Inliners International Forums General Discussion Electrical Current draw from electrical components?

I've been unable to find any publications that shows the current draw for different components like, HEI distributors, Electric carburetor chokes, excitation field on SI-10 GM altinators, ect, ect. Does anyone know of a publication that has these figures? Factory GM manuals do not show these values. I don't have an ammeter with the capability to accurately check, or I'd find out on my own. Any help a member can provide will be much appreciated.

Any reason why you needed this info.? Just curious, because I've never heard anyone for that information before. I don't know the answer. John

Dear Dennis;

I have never heard of, seen a publication of that type either after 38 yr in the auto "aftermarket" repair industry.

If you really 'need to know' get a digital volt/amp/ohm meter & do the math.

I can't see how it's relevant to anything but, Good Luck, John M........

Guys, I been looking at this post for a couple days thinking I have never seen this info either. Then I said gee that is the owners manuel for each car. It is the section on fuse size. If the heater motor has a 15 amp fuse you can pretty much bet that the heater draws 10 to 12 amps normally. Likewise if the radio has a 4 amp fuse it probably draws 2 to 3 amps normally. Sounds logical to me anyway.

Gael

Add me to that list of guys who never saw an amp chart for accessories. For a quick guess I use the same method that is code standard for household AC circuits: the continuous load should not exceed 80% of the circuits rating, eg: a 15 amp circuit should not have more than 12 amps on it. Gael's info above is close to this spec. The alternator excitation is pretty much nill as once it is putting out it is self exciting as long as it is still connected to a battery, which of course it must be to keep working. An HEI at full boogy probably draws about 6 to 8 amps as a guess based on the 12 gauge wire that is usually recommended for hooking it up.

I once measured and HEI on the bench using a battery charger and a large electrolytic cap for filtering. It drew about one amp. I don't think the battery charger is very accurate but definately not 6-8 amps. I have no idea why some recommend 12 guage. 12 guage in your house is rated for 20 amps.

Dennis,

I join the group that wonders why you want to know this, please break the suspense.

If you are trying to decide on the size alternator you need then just do as the others have suggested and add up the total of the fuses or slightly less.

For airplanes we use the total fuse size just to be safe.

Some of the things you listed do not draw current all the time or do not draw the same current for very long and most things required to operate the vehicle are in this category.

Of course this does not include monster sound systems and light systems.

The reason for the 12 gauge wire for an HEI is because the more voltage it gets the more it puts
out. They run without problems up to 16 volts.
To eliminate any voltage drop no matter how small, a 12 gauge wire is recommended for any HEI in a performance application. Over the years I have diagnosed many ignition problems with HEI's that were because of too small wire and the second big fault was poor grounding. They love voltage so we find its best to let them have it.

#12 wire is in fact rated for 20 amps in normal AC use. Interestingly enough at least one aftermarket fuse panel maker provides a 15 amp fused circuit for the ignition system and this circuit on the panel is in #12 wire. It may be overkill or just protection against someone wiring half the vehicle to that fuse.

Mike G, How do I make sure my HEI is properly grounded??? Running Langdon's mini HEI for a few years now, no trouble so far. Also running stock square coil, not in the cap.
Jim

Assuming a ten foot run and two amps, the difference between 12 and 14 guage is 19mV. It's not going to make a difference.

HiTork,

For street applications we make sure that the hold down clamp, the distribs base collar, and the block ( or manifold - on a GASP! V type engine ) are shiney metal and free of all paint and corrosion, and the engine has a good ground directly back to the battery.
On an all out race only application we drill and tap the distrib housing for a short 8-32 screw and run a dedicated ground wire back to the battery or to a known good ground cable that connects directly to the battery, whichever is the shorter distance. Admittedly this is a bit of overkill on the average street engine.

Another thing we insist on is all the electrical terminals on all wires are soldered and not crimped. You only need to lose one race or get stranded on a deserted road one time due to a failed connection to make a believer out of you.
Everyone has their methods and this is ours.

Sorry to take so long to get back on this, but I had an emergency and had to be gone for a few days.

I'm back in the process of making up a wiring harness for my Model A and I just wanted to know what each component would pull from the system. I know I could have just used the recommended fuse for each circuit and not worried about it, but I wanted to know for myself the values. Like they say, "Inquiring minds wanna know".

I took a good 0-50 amp range ammeter and tested each item individually, to see what the amperage draw was. Here's what I came up with:

1. Radiator cooling fan. It initially surges about 28 amps to start, then settles to a steady 9 amps.

2. Alternator energizing circuit/ electric chokes (2 carbs)/distributor (HEI)/ instruments. All four components are fed with Ign switch ON. I checked current flow on the feed side of the Ign switch. Ammeter goes up to 15 amps, then slows down to about 4 amps in just a few seconds, at Idle.

3. Park lights- 1.2 amps

4. Dome lamp-.95 amp

5. Headlights- almost 9 amps

6. Heater motor- 9.5 amps

7. Stop lights- 4.2 amps

8. Turn signal- 4.3 amps

9. Wiper motor- 4 amps

Hope I didn't leave anyone hanging.

Oops, I forgot to test the solenoid operating amperage! Will be back later.