# Meter?



## dommm (Oct 27, 2014)

Hi

I am planning to do a parasitic draw test on my car. I have learned from a youtube video that I need to remove the negative/back cable from the car battery & make sure everything possible is turned off in my car before starting the test. I then need to put the red prob from the meter on the removed negative/black cable clamp & put the black prob from the meter on the negative/black battery post. Once all of the above is done, if there is a draw it should show on the meter (over .1 is bad). I then start pulling fuses one by one until the meter number drops to next to zero (the youtuber says under .05). Once I find the offending fuse I can then narrow down the problem to whatever that fuse controls.

My first question is: am I understanding the youtube video correctly?

My second question is: What do I set the dial to on my meter (pic included) & what red port do I use when inserting the red probe plug?

Thanks for any help.

PS: I have no electrical knowledge so please keep it simple if possible lol.


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## ukrkoz (Dec 31, 2010)

_To measure the car-off current draw, *you'll need a multimeter capable of reading current, preferably one with a 10- or 20-amp capacity, but a 200 milliamp lower scale. *Start with a fully charged battery. Either make sure the doors are closed or wedge the door switch shut. Turning off the dome light isn't good enough—on many cars, an open door will activate several circuits. _
_Unplug any power-draining cables from the lighter socket, such as a cellphone charger or GPS. Even if the device itself is unplugged from the charger, the plug may still consume a few milliamps of current. Got an ear-bleedin' stereo amp in the trunk? Pull the fuse, because it may be in standby mode rather than completely shut down._
_One caution: If your radio or antitheft system requires you to input a code after the power is interrupted, better hunt it down now. It's likely that you'll need it. Don't let the dealer entice you to bring the car in and pay him to input it. The code should have been included with the owner's manual when you purchased the car._
_Start hunting by putting your ammeter in series with the battery's ground circuit. Disconnect the battery's ground cable and wire the ammeter in series between the battery terminal and the cable. Start with the meter on the highest range, probably *10 or 20 amps*. Warning! Doing something silly, like trying to start the car or turn on the headlights—anything that draws more than the meter's rated capacity—can blow the meter's fuse. _
_*Once you have determined that the current drain you're reading is safe, gradually reduce the meter's scale to the appropriate low range, probably 2 amps or 200 mA. You are now reading the parasitic drain on the battery. Some vehicles will show as little as 10 mA residual drain. *Others, probably high-end cars with lots of high-end gadgets, will draw more. _
_An important note: Some devices, like alarms and automatic-dimming lights, will draw substantial amounts up to 20 minutes after they're deactivated. So if the reading is high, wait a few minutes to see if it changes_.


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## iamrfixit (Jan 30, 2011)

You have to use the DC 10A port, and the COM port. You then set the meter to DC 10A. This is the setup to test amps, which is what you want to do. You will notice at the very bottom it says your amp port is *unfused*. That means if you exceed 10 amps you will probably burn up either the meter or the leads. It has a very low duty cycle too as it can only handle 10 amps for 15 seconds every 15 minutes. If you do accidentally apply a big load you'll fry your meter. When testing like this the full load of the vehicle passes through the meter, so anything you turn on will increase the load through the meter. Something large like if you bumped the starter would exceed the amps by several times and almost surely smoke your meter instantly.

Testing amp draw to find a parasitic draw on a modern vehicle is more difficult because they have lots of modules and relays that can take a few minutes to several hours to fully go into sleep mode. Each time you disconnect the battery, turn on the key, or maybe even open the door you wake many of them up and have to wait for them to shut down into sleep mode again.

You should investigate how to test for voltage drop, that is probably a better way to find a parasitic draw on a modern vehicle. Doing this you just test DC voltage to look for small voltage drops across each fuse. When current flows through a fuse it encounters resistance, any time you have resistance you lose a small amount of voltage. That means measuring a small voltage loss across a fuse would indicate current is flowing through it. 

This is better on modern cars with complex systems because you don't have to disconnect the battery, you can wait for modules to sleep and then check. Remember to disable or bypass the door switch. If you open the door and activate the switch it will likely wake modules up and indicate voltage drops that may not be part of the problem.


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## Guap0_ (Dec 2, 2017)

Why are you doing the test? Is the battery draining over night?


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## dommm (Oct 27, 2014)

Guap0_ said:


> Why are you doing the test? Is the battery draining over night?


The car I am working on is a Lexus es330 2004. My old battery would not hold a charge (took it to Canadian Tire to get tested) so I replaced it with a new one. It is a second car that does not get much driving. I drove it a few times with the new battery with nothing unusual & starting fine. The car then sat for around one month & when I tried to start it, the battery was so dead the door locks did not even work. I have now charged the battery back up & now I'm searching for the cause of the drain. I'm learning all of this from sites like this a youtube videos. I have no mechanic of electrical experience.


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## Guap0_ (Dec 2, 2017)

I used to do that test with a simple 12 Volt test light. It's more complicated these days because there are more things that drain small amounts of power when the car isn't running. The clock is just one example. The dome light is another so make sure that the doors & trunk are closed. If there is a light under the hood, disconnect it. I used to disconnect one terminal on the battery & connect the test light between the cable & the post. If the light lights, something is still draining the juice.


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## Bud9051 (Nov 11, 2015)

Hi dommm, that meter should be giving you some reading if you have it connected correctly. I haven't reviewed the thread but did read you got zero results. Repeat the test with the 10 A connection and open a door (or other small light) to turn the inside light on, that should give you a measurable current. Then turn that light off and if the reading is low enough as per previous instructions move red probe to the right hand red port. 

As for the vehicle setting unused for long periods of time consider a solar trickle charger. I haven't checked in awhile but I know they make them and it should offset any residual draw.

Good luck,
Bud


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## iamrfixit (Jan 30, 2011)

I'd say you might not really have a problem. For a modern vehicle with all the electronics on board, more than a couple weeks is probably just too long between starts. Any time a battery is deprived of charge the plates inside will begin to sulfate, this can severely reduce the capacity and shorten the life of the battery. If you aren't going to drive the vehicle regularly you should start and run it more often so the battery can recharge or install a battery tender to continually maintain the charge. 

This type of charger applies a small float charge to keep the battery fully charged over long periods without use. These chargers come with a small plug you can install on the vehicle making it quick and easy to reconnect the charger when you park. You can route the wire and place the connector through the grill or into the passenger compartment so you don't even have to open the hood.

I began using a tender on my motorcycle battery over the winter months, it made a huge difference in battery life. Removing the battery and charging occasionally was not enough, the battery rarely lasted more than a couple years. Since I began using the tender the battery was still going strong at 7 years. It seemed to crank over a little slow one day and 7 years is on the high end of life expectancy for a battery, so I replaced it as a precaution.


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## dommm (Oct 27, 2014)

So here is my update. 

I finally got a reading on the meter & I'm figuring the reason I was not getting a reading before was because I was not getting good contact with the probe on the black probe & the negative battery post. I used a plastic clamp to hold the black probe tight to the negative battery post & that seems to have done the trick. 

So now for the meter reading. I had the meter dial set to DC10A & the red probe plugged into DC10A. The meter bounced around from .40 up to the .95 range but mostly at the lower end of the above range. The meter only shows for 15 seconds & then it defaults to .0. During that 15 seconds the meter reading never settled, just kept going up & down from the .40 range to an upper end of .95. I could also here the car making strange noises during the test.

So two questions: does the reading make any sense & what was all the noise? Thanks


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## Guap0_ (Dec 2, 2017)

Try the test that I described in post #6. A simple 12 volt test light is all that's needed. I have no idea what all that jumping was.


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## iamrfixit (Jan 30, 2011)

Think you need a better meter if you're going to do this test. Your meter says right on it "15 sec max each 15 min". That seems to mean that amp mode shuts off after 15 seconds and your test seems to confirm it. Found this in an online manual for that meter:

*The DC10A range is not fused. To avoid current hazard and/or damage to the tester, DO NOT try to take measurements on circuits that have more than 10 amps. DO NOT take more than 15 seconds to take the reading. A waiting period of AT LEAST 15 MINUTES is necessary between every 15 second testing period.*

Your cheap meter is useless for this test. It's not capable of handling amp loads being drawn through it for longer than 15 sec, this test is going to require a meter that's able to do that continuously.

Using a test light won't really tell you a lot, other than you have current being drawn. It won't tell you how much. The bulb will be dimmer with a small load or brighter with more load. If you have more than an amp or two being drawn the bulb *will* become a fuse. This method worked for older or very simple electrical systems, vehicles that don't have a continual draw on the battery, but not so much for more complex systems.

I would still charge the battery up fully and let the vehicle sit for a week. If the car will start after a week, you probably don't have a parasitic draw.


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## dommm (Oct 27, 2014)

iamrfixit said:


> Think you need a better meter if you're going to do this test. Your meter says right on it "15 sec max each 15 min". That seems to mean that amp mode shuts off after 15 seconds and your test seems to confirm it. Found this in an online manual for that meter:
> 
> *The DC10A range is not fused. To avoid current hazard and/or damage to the tester, DO NOT try to take measurements on circuits that have more than 10 amps. DO NOT take more than 15 seconds to take the reading. A waiting period of AT LEAST 15 MINUTES is necessary between every 15 second testing period.*
> 
> ...


You make a very good & logical point regarding my meter not being up to the job I am looking to accomplish. Live & learn. Thanks to everyone who tried to help.


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## Brainbucket (Mar 30, 2015)

I test draws with a test light with a normal bulb. Stick it between the negative cable and negative batt post. If the light is flashing, that is a computer waiting to fall asleep. wait a few min and see if it goes out. You might find it getting dimmer as modules fall asleep. Test light should go out after a few min. When you buy a new battery, it isn't charged all the way up so if you install it then let it set, it might just drain down from security systems. I would charge the battery, then test for draw. If you find a draw, start pulling fuses, one at a time and reinserting it as you go. When you pull a fuse and the test light goes out, bingo! Now you have to find out what is on that circuit and start unplugging items until the light goes out.:vs_cool:


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## Guap0_ (Dec 2, 2017)

> Using a test light won't really tell you a lot, other than you have current being drawn. It won't tell you how much.


It's not a complicated as everyone is making it. If the test light shows that juice is being drawn, pull fuses one at a time, until you see where it is. Don't forget to include alarm fuses that might not be in the main box. In fact, I would look at after market installations first.


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## GrayHair (Apr 9, 2015)

If it seems impossible to find, don't forget the actual ignition switch. I chased mine for several weekends. :vs_mad:


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