Date: Sun, 11 Nov 2007 18:14:59 -0500
Reply-To: Mike S <mikes@FLATSURFACE.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Mike S <mikes@FLATSURFACE.COM>
Subject: Re: Electrical Glitch causiing a dead Aux battery...more..
In-Reply-To: <001001c824b2$2a1d48c0$68b2d8d1@laptop>
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At 05:28 PM 11/11/2007, Don Hanson wrote...
> Many people gave me instructions on using my multimeter to trouble
> shoot
>stuff like current drain, etc..Well, I never could get any real
>readings..I
>could get DC volts to tell me the battery was down, AC amps to tell me
>my
>charger was on, all that kinda stuff, but no current readings no
>matter how
>I hooked up or turned dials, etc..
AC Amps is a current reading, so something is wrong with your
statement. However, nothing in our cars uses AC amps (Westy AC outlet
excepted). You may get a reading for DC amps when the meter is set to
AC amps, but it won't be accurate.
>battery and a blown fuse..which I fixed..That one gave me a good
>current
>reading (I think, it has all kinds of strange writing and numbers on
>the
>face, but at least the needle moved) Then, I tried my 'good' almost
>new
>Radio Shack idiot proof digital read-out one on the very same
>circuit...It
>didn't read anything on the DC amps scale..Nuttin! never has
Probably another blown fuse. That will happen if you try to measure
current on the wrong range (e.g. set to mA, and measuring Amps, or
trying to measure more Amps than the meter was designed to handle.
Note that when hooked in series (in-line), which is how you measure
current, you will be able to measure a voltage if something is trying
to draw power.
>properly..I guess.. Why the hell does a multimeter even have a fuse,
>any
>how?
To keep the smoke in if it's connected wrong.
Here's a tutorial on using multimeters -
http://www.doctronics.co.uk/meter.htm
In general, when trying to find current drains, you disconnect the wire
providing power to the suspect component, connect the probes to use the
meter's highest current (A) range, then connect it in line to get a
measurement. If you don't get a measurement, you use progressively
lower current ranges until you do get a measurement. Don't try to
measure a current which is too large (e.g. a starter draws way more
current than your meter will measure, you'll blow the fuse if you try
to measure the starter current). 1 Amp (A) = 1000 milliAmps (mA)
All meters have a ground terminal, to which you connect the black
probe. Most have 3 other terminals (maybe more for special functions,
sometimes 2 if they combine V and mA), one for Volts, one for high
range current (10-20 Amps), and one for lower range current (maybe 1 mA
- 500 mA). You plug the red probe into the correct terminal for what
your're trying to measure.
ALWAYS connect the probes to the meter for what you want to measure and
set the dial/buttons for the range FIRST, then connect to the circuit
you want to test. Otherwise, you're likely to blow the fuse.
