Hello. My name is Kevin Cavell. And I'm a product manager at Agilent Technologies. Today,
I'm going to show you how to quickly charge an ultra-capacitor using a power supply that
has a high current capability. We have another video which shows the characteristics, or
gathering the characteristics, of an ultra-capacitor. In that video, we used one of our N6780 SMU
modules. This module has a maximum output current of three amps. So in order to charge
the capacitor with this module, it would take a little bit longer. So we have some other
modules in the N6700 family that have higher output currents, such as the one I have installed
in the DC power analyzer mainframe. The one I have in here is the N6764A, which has a
maximum current of 20 amps. And if you have that, you can actually charge a lot faster,
by sourcing 20 amps to the capacitor. But we have modules that actually go even higher
than that. This is an example. The N6765A, you can see, has a very large output connector
to handle the 50 amps. So you can actually charge faster with this one, if you wanted
to use this one. Okay. So the device that we’re going to charge today is a 310-farad
capacitor rated at 2.7 volts. So, again, that’s 310 farads, not microfarads. I know, as engineers,
we’re all used to saying microfarads. But this is a very large capacitor, so a lot of
energy. So you want to be careful when you set something like this up – make sure you’re
not shorting any of the leads. So what we’re going to do is – this is discharged. We’re
going to use the DC power analyzer and the N6764A module to charge it. And we’re going
to use the data logger feature of the DC power analyzer to watch what it looks like, as the
current goes into the capacitor, and the voltage will start to raise. So I have everything
set up in the data logger. We’re going to do a data log of 60 seconds. So that’ll
continually measure the voltage and the current for 60 seconds. Since the module that we’re
using is of the Precision series – the N6760 series, which actually has two built-in digitizers
– we can measure voltage and current simultaneously. So we can also calculate the power and look
at what that’s like. But since this is just a charged, we’ll just look at the current
and the voltage. So I’ll start the data logger now by pressing the Run/Stop key. At
the bottom, we’ll see the voltage and the current are being measured. Nothing’s happening
because the output is off. So if I turn the output on, we’ll see the current, which
is the top wave form jump up to 20 amps. And now the capacitor’s being charged with those
20 amps of current. And you can also see the bottom wave form here is the voltage. The
voltage is slowly being raised, up to 2.5 volts, as the capacitor is charged. And since
this is a 310-farad capacitor at 20 amps, if you do the calculations, it’s roughly
40 seconds or so before the capacitor is fully charged to 2.5 volts. Once it gets there,
which – it’s getting pretty close now – we should see the current start to drop
down now. And it’ll slowly drop down, continuously. Our 60 seconds that we set for the data logger
is now done. It just gave us an indication of that. And it tells us that all of our data
has been stored in the default .DLOG file. If I hit Enter, it’ll clear that, and we
can take another look at the data log again. The current was here at the top, at 20 amps.
Once it was fully charged to 2.5 volts here, you can see the current starts to drop down.
And then this, here, is actually the voltage at 2.5 amps. Because we set the scale kind
of too close to each other, it almost looks like this is the continuous wave form. But
this is actually the current. And then it drops down. And this is the voltage. And once
it gets to 2.5 volts, it stays up there at 2.5 volts. All this data is saved to the .DLOG
file that was just shown to you – default .DLOG. You can do all the post processing
that you’d like on this data. You can calculate the dV/dT of the charge. Anything you’d
like to get – you have all the current and voltage points that you need, in order to
make those measurements. Again, we were able to do this very quickly because we were using
a power supply that has a high current capability, so you can charge a lot faster. In the other
video, the maximum current was 3 amps, so that’s a slower charge than here. So this
is just a way that we can use a higher current power supply to do faster testing. Thank you.