Good afternoon all i have built on a smaller piece of wood uh, this decking timber, the simplest implementation of an evse, an electric vehicle charger that i could think of. So this is an arduino here to generate the one kilohertz square wave. Now that's between zero and five volts pulse width is variable with this potentiometer um. This is a sort of level translator or a line driver.

It is simply two opto isolators, a few resistors and two power supplies: a plus 12 volt power supply and a minus 12 volt power supply and for simplicity. I've just used these little 12 volt cylindrical batteries they are, they contain. I think eight cells in each battery yeah, you typically see these in those wireless, remote controls, transmitters or all the doorbells. Actually wireless doorbells tend to have these little 12 volt batteries and then the center point of the two optos.

With these two 1k resistors is cp. That goes off to control pilot to the car and uh - that's referenced, of course, to pe protective earth so that just connects into uh ground or earth or p e, as it's called here now. There are no relays on this, unlike my uh, easy evse, which had um the relays to cut the mains from input to output. Here, i'm just not bothering now i'm using, of course, i'm not using house mains, i'm using power bank mains, because it is a bit safer.

It's not safe. If you put one part of your body on neutral and one part on life, that would still hurt, and i know how badly it hurts, because i did that once when i was a youngster about 12 years old lept across the room. I actually grabbed live and neutral with my two hands. So of course the current goes across your chest, not a clever idea, but here i'm using power bank mains.

Now i believe that if you accidentally touched either live or neutron, you've got to remember that the mains coming out of a power bank there's no real difference between live and neutral. Nothing is ground, referenced um. You would yes ground one side of that power bank, but then the other side would fly up and down in relation to that. So my belief is that that wouldn't hurt quite as much i mean i wouldn't do it.

I mean i wouldn't do it deliberately, but if you haven't done it intentionally, it perhaps wouldn't be so bad but yeah. Certainly you wouldn't want to put one part of your body on neutral in one part in life, that's still a no-no, but um. I tried this on the car yesterday and it works, and i've got some footage of that. It's not fantastic because i was having problems focusing the camera on the power banks display, but i'll put that footage in now, and you can see that this thing was indeed charging the car right.

Here's my setup, the car is there my evse most simplified evs e. I can think of: is there that's plugged in via the white wire into the power bank, not easy to see the display, but you can see that it's pulling 1400 watts. I think you can see that and and if i turn the pot on this thing, i'll turn it up to halfway the fans on the power bank suddenly come on loud now. Can we see that power level uh it's not well in focus, but it's 1600 watts i'll, try and get a new focus on the camera.

Yeah 1610 watts. So now i'll turn the pot a little more well i'll turn it up to max, and now the power bank is pulling well. The car is pulling from the power bank two thousand and something watts. So, just over two kilowatts, which is uh really the limit of this power bank, it can't go higher.

I have had it up to 2.2 kilowatts, but certainly the pot adjusts the amount of current the car pulls and that works i'll, try and adjust the pot in real time. So let's look at that, but be careful because i don't want to touch the mains down to minimum and very quickly the fans on this thing went off and it's on 1400 watts. So i can vary it between 1400 watts and 2 kilowatts. It's a bit awkward because we've got bright sunshine there, i'm trying to work in the shade here, there's only just enough cable length on this thing to keep it out of the sun, not that i'm worried about it getting hot, but just to film it yeah slightly Tricky a dull day would have been better so yeah.

That was my testing of this thing yesterday, and one of the things i wanted to know was: how quickly does the car respond to changes in the pulse width and it appears that it's near instantaneous it's hard to tell, because the power bank probably takes a little While to indicate the change in power level on its own display, but certainly it's - i don't know, half a second or less when you change the pulse width using this potentiometer, the car responds virtually immediately and starts drawing either more or less power. So that was very important that i knew that it responds quickly because when i've built the final system, of course, this will be responding to changes in power levels coming from my solar panel. So if a cloud goes in front of the sun, what you want is for the evse to respond very quickly, turn down the power level, the sort of pulse width that it's sending to the car and therefore the car will immediately draw less power from the mains. Thus matching the car's power draw with what's coming from the solar panels, depending on how much sun there is, so that was important, but the other thing i wanted to know was what would happen if you put mains into the car with no um one kilohertz square Wave going into the cp, the car obviously doesn't pull any power because it doesn't know how much to pull.

This is what the control pilot is, for. It tells the car you can pull this much power, don't pull any more, though, because if you do, you might blow something up like a circuit, breaker or something, because at the maximum setting of the pulse going into cp, the car can pull a lot of amps At 240 volts it's a lot of power, so that was important to check what happens if you put mains there first now, when i did that, and i then i switched on the uh cp uh square wave between plus 12 and minus 12.. It took a while for the car to sort of say: oh well, that's kind of the wrong way around. I normally would expect to see the cp signal and then, when i respond saying yes, i like that cp signal.

That's nice, then the mains will suddenly appear. Um doing it the wrong way around the car did respond eventually, but it took its time and then i wanted to see what would happen. If i put the cp signal on first with no mains, which is the normal way around, but then i was a bit slow in putting the mains on so i put the cp signal into the car the car says. Yes, that's i'm happy with that cp signal.

I know how much mains to pull, but then the mains just doesn't appear for 30 seconds and as far as i remember, i'm going to do some more tests because i couldn't fully um concentrate yesterday. But as far as i remember, the car responded fairly quickly and started to pull power immediately. It saw the mains appear here, but i will do some more tests, but i i wanted to see what the sequencing was like. I wanted to see whether there are any sequencing rules and it doesn't appear that there are and timing requirements, and it doesn't appear that there are any of those either and certainly there's nothing in the j1772 spec to say that you know cp.

The cp signal has to appear so many milliseconds before the mains or whatever, there's nothing to tell you that, so, of course, i had to do this by experimentation. Now, when i do the next test on this, i've got enough mains cable, this cable that runs out to the type 2 plug of course means that this piece of wood has to sit outside on the front steps. But i've got enough. Mains leads and extension leads on this side.

This side just has the commando plug on it, so that i could put the power oak power bank inside the house, which makes it much easier to to use, but of course, this thing's sitting outside. So i can't turn this pot, but what i thought is, if i now introduce the radio receiver on here and i'll just go and get that. So i don't know if you remember this thing. This was um the giuliano pro minty sort of my homebrew arduino clone with a board here to enable you to put two oleds and a switch on, and then what i call my radio tower, which is just a pcb with a regulator on it.

I think that's a 3.3 volt, isn't it to provide power to the nrf24l01 plus transceiver. Now, if i take that off there - and it just has a pair of wires for vcc and ground, this radio tower can be put on here - i think it just sits on there like that, and then i could have this oh and i need five volts and Zero volts, which can be taken off these pins here. This can then receive um commands from a radio transmitter, also using a nrf24l01 plus, where i will have the pot i'll move the part over across to another arduino, which will be the transmitter. That means i can have the pot inside the house next to the power bank in the quiet in the shade.

So i can get a much better camera setup and the sound will be better, vary the parts and watch the response on the display of the power bank um with this radio link and of course, ultimately, there will be this radio link. So this is something i need to do, because the transmitter will sit on the device. That's currently measuring my solar power um yield, in other words, how much power is coming from the solar panels on my roof. Now i did a video review of that device and that's the device i intend to use to measure what's coming from the solar system.

It is now in my fuse box measuring solar power, i'll put a link up there um. So you can have a look at that review. It's a it's a two-year compatible wi-fi um measuring device to measure power and current and voltage, and all that stuff at 240 volt mains. It also has a giant relay in it, so you can switch it on and off, not that i ever use that.

So have a watch of that. Just to remind yourself what that device is, but that'll be the device that an arduino will sit looking at, because it has an output which is also isolated, pulses, which the arduino can measure the time between those pulses. That will tell the other arduino uh how much solar power there is. It will then transmit across this radio link to this receiver, telling this arduino where to set the pulse width, which will then ultimately tell the car how much power to pull that's where this system is heading.

Ultimately, so i'm going to take this outside now and just do more tests with the big power oak power bank on here test. You know putting the mains on first or putting the square wave on first just seeing what the car's response is to those combinations and again checking this variable, pulse width and then i'll come back later with another video related to integrating this radio tower. As i call it, the radio receiver with its 3.3 volt regulator, power, supply and starting to receive commands from another arduino to vary this pulse width but uh for the moment. That's it cheerio.