Does some one have a list of current draw for automotive circuits? Headlights and others. 12 Volt Thank you for your time Terry
There must be some generic charts out there, but as even headlight types are so varied, it might be best to test your parts. You need an ohmmeter to test each part. Then use an online ohms/amps/voltage converter page and fill out two boxes to get the amps. You would fill in "12" on volts, and whatever ohm reading you tested, in the "ohms" box, then it will give the amps.
Headlights draw approximately 5 Amps, however this figure can vary a great amount depending on what sort of headlights you have and the voltage of the car's electrical system. Now add, other lights, horn, starter relay, generator / alternator windings, battery...etc. If the car is running put an amp gauge on the battery to check overall system draw. There are no "charts" as parts are different from manufacturers, wear and tear on used parts as well will effect the overall system draw. Also you have to account for resistance of all connections and wires.
The whole headlight circuit on cars is usually a 10amp circuit. I've gotten on advanceauto.com and looked up headlights, they usually have full information on each headlight.
volts = amps x resistance. So, if you know any two of those values, you can find the other one by jiggering around the formula thus: amps = volts/resistance, and, resistance = volts/amps. As F&J said above, find resistance in ohms of the part and apply the formula using 12 as the volt value. In a similar vein, when I put halogen headlight bulbs in my OT car, I put a relay in the circuit. The original wire and headlight switch operate the relay which sends high(er) amp current through the relay out to the new lights. So the original switch is carrying a small current to pull in the relay, saving the switch from death by fire.
Gentalman thanks I am looking for ball park numbers. headlights 10A also would like horn, heater motor wipers and such.
Lights Headlights (high beam) 10-22 Headlights (low beam) 8-15 Tail Lights 8 Safety Emergency brake light 4 Emergency flasher 15 Turn signals 10-15 Windshield wipers 6-20 Horn 15 Brake lights 15-20 Running lights 8 Ignition Winter starting 225-500 Summer starting 100-400 Approx. Avg. 300 Courtesy Cigarette lighter 15-20 Interior lights 10-15 Instrument panel lights 4 Entertainment Radio 10 Stereo Tape 10 Electric antenna 20 Comfort Air conditioner 10 Heater 20-30 Defroster 15-30 Electric seat 20 Electric windows 20-30 This is typical fuse ratings to safely cover these circuits, not the actual draw.
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