Measuring Battery Drain with a DMM

phillip · May 12, 2004, 06:30:26 PM

Okay, I've been trying to measure the battery drain of my MKII, but I can't get either of my DMMs to read anything.

I've put the meter in series with the positive AND negative poles of the battery and the battery clip, and I've also tried both sides with the leads one way and the other....NOTHING

Fuses aren't blown.

What's going on?

Phillip

Hal · May 12, 2004, 06:32:55 PM

i _really_ hate to be the one to ask, but is the battery dead ?

what are you trying to measure, current or voltage of the circuit?

phillip · May 12, 2004, 06:36:13 PM

Nope it's a fresh battery...measures 9.5V.

I'm trying to read the current draw of the circuit by putting the meter in series with the battery and reading the current being used. I have the leads plugged in to the right "ports" on the meter and have it set on DC amps...still not reading anything

Phillip

Hal · May 12, 2004, 06:38:22 PM

is it auto-ranging? Most pedals draw in the 10ma range, and this might be too low for what you have....??

phillip · May 12, 2004, 06:45:11 PM

One of them is auto ranging, and the other isn't.

I think I finally got something with the non auto ranging one. When set in the 20A position, it measures 0.01, which I assume means 10mA...

Phillip

petemoore · May 12, 2004, 08:26:06 PM

The manual is like probably easy to understand if you know how to use the meter...lol/ just doesn't 'scale' it where I can figure what to call amps milliamps etc or where to put the decimal point.
I tried to do comparison checks...ie try getting a current measurement off a 1Q booster, the try getting one off of a 5 stage OA build...uh I dunno...manual is kinda sketchie...

phillip · May 12, 2004, 08:38:38 PM

The Manual would probably help

The problem is that I got both these DMMs used, so the manuals are long gone...

Phillip

ErikMiller · May 13, 2004, 02:50:31 AM

This may seem obvious, but since you're flying without a manual, most meters require that for current measurements, you plug your "hot" test probe into a different socket on the meter.

Do your meters have that requirement? Do you have the probe in the right socket? It's usually fairly easy to tell from the markings on the sockets.

Ge_Whiz · May 13, 2004, 05:50:50 AM

The 20A input is usually a fuse-protected special input for high currents - don't the DMMs have 200mA or 20mA ranges via the normal sockets?

phillip · May 13, 2004, 12:40:29 PM

Yep both of the meters have 200mA and 20mA ranges that use the same plug in spot as the other standard functions. I can't get them to read anything using the 20mA mode.

Phillip

petemoore · May 13, 2004, 01:12:35 PM

What are you running the test on?
Not many circuits pull more than 20ma. IIReadC.

phillip · May 13, 2004, 01:39:13 PM

It's a ToneBender MKII Professional...NPN version with a LED. The LED will increase battery drain...probably uses more current than the circuit itself

I wouldn't suspect that it would be more than 10-11mA though.

Phillip

petemoore · May 13, 2004, 01:43:21 PM

ToneBender should be fairly easy on the current drain. 10ma. I think is on the high side especially for a TB.
Hmmmmm...I need to run some new tests.

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Measuring Battery Drain with a DMM