Dying Battery or Phantom Drain

[orbitron3000]

I am experiencing a frustrating issue with my car. About a month or so ago, it wasn't driven for 4 or 5 weeks. During that time, the battery on the car died completely. Wouldn't turn over, wouldn't have enough juice to turn on any lights, interior or exterior. So I charged my battery with a battery charger. Now, unless the car is driven regularly (2-4 times a week) the car's battery won't have enough juice to start the car.

My question is this: is this more likely to be the symptoms of a battery nearing the end of it's lifecycle? Or, is there some component in the system that is draining power faster than it should? It is worth noting that I have installed Toby's remote lock/unlock system. It was installed by me, and I am nowhere near a professional electrician or mechanic.

If it is the battery, should I consider replacing the battery? Which brands have you had success with or are happy with?

If it is a phantom drain, what is the best way to go about discovering the culprit on our cars?

Any help is greatly appreciated -- it's getting old having to charge the battery every week or so.

[Ron]

As a test, just leave it disconnected to see if it is a drain...

[Bitsyncmaster]

If you get a full charge into the battery and it won't start after a week then you may have a curtisy light not shutting off or the battery is shot. Pull the #12 fuse and leave it out. See if that cures your problem.

[Notifier]

If you get a full charge into the battery and it won't start after a week then you may have a curtisy light not shutting off or the battery is shot. Pull the #12 fuse and leave it out. See if that cures your problem.

If it is the courtesy light switch your simple fix (at least it was for me) was to simply install a shim on the door to get the plunger to fully depress when the door is closed. I had the same issue, battery drained only after a few days. Noticed when I drove the car at night the interior light would blink, pushing on the door made it stay on. I think it was just at that point to make contact and drain the battery.

[nofear365]

Just as a point of reference - Last summer I disconnected my battery and put my car away for 2 months. To my surprise the car fired right up as soon as I connected my battery

I don't think it would have started if the battery was connected.

[David T]

If the battery is over 5 years old, replace it. If it is younger have it fully charged and load-tested. To reduce the standby drain install a master switch. You can also check to make sure the radio is hooked up correctly, the cigarette lighter is not stuck, and upgrade or disconnect the door lock module. Make sure when the doors are closed the courtesy lights are all off. Add rubber tips to the plunger switches if they are missing.
David Teitelbaum

[Kevin]

If it is a phantom drain, what is the best way to go about discovering the culprit on our cars?

If leaving it disconnected works, then it's likely some parasitic draw. If you have an amp meter handy, wire it in series with the battery and see how many milliamps are being drawn. Typical parasitic draw on a car with everything off is 30-50mA. If you're getting a lot more, that's likely causing your drain. To find the cause, pull each fuse and use the meter to connect the two terminals in the fuse box to measure how many milliamps each circuit is using and see which is the culprit. Let us know if you need more explanation.

[Ozzie]

A few years ago, all of a sudden, my battery would drain within a week, so that my weekend drives would start with a battery jump.

Soon thereafter I traced the leak to my radio's standby current requirements (for preset stations/options) having gone haywire. I fixed that and I can now start the car up after 3 weeks w/o use (which was a record for me in not using the car), battery plugged in.

You can easily diagnose the source of the leak with a multimeter that measures DC current (most do). Here's how:
1. Open fuse access panel.
2. Disconnect (or tape off) the door plunger switch, of the door that will be opened during this test.
3. Disconnect the battery ground.
4. Set your multimeter to DC Amps
5. Hook the meter between the battery and the cable you removed from the battery (big wire clips work well here).
6. Check reading.

That reading with the car off is your standby current draw. It should be well under 50 mA. The draws on standby would be: Radio, Clock, Keyless entry (if you have one), door locks.

If you have a high current draw, then the next step is to try to isolate it's location.

7. Keeping the same set up from above, pull one fuse at a time, check reading, put fuse back in.

Once you find a fuse that drops the standby current the greatest, now you have isolated which circuit to follow. That is how I traced it to the radio, and corrected the current leak.

[orbitron3000]

Thanks everyone for the responses! This morning I disconnected the positive terminal from the battery and will see if the battery drains all by its lonesome.

If it turns out to be a phantom draw, then is it necessary to disconnect the ground (negative) terminal? Or can I disconnect the positive and wire in the multimeter from there?

[Ozzie]

....is it necessary to disconnect the ground (negative) terminal? Or can I disconnect the positive and wire in the multimeter from there?

lol. I've seen raging forum debates on this, but I generally follow the recommendations to remove the ground cable from the battery. Check this reference for um, well, reference:

"...always remove the battery's ground clamp before loosening the positive. If you remove the negative clamp and inadvertently complete a circuit to ground, there will be no current flow because the ground clamp is already grounded. Subsequent shorting of the positive terminal to ground will then produce no current flow because the current has no return path to the negative post. And, of course, always reconnect the ground last."
Reference Link (http://www.popularmechanics.com/cars/how-to/repair-questions/4213127)

[Kevin]

lol. I've seen raging forum debates on this, but I generally follow the recommendations to remove the ground cable from the battery. Check this reference for um, well, reference:

"...always remove the battery's ground clamp before loosening the positive. If you remove the negative clamp and inadvertently complete a circuit to ground, there will be no current flow because the ground clamp is already grounded. Subsequent shorting of the positive terminal to ground will then produce no current flow because the current has no return path to the negative post. And, of course, always reconnect the ground last."
Reference Link (http://www.popularmechanics.com/cars/how-to/repair-questions/4213127)

I'll agree for safety's sake, best to follow the textbook safety instructions, this is what they'll teach in any automechanics school. Don't want to be burned or blow up a battery.

But for electrical theory's sake and posterity, you should get the same amp reading on either side.

[orbitron3000]

lol. I've seen raging forum debates on this, but I generally follow the recommendations to remove the ground cable from the battery. Check this reference for um, well, reference:

"...always remove the battery's ground clamp before loosening the positive. If you remove the negative clamp and inadvertently complete a circuit to ground, there will be no current flow because the ground clamp is already grounded. Subsequent shorting of the positive terminal to ground will then produce no current flow because the current has no return path to the negative post. And, of course, always reconnect the ground last."
Reference Link (http://www.popularmechanics.com/cars/how-to/repair-questions/4213127)


I'll agree for safety's sake, best to follow the textbook safety instructions, this is what they'll teach in any automechanics school. Don't want to be burned or blow up a battery.

But for electrical theory's sake and posterity, you should get the same amp reading on either side.

Very interesting. Unfortunate, then, that (1) I've historically been just removing the positive terminal whenever mucking around in the fuse box and (2) the ground terminal is on the far side of the battery (have to physically remove the battery from the compartment in order to get to the ground)

[Bitsyncmaster]

Very interesting. Unfortunate, then, that (1) I've historically been just removing the positive terminal whenever mucking around in the fuse box and (2) the ground terminal is on the far side of the battery (have to physically remove the battery from the compartment in order to get to the ground)

I hardly ever remove the ground. Like you said, it's way back there. You can measure your current on either side of the battery.

[Ozzie]

I'll agree for safety's sake, best to follow the textbook safety instructions, this is what they'll teach in any automechanics school. Don't want to be burned or blow up a battery.

But for electrical theory's sake and posterity, you should get the same amp reading on either side.


I hardly ever remove the ground. Like you said, it's way back there. You can measure your current on either side of the battery.

Absolutely, no argument. Same reading on both sides, my post was merely for the sake of awareness and safety.




....the ground terminal is on the far side of the battery (have to physically remove the battery from the compartment in order to get to the ground)

Not really. I just pull the battery up and over it's well, and pull it forward a bit. Plenty of access, no need to remove the battery. In fact here is a picture of when I did the measurements for the LED conversions, that is as far as I had to move the battery:
http://4.bp.blogspot.com/-O2h6bnUSzaA/ThtYWE-DkdI/AAAAAAAAAiU/0wd8Ph8lGoA/s1600/Meter+Reading+Standy+Drain.jpg

[outatym2001]

I can’t believe I learned this in a Popular Mechanics magazine and not in an Automobile magazine or here on DMC Talk.org
In Popular Mechanics, February 2011, on page 98 is the following article.

A Draining Experience
I had this problem recently on a 1976 Corvette. My meter showed a 200-milliamps drain with the key off. Seeing that the fuses are behind and above the clutch pedal, I really wanted the culprit to be something that didn’t go through the fuse block. When I disconnected the alternator, the drain completely disappeared. I was able to find one shorted diode in the rectifier (I would have thought it would take two to get a path to ground), and a new alternator solved the problem.

Amazingly, an alternator with a shorted diode-there are six in total-will usually (barely) keep up with battery charging and running the car but discharge the battery in spite of the key being off.

So everyone with a DeLorean whose car battery seems to not last very long try disconnecting the alternator and take a reading with a digital volt meter. While you’re in there disconnect any electrical connections and clean them and put it all back together.
My D goes through a battery every several years. I had a mechanic install a Bosch 110 amp alternator about ten years ago. I have cleaned all the electrical connections I can find and perhaps soon I’ll try my recommendation of disconnecting the alternator to see if there is a drain.

[orbitron3000]

I can’t believe I learned this in a Popular Mechanics magazine and not in an Automobile magazine or here on DMC Talk.org
In Popular Mechanics, February 2011, on page 98 is the following article.

A Draining Experience
I had this problem recently on a 1976 Corvette. My meter showed a 200-milliamps drain with the key off. Seeing that the fuses are behind and above the clutch pedal, I really wanted the culprit to be something that didn’t go through the fuse block. When I disconnected the alternator, the drain completely disappeared. I was able to find one shorted diode in the rectifier (I would have thought it would take two to get a path to ground), and a new alternator solved the problem.

Amazingly, an alternator with a shorted diode-there are six in total-will usually (barely) keep up with battery charging and running the car but discharge the battery in spite of the key being off.

So everyone with a DeLorean whose car battery seems to not last very long try disconnecting the alternator and take a reading with a digital volt meter. While you’re in there disconnect any electrical connections and clean them and put it all back together.
My D goes through a battery every several years. I had a mechanic install a Bosch 110 amp alternator about ten years ago. I have cleaned all the electrical connections I can find and perhaps soon I’ll try my recommendation of disconnecting the alternator to see if there is a drain.

That's quite interesting. I never knew an alternator could be the source of a drain on the battery. I will keep that in mind as I diagnose the issue. Thanks!

[orbitron3000]

I checked the voltage on the battery today. It was 12.3 volts after being disconnected from the car for several days. This fact leads me to believe that there is some phantom drain within the electrical system. My list of potential culprits are:

Blown fuse in alternator
Fuse circuit
Bad relay? (Maybe door dimmer relay?)
Installation of DMCNW Wireless system
Radio


So in order to find the base drain, I reconfigured how I unplugged the battery -- I now have the positive terminal connected and the negative (ground) terminal disconnected. Curiously, when I placed my multimeter (in mA mode) between the ground terminal and the (-) Battery post, the reading was 0.16 mA. Which must be wrong. Could I be in the wrong mode on the multimeter? Any ideas what my error is? I should also note that I do not have clamps attached to the multimeter -- I am measuring with the prongs.

[Kevin]

Curiously, when I placed my multimeter (in mA mode) between the ground terminal and the (-) Battery post, the reading was 0.16 mA. Which must be wrong. Could I be in the wrong mode on the multimeter? Any ideas what my error is? I should also note that I do not have clamps attached to the multimeter -- I am measuring with the prongs.

You may have blown a fuse in your multimeter. This can happen if you have your meter set to measure amps and then try to measure voltage, basically because when you hook your multimeter up in parallel, you're allowing the current to bypass the load, so it fries your fuse. You should be able to open the meter up and take a look.

[Bitsyncmaster]

The standard door lock ECU draws about 12 ma. but you must have some other ECU if you have wireless.

The clock in the center console was about 7 ma (may be more but that rings a bell).

If you have a clock in your radio they typically draw 5 ma.

The fanzilla draws about 3 ma.

So your reading of 0.16 ma. does not seem correct.

[orbitron3000]

You may have blown a fuse in your multimeter. This can happen if you have your meter set to measure amps and then try to measure voltage, basically because when you hook your multimeter up in parallel, you're allowing the current to bypass the load, so it fries your fuse. You should be able to open the meter up and take a look.

I'm hoping this isn't the case, but I'll make sure.


The standard door lock ECU draws about 12 ma. but you must have some other ECU if you have wireless.

The clock in the center console was about 7 ma (may be more but that rings a bell).

If you have a clock in your radio they typically draw 5 ma.

The fanzilla draws about 3 ma.

So your reading of 0.16 ma. does not seem correct.

I have the DMCH Digital Door Lock ECU, if that helps.

The radio in the car has a detachable faceplate, which i had removed -- I don't know if that would still draw power or not.

I don't think the car has fanzilla, but it does have upgraded fan fail modules.

I'm going to go later tonight with a different multimeter to try and get a different reading. Hopefully, this is all user error...

[Ozzie]

I'm hoping this isn't the case, but I'll make sure.

I have the DMCH Digital Door Lock ECU, if that helps.

The radio in the car has a detachable faceplate, which i had removed -- I don't know if that would still draw power or not.

I don't think the car has fanzilla, but it does have upgraded fan fail modules.

I'm going to go later tonight with a different multimeter to try and get a different reading. Hopefully, this is all user error...

Yeah the radio's head unit will still draw standby current, w/o the face plate.
Hate to ask but: Sure you're reading it right? Maybe it's showing 16mA...with that digital door lock unit, I wouldn't be surprised that is your car's standby current.

[orbitron3000]

Yeah the radio's head unit will still draw standby current, w/o the face plate.
Hate to ask but: Sure you're reading it right? Maybe it's showing 16mA...with that digital door lock unit, I wouldn't be surprised that is your car's standby current.

I'm fairly certain I'm reading the display correctly. With the dial on the mA it read "00.16". I did notice that when it was reading in terms of Amps, it read "0.016", which would make more sense. I could have mistaken the decimal place on the mA setting for something else. I will try to take a picture of the meter so that the mystery can be solved. Either I can't read the multimeter or my car is watching it's electrical intake...(probably the former)

[orbitron3000]

OK so I've managed to capture exactly what the multimeters say. I set these up with two different multimeters.

The setup is this: I've removed the black (negative / ground) cable from the battery's negative terminal. The red cable remains connected to the battery's positive terminal. As shown in all three images, the red multimeter prong is connected to the VmAO port on the multimeter, and the black prong is connected to the COM port on the multimeter.

In so far as bridging the connection, I've connected the red multimeter prong to the black cable from the car, and the black multimeter prong to the battery's negative terminal. These are the results:

Digital Multimeter, on mA setting:
7941

Digital Multimeter, on A setting:
7943

Analog Multimeter, on 250 mA setting:
7942

I'm hoping other people are as confused about these readings as I am. The analog one (which I know has a working fuse because I replaced it shortly before testing with it) has the strangest results.

On a related note, I tested the voltage on the battery again. It read 12.29 V, a drop of 0.01 V from just about 4 or 5 hours ago.

[Bitsyncmaster]

Looks like your DVM meter fuse is blown for reading current. Very common to blow that fuse by accidently touching the probes to voltage when plugged into current jacks.

Your analog meter is reading 52 ma which is higher than I would expect to see in our cars. That current draw would drain a lot of power from the battery in a week or two.

[Elvis]

+1

to be sure try to measure another circuit with the DMM or turn something on that needs
just some few more milliamps and see what difference the display says.

one of the interior lights, glove box, plug in a cell phone or navi charger...

[Ozzie]

Win: Analog meter.
Good way to isolate the issue to the meter.
Once you get the digital one back up, or you could continue with the analog: You are off on your drain hunt.

[Ron]

Looks like your DVM meter fuse is blown for reading current. Very common to blow that fuse by accidently touching the probes to voltage when plugged into current jacks.

Your analog meter is reading 52 ma which is higher than I would expect to see in our cars. That current draw would drain a lot of power from the battery in a week or two.
+1

Double check, but I believe there are only two options for that particular meter- For measuring amperage greater than 0.4 Amps, you use the Left two probe ports ("10A" and "COM"). For ALL other mesurements use the right two....

If you measured voltage... then fliped to "mA" without moving the probe over to "10A" and the door was open - GOT YA!

[orbitron3000]

+1

Double check, but I believe there are only two options for that particular meter- For measuring amperage greater than 0.4 Amps, you use the Left two probe ports ("10A" and "COM"). For ALL other mesurements use the right two....

If you measured voltage... then fliped to "mA" without moving the probe over to "10A" and the door was open - GOT YA!

This makes the most sense -- the DMM does have a 10A port, so I ought to be able to still measure with it in that one...still have to replace the fuse :disapprove:

[DMC5180]

Not to hijack this thread:

Is their a simple way to add a 12V Li standby Clock/Radio memory battery that could last for weeks/months if the main battery is disconnected during extended periods of inactivity?

[Kevin]

Not to hijack this thread:

Is their a simple way to add a 12V Li standby Clock/Radio memory battery that could last for weeks/months if the main battery is disconnected during extended periods of inactivity?

When considerate auto shops have to disconnect a customer's battery, they use a little device that's basically just a 9V battery that you can plug into a cigarette lighter to retain the memory in all the computers. Not sure how long it'd last for long term purposes, but I know they're cheap and easy to use.

EDIT: Here's an example just to illustrate, doesn't have the best reviews though: http://www.amazon.com/12V-Automotive-Settings-Keeper-Battery/dp/B002C0NP5I

[Bitsyncmaster]

Let's say you have a 12 ma. door lock load and a 7 ma. clock load. That would require a battery rated for 13.68 amp hours to run for 30 days. Actually you would need a larger battery because the voltage would drop to low before you reach the batteries rated capacity.

[DMC5180]

HMM, That cigarette adapter is pretty slick.

I was figuring only isolating Radio/clock memory with diodes . I thought the DDLM (Digital Door Lock Module) shuts down completely after a few seconds as to not drain
the battery.

Dave,

FWI: I just a replaced a couple board mounted (3V-Li) back-up memory Batteries for retaining User Way-Points and internal clock in a couple Garmin 430's last week . Garmin says they have a typical lifespan of 5 years and should be replaced when you get a "back-up battery low voltage" message.

I was wondering if an external memory only battery could do the same thing if isolated to radio and clock.

[Bitsyncmaster]

HMM, That cigarette adapter is pretty slick.

I was figuring only isolating Radio/clock memory with diodes . I thought the DDLM (Digital Door Lock Module) shuts down completely after a few seconds as to not drain
the battery.

Dave,

FWI: I just a replaced a couple board mounted (3V-Li) back-up memory Batteries for retaining User Way-Points and internal clock in a couple Garmin 430's last week . Garmin says they have a typical lifespan of 5 years and should be replaced when you get a "back-up battery low voltage" message.

I was wondering if an external memory only battery could do the same thing if isolated to radio and clock.

Memory retain draws very little power. Micro-amps compared to the ma. draws of our old circuits. Circuits are designed to reduce power by running slower clock frequency and high impeadance logic. Lots of circuits can run down to pico amps of power. That is 0.000000001 amps = 1 pico amp.

[DMC5180]

Memory retain draws very little power. Micro-amps compared to the ma. draws of our old circuits. Circuits are designed to reduce power by running slower clock frequency and high impeadance logic. Lots of circuits can run down to pico amps of power. That is 0.000000001 amps = 1 pico amp.

I was planning on installing one of those VR3 640's (Like OZZY's). Perhaps It's memory doesn't drain like the old Craig.

[Bitsyncmaster]

I was planning on installing one of those VR3 640's (Like OZZY's). Perhaps It's memory doesn't drain like the old Craig.

You need to get someone to measure the standby current. Most of the radios do not bother to design using less power. They expect them to be installed in daily drivers.

[Elvis]

I experienced that it often makes a difference if you install the radio so that you
have to turn it off manually or if install it like the manufacturer wants you to -
so that it turns off when you pull the key.

[David T]

With older radios and clocks no one cared about trying to reduce standby current drain. On newer cars it started becoming an issue as more and more electronics was added. It is so bad now that if you park some newer cars for more than 2 weeks they won't have enough oomph to start! Newer devices are now smarter and not only go into "standby" but also have a "sleep" mode where they draw even less current. One thing you can check is if your electronics is hooked up correctly. There is usually an "always hot" wire and an "ignition" wire that is supposed to have power ONLY when the ignition is on. All too often an installer will take a short-cut and hook them both together to an always hot power source. Causes a much higher drain. Another problem is if the battery is old. It will still work but has a much reduced capacity, ie, if it says 500 A/H maybe it is less than 1/2 that capacity when it is 5 years old. Temperature also reduces capacity. A cold battery has less power than a warm battery. Add some corrosion to the connections and now you don't have enough power. Here is my answer to your problem. Add a battery master switch. Run a wire with a fuse directly from the battery around the master switch to the "always on" wire for the clock/radio. Now you don't have to worry about any parasitic drains and your clock and radio presets will stay up. This should get you at least a month with a good battery. No remote launcher or door locks. Past that you will need a trickle charger or battery tender to help keep the battery up.
David Teitelbaum

[DMC5180]

I like your idea David. I do have a Cut-off at the Battery, but always have to reset the clock and presets when I turn it back on. Very easy to do with the Graig Radio and Console Clock, it's just an annoyance to have to it all the time. I have gotten into the habit of using the cut-off regularly. After a weekend of driving I will always turn it of because I'm never sure when the next time I'll drive it. Could be 5 days or 3 weeks.

I'm anticipating the NEW radio won't be as user friendly as the simple push buttons of the Craig. This is why I want to go with a "keep-alive circuit" just for the radio memory.

[dmc6960]

I'm anticipating the NEW radio won't be as user friendly as the simple push buttons of the Craig. This is why I want to go with a "keep-alive circuit" just for the radio memory.

Its almost a shame car stereos aren't being developed as much now as they were in the 90's and early 2000's. With the tech available now there could really be some nice units for decent prices. Store all settings and pre-sets in NVRAM and use Cellular or NIST-based automatic time setting with GPS to automatically change it when you drive into a different time zone. All of this tech is easily available on even some of the cheapest cell phones, yet absent in all but the high-end car stereos.

[sean]

Hidden audio tangent moved here:
http://dmctalk.org/showthread.php?2954-Hidden-audi-system-chatter***Split-from-Battery-drain-thread***

[Ron]

Here is my answer to your problem. Add a battery master switch. Run a wire with a fuse directly from the battery around the master switch to the "always on" wire for the clock/radio. Now you don't have to worry about any parasitic drains and your clock and radio presets will stay up.
Good mod as long as the problem isn't in one of the circuits you feed with the bypass wire...

While you are in there:
Another option is a high power relay. At the sacrifice of a very small amount of power, you gain never having to screw with a manual switch in the battery compartment again! (eg. Quick Google has a 200 AMP (http://www.wiringproducts.com/contents/en-us/p4000.html) for the super boom boxers.)
You can run the main power wire through it like a manual and bypass those requiring constant power (as suggested), or, leave both alone and switch the others...
We use lower power electronic type units for the latter option on our firetrucks (one or two would handle all a D would ever need)...these are $weet!

I think it would be a lot wiser to first find the problem in any event.

[Ozzie]

Good mod as long as the problem isn't in one of the circuits you feed with the bypass wire...

While you are in there:
Another option is a high power relay. At the sacrifice of a very small amount of power, you gain never having to screw with a manual switch in the battery compartment again! (eg. Quick Google has a 200 AMP (http://www.wiringproducts.com/contents/en-us/p4000.html) for the super boom boxers.)
You can run the main power wire through it like a manual and bypass those requiring constant power (as suggested), or, leave both alone and switch the others...
We use lower power electronic type units for the latter option on our firetrucks (one or two would handle all a D would ever need)...these are $weet!

I think it would be a lot wiser to first find the problem in any event.

Oooh, that's cool.
How are these typically hooked up? One pair of terminals between the Neg battery cable, and the other pair to an On-Off contact switch...or something more sophisticated like ignition wiring?

[Ron]

Oooh, that's cool.
How are these typically hooked up? One pair of terminals between the Neg battery cable, and the other pair to an On-Off contact switch...or something more sophisticated like ignition wiring?Either way works for total shut off. The way we do it is on the POS side wire(s), which is actually easier if choosing circuits of coarse- Ground one side of the coil with a short jumper (typically under one of the mounting bolts) and, like you said, a tap off of the ignition switch or simply find an original 'hot only when key on' nearby to power it...or, as we often add one with, a 'hot only when ignition on' for the dummies that leave the one of the radio(s) turned down but not off, etc. (And in a fire department, you don't have to remember where the switch is on all kind of different vehicles...or if it even has one if the battery "seems" dead...;-)

[orbitron3000]

Looks like your DVM meter fuse is blown for reading current. Very common to blow that fuse by accidently touching the probes to voltage when plugged into current jacks.

Your analog meter is reading 52 ma which is higher than I would expect to see in our cars. That current draw would drain a lot of power from the battery in a week or two.


+1

to be sure try to measure another circuit with the DMM or turn something on that needs
just some few more milliamps and see what difference the display says.

one of the interior lights, glove box, plug in a cell phone or navi charger...


+1

Double check, but I believe there are only two options for that particular meter- For measuring amperage greater than 0.4 Amps, you use the Left two probe ports ("10A" and "COM"). For ALL other mesurements use the right two....

If you measured voltage... then fliped to "mA" without moving the probe over to "10A" and the door was open - GOT YA!

So, I replaced both fuses in the DMM in hopes that that would fix the reading error, but even after replacing both, the amperage reading on the DMM is still the same as the pictures, even with the black cable in either the 10A or COM. Could the actual DMM unit be malfunctioning? It does still read voltage properly.

[Dangermouse]

So, I replaced both fuses in the DMM in hopes that that would fix the reading error, but even after replacing both, the amperage reading on the DMM is still the same as the pictures, even with the black cable in either the 10A or COM. Could the actual DMM unit be malfunctioning? It does still read voltage properly.

Did you test the old fuses to see if they were, in fact, blown?

[Ron]

... even with the black cable in either the 10A or COM.
...
Could the actual DMM unit be malfunctioning? It does still read voltage properly. Although colors don't really matter, the Black one always goes in the COM ("common") port. The Red one goes in the Right port unless you want to read amperage between 400Ma = .4 Amps and 10Amps (anything higher can toast the meter).
Sounds like you may have used the two outside ports (a No-No)...recheck your fuses (ALWAYS replace with 'fast blow' fuses).

Yes, one part of the meter can read correctly while others don't.
Did you try what Elvis suggested to test it?

[David T]

That's the way they do it in airplanes. I like the manual master switch, you have to know where it is. Some types have a key which is also the handle so you can remove it, making turning the car on even harder. Most people would not know where to look for the battery OR the master switch. I agree if there is a problem on the wire to the radio for constant power, the bypass does not fix the drain problem. In that case just don't use the bypass (or find and fix the problem!). Instead of playing with your meter just get an old-fashioned 12 volt light bulb and hook it in series with the red battery cable to the battery. It will light up if there is a large enough current. Pull the wires off both door switches and start pulling fuses till the light gets dim. The fuse that gets the light dim is the circuit drawing too much power. This trick won't work if a diode in the alternator is shorted. In that case disconnect the alternator.
David Teitelbaum

[Bitsyncmaster]

There are some loads not fused. The door lock controller is one.

[Ron]

This trick won't work if a diode in the alternator is shorted. In that case disconnect the alternator.
David TeitelbaumMaybe you should re-think this part....

[David T]

If a diode in the bridge is shorted it will drain the battery and if the regulator is bad it can drain the battery. The only way to know using a bulb in series with the battery is to disconnect the alternator since it is not fused. As bitsyncmaster points out not every load in the car is fused. That is correct but most of the time a drain is going to be on a fused load. We all know the door lock module has a significant standby drain. What I presume the original poster is looking for is something much larger and out-of-the-ordinary. Like a short in the cigarette lighter, door courtesy lights that don't go off, a burglar alarm, etc. My tip is a short-cut to find any large drain quickly with a minimum of test equipment.
David Teitelbaum

[orbitron3000]

If a diode in the bridge is shorted it will drain the battery and if the regulator is bad it can drain the battery. The only way to know using a bulb in series with the battery is to disconnect the alternator since it is not fused. As bitsyncmaster points out not every load in the car is fused. That is correct but most of the time a drain is going to be on a fused load. We all know the door lock module has a significant standby drain. What I presume the original poster is looking for is something much larger and out-of-the-ordinary. Like a short in the cigarette lighter, door courtesy lights that don't go off, a burglar alarm, etc. My tip is a short-cut to find any large drain quickly with a minimum of test equipment.
David Teitelbaum

Yes, I'm looking for something that would cause the battery to drain in about a week's time if the car is just sitting.

I did replace the cigarette lighter with a similar model that I found on another thread here. I wonder if that could be the problem.


Although colors don't really matter, the Black one always goes in the COM ("common") port. The Red one goes in the Right port unless you want to read amperage between 400Ma = .4 Amps and 10Amps (anything higher can toast the meter).
Sounds like you may have used the two outside ports (a No-No)...recheck your fuses (ALWAYS replace with 'fast blow' fuses).

Yes, one part of the meter can read correctly while others don't.
Did you try what Elvis suggested to test it?

Well that'll probably be a problem -- I had the red in the right most and the black in the left most. That'll teach me to skim the directions...:bang:

[orbitron3000]

I have found my leak! It was, in fact, the remote functionality system from DMCNW that I installed. Putting the black prong in the 10A and red in the COM port on the DMM, I was able to replicate the readings I saw on my trusty ol' analog meter. After disconnecting the remote system, I saw a familiar reading of 0.011 A (11 mA). Yay! Clearly, I've mis-installed the remote system, so I'll be spending a weekend or two reinstalling and organizing the rat's nest of wires that currently resides there.

Thanks to everyone for their advice, patience, and support in helping me figure out why my battery was draining so quickly.

[Ron]

If a diode in the bridge is shorted it will drain the battery and if the regulator is bad it can drain the battery.
One shorted diode in the bridge rectifier will not drain the battery.


The only way to know using a bulb in series with the battery is to disconnect the alternator since it is not fused...
The battery don't know/care if a load is fused or not.

=======



Success

Putting the black prong in the 10A and red in the COM port on the DMM,...

Cool Beans!

I hope that's a typo...Black in Black hole, Red in Red hole(s) :deviltail:

[David T]

A shorted diode (or a leaky one) in the diode bridge can certainly drain a battery. I understand the battery can't care about fused and unfused. The point there is even if you pull every fuse and circuit breaker there is no way to disconnect the alternator from the electrical system unless actually remove the wires to it. A moot point now since the problem was not the alternator (in this instance anyway). Diodes are typically blown by jumping the battery but accidentally reversing polarity. Even for a second, once you see the spark, you could have fried one or more diodes.
David Teitelbaum

[DMC5180]

David,

You mentioned Cigarette lighter earlier (I assume you meant the Socket) I would not see that as a source for a drain in and of itself. (empty) It can be a source for a dead short and blown fuse under the right circumstances though.

Example: Many years ago I was asked to look a car that kept blowing a fuse, a mid 80's Cadillac Seville. The fused circuit was the radio/Cigar lighter. Took me about a minute to find the problem. This was a NON-Smoker vehicle, so the lighter was never used and had been removed. It was one of those Lighter / Ashtray combo units. Upon close inspection I found the source of the dead short. Since they did not smoke they used the ashtray for other things as in Loose Change. Somehow a DIME had found its way to the bottom of the 12V socket (dead short). Being that a 12V power socket like that is a simple POS/NEG contact point I don't it as being a source of a slow drain. Of coarse an accessory plugged into it could be.

[Ron]

If a diode in the bridge is shorted it will drain the battery and if the regulator is bad it can drain the battery. The only way to know using a bulb in series with the battery is to disconnect the alternator since it is not fused. As bitsyncmaster points out not every load in the car is fused. That is correct but most of the time a drain is going to be on a fused load. We all know the door lock module has a significant standby drain. What I presume the original poster is looking for is something much larger and out-of-the-ordinary. Like a short in the cigarette lighter, door courtesy lights that don't go off, a burglar alarm, etc. My tip is a short-cut to find any large drain quickly with a minimum of test equipment.
David Teitelbaum

David,
You are one of the hardest people for me to follow on this forum. In all seriousness, please tell me:

As I assume you knew to begin with, not every thing in the car is fused. I happen to have a list saved off of the ones that are hot at all times:
*dip beam relay
*luggage compartment lamp
*glove compartment lamp
*main lighting switch
*fan speed thermal trip
*door lock thermal trip
*cooling fan relay
(and devices behind some of these)

You must know he is not as familiar with this as a lot of us are, so why would you single out the the alternator, especially when he didn't report a charging problem? And why while mentioning it v/s pulling fuses, which is really no different than 'disconnecting' something down the line?
FWIW, I'm sorry if that was your point, but it seems like an odd way to get what he need(ed) to me anyway.

And on the other hand-
You call a point moot, then immediately elaborate on it giving examples and causes???

Me=> :smashfreak:

========

RE: One diode in rectifier able to draining the battery.
If so equipped, one diode in the diode-trio (not part of the rectifier) can short out and the light can glow and the battery will be drained. I do not see how this can be so with the bridge rectifier.
The alternator will not put out correctly, of coarse, but I believe it take at least two diodes to drain the battery and you need one each, negative and positive, at that.
Please show me how that is not the case:
Below is a schematic of an 3 phase alternator, a stock D Motorola. Assuming the Green Diode is shorted, show me the path (using "conventional flow", IE Positive to Negative) the short takes.

8197

[kings1527]

I have found my leak! It was, in fact, the remote functionality system from DMCNW that I installed. Putting the black prong in the 10A and red in the COM port on the DMM, I was able to replicate the readings I saw on my trusty ol' analog meter. After disconnecting the remote system, I saw a familiar reading of 0.011 A (11 mA). Yay! Clearly, I've mis-installed the remote system, so I'll be spending a weekend or two reinstalling and organizing the rat's nest of wires that currently resides there.

Thanks to everyone for their advice, patience, and support in helping me figure out why my battery was draining so quickly.

Did you ever find out what exactly went wrong with your DMCNW remote system? I think I have the same type of drain happening with mine and I've gone over the install way too many times and found nothing that I've done wrong with the install.