Dying Battery or Phantom Drain

[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

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

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:

[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...