Let's take a look inside the Aldi Farax Active Energy 20 and 40 volt charger. And this charger is designed to work with. These battery packs effectively contain two batteries with a control circuit board with two separate processors, two separate fuses. It's two separate batteries, but without twice later, so that one master processor communicates between the two processors and sends signals back to the air mode to the power tool.

I Have done some tests all the power tools seems to want to operate is the thermistor signal on the temperature, the NDC thermistor line? and because the processor can actually activate or deactivate thermistors if the battery is running low, it can actually just kill that thermistor signal. and the power tool won't operate inside the actual pack itself. That's the circuit board. We just have two batteries, and if the tool operates at 20 volts, it connects them both in parallel on the tool.

And if it operates in 40 volts, it connects them both in series. I say 20 volt and 40 volt. It's 18 volt and 36 volt binomial tool voltage levels. But anyway, I shall put this out the way and we shall get into this: What? Am I Expecting basically two battery chargers, but with a bit of communication because I Don't think there's enough connections.

It's not like it's treating us two completely separate batteries, so there is a bit of a a bit of magic going on with the processor, so let's get the cover off this to save time. I Got the cracked screwdriver ready. I Think that's it? Is that it? It is it. Almost.

it. that one screw is not quite out. That's fine. It is now not reviewing an awful lot revealing this.

Uh, the battery connector is connected to these loose wires, so that's quite odd. Does this come out directly? Yes, it does anything holding in any screws. I'll put those bits out the way as well because this circuit board is what we're interested in. So I'm seeing filtering here.

Let's Zoom down this: I'm seeing that filtering. Uh, the commode suppression. We've got the incoming Supply Here we've got a fuse. We've got an NTC in Rush limiter.

Um, which is designed to limit the current. Uh, initially because when you connect it up, this capacitor here is empty. It's at zero volts and when you initially apply the power, there's a surge to charge that capacitor up. and uh, that can damage the rectifier and other components.

So what they do is they put this device here. This little black disc marked 2.5 d11. The D probably means disk 11 probably is the diameter. Let's check that.

let's see if it is 11 millimeters diameter or Not Really Gonna I'll have to get clever here. Uh, yes, Well, 10.5 close enough. And the uh. the 2.5 is probably the initial resistance when it's cold.

Uh, and what happens is uh, that resistance limits the current and then as it heats up with the current flowing through it, that resistance drops because it's not really needed anymore. So we've got the Uh in Rush limiter, the filter capacitor, the X2 capacitor, the commodity suppression choke, the bridge rectifier, anything else here? Uh, and the smoothing capacitor that then feeds this mosfet unless it's a full control chip. Now there's a control chip, but there's the opt to isolation feedback. Um, and that's driving this transistor to switch this Transformer which is generating a single voltage will look of it.

is that diode that is a diode here with the big heat sink on it. that's then going across to the output capacitor. Um, and then it's going to the battery packs, right? Tell you what. I'll take a picture of this and we can take a closer look one moment please.

Okay, let's explore and I will not lie. that took a lot of reverse engineering. So this is the top of the circuit board flipped so you can get the reference positions. There's the wires going out to the battery connector.

There's the rectifier on the low voltage side, the Transformer the the clasp and why capacitors on either side, the Transformer the switching mosfets which is a big fat baster and filtering and rectification circuitry. That's that area. Uh I shall Zoom down a bit. In fact, because we're gonna have to zoom down.

this is where it gets all complex. I've got a schematic for you. A proper schematic? Uh, five pages of schematic? I'm afraid. So I'll give you the quick summary.

The main Supply comes in. it goes through the fuse, has the inrush limiter. It has a class X Suppression capacitor filtering noise with discharge resistors across it Con Mode suppression choke and then it goes through a bridge rectifier and charges up at the 100 Microfarad Death Beam capacitor at 400 volts, that then provides power to the switchward power supply circuitry, which uh pulses this Transformer using the mosfet under that is then rectified on this side by a short key pair of Schottkey diodes in one package with some filtering and puts us voltage over here of between 14.5 to roughly 22 volts depending on what's needed. The current is switched to the individual battery packs by these two mosfet packages and these two diodes and the current that's going into the batteries is sensed by the common negative here for both batteries that goes around via this resistor to the negative that's a current sense resistor 0.05 ohm and that then signals over to here as well as a voltage and it will.

Basically, this will use this up twice later to disable the power supply when it reaches the voltage that it's happy with that, it's going to put the right amount of current into the cells in the batteries. Um, and then once One battery is fully charged, it can disconnect it and once they're both fully charged, it can disconnect both. That's how it works, right? Let's take a look at the schematic. That was a super short summary.

This is not a short summary. This is a monster schematic. Here is the power supply section: Live on YouTube in the live via the fuse, the neutral via the negative temperature coefficient in Rush Limiting resistor. there is that uh, Class X capacitor.

It's all small here because it had to fit all this in with its discharge resistor across at 600k. it's actually two 300 key resistors in the series. the common mode to pressure choke the bridge, rectifier the Big Fat 100 Megaforce Death Beaming Capacitor and that gives us a supply reel of about 340 volts and zero volts. Not actually zero volts to touch though, it's just a the internal circuitry reference.

Zero volts. The control chip, which is a bit vague I found one that looks a bit like and a similar pinout is powered via initially via these resistors. Here, current flows through these resistors and charges this capacitor. Once it reaches a high enough voltage, the unit kicks into life.

It starts driving this transistor which pulses the primary of the Transformer and the secondary, then on the other side, the next bit of the schematic gets the low voltage Supply But there's also a small leveled Spike Move over to here via the style charging this capacitor, but it's different from the normal circuitry because the output can vary so much in the voltage that normally just of this diode coming straight over and charging this capacitor over here. But they've not done that because the voltage is variable, they're using to charge a separate capacitor and then they've got a very simple voltage regulator based on an Npn transistor, a resistor, and a Zener diode and that just provides a stable voltage there. So once that started, it just provides a nice fixed voltage for this unit. The when it's pulsing the mosfet, it has a couple of Uh facilities for feedback.

It can detect the feedback on the collapsing field of this 220 key resistor to avoid over voltage situations. but when it pulses the most of it initially turns the mosfet on. Current flows through this coil and that builds up a magnetic field in the Transformer. Then under a couple of circumstances a sense resistor.

here. if it reaches a point that the current reaches a threshold Uh, then it will turn that mosfet off. Some of them use a fixed frequency and that is just a backup, but um, it that is then filtered via this 100 ohm resistor and capacitor. The feedback from that, but when it turns off because initially the other side doesn't start conducting straight away.

But as the magnetic field collapses, it normally puts power out into the other side, the low voltage side, and also to the feedback circuit that has to have something to catch that slight voltage transient. So there's a capacitor across the mosfet to protect it. but there's also a diode that diverts the Uh initial collapsing field as a sharp Spike to this capacitor to shunt that and then this resistor slowly discharges that in an ongoing basis just to basically prevent high voltage spikes that could damage the mosfet. Feedback from the electronic circuitry is via this up to isolated transistor with a little capacitor.

cross it for stability and that uh, when the LEDs turned on the other side to say stop running it will put this into a standby mode that are just uh I Don't know if it shuts it off completely or just keeps pulsing every so often, but I guess the other side will, uh, ultimately take full control of the running of this so it will only just power up when it's needed. Okay, next page of the schematic: I'm just checking I've covered I have covered everything there I Didn't originally intend to go quite so deeply into this, but I did that happens? The first version of this video was just woefully inadequate, but uh, I'm making up for it now. let me just uh, see if I got the correct? Yep, here we go. So the second derivative Transformer The bit that's receiving the energy of the clapsing magnetic field, it's diverted through these two shot key diodes that are in parallel.

And there's also because shocky dials do not like not like reverse spikes to avoid damage when the the other side's being energized as opposed to the collapsing field going into here. It's got a little snubber Network 12, Ohm resistor and capacitor across it that just basically avoids Uh transients causing damage to these transistors that then charges a 1 500, Megaforce 35 volt capacitor and that then creates the main positive Rail and uh, the zero volt rail. Now the batteries themselves are charged when the microcontroller sends a signal I'm not sure what the chip is um, but I've worked out most what it does when it sends a signal to this transistor, which is these uh, resistors are built into the transistor. It's a sort of economy sort of space-saving thing.

So it sends a signal to this, which Uh turns on the mosfet by pulling it to the zero volt, the gate to the zero volt Rail and when the mosfet turns on, current can flow through that diode to the and charge up the battery. and there's two identical circuits I've omitted uh the transistor here just to keep the circuitry cleaner and when the current's flowing through, it creates a slight voltage differential across the sense resistor and the I sense. the current sense then goes to the rest of the circuitry. The mosfets are I'm guessing AP 4407c The diodes are Sb1045l just for reference just in case they blow so you can get Replacements if needs B Goldie blue I don't know.

The next page of the schematic is by far the easiest. The main Supply voltage is not just charging the batteries, it's also being monitored by the circuitry with a couple of sensing systems. but it's also providing. it goes via a diode via a resistor to a partly limit in Rush also partly to take the load off these two voltage.

Regulators There's a 12 volt regulator and a 5 volt regulator. The five volt regulator power the microcontroller. The 12 volts is purely for communication, the battery quite unusual uh, that also has a sense line going to some odd circuitry around the microcontroller. And also there's another thing monitoring the voltage across between the main line and zero volts and it's going to the microcontrol on another pin.

Possibly just looking for a major anomaly because that that bit the screen over there looks as though it controls the switching of the power supply via the Op twice later. This bit here um is possibly just looking for detecting the unit being turned off I'm not sure and the voltage dropping before the voltage to the processors dropped. Very strange. Okay, next page, this is a communication with the batteries.

It's quite complex, rightyhole. Let's start with the the thing can actually communicate in both directions of the batteries. In the case of the one pin is the Uh signaling by in the battery it's given us current limited Supply via 5.1 K resistor and that is then switched by the battery shown here in the red to the zero volt rail Vr-100 Ohm resistors. So the processor by using a divider can then detect that 12 volt Supply actually switching on and off and that's how the battery communicates back to the microcontroller to actually communicate to the microcontroller.

you have another of these combined transistors and that is used to turn on Uh, this transistor a B Channel transistor which switches up PNP should I say which switches up to 12 volt reel and uh, when it raises the thermistor, contact t or NTC of the battery to 12 volts and that then goes through a potential divider here and drives a mosfet which then pulls internally in the battery. it pulls a resistor tied to the 5 volt rail to the zero volt rail. So basically speaking. long story short, when the processor sends a positive signal out, the microcontroller in the battery pack will see a zero just through that voltage conversion.

there is another auditing. The microcontroller in the battery pack can also turn on the thermistor and the this charger needs to monitor the battery temperature so there's actually two thermistors in it, but they're both in the same position which is pretty odd. But so this circuitry is duplicated twice. It's got them the most fat, controlled by the batteries controller that can switch them the NTC temperature sensing 10 key resistor down to the zero volt rail within the battery and I would guess I would guess there's two connections to the maker controller I'm going to guess that this one goes high at 5 volts and basically forms a potential divider with that uh, thermistor and then the voltage is then measured with some filtering via this resistor in this capacitor to the microcontroller.

so it can actually work out with the temperatures across that. But there's one odd thing if this is switched to 12 volts via the 750 Ohm resistor, that's pretty much going to put 12 volts in these resistors. And although they're going to limit the current significantly, it does mean that there's currents going to be flowing into the microcontroller pins because they're effectively 5 volts and the 12 volts will potentially do that I'm pretty sure. very strange.

Now comes the very weird circuitry. This is where I need the analog passage, Chairman. So here is the microcontroller itself. It's got its five volt, Supply and uh, the main positive supply for for the batteries.

The main power supply comes in Via this potential divider and goes into the microcontroller. but also when the microcontroller turns on the LED in the opto isolator here, which is a 1K resistor to up to the 5 volt rail. So the op the microcontroller pulls that to the zero volt Rail and that turns on and it basically inhibits the Uh switch load power supply. But when it does that, when it pulls us to negative, it also affects this little capacitor resistor.

Network I'm wondering if that's a sort of hysteresis thing. Um, because they're doing quite a lot with analog modules within the processor. Likewise, in the current sense side, that's the sensor voltage across that resistor which is quite low. One part of it goes via one key resistor, a little filtering capacitor and then straight and the other part goes via a 10K resistor.

and in um, but also has this little um, snobbery thing. this little thing that might be for a hysteresis again, I'm not really sure. without I can't identify what the chip is you I don't even if it was there. If it's a standard microcontroller with analog modules, then depending on how they're configured because with those microcontrollers, one pin can do lots of different things so it will depend on the software.

But this is, uh, odd. That took me a bit of puzzling. In fact, you can't imagine how long it took me to reverse engineer this. It was an astronomical amount of time.

I mean I Feel like I deserve a subscription If if you're ever going to subscribe to me, it's because of this because it took ages. but there is a I'll point out the random bits now that you know what they are. There's a 12 volt regulator. There's the 5 volt regulator.

There is the transistor that switches to the positive Supply to signal to the battery. There's the little all-in-one uh, transistor and resistors controlled by the microcontroller that then switches that transistor on. And there is this hideous combination of resistors that senses the voltage and current and it's all on one side of that, making me think there's something fancy about this. This side, if it's the analog side, maybe a hybrid analog and digital chip? Um, but the number in this through have a complete blank.

Uh, I'll leave a note the number in the description Google did not find anything at all. So components that are likely to fail Um, the catastrophe over here is the one that gets stressed the most with switch mode power supplies. The other components I like to feel is the little NTC resistor I have where is the other side? I'll show you these so it could be that capacitor over there or that little black uh, thermistor there. that uh, the in Rush limiter that often goes pop and fills open circuit.

Um, and that is it. So yeah, Interesting thing indeed. It's one of those things that you know because the Uh circuitry is so heavily integrated you can it's very hard to reverse engineer because it is very software dependent unless that is I Don't think it's a dedicated switch mode power supply or Charter chip because of that Communications thing going on. I Mean when this thing's coming, when this thing's charging a battery, there are three microcontrollers involved, two in the battery and one in this.

Um, there's that little black NDC and Rush limiter. Um, yeah, 2.5 ohm disc 11 millimeter and there's that capacitor will be the one that gets stressed most. Sometimes these diodes can feel too. Uh, if they do, they feel short circuit.

When you measure across the back, you'll see the two outer pins are connected, but they'll sometimes be Abridged to the middle pin if it goes short socket. Um. But you also have to allow for the fact that uh, that is in line with the rest of the circuitry as well and the windings. The Transformer has a good spacing there.

It looks like they've made an effort to make it electrically safe, which I'd expect for these things. It's very stylish Isn't it nice symmetrical heatsinks, but there we go. That is the Audi Ferex dual voltage 24 to volt charger. Just basically treating the battery pack as two separate batteries.