k1w1rodder

I have a problem with a newly purchased 71 Duster. If the battery is left connected it goes flat over a day. Is there any know problems which would cause this. From my measurement it looks like a draw of about 1 amp. There are no lights going I can detect, so what else might cause this sort of battery drain?

Rooty

There is obviously some kind of draw on the battery when it's sitting, it's just a matter of what is causing this. Put an ohm meter set to volts and put it between the battery post and the disconnected + cable. Sometimes you can tell if there is a draw by touching the positive cable to the post quickly in sucession - sparks can be seen. There are some things that can contribute to continuous power draw - clock, one wire alternators, unseen trunk light and sometimes certain ignition components. Faulty or deterierated connections can arc to ground as well. You can connect the battery cable as above and remove one fuse at a time to narrow down which circuit it is on. A pigtail with a small amp light should illuminate if connected between a disconnected battery cable and it's battery post so the light will remain lit until you find the culprit by pulling fuses or disconnecting wires.

k1w1rodder

thanks yes there is a definite draw. will check the fuse test

DDodger

This part of your post is incorrect. Us amperage not voltage. But draw more than the meter can handle can damage some meters, or blow and internal meter fuse if equipped. On an unknown draw, ALWAYS start with the highest current scale of the meter, 20A if equipped. But start FIRST with a test light in series

I use a "heavy" wattage lamp at first, an old headlight or a stop / tail lamp. If and when I find something, I drop down to a regular 12V test lamp which is less wattage, and THEN get out the multimeter.

FIRST THING I would try after checking for "stuff left on" (don't forget trunk lamp) and after pulling fuses

Is to disconnect the ammeter output wire and see if that's it. A leaky diode is a very common cause.

DDodger

Except for the voltmeter comment, agree completely.

Disconnect the alternator.

Also do you have an aftermarket radio, or a system with an external amplifier? If you have a radio wired "hot" (not through the key) or with an external amp, these often leave the audio power amplifier stage permanently hooked to power, and components there can become leaky

I assume? you have checked for obvious such as brake lights

Rooty

Using anything heavy ( like a headlight ) isn't going to cut it. The element in the bulb will be a resistive load and probably won't iluminate at all ( sorta like the resisters in your heater's motor speed control). You figure 1 amp of leakage? A light amperage bulb will only blow on higher voltage not amperage. Run the leads of the bulb across the battery terminal and "voila" it lights up with a 1000 amp battery. I know of no ammeters that don't have over protection for wrong connection or dial selection unless ypur shopping Walfart, and even that's unlikely. These thing are digital nowadays. If the alternator is your source of leakage, it to will show up during testing, so yes, this is one item you will unplug to find if it causes a draw provided it is not a direct connection to battery (+) terminal. Carry on.

k1w1rodder

ok from my testing the only thing i can find is the memory on the after market radio. i've fully charged the battery and hooked it back up. i'll wait a day or so and check how things are going. thanks for all the replies

Iowan

Don't forget to check the battery while your at it.

TVLynn

One amp draw ? If there are no lights on ? I would check how they wired the ign

DDodger

Once again you are partially INCORRECT

You START with a headlight or tail/ stoplight and "work down". Or if you like, START with a 12V test lamp and when it lights up full brilliance, then you have no idea of what you are facing. Then work "up" to the tail light or head light. The REASON you do this is to protect your meter from blowing a fuse, or (see below) blow up the meter current circuitry. I am NOT concerned with "blowing bulbs"

I'm speaking here in more general terms, a strategy that can be used to find ANY draw even a fairly heavy one

You are ASSUMING this 1A figure is accurate, and it "might not be"

So far as ammeter protection, AGAIN you are incorrect. MANY guys I know have bought the equivalent of Horrid Freight and yes, to coin your term, "Walfart" meters. At least some of these have ZERO protection in the ammeter circuit.

So far as the ones that do........don't push. Fluke uses a VERY expensive fuse in those meters which is not carried locally by anyone. Last time I bought a couple of those for spares they were more than SIX DOLLARS apiece. So you don't really, want to go around blowing those things up.

So, maybe maybe not. Maybe in THIS SPECIFIC instance something heavy like a headlight will be inconclusive, but IT WILL TELL YOU THE FOLLOWING!!!!

You start with the headlight and you see no apparent glow. WHAT DOES that tell you? For one thing it tells you that you are not drawing very much current, certainly NOT 10 amps and so now it's safe to hook your fancy expensive digital Wally Freight ammeter up in the circuit, and that YOU WILL NOT blow up the six dollar fuse!!!!! if it has one at all.

Below are photos of a "popular" dime store meter, which some guys actually use. Unlike YOU and I who use ONLY the most expensive lab quality equipment, some guys use, well, not so much. Not that there's too much wrong with that. In any case please NOTICE the ammeter shunt. What you are looking at there is the factory poorly soldered 10A ammeter shunt connected directly to the meter probe jacks THERE IS NO FUSE which means that if one was to make a mistake, you are either going to melt the solder, the shut, or something on the board.

k1w1rodder

My error It was 0.1 amp (damn glasses) I think it was a combination of loose terminals radio memory draw and my nervousness with a new purchase. All seems well now. Thank you all again for your helpful tips it was most appreciated.

RacerHog

Keep use posted....