VCCA Home Forums TECHNICAL - GENERAL Electrical - 6 volt Parasitic load

My 53 210 has a 9.7 milliamp parasitic load. I've only started the trouble shooting to find the drain. I wouldn't think a 6v 53 would have any load with the key off. I've been around the car in the dark looking for a bulb that may be barely glowing and found nothing. The dome light isn't on nor is the glove box light or any of the dash lights. The clock is wind up so no draw there. I've not yet started crawling around under the dash disconnecting things. That is a real chore for me so I'll probably end up paying someone to do it if necessary. My question. Is a <10 mA discharge really a problem? If it would take a couple of weeks to discharge the battery to the point the car won't start I may not even mess with it since I normally drive the car a couple of times a week.

Hi Tiny,

I agree that right now I would not be concerned due to the very low level of drain.

Over the longer term I would keep troubleshooting to find it. My thinking is just like yours. I do not know what normally would create a parasitic drain on an 1953 car. My concern is that there is a place on a wire where the insulation has cracked or is worn thin and there is a small contact between that wire and ground. Or maybe the voltage regulator in your conversion alternator has a bad diode.

Like you, working under the dash is not an activity I am excited to do. I would start troubleshooting with the areas that can be easily reached. Do the simple and obvious things first.

I would get a hard copy of the wiring diagram that you can mark-up to keep track of what you have checked. I assume you have the ammeter connected between the positive battery terminal and the cable to the starter.

Then do simple tests like remove each bulb one at a time to see if that affects the reading. See what happens if you pull each fuse one at a time. Disconnect wires that you can easily reach such as the power feed to the whole system from the starter terminal, wires to the horn, etc. At a minimum you will be able to isolate the area that needs more attention.

Patience and organization are the keys.

Hi Tiny

I wouldn't be too concerned yet either. At 10 milliamps it would theoretically take 833 days to fully discharge a 200 amp/hr battery.
That said, there a couple of potential sources of loss that don't get cut off by the ignition switch, and I'd start there.

Disconnect the ground cable first of course...
Then disconnect the wire to your cigar lighter. It should be coming directly off the ammeter now and thus is not running through the ignition switch.

If that doesn't stop the drain, look at the horn next.
You should be able to stop any drain there by disconnecting the wire to the horn relay from the battery terminal of the voltage regulator.

Hope this helps and you find your drain!

I have the ground battery cable off of the battery. When I put the multimeter on the 200mA setting, the red lead on the ground battery cable & black lead on the battery it shows 9.7 which I assume is a 9.7mA drain. I've disconnected the power lead from the alternator with no change to the multimeter reading. I removed the glovebox bulb and no change. We did put a 6 to 12 volt converter on the lighter circuit to power the GPS so it's possible that's the culprit. Again, that's a chore for another day.

You are powering a GPS off the lighter?
That's almost certainly where your loss is.
Yes I think you are reading your meter right, and unless you've already experience problems with the battery going down, I wouldn't worry about it.
The convenience of the GPS is probably well worth the small risk of a dead battery to you.
Enjoy your car!

Tiny first the GPS will work with 6 volts and also charge your phone, (ours work with 6 volts). The new cars with computers we always figured anything less than 50 mA was ok. Do you have the converter wired through the ignition switch or hot all the time?

It's tied into the wire that fed the lighter so it's hot all the time. I tried it on 6 volts and it kept shutting off. It would work part of the time and not others.

That would definitely produce a draw. That is a pretty efficient inverter I must say.

I agree that the voltage converter is probably the source of the continuous drain. It will be easy enough to confirm that.

While I do not claim to know the “why”, I know that converters, inverters, and chargers we use for phones and similar items all have a small current draw to keep their circuitry active even if there is no working load on them.

My primary concern was that you have a wiring flaw that could get worse.

Tiny,

Seems from the above discussion that the voltage converter is likely the culprit. Serves you right for that modification right there.

Why not disconnect the juice to lighter and then see if the drain dissapears? If so then either remove the converter (which it seems you may not need for the GPS anyway) or switch the wire from the hot side of the ignition switch to the "switch on" position in order to produce the juice. Ever heard of road maps?.

That converter right there is another modivication. Yes, a loss of some points in the preservation poll. Is too!

Best,

Charlie

BTW: Maybe you shouldn't be smoking anyway. Could stunt your growth. I know, I know. But what if you was to accidentally drop a hot cigarette in you lap as you wus a=cruising along in heavy traffic? You know. As a minimum you could scare the he--l outa your "Leroy." Could too!

BTW2: Even if you wanted light up without the lighter hooked up, You could always ease your hand in your trouser pocket and remove a BIC.

BTW3: Speaking of BICs. Ever heard that contest winning opening line to a story? It goes like this here: (The sword wielding hero suddenly arrives on the scene just as the warrior chief is about to burn the beautiful princess at the stake) Hero immediately addresses the chief in a loud, deep toned, threatening voice, "Flip that BIC, toast that chick, and you'll feel my cold steel through your last meal." Source obscure.

The key here very well could be when you mentioned the A word. Alternators use diode bridge voltage rectifiers that deteriorate over time. Eventually the drain will get to a point that it will drain the battery enough that you won't be able to start the car after sitting for even a short amount of time. Disconnect it from your voltage path and see what happens. The solution is to either replace the alternator, or the bridge. Keep us posted as to what you find.

Art

If it happens to be a GM/Delco style alternator, 10si or similar, with an internal regulator, then any small wires should on the alternator should be disconnected at the same time as the big wire to check. See this: https://forums.aaca.org/topic/310489-current-leakage/