EEVblog 1507 - Mida: A surprisingly good cheap portable Electric Car EVSE Charger 

I do love it when you say "yankee bucks"...

Latching relays are really common in these - it's about coil heating. You'll probably find it unlatches immediately on power-up. I think I've seen one with a big cap that unlatches on powerdown

Would like to see the earth wire longer than L/N. If the cable would be janked out the earth would disconnect last

Uncommon these days to see a consumer electronics teardown that isn't shoddy or downright dangerous. Good on Mida.

Thank you for your recognition and evaluation of our products

As a person who works on these; with big 50+A relays the coil thermal dissipation is substantial. We definitely pay attention to the latching vs holding current and do stuff like adaptively PWM the coil after contact. PCB trace dissipation also all adds up, we have a lot of thermistors. Also; things like UL safety tests for these can be a bit of a PITA...

I learned, to leave the ground wires always a bit longer, in case of a damaging pull at those cables, the 'hot' cables will disconnect first.

EVSEs that ignore the diode are surprisingly common - the standards do require diode checking, but I tested one that had been tested by TUV that didn't. Strange as it's not hard to do.

The NTC is for the input cable so it can monitor the connector temperature. Not sure where it is mandatory but some places it is. Especially if passing the 10 amp limit on a schuko.

Nice! I like the curvy PCB traces. Somebody had fun 🙂

I have a 32A version (identical on the inside and outside, another brand, again cheapest on Amazon) and it has been charging my car wonderfully for 6 months. Love the extra display

As for the thermistor: Believe it or not, they more often insist on it more for use with low amperage outlets which might not be able to safely handle sustained loads from vehicle charging. They can get hot and melt. This was contrary to your speculation so I thought I’d mention it. I have a real-world example, if you are interested: I have two EVSEs with the exact same ClipperCreek Gen2 EVSE board inside, one running GM’s firmware with a NEMA 5-15P 120v plug and a 12A limit (bundled with the Chevy Volt/Bolt) and the other running ClipperCreek’s firmware with a NEMA 14-30P 240v plug and a 16A limit (sold as “AmazingE” brand). Only the GM firmware with the 5-15 plug has the thermistor… and it won’t work without it unless you use a resistor to bypass. I know because I found the populated PCB for $30 as a new GM spare and used it to build another EVSE, so I really have three with the same board. ;) The AmazingE unit does not have/require the thermistor/resistor because they expect a NEMA 14-30R to easily handle 16A without getting hot. A NEMA 5-15R, on the other hand, is often worn out and gets hot. Though his Volt would default to 8A on 120v my brother would routinely override and set it to the theoretical safe limit of 12A until the outlet in his garage melted. After that we converted his GM unit to 240v and gave it a NEMA 14-XX plug (no neutral to fit more receptacles).

Hope the price doesn't go through the roof after this review, I'd definitively get one of these if I ever need one ;) Also the rounded traces on the bottom are a real joy to look at.

They should also attach the ground together with a wire instead of just the board. If the board breaks it has no more ground connection. (even if its hard to break, it can happen.)

Good to see easily replaceable power cables on both ends.

Great video, thanks!! So much good details for use to learn, great job.

as for the additional connectors inside by what i would conclude this is likely just an alternative way to install the board in a different enclosure where you may not directly screw on the wires but instead put them in such a connector, maybe the board is used in other products too

Thanks for the really comprehensive review. The dip switches do set current and region, anything from locking in at a specific current to 1-40amp selectable at 1amp spacing! I've upgraded my unit from standard UK 13a plug to 16a commando plug, then adjusted the dip switches and got 16a option enabled. I've got a badly handwritten table of which switches do what if anyone needs it.

Those relays can go into one on one off when there is a power failure. My unit needed me to manually switch both off to recover. I also have a Khons 22kW adapter, pretty bullet proof and a gen2 Tesla HPWC which has an ABB 64A contactor and is converted to charge from an 12kWp off grid solar (charge rate according to solar input).

The NTC is for the temperature sensor in the plug(the EV charging plug, not the 3-pin plug). The older design normally has this feature for redundent protection. But you need special cable and special plug to accomate this feature which adds cost. Anyway, it's not mandatory, at least not in China. BTW Chinese standards do not permit 32A on this kind of boxes, they have to be permanently installed.

Thank you. Good video and enjoyed the comments.

I love these teardowns. Cheap Chinese equipment these days can be quite good quality, but can also be absolutely crap. Nice to see the examples of manufacturers over there upping their game. Nerds taking some pride in their work

I Dave, I have one just like that. Working fine since May/June 2021. At the time, it cost me about: 90~100€ (delivered).

Nice to see the you turn it around to match normal circuit flow convention of left to right. everyone knows electrons don't like to flow right to left on paper 🙂

In 2000, Australia converted to 230 V as the nominal standard with a tolerance of +10%/−6%

Good to see these things coming down in price. Now we can hope that proper type2 cables will come down in price as well so they are no longer +$250 items.

Since the hold current is much less than the toggle current you can cut relay power by over 75% by reducing the voltage.

As an Aussie who has 15A equipment in my garage, I know exactly why you may want to limit the current to 10A......

It’s 1m waterproof, but the cable to the plug didn’t look like a meter long!

I would’ve liked to see them leave a bit of slack length on the ground wire to help ensure that the ground connection is the last thing to break in case the cable is forcibly pulled out of the housing.

The only complaint i have is i would like to see some plastic over those input terminals so that ribbon cable does not rub over those screws

Loving the curvy traces ;^)

The reason for that power monitoring chip is that you have to limit RMS current and it's really hard to measure RMS current if current is not sinusoidal, which you bet it isn't, particularly when you are driving the car charger at very low load factors, down to 1kW for a 22kW charger.

Also available in Europe, as modell MIDA-EVSE-PE16S with a higher current rating: 8A 10A 13A 16Amp. I wonder if there are any differences, I guess: no. ^^

Good video and all in one breath.

The best description of an EVSE is a smart safety switch. It only allows power to flow when all of the safety criteria has been satisfied.

Great video! Do you know how they actually limit the maximum current through to the car?

Given that the 15A plug has sleeved pins for the hot and neutral, while the 10A plug doesn't, I would expect the standards for the 15A outlets are substantially higher so they are able to reduce the potential contact area on the pins.

Fine build quality indeed, interesting relays and oh my, just look at those curvy traces! Old style PCB design, thing of beauty, joy for ever. Wonder if it was designed in modern Kicad. It's good to see an integrated RCD here, very smart to have it if your house's wiring doesn't have one and you get a breakdown between the primary and secondary side in the car's converter. Cool EV simulation circuit :) BTW the larger ground contact on a plug is pretty sensible, allows a lower current rated plug in a larger current socket but not the other way around, making it impossible to connect heavy loads to the wiring that can't handle them... Unfortunately this doesn't prevent the "wise guys" from circumventing this safety measure by cutting the ground prong off.

Thanks for the review - I got this one in 10amp! This might be a silly question, but is it safe to use outside if the ground is damp or it is raining? Assuming the power point itself is covered. What about if I use it with an extension cable - is there anything to keep in mind? Most of the time it would be in a covered in a garage, but I'm thinking of when we are on holiday where the car is outside and the power point is a little while away (i.e. cable will be running along the ground possibly with a extension cable)

The Latching relay should not be a problem. At least for the car, because the contactor block on your ev battery will disconnect when the communication is interrupted.

In the UK most electricians will tell you these are only for emergencies as PEN faults (when the neutral in the street drops so neutral comes live, and so does earth) just want to kill you at any moment. The same electricians will go lash up a load of class I outdoor lighting in the flower beds of your garden where the kids play. Its a huge money spinner installing fixed charge points at the moment here, part of the sales pitch is scaring people off of using portable EVSE's and weirdly (or not) the NICIEC and IET are behind it.

Hi Dave, if I may suggest maybe you can do a tear down of a Vitron Energy Inverter Single phase and three phase.

Interesting it uses latching relays. Another approach might be to use 12v to activate the 12v relay, then drop the voltage to reach it's holding current. This would drop power consumption from 1.5w per relay to maybe 0.26w per relay.

I think the two green connectors are just there for the wires to rest on as a sort of strain relief to help keep the screws from coming loose due to vibrations. Or maybe they could be secondary connectors for the lower current model.

Type 2 goes up to 44kW or 64A 3 phase. Early Renault Zoe could be charged at that rate.

I was of the understanding that these must prevent any dumping of supply into your house wiring should a fault develop in your car which would potentially smoke your house wiring in an instant.

They don't have a live/neutral swap relay? For example schuko plug is unpolarized, but probably the car expects N and L1 to be in the right order.

Sad to see the dip switches left alone, what modes hide within?

I hope those white wires going to the front panel board have a suitably high insulation voltage rating, given that it looks like they'll be folded up against the mains screw terminals when the thing is closed up. :) Also not sure about the fact the earths are linked only by PCB trace. Looks like, what, 5mm wide trace? On 1oz copper? Might just be able to handle 15A without burning itself. But then if there's any significant earth current, it'll shut itself off anyway, right? So probably not an issue.

Great video! I don't have an electric car (yet!) but I would really like to see this modded into a smart extension lead, possibly with remote on/off capability. The remote on/off would be good if it was 5V triggered so it could be activated by, for example, the 5V from a USB lead becoming live when a computer starts up. It could also be triggered as part of a non-EV battery charging setup, to switch on a 12V car battery charger when it is connected to the battery, for example, and show the amount of charge going into the charger and on into the battery.

Is it safe to let these draw the maximum current the socket supports (16A) for several hours?

Should the earth lead be longer?

14:07 That odd kink in the application schematic at the line side; I don't understand why they would draw it like that. Splainy?

Surprising that they have the metering stuff in there, and the load current sensing - no need at all for these in a low-cost EVSE and some significant cost savings possible without impacting functionality or safety. Also the display for that matter...

I would have put the screw lugs further apart avoiding the possibility of ring terminals rotating and causing a short across.

Dave, Wiha or Wera as for the best screwdrivers ? :)

The Tesla EVSE definitely has an NTC sensor in the mains plug in the UK.

Speaking about the copper thickness @10:32..... I'm designing a pcb in which one polygon holds 25A.... how can I decide the proper thickness...thank you

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I'm surprised they didn't use a super-capacitor somewhere to unlatched the relay if power is lost while charging.

Do these EVSEs work on an inverter? Is it possible to charge your car from one of these battery packs with 2000W output? Just to have a few extra kilometres for emergency.

Why is there only one pwm control wire? Does it use one of the power wires as reference? But the power wires will have a voltage drop due to the high current. Doesn't seem practicle to me! Or the earth wire?

Where the ctick(or equivalent) Aussie stand mark?

You might want to go lower when using with a source that you know can’t handle 15A. For example, a worn out outlet. It’s why 120v EVSEs often default to 8A and require a manual override for 12+A. Adapters to fit higher amperage outlets often signal this to the EVSE so it can default to 12A or 16A or more. Though a standard NEMA 5-15 in the USA should be able to safely handle a sustained 12A (80% of the maximum 15A rating), they often can’t because they are worn out and loose from too much use.

nice video

Neat! Thanks, I just learned something new. EV's are getting more common around the world than downunder. Tesla mounts this sort of box on a house wall. Mercedes takes big money and only gives you a 10A box just as cheap as the MG toy. Well more to come I guess.

Quick question. Is this RCM approved? I want to know how I can check if this meets the AUS standards. Cheers

Dave throw it outside overnight with the rain you'll be having you'll know if the ip rating would hold up the 8amp feature would be good for those who attack the earth pin with a grinder (not using safety glasses just the safety squint) so it can fit in a standard 10amp socket

1:40 100% Chinese font detected. Doesn't mean Chinese quality though. Where I work we closely collaborate with a Chinese manufacturer and for the final products it's quite random which parts of each product they will design and what parts we design.

Phoenix connectors are probably there for factory test purposes, simply plug in a loom and no need to use the heavy connectors or a special test jig, just 2 flying leads on cables for multiple models.

That means the device is NOT SAE J1772 compliant or the European equivalent. That diode is there so that if the plug is dropped in a puddle of water the power can't be switched on. It should also throw a fit because the earth circuit is open. Even the piece of junk that came with my Leaf stopped when the earth connection opened.

Funny how Dave is scrolling Chinese datasheets like he can read them

“Minor band”? Possibly I don’t know. The top right corner of the schematics shows Fudan Microelectronics. Fudan is one of the top universities in China.

Where did you get it ?

Can I mod a three phase mobile charger to allow more current. I have a common three phase charger from Aliexpress, that is limited to 16A per phase. It works also with single phase, but limited to 16A or 3.7kw. I want to mod it to draw 24A single phase. Is it possible?

Looks like designed by one of the daughter companies of the State Grid. These guys dont mess around, absolute all of their products spare no cost, but not necessarily good looking. For normal Chinese companies, at least the phoenix connectors won't be there during mass production.

Nice parts, should be rated for 20amp like most heavy usage appliances in the US. My freeze dryer requires a dedicated 20smp circuit. It's funny an electric car does not.?

Why are these not available without the typ 2 cable and just a socket? Everyone already has a typ 2 cable and now i have to drive around with two

I expect cordless charging to be built into all parking places, especially in a new home driveway and garage. You pull your car into a spot that automatically charges your car, like your phone. The user ID will be detected and the usage will go onto your monthly bill.🚙

Here we have brown for the color that your pants go when you touch it, blue for neutral and a fancy yellow/green striped one for earth.

You must hate guitar pedals with their backwards signal flow.

The company that made the device is related to State Grid of China, and that company has rigid safety standards for its products and services, That may just propagate to its subsidiaries.

Chief engineer, we need a plug that carries more amps... I know, let's take the last one and make the GROUND pin bigger.

We should really standardize on a single plug to rule them all.

I’d have thought you’d go the OpenEVSE route. Build one yourself.

Great video, thanks. Any chance you'll open up a Tesla model?

Power other stuff is the main reason to select lower:

@6:20 green for earth, I'm sure that is yellow

this looks like '90s mid 90's build quality.. Everything crimped / connectors wonder what the top range models look like inside now.

Isn't risky to have the cables screw like that? If for any reason a screw get loose, a cable can rotate and touch the neighbors...

is there any reason this couldn't be built into the handle? so the wall plug is on one end, then just a rather bulky handle with all this in it. nothing between. The only issue I could maybe see is the electronics need to be away from the handle in case the handle is tripped or Loses waterproofing and the relays need to be switched off

So you could just hack together a simple circuit to fool the car's charger, and apply mains to charge it without this box?

What about HF harmonics? For those radio enthusiasts out there?

I have a 32A version

Dreams in South African of one day having a ev....we don't even have reliable electricity supply.

Ground wires should always be longer than phase wires.

Ehh I'm pretty sure this thing does not comply with standard. It is NOT supposed to charge without PE properly connected. It is designed for crazy domestic market which PE connector is not always available( PE connector is mandatory, but dut to various reasons it is possible to be absent). Older EV charger just follows the code, but get too many complaints from the consumers due to missing PE connector. The new design, as you see, completely ignored PE connector detection feature described in the standard.

The 2902 may be driving the PWM as it's a bipolar signal

Zappi Charger is still the king of them right? @ 10 times the price...