checking electrical drainage

I have a 01 VW cabrio and recently the battery has become stone dead a few times. After I recharged it I disconnected the Neg. and put a test light inline between the post and the neg cable and the light lights up. Would the security led and clock timer use enough juice to light up the testlight? I have an electrical test meter, can I use it to test how many amps are draining, if so what is procedure and what is a normal load while ther car is turned off? The battery is original and might just need replacing but would like to know for sure. Thanks

Reply to
mark
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One way if your meter is sensitive enough is to set the meter on the lowest voltage range (about one volt FS is recommended). Now place the + lead directly on the battery post, and the negative lead on the connector. Any voltage shows a drain. However, this alone will not show how MUCH, because the voltage read shows the voltage across the connection resistance which is variable. However, as long as the reading is not too high, this shows it is okay to place the meter in SERIES with the connection and measure the current.

Unfasten the connector, and clip the positive lead to the battery terminal, the negative lead on the connector, and the meter set to the CURRENT position.

Reply to
Don Stauffer in Minnesota

That is too much drain. Start pulling fuses and see which fuse is responsible for the drain.

--scott

Reply to
Scott Dorsey

You can use your VOM in many cases to trace the drain, as was described by another poster. Drain, once all the systems have gone dormant, should be in the range of 30 milliamperes up to perhaps 60-100 milliamperes.

On some cars, systems can be active which will give you a lot more current draw than this for a relatively short period of time. My Reatta, for example, may draw

2-4 AMPERES briefly after shutting the car off, or after taking off a terminal and inserting the VOM in series with the battery and cable. So start with a high range on your VOM if you are going to do this, and work downward. You can blow the fuse in some VOMs if you run them out of range.

If the current is significantly over the 100 ma level or so, wait a while and see if it will drop out.

Then, if you are sure you have excessive drain, do as Scott has mentioned...Start pulling fuses, and eliminating circuits systematically.

Reply to
HLS

I just checked again with meter. 12.5 volts between + and -terminals with neg. disconnected and when I connect the meter set to 10 amps inline between neg post and neg cable a few things activate and then the meter settles down to .75 on the 10 amp scale. How does this sound?

Reply to
mark

Sounds like 750 milli amps. WAY too much.

Reply to
aarcuda69062

0.75 amps means that if you have a battery with 50 amp hour capacity that it will take 67 hours to run a fully-charged battery down flat.

This means after two days or so, the battery will be down to the point where the car will no longer start and by three days it will be severely damaged.

This is way too much draw.

--scott

Reply to
Scott Dorsey

I checked it again but this time I left it connected, after about 2 minutes it dropped from .75 down to .03 and remained there until I disconnected it after 15 minutes. Does this sound more normal?

Reply to
mark

Yes. Some things need time to figure out they are off or they use a little more to turn on before they go into 'sleep' mode.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 'New' frame in the works for '08. Some Canadian Bush Trip and Build Photos:
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Reply to
Mike Romain

You sure got a lot of use out of that old battery.Dont you think it's about time for a new one? I always replace the battey in my vehicle after about five years.I dont know what the average lifetime for a battery is, but I dont want to be stranded somewhere with a dead battery.A few months ago I went to the Sears store for a new battery, Sears didn't have what I wanted.I went to a nearby Autozone store and I bought a new battery. cuhulin

Reply to
cuhulin

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