation) and I saw that spike and I had though to myself that can't be right and I haven't experiance a spike like that when I was running everything but fog lights before and I also wasn't hauling a trailer so I didn't have trailer brakes or lights tapping into the truck either, I was just at a lost what could it have been.
Fleet Mechanic
Joined: Feb 2007
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Hey Tex, what's really important is where the voltage gauge is connected. It should be directly across the battery. If it is anywhere else in the circuit it is very possible that the voltage deviation that you are seeing is due to a voltage drop on a wire (caused by the current to the lamps), and not a true indication of what the battery voltage is.
I would run both the positive and negative leads of the voltage gauge directly to the battery, without sharing the wires with any other circuits.
I would run both the positive and negative leads of the voltage gauge directly to the battery, without sharing the wires with any other circuits.
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Post Fiend
Joined: Oct 2005
Posts: 10,626
Likes: 7
From: Plano TX and Brentwood TN
Originally Posted by KelVarnson
Hey Tex, what's really important is where the voltage gauge is connected. It should be directly across the battery. If it is anywhere else in the circuit it is very possible that the voltage deviation that you are seeing is due to a voltage drop on a wire (caused by the current to the lamps), and not a true indication of what the battery voltage is.
I would run both the positive and negative leads of the voltage gauge directly to the battery, without sharing the wires with any other circuits.
I would run both the positive and negative leads of the voltage gauge directly to the battery, without sharing the wires with any other circuits.
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