At least this means that means i do not have to go track down a battery drain

Thanks guys

 

I've been using digital multimeters since they came out, with your meter on the 10A scale 0.03 is 30 milliamps, 0.30 is 300 milliamps or about 1/3 amp. A milli amp is 1/1000th of an amp, so 30 milliamps isn't that much. I've never measured mine so I don't know what is normal, maybe Bill knows. If we can't find anyone who knows I can go hook up my Fluke meter and find out.
Have you measured the voltage on the battery? I posted the other day what the battery voltage should be for various states of charge and temperature. It's on page 42 of this long post:
http://forums.corvetteforum.com/c5-t...n-long-42.html
Maybe you have a bad battery. It shouldn't run down overnight with just a 30 ma pull....
DocOhm

 

I do know a lot of posts on the forum cite 20ma as the magic number, but i can certainly live with 30ma.

My voltage after a week was 12.5 this week. It is taking about two weeks to drain down, it is not an overnight problem. I just felt it was more than average, so I wanted to check it out.

Now that I know i do not have a drain, Ill bring in my battery for a load test. It might just need replacing.

 

Byron didn't show all his work for full credit....

Maybe this will help.....

 

Why would 0.03 be 300mA and not 30mA? I pretty much guarantee that's not right. 0.3 on the meter would be 300mA. I don't recall ever seeing a digital meter that would read 0.03 but mean 0.3...

For the 10A setting you have to use the 10A socket and for the 200mA and lower settings you have to use the 200mA socket.



Based on you doing all those measurements while using the 10A socket the only one that might be reliable is the 10A measurement. However, you get the same number (the 3) as some of the other scales so there seems to be a problem. Check the 10A input fuse in the meter and tell us if it is blown.

I would have expected the 200mA scale to read up to 199.9 in mA. The 20mA scale should read up to 19.99mA.

I'd guess the 0.3 shown when you used the 200mA scale while plugged into the 10A connector was actually 0.3mA since the meter was not connected correctly. Since the meter scales the signal on each setting this also explains why you got 0.03 on the 20mA scale - you went down in range from 0.2 to 0.02 so the meter also shifted the "error" reading of 3 down by a decimal place from 0.3 to 0.03 or 0.03mA.

Finally, the 10A scale is really a 20A scale that has been limited to 10A because the meter can't handle 20A on it's circuit. So, going from the 200mA scale with an error of 0.3mA to 20A with an error 0f 30mA also makes sense. Both shift the decimal place by 100.

So, based on the above, my guess is the meter is never actually showing you the real current.

I'm not sure why the meter showed 0 on the lower ranges but it might be because it switches to a different circuit which is calibrated better and doesn't give an error.

If you want to know for sure then hook it up with the 10A input and 10A setting and do something like turn the running lights (NOT the headlights) on and see if the meter shows the light draw as a higher current.

Peter

 

This has been discussed ad nauseum......and Bill has it well documented in the electrical sticky.....and yes....30mA is a little high for full sleep mode.

 

The only real caveat is to make sure the car is actually in the full "sleep" mode when doing all this. Seems like battery condition would be the determiner of how quickly it would get discharged significantly (unable to crank engine over, etc) with a 30 ma drain.

 

Lucky, I'm not looking any credit. By now it's really been explained, so I'm now!

 

explained and understood are two different things....

 

I performed this test a while back and posted a 40 milliamp draw on my wife's C5. I suspected the Red top was already dying due to the 1+ year of the Garmin sapping it - I was right. I had to replace the Red top when I did the audio install in her car in December. Advanced Auto gave me a new Red Top at no charge since it was still within it's 3-year full replacement warranty period. It's had no problems since even after sitting 2 weeks at a time without a charger. Here's the thread I posted.

http://forums.corvetteforum.com/c5-g...raw-issue.html

 

Find your meter directions. Most meters are not designed to measure current without putting it in series with the circuit, so you have open the ciruit up and install the meter. I use a clamp meter when measurring current. They are not intrusive to the circuit.

 

He DID hook it up correctly.

 

What is the stated error of your meter? I highly doubt that the least significant digit of your meter will be accurate within 1 count - in your case don't believe that reading 0.04A actually means the current is between 0.035A and 0.045A. It could easily be out by 20mA or 30mA.

Peter

 

My meter specs from the OM:

DC current 3, 30, 300 mA and 10A max
+ 1.5% of reading and
+ 0.2% of full scale,
+ 1 in last digit

So, the .22A (+ 3.3 mA error) draw I measured with my Garmin vs. the 40 mA (+ 0.6 mA error) without is a believable result and certainly accurate enough for this exercise.

 

Well, you can't just use that 1.5% error and conveniently ignore the other parts of the meter specs.

Here is how I calculate the accuracy of the 0.22A reading;

error = 0.22 x 1.5% + 10A x 0.2% + 0.01 = 0.0333A or 33.3mA, not the 3.3mA you believe it is.

Similarily, the error for the 0.04A reading would be;

error = 0.04 x 1.5% + 10A x 0.2% + 0.01 = 0.0306A or 30.6mA

Seems to be the kind of error exactly like I posted there could be.

Like you posted, it's good enough to know that removing the Garmin fixed the problem but you can't read 0.04A on a scale that only reads down to 0.01A and say I have between 0.035A and 0.045A. In your case, the 0.04 on the meter could mean 9.4mA to 70.6mA.

My point is that if you need to confirm the car is drawing less than 30mA in sleep mode then you must use a more accurate range than the 10A scale on your meter.

Look back at the OP numbers and my first post in this thread. It sure apears to me that the "3" he reads on the different scales is nothing more than a meter error. The same 3 error keeps being shifted around depending on where the meter puts the decimal place.

Peter