Current draw

[terrymb]

Does anyone know what the current draw on a 52 Commander should be when the car is not running, all swiches are off and the doors are closed so the interior lights are not lit and no clock. I just finished the rewiring job and checked with an old cheap meter that reads current but doesn't indicate how much. Very useful, I know. I inserted the meter leads between the positive terminal on the battery and the engine ground.
The car seems to operate normally and after sitting for 24 hours, the interior lights illuminate normally. I'm concerned if there should be a current draw at all.
Thanks,
Terry

1952 Commander Starlight

[PlainBrownR2]

I wouldnt think it wasnt productive to do something like that. For long term storage this could be quite useful . I would not expect a large current draw provided there is no electronics or electrical equipment, that uses a "memory", or a considerable short circuit. Now, if it was a season (such as 3-5 months of cold storage or wintertime) I would think there would be some sort of leaching from the battery. There's probably half a dozen theories on here beyond the leaching through the plates, terminals, wet concrete floor, anything that is conducive to a charge. Thank the great Dude for Battery Tenders and Rechargers for that.


1964 Studebaker Commander R2 clone
1950 Studebaker 2R5 with 170 turbocharged
[img=left]http://i158.photobucket.com/albums/t102/PlainBrownR2/DSC00003.jpg?t=1171152673[/img=left]
[img=right]http://i158.photobucket.com/albums/t102/PlainBrownR2/DSC00009.jpg?t=1171153019[/img=right]
[img=left]http://i158.photobucket.com/albums/t102/PlainBrownR2/DSC00002.jpg?t=1171153180[/img=left]
[img=right]http://i158.photobucket.com/albums/t102/PlainBrownR2/DSC00005.jpg?t=1171153370[/img=right]

[terrymb]

Sorry, I meant the meter I used was not very useful.
Terry

1952 Commander Starlight

[gordr]

quote:Originally posted by terrymb

Does anyone know what the current draw on a 52 Commander should be when the car is not running, all swiches are off and the doors are closed so the interior lights are not lit and no clock. I just finished the rewiring job and checked with an old cheap meter that reads current but doesn't indicate how much. Very useful, I know. I inserted the meter leads between the positive terminal on the battery and the engine ground.
The car seems to operate normally and after sitting for 24 hours, the interior lights illuminate normally. I'm concerned if there should be a current draw at all.
Thanks,
Terry

1952 Commander Starlight

The current draw should be zero under those conditions. A few milliamps of leakage current might flow across dirty insulation at some point, but zero is the goal to shoot for.

Is there a trunk or glove compartment or underhood light? Sometimes they can come on when the lid in question is closed, and they glim away unseen. Trailer connector? They are notorious for growing green fuzz that conducts slightly. Stoplight switch covered in conductive dirt, or simply old and sort of flaky, and making partial contact? That's an important one to check, because there is power to the stoplight switch even if all switches are off.

Try disconnecting one battery cable, and interpose a small lamp bulb (e.g.dash lamp bulb) between the battery post and the terminal. A test lamp, the kind that looks like an icepick with a bulb in the handle is ideal for this, and belongs in every car nut's toolbox. If, with all circuits OFF, you see so much as glimmer of red in the bulb filament, you've got more leakage current than you should have. Try removing fuses, one at a time, and see if removing one causes the bulb to extinguish. If so, then the leakage is in the circuit controlled by that fuse. If pulling fuses has no effect, start disconnecting major power wires: "bat" terminals on voltage regulator and ignition switch, again one at a time, the hot lead to the stoplight switch, etc. Eventually, you'll find it (assuming a current leak exists).

BTW, a stock Stude clock with the electromagnet winder will pull about 1 amp for 1/4 second about once per minute as it winds, and zero when it's not actually winding. A quartz clock conversion will draw a few (<10 mA???) continuously.



Gord Richmond, within Weasel range of the Alberta Badlands

[John Kirchhoff]

The old tale about not setting a battery on concrete is just that, a tale. A battery doesn't really care where it's setting and isn't going to discharge because of that. What will discharge them is the thin film of acidic material that accumulates on the top of the battery through use. On a damp morning you can run your finger across the top and see the stuff or if you don't believe it's there, mix up a little baking soda and water and drip onto the top of the battery. Unless the battery is new or you wash it regularily, I can assure you there will be a lot of foaming going on from the acid-base reaction.

Something else that can discharge an older battery is when the sediment in the bottom of the battery gets deep enough that it begins to touch both plates, which then creates a short between the positive and negative plate. The sediment accumulation is created whenever a battery is discharged and charged and a tiny bit of the lead sloughs off. Small powerful batteries are more prone to this type of discharge because one way to cut external size is to reduce the distance between the bottom of the plates and the battery case. Less distance and the sooner the sediment touches the plates.

[vegas paul]

Hey John, with your last name, I'd trust anything you said about electricity! I remember memorizing Kirchoff's Law in college... didn't make as much sense then as it does now - now that I can apply it to something real. From now on, you're the go-to guy for all electrical woes.

Las Vegas, NV
'51 Champion Business Coupe G899965 10G-Q4-1434

[curt]

Removing fuses on my 1955 is not easy. I hope the 52 Commander has easier to reach fuses. Fuse removal seems like a good route to go after checking for a trunk light on, glove box light on , and the obvious things that I'm sure you have done.

[John Kirchhoff]

vegas paul, giving a worn out plow horse the name "Lightning" won't make him fast any more than my name makes me smart! Years ago in the mail we would get pictures of the Kirchhoff family crest that we could have...for a price. Supposedly they'd done all kinds of research, blah, blah blah. All I know is great grandpa Kirchhoff was a merchant marine and to escape conscription in another one of Germany's wars with its neighbors, he jumped ship and went awol when they docked at New York City, eventually making his way to Missouri. Hmmm, I think I like the sound of the family crest nobility a lot better than the truth!

[terrymb]

I got my real meter from work today and measured .03mA. Guess I have nothing to worry about.
Thanks for all the replies.
Terry

1952 Commander Starlight

[Dan Timberlake]

My 1960 Hawk is drawing about 0.1 amp / 100 milliamps when I connect the battery cable (no noticeable sparking) , and the clock starts running instantly. I used the 10 Amp function on a moderately cheesy no name digital multimeter as sold at an auto parts store. I have tested it for maybe 30 seconds. I'll test it for a full minute today, and maybe play with fuses to see if its 100% clock.

Is 100 mA "normal?"

Thanks,

Dan T

[gordr]

Dan, 100mA sounds like a lot of draw for a car with everything off. You say the clocks starts running "immediately". A normal 1960 clock has a spring-wind/solenoid movement in it, and should "wind" itself with an audible "thunk" when first powered up, and then thunk at roughly 1 minute intervals thereafter. During the "thunk" it should draw an amp or two, but between thunks, nothing. I'm wondering if someone did a quartz clock conversion on the car?

Otherwise, 100 mA is about the current I'd expect from a small lamp bulb like a dash lamp.

Gord Richmond, within Weasel range of the Alberta Badlands