Hi. This is Amy from the altE Store. Well, winter is finally over, spring is here, the
sun is out, and so I'm finally going to be able to show you all of those demos that I've
been promising you all winter. So what we are going to do is, we are going to answer
a lot of those questions that we get all the time. And instead of just telling you, we're
going to actually show you. So we are going to put together a whole list of them, and
we'll do a playlist, and we'll have it here, so you can actually go and watch all of the
common questions being answered. Alright? So. The first question that we get all the
time is, "I bought a great deal on a 20 or 24V solar panel, and I want to use it to charge
my 12V battery. What do I need to do it?" Well, the answer is you need an MPPT charge
controller to reduce the voltage down to the right voltage, about 14V to charge the battery.
But also, increase the current on the output. So because watts, or power, equals volts times
amps, if you drop the volts down to the right voltage for your battery bank, what's going
to happen is if you use just a PWM charge controller, the volts are going to drop, the
amps are going to say the same, and so you're going to lose about half of the power. So
what you can get with an MPPT charge controller, is it will drop the volts, but raise the amps.
And so you're going to get more of that power from that solar panel to your battery. So,
let's take a look here. What I've got, is I've got two identical 100W 24V solar panels.
And their short circuit current is about 3A, but their Imp, their maximum power current
output is 2.78A. And I did measure them both, and they are both getting right about that
amount of output. The Vmp is 36V, so that's the max power voltage that it will be putting
out, and trying to charge a 12V battery. But you're not going to want to put 36V into a
12V battery. So what's going to happen is it is going to drop that voltage down to around
13.5 or 14V, depending on how you've got your charge controller set. And let's take a look
at what happens. Alright, so first I wanted to show you, this amp meter is actually measuring
the output between the charge controllers and the battery. And you see I'm at -0.26A.
What that is showing you is that when the charge controller is actually up and running
and working, it will actually draw a little bit of current. So the PWM really doesn't
take much power at all, the MPPT, when it's active, is going to be using about 1/4 of
an amp. Now that does shut down fairly quickly if it senses there's no solar coming in, it
does shut down pretty quickly. But just keep in mind, that the MPPT charge controller will
actually use a little bit more power than the PWM. So, keep that in mind, if you're
considering using it on a very very small solar panel, the increase of output may not
be worth it if you are talking only about 1/4 amp. OK? So, let's actually turn off the
MPPT charge controller. We're going to turn on the input to the PWM, so again, my Imp,
my maximum power current is about 2.78A, and I am actually seeing 2.83A output from the
charge controller, the PWM charge controller. That's great. But my voltage, again, has dropped
from 36V down to 13.2V, because I'm charging that 12V battery. So that's really cut the
output of that panel down dramatically. Now, let's go the other way. Let's actually turn
on the MPPT charge controller, I'm just turning that on, and you see now that it's actually
dropped down to 0.03A. That is the MPPT charge controller dropped back into standby mode.
So you know that it's not going to be drawing 1/4A all the time, but again, just kind of
keep in mind that when it is actively working, actively charging, you are going to see a
higher current draw than with the PWM. So, we've got the MPPT charge controller turned
on, I'm going to turn on the input, and we now are seeing 5A coming out. So that voltage
is 14.1 volts, it's actually putting out a little bit higher voltage that the PWM one
was. 14.1V and it's dropping down to 4.6A, it's kind of going all around, but anywhere
between 4.6 and 5A output. That's a pretty significant difference from the 2.8A we were
getting from the PWM. So you can see how having a MPPT charge controller really does increase
the output and gets you a lot more of the power out of your solar panel, than if you
were to just use a PWM. So, using PWM pretty much cuts your solar panel in half, whereas
the MPPT will really maximize your output. I hope that's helpful. If so, give us a like
and a share. And be sure to subscribe to our channel so that we can notify you when we've
got new videos coming out. And make sure you go to our website at altEstore.com, where
we've been making renewable doable since 1999.