How to check if there is draw on battery? Options

[nitemare]

Hi,

I purchased a Craftsman Digital Multimeter with AC Voltage Detector:
http://www.sears.com/sr/javasr/product.do?...0383&AFFL=Y

Now, I want to test my car battery to see if there is a draw when its off.

I watched someone else do it.

I believe he took neg lead off batter. Connected one end of multimeter to battery neg post - then clipped on other end to any part of car. Light was on - which indicated a draw. The light was always on even after pulling fuses out.

Is this the correct way to test? Please see the multilmeter I purchased and let me know how you would test for a battery draw.

Thanks!!

[nitemare]

After further research - it seems I need to:

1) Turn off everything
2) Set multimeter to amperage
3) Disconnect negative lead cable
4) Connect one ammeter lead to the negative battery post
5) Connect the other ammeter lead to the negative lead cable

Normal current drain on most vehicles should be about 25 milliamps or less

Let me know exactly which settings and and how I connect leads to this meter. I see 3 different inputs on this meter (10A/COM/V)
Im guessing I need to connect leads to 2 of those ports- Would it be 10A and COM or the COM and V port?
Set Dial to Adc, 10A?

This post has been edited by nitemare: Mar 4, 2007 - 11:48 AM

[eliaz]

The multimeter is fused, so the 10A means that it has a 10A fuse. I guess you have a 200 mA fuse where you have the VΩmA port. So, connect the red lead to the 10A port first to check if the draw is higher than 200mA, if not, you can connect the red lead to the 200 mA port. The black lead goes to port COM. Set the dial on the multimeter to ADC 10A first. You can clamp the black lead to the battery negative post, and the red one to the negative lead cable. Then start pulling fuses and you can see wich circuit that has the draw. Hope this helps

[nitemare]

Thanks so much! Great directions. I will test out.

I have a strong feeling my 2 amps are always drawing power- even when car is turned off. Are amps supposed to be wired in some 'special' way that they stop drawing from battery when car is off? Is there any way to tell if they are wired that way currently?

[eliaz]

Your amps should have a remote wire connected to +12V on your cd player/head unit. The amps will then power up when you turn your key one "step" in the ignition.

This post has been edited by eliaz: Mar 4, 2007 - 3:39 PM

[Manny]

Yea... your amps should be wired to the system remote wire on the head unit.
The wire should either be blue or blue with a white stripe.

[nitemare]

I do have a blue wire coming out of the +12V port of ONE of my amps. The 2nd amp does not have a blue wire.

So, maybe thats the problem.

So - Do I need BOTH amps have a blue wire connected to _12V port- both going to the same +12V on back of head unit?
Will the amp work fine without this blue wire? - I suspect maybe when I pulled out 1 of the amps - I didnt connect this blue wire to the back again.

[nitemare]

What is the expected parasitic draw (in mA) for a 95 Celica GT?

Is it about 20-25?

Say if the expected draw is supposed to be 25ma

When Im on the 10A scale - should the readings be displaying decimals or would it likely be just a whole number like 25

http://s7.sears.com/is/image/Sears/0348214...=1&fmt=jpeg

This post has been edited by nitemare: Mar 5, 2007 - 11:26 AM

[nitemare]

Well, after months of not driving my celica - I tried to start it and it was completely DEAD!

Jumped it, few weeks later, dead again!

So - I have to bring it to a electrical shop. My usual private mechanic can give a rats *ss to t-shoot it.

I pulled the fuses out for both amps and car alarm - still died!

[Hanyo]

once a battery has been drained all the way to zero volts. Then the battery can/will be damage. It will be unable to holds electricity anymore.

So in your case, you may beed a new battery.

If that doesnt help, you either still have a draw on the battery when the car is off, or your alternater is dead.

[nitemare]

Battery is brand new. Probably less than 1 month before car began dying.
Alternator has been replaced 3x already. Alternators are all rebuilds though from R&S strauss.
I wonder if the alternators are no good.

Well, both Ill have him see if there is a draw while car is on. My private mechanic said no draw on battery while car is on.

Another note to mention is when they installed the alternator, the harness attached had to be re-wired or reset to make it connect. I wonder if that wiring job is faulty.

[alltracman78]

All cars have some parasitic draw.
If you leave them sitting for months, there are very few batterys that won't be dead, or dead enough to not start your car anyways.

Once your battery is dead it sometimes takes a good bit of charging to fully restore it so it can sit again for a bit.
First make sure your battery is good.

In your car normally the clock, radio, and ECU will draw power.
The amps shouldn't be drawing any power at all, only the radio.

A milliamp is .001 amps.
25 milliamps is .025 amps.

You want the red lead on your multimeter at 10A.
There should be a common ground for the black lead.
It should be black.

Put one lead on the battery post and the other on the battery cable.
If you're good, you can touch each first, then slide the terminal off the post. This will keep your memory intact.

It should be less than .050A.
Your car is actually a bit less, but that is fine.

If it's more, start removing fuses one at a time.
If the draw doesn't change, put it back and go to the next one.
You have to give the reading a minute to stabilize between fuses.

If it is too high, removing one [or more] of the fuses WILL lower it.
If you can't find one that will, you missed at least one.
The ONLY thing that isn't fused in your car is the starter itself.
Unless you wired something in [like your amps] with no fuse.
If that's the case, try disconnecting them as well.
It actually has a fusible link built into the cable, but you can't remove it.

[nitemare]

I had bought a meter, hooked it up - tested it. There is a draw on the battery. Removed the 3 fuses (2 amps and Alarm) - still draw. I am dropping it off to a Starter/Alternator specialitst. For $75 he will do all the stuff you just said to find the draw. Battery is brand new. And yes, I was starting car atleast 2x a week for a few minutes. But this has been going on for years- even when I drove the car alot daily...
Thanks for your advise!

[Jaws4God]

well I checked mine today..

it was drawing .2 amps when off

I started pulling fuses and wires and found that:

Pull Main Fuse - drops .1 amps
Pull my UnderCar LED wire - drops .05 amps
Pull Capacitor - drops .05 amps..

So I hooked up a switch to the Undercar, and disconnected the cap for now..
but I still don't know what all is drawing the .1 on the main fuse circuit

[stephen_lee]

To make you all feel better my draw is .7 amps! but its mostly my CarPC.
plus i have two optima batteries so i have no worries of a dead battery