Search



Go Back   Third Generation F-Body Message Boards > Tech Boards > Electronics
Register Forgot Password?

Electronics Need help wiring something up? Thinking of adding an electrical component to your car? Need help troubleshooting that wiring glitch?

Welcome to ThirdGen.org!
Welcome to ThirdGen.org.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join the ThirdGen.org community today!


Reply
 
Thread Tools Search this Thread
Old 08-15-2012, 09:24 AM   #1
Moderator
 
Abubaca's Avatar
 
Join Date: Feb 2001
Location: JAMESTOWN, NC
Posts: 4,751
Car: 1989 Iroc
Engine: L98
Transmission: T5
Axle/Gears: 3.27

Classifieds Rating: (0)

Multimeter - Properly measuring Milliamps???

OK, I've been fighting a drain/Charging/alternator issue, and I'm trying to properly remove variables. I suspect the battery, but the MASTER mechanics (lol) at Autozone say it's good. ...anyhow, the problem itself is for another thread, but this is simply to be sure I'm reading my multimeter properly.

OK.

I'm looking to see if I have a drain on the system with everything OFF. I disconnected the negative cable, and (obviously) putting the multimeter in the line to read how many amps/milliamps I'm drawing. I've read for newer cars, you don't want to see over 50 Milliamps, but I suspect it would be less for our cars.

I first connected the positive lead to the 10A terminal and set the multimeter to the 10A scale. No reading whatsoever. 0.00 I expected this. Then I moved the lead back to the 200mA "max" terminal, and set the dial to 200m, and I read 4.3 ....then moved the dial to 20m, and read 4.32 Now I'm not real good with electronic circuits, but this all appears to make sense, and at the very least, it appears the multimeter is reading properly. Stop me if you disagree.

.....so here's the million dollar question: Is that 4.32 MILLIAMPS????? Logic would suggest that it IS in fact only 4.32 Milliamps. It's not 43.2 Millamps? Not 432.00 Millamps?

The reason I ask is because I guess I was expecting to see a number OVER 50 milliamps. When I saw 4.32 I thought maybe I was reading it wrong. I hope I'm right. I hope there is NOT a draw that I have to chase down. 4.32 milliamps would be just fine with me.
__________________
1989 Iroc
Abubaca is offline vBGarage Page   Reply With Quote
Old 08-15-2012, 09:26 AM   #2
Moderator
 
Abubaca's Avatar
 
Join Date: Feb 2001
Location: JAMESTOWN, NC
Posts: 4,751
Car: 1989 Iroc
Engine: L98
Transmission: T5
Axle/Gears: 3.27

Classifieds Rating: (0)

Re: Multimeter - Properly measuring Milliamps???

Just so we don't go off on a tangent here, I have two alternators, both charge just fine, both check out fine, and one is new so I don't see that being the problem. AND....when I tested amp draw on the battery, it was freshly recharged. This thread is intended to clarify that I am in fact reading the multimeter properly, and can focus my attention elsewhere.
Abubaca is offline vBGarage Page   Reply With Quote
Old 08-15-2012, 09:38 AM   #3
Supreme Member
 
red rock's Avatar
 
Join Date: Sep 2009
Location: WISC.
Posts: 1,008
Car: 1987 iroc
Engine: 5.7 TPI ported, 52mmTB
Transmission: 700R4 w/transgo 2-3
Axle/Gears: 3.27/3.70 borg warner 9 bolt

Classifieds Rating: (2)
Re: Multimeter - Properly measuring Milliamps???

If your using a digital meter, you should be at 4.32 mA no matter what your max setting is.
red rock is offline vBGarage Page   Reply With Quote
Old 08-15-2012, 10:05 AM   #4
Moderator
 
Abubaca's Avatar
 
Join Date: Feb 2001
Location: JAMESTOWN, NC
Posts: 4,751
Car: 1989 Iroc
Engine: L98
Transmission: T5
Axle/Gears: 3.27

Classifieds Rating: (0)

Re: Multimeter - Properly measuring Milliamps???

Exactly what I was thinking. So if newer cars can potentially (and safely) draw up to 50 Milliamps, and my old 89 is reading only 4.32 milliamps, then I can probably cross a short off my list. I really suspect the battery. It's been beaten on over the years, but when they said it tested good, it threw me off. I may just swap batteries with Trailblazer and see what happens, just to be sure.

Thanks,
Chris
Abubaca is offline vBGarage Page   Reply With Quote
Old 08-15-2012, 10:24 AM   #5
Moderator
 
Abubaca's Avatar
 
Join Date: Feb 2001
Location: JAMESTOWN, NC
Posts: 4,751
Car: 1989 Iroc
Engine: L98
Transmission: T5
Axle/Gears: 3.27

Classifieds Rating: (0)

Re: Multimeter - Properly measuring Milliamps???

OK, see....this is what's throwing me off. I just watched this video.


He also states you shouldn't see more than 50 milliamps, BUT.....when he puts the meter on the battery, it's reading only 3.6 and he says it's way too high, suggesting a drain. ....which of course suggests that it's actually 360 mA, not 3.6 mA.

....so back to my reading of 4.32 ....is that 4.32 ma, or 432.00 ma? I can't seem to get a clear answer anywhere. I have a reading of 4.32 somethings. 4.32 pounds of spaghetti? 4.32 gallons of water? 4.32 amps? Milliamps? The difference is HUGE, BUT.......no one knows what unit of measure that 4.32 is!

Last edited by Abubaca; 08-15-2012 at 10:39 AM.
Abubaca is offline vBGarage Page   Reply With Quote
Old 08-15-2012, 10:42 AM   #6
Supreme Member
 
Join Date: Jun 2005
Location: Sydney, Australia
Posts: 1,371
Car: '86 TA
Engine: '74 350
Transmission: 700r4
Axle/Gears: 2.77

Classifieds Rating: (0)
Re: Multimeter - Properly measuring Milliamps???

Easy - it's 4.32 milliamps. If it was 432 milliamps, the meter on the 200mA or 20mA ranges would read Overload. Also the 10A range would read 0.4.

Not enough to flatten your battery in any meaningful time period.
TreeFiddy is offline vBGarage Page   Reply With Quote
Old 08-15-2012, 10:52 AM   #7
Moderator
 
Abubaca's Avatar
 
Join Date: Feb 2001
Location: JAMESTOWN, NC
Posts: 4,751
Car: 1989 Iroc
Engine: L98
Transmission: T5
Axle/Gears: 3.27

Classifieds Rating: (0)

Re: Multimeter - Properly measuring Milliamps???

yeah, that's what I thought, but that video threw me off. Maybe that guy had something set a certain way that I missed.

Thanks.
Abubaca is offline vBGarage Page   Reply With Quote
Old 08-15-2012, 11:49 AM   #8
Supreme Member
 
BigBadLou's Avatar
 
Join Date: Jul 2004
Posts: 2,974
Car: '91 Z28 convertible
Engine: TPI
Transmission: T5
Axle/Gears: 3.27 posi disc

Classifieds Rating: (3)

Re: Multimeter - Properly measuring Milliamps???

The guy on Youtube set his multi-meter to the 20 Amp scale. That means that the multi-meter will be reporting any numbers in Amps. His video shows approx 3.5 so that means he's reading 3.5 amps.

If you set your multi-meter to 200 mA, it means that any readings you will be getting are in milli-amps and the maximum it can display is 200. So a reading of 4.32 will ALWAYS mean 4.32 mA. When you set a multi-meter to a certain setting, you do not have to recalculate the result. Milli-amps mean milli-amps, amps mean amps. It is simple and clear. If I found a multi-meter that would make me recalculate every result to some strange scale, I would give it away.

So now to your result, 4.32 mA is expected draw on the battery and will not drain it overnight. For that, you would need to see a few amps to drain the battery.
Simple math here: if your battery is rated at e.g. 40 Ah, that means that it can supply X amps over Y hours. It could be 4 amps over 10 hours, 10 amps over 4 hours or even 1 amp over 40 hours. So from the Youtube video, a 3.5 amp draw would definitely kill the battery overnight.

One more clarification: you want to use the word "draw" or "drain" instead of "short". Short implies a short circuit of power to ground (without any device or load in the path) and usually has damaging consequences and kills power fast and can cause fire. Drain or draw is usually small and happens while some devices are drawing and using power.

Sorry, I didn't mean to type so much, I just wanted to clarify.
__________________
'91 Z28 convertible w/305TPI WC T5 (no more auto)
"Nothing screams more of poor craftsmanship than wrinkles in your duct tape!"
BigBadLou is offline vBGarage Page   Reply With Quote
Old 08-15-2012, 12:44 PM   #9
Moderator
 
Abubaca's Avatar
 
Join Date: Feb 2001
Location: JAMESTOWN, NC
Posts: 4,751
Car: 1989 Iroc
Engine: L98
Transmission: T5
Axle/Gears: 3.27

Classifieds Rating: (0)

Re: Multimeter - Properly measuring Milliamps???

Type all you want! ....I appreciate the info. I admit that my electrical knowledge is the bare minimum of what I need to get by!!!! Any knowledge helps!!!!!!!!

Thanks
Abubaca is offline vBGarage Page   Reply With Quote
Old 08-15-2012, 05:10 PM   #10
Supreme Member
 
red rock's Avatar
 
Join Date: Sep 2009
Location: WISC.
Posts: 1,008
Car: 1987 iroc
Engine: 5.7 TPI ported, 52mmTB
Transmission: 700R4 w/transgo 2-3
Axle/Gears: 3.27/3.70 borg warner 9 bolt

Classifieds Rating: (2)
Re: Multimeter - Properly measuring Milliamps???

Hi Chris, The fellow in the video had his meter set to the amp scale, not mA. He was reading 3 amps, which is a draw. I think your getting the two amps mixed up possibly? This may help; http://www.convertunits.com/from/milliamps/to/amps 1000 milliamps = 1 amp
red rock is offline vBGarage Page   Reply With Quote
Old 08-15-2012, 09:20 PM   #11
Moderator
 
Abubaca's Avatar
 
Join Date: Feb 2001
Location: JAMESTOWN, NC
Posts: 4,751
Car: 1989 Iroc
Engine: L98
Transmission: T5
Axle/Gears: 3.27

Classifieds Rating: (0)

Re: Multimeter - Properly measuring Milliamps???

Yep. That's exactly what I did. Everything checks out. No drain.
Abubaca is offline vBGarage Page   Reply With Quote
Old 08-15-2012, 09:20 PM
ThirdGen
1992 Camaro




Paid Advertisement


Reply

Go Back   Third Generation F-Body Message Boards > Tech Boards > Electronics

Tags
000, 200, 200m, 50, amps, car, dmm, draw, is008, measure, miliamps, milliamp, milliamps, multimeter, showing
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 


1982 Camaro '82 || 1983 Camaro '83 || 1984 Camaro '84 || 1985 Camaro '85 || 1986 Camaro '86 || 1987 Camaro '87 || 1988 Camaro '88 || 1989 Camaro '89 || 1990 Camaro '90 || 1991 Camaro '91 || 1992 Camaro '92


All times are GMT -5. The time now is 12:27 PM.


Powered by vBulletin® Version 3.7.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
All content copyright 1997 - 2014 ThirdGen.org. All rights reserved. No part of this website may be reproduced without the expressed, documented, and written consent of ThirdGen.org's Administrators.

Emails & Contact Details