Hi. My name is Bob Zollo. And I'm a product planner with Agilent Technologies. Today I'm
going to do a demonstration of the DC Power Analyzer – that’s model number N6705B –
with the battery drain analyzer module installed.
The device I'm going to be testing with this test setup is a digital camera. Let me tell
you a little bit about this digital camera. It runs off two AA batteries, so it’s a
three-volt drive. What I’ve done is I’ve taken the AA batteries out, and instead,
I’ve put some clip leads in and clipped on to the terminals.
What we’re going to do for the first part of the demo is power this camera from the
battery drain analyzer module, so that when we take a picture with the camera, we can
actually record the current being drawn from the batteries, which is being substituted
by the battery drain analyzer.
Once we record that current, we’re going to take it, and we’re going to then play
it back onto the battery pack, which I’ve got here – the two AA batteries. We’re
going to play it back on that battery pack, and we’re going to see what happens to the
batteries when you take a picture. So that’s an overview. Let me just get started.
So the first thing that I want to do is set the DC power analyzer up
to power up the camera at three volts. So I’ll go over here to the voltage setting,
and I’ll enter 3 for three volts. And we’ll just leave the current settings as they are,
which is a maximum of three amps. We won’t need that much current to power up the camera.
So I’ll turn the output on. And now, as you can see, we’ve got three volts on the
camera. But there’s no current flowing because the camera’s not turned on. Let me go ahead
and turn the camera on. That’ll take a moment for the camera to start up.
And you can see the startup procedures pulls, it looks like an amp, at this point in time.
And then it’s going to drop back down to about 600 milliamps. And then I think it’s
going to settle out at about 200 milliamps or so, when the camera boot up process is done.
Okay. Looks like we’re pretty much there. It’s about a half an amp static current.
Now most of that current actually is being drawn by the backlight on the camera.
Let me see. There it is – down to about 200 milliamps. And that’s when the backlight
went off. So you can see, just the backlight itself was pulling about 300 milliamps.
So we’re learning a little something about how this camera works.
Now the primary tool I'm going to be using for analysis is the software, and that’s
being shown on this large monitor here. This is the 14585A Control and Analysis software
for the DC Power Analyzer. And in the mode I have it right now – it’s in data logger
mode, and it’s a grid. So we’re going to see volts or amps in this direction,
and time in this direction.
And we’re going to set it up to take a picture and capture that waveform. So let me make
a few adjustments to the data logger mode. I want to set the duration to be 30 seconds,
which is good. So I'm going to take a picture. We’re going to record 30 seconds when we
take a picture, and we’re going to save that to the data log file, which is fine.
All I need now is to set up the amps per division, and we’ve got it set to 500 milliamps
per division. Okay. So let me start the data logger, and then I’ll take a picture.
So here is the data logger started. And now I’ll take a picture. Okay.
And now let’s look and see what happens as we go along. So it’s going to take about
30 seconds. We’re about 15 seconds into the data log right now. And in another
10 seconds or so, the data log will be done, and we’ll have a 30-second long trace, and
then we can analyze that waveform and see what interesting information we may learn.
Alright. Looks like we’re about done. Okay.
So the data log is done. Let me first blow this up a little bit to make it a little easier
to see. So I'm at 500 milliamps per division. I’ll jump it down to 200 milliamps per division.
Okay. Now we can see something a little more clearly. So let’s use the marker,
this marker number one here, to make some measurements.
So before I took the picture, the marker was showing 223 milliamps, and that was the current
that the camera was drawing with the backlight turned off, which is the state it was in before
I took a picture. Then, at this moment,I took the picture, and you can
see a pretty high peak current.
If I move the marker into the area, the peak current was about 1 amp – 1.08 amps.
It did some activity as it took a picture. And then there was some period of time out here,
when the backlight was on, but nothing was happening. And the current there was
about 500 milliamps.
And then, a few moments later, the backlight turned off, and the current level dropped
down to about 220 milliamps. So this was the complete cycle of taking a picture, from the
backlight off, to taking the picture, to the backlight on, to the backlight off again.
And, in fact, one of the interesting things you can do with this software is, I can
use the markers to denote a section of time, which I'm about to do right now.
And we’ll put the markers over the entire event, from start to finish. And we can
read off, on the screen, that that time is about 21 seconds. And this is a nice feature.
Here, it shows the capacity of the battery that was consumed during that event. So this took
about 3.5 milliamp hours of energy out of the battery to take a picture.
And that’s what’s going to limit how many pictures you can take. Each time you take
a picture, 3.5 milliamps comes out. So you’ll end up consuming the battery at that rate.
What we really want to do is actually measure that from the battery.
So the first thing I want to do is save this waveform. So I go File. We want to export
the data. And we’re going to export Channel 3 – the current measurement on Channel 3.
Okay. And we say, “OK.” And let’s just leave it on the desktop, and we’ll call it “camera 1”.
And I already have one named that, so I'm just going to overwrite it. Yes. And now it’s saving it.
So now that we’ve saved the data, what I want to do now is invert the data,
in order to play it back as a load on the battery. So think about it.
Right now, what we’re seeing is positive current. That was current flowing out of the
power supply into the camera. What I'm going to do now is disconnect the camera, and I'm
going to plug in the battery in its place.
So here’s that battery pack. And it’s just got a set of clip leads on it – that
has it clipped on. So we’ll leave the battery there. We will connect it up to Channel 3.
Now as we discharge that battery, which in fact, it’s discharging quite a bit. So let
me turn the output off, so it doesn’t do that.
When we discharge the battery, we’ll have a positive voltage and negative current, as
the current flows out of the battery, into the power supply. Whereas the power supply
now – the battery drain analyzer – is acting like the camera on the battery. So before,
it was acting like the battery on the camera. Now it’s acting like the camera on the battery.
So let’s get that set up. So the first thing I want to do is set the voltage – change
the mode on the instrument. So I go to Settings. And right now, it’s set up as a two-quadrant
power supply. I want to set it up as an electronic load, so we’re going to set it up as a CC load.
That’s, I think, all I need to do at this point.
So I go back to the meter, and I’ll set the load current to 0 amps, and I’ll turn
the output on. And what we should see is, this is the natural voltage on the battery,
2.9 volts and no current flowing. And if I disconnect the battery, we can see the voltage goes away.
If I connect the battery again, there you can see – that’s the unloaded battery
voltage of 2.9 volts. Okay.
Now I'm going to go back to the computer software and do what I need to do there. So this waveform
you see on the screen right now is positive current flowing from the power supply into
the camera. I want to invert it and make it negative current flowing out of the battery,
back into the power supply.
So let me go to the arbitrary waveform generator function and do that. I go to Arb. And what
I want to do is – I want to go to this channel here – Channel 3. And I want to make the
voltage fixed. I don’t care about voltage; I care about current. I'm going to do what’s
called an Arb on Channel 3.
So let me get this guy – as the one I want to talk to. So the first thing I want to do
is built up a sequence, so I say, “Add.” And I want to import a file. And the file
that I want to import – New – is this “camera 1”. And I import it. Okay. And there
is it – “camera 1”. And now I want to invert it from positive current to negative current,
so I say, “Modify”, and there’s the positive waveform.
And instead, I want to mirror it. Now it’s negative current. So now instead of being
positive, you can see that everything is negative. And this would be the load current that we
apply to that battery. So we say, “Save the Result.” And let me rename this,
so I know what I renamed it. And we’ll call it “flipped 1.” Okay.
There we are. So we’ve added that in. We say, “Done.” So there is that negative
current. And the last thing that I want to do is – I want to have it go back to 0 amps
when we’re done, so we don’t discharge the battery unnecessarily. So I’ll add another
step, and that step – so that’s done. I want to add another step.
This time, I want to add in a step waveform, and I just want to go to 0 amps on the step
waveform and say, “Done.” Now it’ll just drop back down to 0. Okay. So we’re all set.
We’ve got the Arb set up to apply the current waveform to the battery.
We’ll go back to the data logger.
Let’s clear the screen on the data logger. This time, we’re going to go negative current,
so I’ve got to slide this guy up. And let’s just make the data log a little bit longer.
We’ll make it 45 seconds, so that we can see the entire waveform from before.
There’s 45 seconds. Okay. We are good to go.
So I will start the data logger. I’ll start the arbitrary waveform generator. And now
you can see the waveform. Here it is. It was 0. I started the Arb. There’s the 200 milliamps.
In fact, I need to bring this up, so you can see it a little clearer. There’s the camera
pulse – the picture being taken, being applied.
Here, it ends up as the backlight on, and nothing happening. And then, in a moment,
you’ll see the backlight turn off, and it’ll drop back down to that lower current level.
And then when we get to the end of the waveform, it goes back down to 0, which was
the last thing that I put in. Okay.
So let me turn the output off. We had it set on continuous. So on continuous, it’s going
to keep applying those. But I didn’t want to do that. That’s okay. This is the part
that I'm interested in. So sure enough, if I bring the marker over to here,
I’ll even bring this up a little higher, we can see the negative current that was applied
was that same 1 amp of negative current at the peak that we had before.
If I put the marker over here, we can see the current is negative – about 500 milliamps
with the backlight turned on. I’ll get this marker out of the way. If I put the marker
over here, you can see the negative 200 milliamps, which is with the backlight turned off.
And then, at the end, it goes down to 0 amps, which is -3 micro amps – basically 0 amps.
And if I use the markers to measure the capacity, as I did before, that was consumed during it,
I put the markers across the entire event. The event is that same 22 milliseconds I mentioned before.
And there is the -3.5 milliamp hours. Or that’s the current we pulled out of the battery.
So, effectively, what we’ve done during this demonstration is – we’ve used a record
and playback feature, where we’ve recorded the waveform from the real device, and then
we’ve played it back on the battery, in order to test the batteries and see how
the battery would react to the camera, having a picture taken. Thank you.