Funky electrical ground - need help

[ZStig]

How do I figure out where I have the electrical short? My battery keeps draining, and this is how my electrical charger is behaving. I tried to connect it directly to the battery in the back, and its doing the same thing

[Geauxkart]

Do you have a multi meter? If so, turn the car comp[letely off and see if there is still current being pulled by the car (Disconnect positive and put meter in between, in series with the terminal and the wire)

If no current, you probably have a bad battery. There are probably some internal shorts causing the charger to react as shown.

Good luck!

[ZStig]

I have a multi meter. I'll put it between the disconnected positive red terminal wire, and the battery's positive terminal. thanks for the tip.

[ZStig]

ok, so the ground cable was connected to the battery.

Starting voltage was 12.60 at rest with everything connected.

the positive cable disconnected from the battery, with a multi-meter connecting the battery to the car's positive cable. Voltage reading started at 11.50, and kept creeping up by .01volts every second. I didn't hold it there for more than 20 seconds. Does this indicate anything?

[Geauxkart]

You need to measure current (not volts) - should be milli amps (mA) - and the meter positive lead probably needs to be moved to the appropriate receptacle on the meter.

No, the creeping voltage doesn't indicate much.

Try again with the Amp reading and let us know. We are looking for how much electricity is flowing at rest. Should be darn close to 0. If it's not, you have something in the car that is leaking voltage / killing the battery.

[ZStig]

Ah, so I'm basically creating an intermediate path for the electricity to travel, to see if any current is moving out while the car is at rest... OK, I'll see if my electrical equipment is sufficient

[ZStig]

Am I using the right setting? If so, I saw 25 on the display when bridging the positive battery cable

Annoyingly, the car was cranking hard and not starting today after a short drive. Eventually started. This is with a new alternator and crank position sensor

edit: oddly enough, I think the DVD player starting up draws that current, and then it goes away. Sometime I press things together and I see 25, then release and test again and see 0

[XMetal]

You're not using the Amp meter correctly. You need to turn the dial to "10A" near your red connector, then redo your measurement. Without knowing how much current is being drawn, I would use that first.

[pungo]

Originally Posted by ZStig

edit: oddly enough, I think the DVD player starting up draws that current, and then it goes away. Sometime I press things together and I see 25, then release and test again and see 0

What do you mean, by "Sometime I press things together and I see 25, then release and test again and see 0" ?
Try switching the DVM to the 10A mode and connect it in line between the positive battery terminal post and the positive battery wire terminal connector. You should have a reading like 0.00-0.01, open a door and you should see the value increase a little. Plug in the cigarette lighter and it should jump to maybe 5.00 or so. You probably will need a extra set of hands.

Did you try to connect your battery charger to the battery with positive battery terminal wire disconnected from the car?

[StickMon]

Like they said, to read up to 10A you have the leads in the right holes.
Set the dial to the 10A setting, connect the red lead to the battery and the black lead to the battery cable(s). The display will be in Amps.

If you get a reading less than 0.2 and want more resolution, move the red lead to the hole marked VΩmA and set the dial to the 200m position under DCA.
The display will be in milliAmps.

The next question is what's a "normal" standby current draw.
I really have no idea. I think you would have to compare it with another car.
As you noticed, the navi boots as soon as you open the door.
Once it finishes reading the DVD, the current draw will decrease, but it's still running, waiting for you to turn the car on. Eventually it will give up and go back to sleep.

Obviously the receiver for the key fob and some brain functions of the central locking module must stay awake.
And who knows what the other modules get up to when the car's off.

[GuidoK]

Originally Posted by StickMon

If you get a reading less than 0.2 and want more resolution, move the red lead to the hole marked VΩmA and set the dial to the 200m position under DCA.
The display will be in milliAmps.

That will blow the fuse. When disconnecting and reconnecting the multimeter in the path of current flow the DME will reboot itself (including al the subsystems) and that will draw more than 200mAh for sure. Always use the 10/20A DC current mode.

Typical draw of current in standby should be about or less than 50mA and certainly less than say 100 or 200mA. But that's not so easy to measure. The time it takes for a car to get itself in standby can take up to 15 min. and for that all doors should be closed. So you have to run the leads between the seals of the bootlid if that's possible.
But if you have a problem, you should probaly measure about (or more than) 200mA in restmode. 200mA still takes about 7 days to effectively empty a standard fully charged battery ( the 70Ah that it says on the battery is in practice not the real useable capacity the battery holds, in reality that's more like half that)

That the batterycharger acts that way is normal: the battery is fully charged and the charger checks occasionally how much amps the battery will charge by a certain voltage (thus checking it's internal resistance)

[StickMon]

Agreed. Good catch.
So someone does know what the modules get up to when the car's off.

[GuidoK]

Rule of thumb is that 50mA draws a moderately aged car starter battery empty for use in about 30 day's (then you've drawn about 35-40Ah).
Maybe a high quality AGM battery will give a bit more % of it's advertised capacity, but none of the car starter batteries are deep cycle batteries (these batteries will give the advertised capacity)

When testing a car battery with a multimeter be sure to use a multimeter with good leads. Thin leads will give a lot of loss when drawing a lot of current and can even melt when the car is booting up all of it's systems. Searching for parasitic currents can be a real pain.

[Geauxkart]

Per Pungo:
Did you try to connect your battery charger to the battery with positive battery terminal wire disconnected from the car?

Try this.

[Beedub]

guido..... you can be an ass sometimes but...... mans got knowledge... respect.

[ZStig]

Originally Posted by Geauxkart

Per Pungo:
Did you try to connect your battery charger to the battery with positive battery terminal wire disconnected from the car?

Try this.

have not

I decided to give up and give it to a german repair shop to see what they find. Their initial though was that my 11lbs battery doesn't have enough cranking amps, but I had trouble getting it started WHILE connected to another running car with jumper cables. Cranked hard, but no start

so who the hell knows. maybe I bought a faulty new crank sensor

[seank]

Originally Posted by Beedub

guido..... you can be an ass sometimes but...... mans got knowledge... respect.

WHS.

[Petrosexual]

I always heard it was safer to test the draw on the Negative side of the battery ( disconnect neg. wire and put meter in series) - -that way if you ground it out accidentailly, you are jut shorting ground to ground, not positive to ground (?)

there are quite a few good youtube videos on tracking down a key-off battery drain as well/

[StickMon]

^ That's true.
For anything you're doing with the battery, it's safest to work with the negative side.

[ZStig]

I was told that my 320 CCA, 16lbs battery didn't have enough cranking power and was causing issues. Replaced with a 34lbs 650 CCA battery. Worked fine for a few days

Then I had issues with the car stalling after a long drive with some heat soak, and not re-starting. Clicks but no crank. Diagnosed with a bad starter, and they said it was probably killing my small battery. Installed new starter.

So car starts fine now, but I had a hard code for low fuel pressure and fuel pump when I brought it in for the starter job. I have a 3 month old Aeromotive 340 pump in the tank, with a new OEM fuel pressure regulator/filter. I'm really upset, and hope that by some miracle the fuel issues were caused by some sort of shorting issues in my starter.

I really don't want to replace the fuel pump if I don't have to. I'm hoping the code doesn't come back. Thankfully my fuel pump is under warranty, but this might be the last straw for me if I have to replace it

[gmd2003]

Originally Posted by ZStig

I was told that my 320 CCA, 16lbs battery didn't have enough cranking power and was causing issues. Replaced with a 34lbs 650 CCA battery. Worked fine for a few days

Then I had issues with the car stalling after a long drive with some heat soak, and not re-starting. Clicks but no crank. Diagnosed with a bad starter, and they said it was probably killing my small battery. Installed new starter.

So car starts fine now, but I had a hard code for low fuel pressure and fuel pump when I brought it in for the starter job. I have a 3 month old Aeromotive 340 pump in the tank, with a new OEM fuel pressure regulator/filter. I'm really upset, and hope that by some miracle the fuel issues were caused by some sort of shorting issues in my starter.

I really don't want to replace the fuel pump if I don't have to. I'm hoping the code doesn't come back. Thankfully my fuel pump is under warranty, but this might be the last straw for me if I have to replace it

The Aeromotive takes a lot of power , when you were low on juice that's likely when it was unable to operate properly .
George

[ZStig]

you didn't have to re-program your ecu for the extra fuel flow?