GWL do an EVSE in a 2 module DIN enclosure that can be controlled via an analogue voltage or directly by an RS485 or UART connection (not sure on the details of the latter two options): https://shop.gwl.eu/Electric-Car-Chargers-1/EVSE-Kit-For-EV-Charging-Station-Cable-Din-Version.html

I played around with the board only version of their unit some time ago and it seemed OK, in fact the home made granny lead I put together for my wife's Zoe uses one of their modules and has been fine for years. The board only module is this one: EVSE Kit V1.1 For EV Charging Station/Cable (Wallbox) - Kit Only | GWL Group

They seem to produce these in batches, so that shop is often out of stock, unfortunately.

I'm not sure about that Chinese ETEK module it may be OK, it may not. ETK do make/supply some OK electrical components, including Type B RCDs, so they may be OK (you just never know with some Chinese electrical stuff though, especially regarding safety).

It's a pity that Viridian no longer make their basic EVSE module. I bought a few years ago, in fact have one sat on my desk at the moment being controlled via an ESP8266 and an MCP4725 DAC module, whilst I try and refine some ESPHome code to get it to integrate with my Home Assistant system. The newer (and a lot more expensive) Viridian EVSE can be controlled using serial, I believe, either RS485 or RS232, can't recall which, but at £120 it's a lot dearer that the GWL modules.

Another option is Open EVSE, although if you buy the modules rather than make them from scratch they are a bit pricy, plus last time I looked they seemed focussed on North American electricity supplies.

 

Been doing some more looking around and have found this Italian EVSE controller, that can be controlled via Modbus RTU/RS485, which may be a contender, perhaps: https://store.creasol.it/en/control...ox-0637902882283.html#/8-protocol-modbus_rtu_compatible_with_almost_any_systems

Cheaper than the Viridian by a fair bit, too, at €92

 

It looks good but doesn’t mention anything about DC or open PEN protection so those components would need to be provided in addition.

Viridian do (or did) a version of their v2 controller that supports control by Modbus. Annoyingly, that version only has voltage based open PEN guessing.

 

Sorry to resurrect an old thread, but I've been looking at the EVSE controller that the OP of this thread mentioned, the ETEK, today, and thought it worth updating this thread. The controller I think they were referring to may be this one: EKEPC2 EVSE controller I thought this might be of interest to you, @barneyd

It costs £30.99 + VAT and having had a look at the user manual (attached below) it seems to have DC tolerant RCD protection, albeit by plugging in the optional RCMU module (an extra £15.49 + VAT). There isn't open PEN fault protection though. The big plus for this cheap controller is that is can be controlled via an RS485 MODBUS RTU connection, which opens up lots of possibilities for a home made charge point.

I've ordered one of these EVSE controllers, together with a couple of cheap RS485 to LoRa transceiver links, which, because this controller has a 5V power supply output can just be wired directly to it, to give remote control of a charge point over a fairly long range (they say up to 3km). This makes building a locally remote controlled charge point a doddle. The indoor bit doing the controlling can also be pretty simple as the other end of the RS485 LoRa link can just be connected directly to a USB to RS485 dongle for both data and power. With this plugged into a machine running Home Assistant or similar control becomes pretty straightforward, with no reliance on WiFi, the internet or whatever. Sending MODBUS commands and receiving MODBUS data back from the charge point should be easy.

 

The Etek EVSE protocol controller has just arrived from China, via Aliexpress, Cost was £37.19 including VAT and shipping, so less than half the price of the Viridian EPC modules. Not yet wired it up for testing, but have taken a few photos and I've had the lid off to see what's inside. I can't get it fully apart as it's riveted together and I need it in one piece for further testing.

The plug at the lower left of this photo accept a DC tolerant RCD module, which is an extra that costs about £18.59 inc VAT and seems to be very, very similar to other RCMU modules, like the more expensive RCM 14 module from Western Automation:

As supplied it could easily be a drop in replacement for something like a failed Rolec controller. Unlike the Viridian controller, the ETEK LED connections are common anode, the same as the Rolec, so this makes it pretty much a drop in replacement for a failed Rolec controller.

Like the Viridian it also has LEDs on the front, so if fitted in an enclosure with a clear front the charge status can be seen without the need for external LEDs.

I popped the top lid off and this is what I found inside:

The connector at the lower left is for an optional LCD graphical display, looks a bit like that on some other Chinese made charge points (I didn't buy one to check). Above that connector is a DIP switch with a bit of kapton tape over the top, to keep out the heavy conformal coating that's on the PCB. Not full investigated all the options this gives, but as supplied it seems to allow the charge point to just work as a dumb one, with the charge current set from a front panel rotary switch. Build quality looks good from what I can see.

Here's some better views of the terminals:

The connection diagram suggests it's straightforward to wire up, very similar to the Viridian and Rolec modules in many ways, but with some extra features:

My plan is to try to use the RS485 MODBUS RTU connectivity (the A+, B- terminals at the top right of the front view photos) to allow remote control, via a pair of cheap RS485 to LoRa modules (which haven't arrived yet). I'll probably start off by trying to control the EVSE remotely with the indoor RS485/LoRa module just connected to a USB port, so I can work out how the thing responds. Looking at the manual it seems that everything can be set via the RS485 port, so the charge point could be turned on or off, have the advertised current changed etc, via this connection.

It may take me a week or two to get it up and running and report back with something more meaningful.

 

Another update.

I've got the thing running on the bench, under control from a USB to RS485 dongle. I've found out a fair bit more than is in the rather sketchy manual, including the fact that this module does have a form of open PEN fault protection!

I've discovered that there are two registers that can be programmed to make the charge point cut off on a defined over-voltage and a defined under-voltage, so setting the over-voltage register to 253V and the under-voltage register to 207V will provide much the same open PEN fault protection as many other charge points provide. Not an ideal way to do it, but if you don't want to make the thing TT then at least this will provide enough protection to comply with the regs.

As this unit also accepts an RCMU add on, for less than £20, that provides DC tolerant residual current protection then it can be used as the heart of a fully UK compliant charge point.

It also has integral dynamic load balancing (DLB), just needs a CT on the incoming supply. The limit can very easily be programmed using the RS485 interface, just a matter of writing a value to the maximum demand register. The way the charge point reduces current when in DLB mode can also be adjusted, there are register values that hold the P, I and D parameters of the DLB control loop.

Switching it on and off remotely is very easy, just send a "1" to the stop/start register to turn it on and a "2" to the same register to turn it off. Much the same for setting the current, just a matter of writing a value to the maximum current register that controls the PWM signal sent to the vehicle.

Lots of data can be read from the unit, including temperature, voltage, CP positive voltage, CP negative voltage, actual PWM being transmitted over the CP, PP resistance (if it's the socketed version, rather than tethered), plus a whole bunch of status indicators that report every stage of the process together with several fault codes to indicate what may have gone wrong. If a DLB CT is fitted then the unit can also report the actual current being drawn and the power.

Only slight gotcha I first encountered was that, as supplied, these units are programmed with an invalid MODBUS address, 255. The highest normal address is 247 and a lot of free MODBUS tools won't work with any address higher than this. Luckily the MODBUS device address is programmable, so once I'd found a MODBUS tool (Open ModScan) that allowed access to a device with an address of 255 it only took a few seconds to re-programme the address to a more normal one. From then on any MODBUS tool can read and write to the units registers very easily.

Next stage is to knock up a simple remote control box. I want to do this so I can play around before integrating the thing into Home Assistant. I'm going to stick an Arduino with an RS485 converter, plus the wireless RS485 to LoRa module, in a box with a simple current display and a rotary control to both switch the unit on and adjust the charge current on the fly. This should give me an easy way of being able to do a fair bit of testing to get a feel as to how the unit responds. After that it should be very easy to integrate it into Home Assistant, just using the same USB to RS485 dongle I've been using for testing to communicate with the LoRa remote link. When it's running from Home Assistant it means that timed and solar charging will be a doddle to set up. With luck I should soon have a charge point that I can remote control from up to a couple of km away, with no needs for WiFi, and internet connection, mobile signal or anything else.

I'm putting together a short English version of the manual key points, stuff that I didn't think was very clear in the directly translated from Chinese manual it came with, I'll try and post it here once I'm happy that it's reasonably accurate.

 

You write a wrong facts. This modul HAS NOT the switching ON / OFF register. All values for On / Off are 0 / 1. I have one on my table and communication with its isn't problematic. The address 0xFF on register 0x64 is normal and usable. But the modul is s..t. I'm sorry, my experience is that.

 

I've knocked up a test charge point, with remote control via a LoRa to RS485 module. Seems to work as expected when sending commands and receiving data directly to a PC. The controller activates the contactor when I stick a diode and resistor from CP to PE OK and it seems to be putting out the right PWM for whatever current I tell it to run at.

I've tested the psuedo open PEN fault protection too, and that works exactly as expected, the charge point shuts down if an out of range voltage is detected. I've not bothered to fit the RCD module as this will be connected to a circuit protected by a DP Type B RCD.

Here's a photo of the prototype in what I think is the most compact enclosure that's practical. Cost of the parts, including the enclosure, in this photo is about £85, so pretty cheap really. Just need to crack on and get the indoor remote control box finished to do more testing before I integrate it into Home Assistant.

 

Very interesting article you posted. I am using a ETEK controller it works OK as a standard setup, ( no connection HA). But can you help, the red LED light always on ( not flashing) the green LED comes on and then starts pulsing and charges correctly. In ETEK instructions it states over heating and will switch off but mine does not.
Regards Martin

 

Sorry for the long delay before getting back to this. I've spent most of today getting my head around the Chinese documentation for this thing, as well as being more than a bit frustrated by the appalling lack of detail, as well as the conflicts and gaps in the manufacturer's (very sparse) documentation.

The good news is that I have the thing up and running, under local control from Home Assistant, but I ended up binning the RS485 interface in the photo, as it turned out to be a LOT easier to control it directly using ESPHome. I used one of the ESP8266 to RS485 interface boards originally designed by Brain Lough, and this proved to be the perfect way to get the ETEK to talk reliably with Home Assistant.

There are a stack of Modbus commands the module can use, but many require it to be connected to external sensors. All I wanted to do was be able to turn a charge on or off and also to vary the charge current, so I could get HA to control charging from excess PV generation. In the end this proved to be really easy, but I have to say that ETEK really went out of their way to make this a LOT harder than it needed to be.

The first hurdle was finding a way to reset the module Modbus address. As delivered it's set to 255, the broadcast address, and the snag with that is that a lot of Modbus tools won't accept an address higher than 254. Once I'd found a way to reprogram it to work within the normal Modbus address range I was able to work through all the myriad of combinations needed to decode the registers. What I've settled on is having control of turning the thing on and off, and setting the PWM duty cycle for the Control Pilot, which in turn sets the maximum advertised current. I'm using 1A steps initially, from 6A up to 32A, but may change that, depends how it works in practice.

So far I've got as far as a working charge point that allows me to send a command via HA to turn it on or off and set the charge current between 6A and 32A. Next stage is to create an automation in HA to read the PV generation and house load and then adjust the charge current to ensure there is no import. I've already got the off-peak bit working, that was remarkably easy, as there's already a built-in way to schedule events in HA.

I'll try and publish the ESPHome yaml here, once I'm happy that it's bug free. i've also written a short manual to help others who might want to use this cheap EVSE module, with a tested table of all the various registers and a brief description as to what they really do. One neat thing is that when you change the charge current the unit responds near-instantly, and it confirms the actual set CP PWM, handy, as it gives useful reassurance that the charge current really has changed.

 

I forgot the link to the ESP8266/RS485 board I've used, it's this one: RS485 to wifi adaptor for Home Assistant

Really compact and it worked out-of-box once I'd plugged in an ESP8266. Probably the neatest solution for interfacing any Modbus device to Home Assistant. It also works from the limited DC supply available from the ETEK module.

 

Just in case anyone is still interested, I'm still playing around with the ETEK EVSE module. I now have it pretty much working as a smart charge point, using Home Assistant to locally control charge times and charge current. I've found I can get a good enough WiFi signal where the thing is going to be located, so I'm controlling the EVSE module directly from a cheap ESP8266, with an RS485 module. The photo below is my test setup, just to see whether I can control the EVSE and change it's advertised charge current OK:

The black box to the lower left is just a vehicle simulator, so I can check that the charge point responds correctly to normal requests for charge, faults in the cable, etc. It's set to signal to the charge point that a vehicle is plugged in and that it's requesting a charge.

The enclosure is roughly EO Mini size I think, it's an IP66 Hylec DIN rail box that is 120mm wide, 175mm high and 100mm deep: Hylec DN15E Grey General Purpose ABS Enclosure 100x125x175mm Grey Lid that cost £11.72, plus VAT and postage.

The EVSE module is this one: https://www.aliexpress.com/i/1005004512138683.html that cost £33.99 inc VAT & shipping.

The ESP8266 and RS485 module, that runs ESPHome and connects the EVSE to Home Assistant is this unit: Epever RS485 to wifi adaptor v1.7 that cost £11.95 plus postage

The contactor is probably overkill, it's a Schneider Acti 9 40A DP unit: Schneider Acti 9 iCT A9C20842 40 Amp 2NO 2 Pole 220/240V 50Hz Contactor | Electrical Discounted Supplies that cost £35.35 + VAT and postage. There are undoubtedly cheaper options around, but I happened to have this one sat on the shelf. A better (as in much cheaper) option might be this 32A one: WCED 2 Pole 230V 32A NO Normally Open AC Modular Contactor at only £5.99 + VAT and postage.

You'll also need cable glands, Wagos, terminal blocks and a few bits and bobs like the butchered Ethernet cable used to connect the ESP8266 and RS485 module to the ETEK. Luckily the ETEK has a 5V 100mA supply which seems fine when running the ESP8266. Fortunate, as it saves having to add a separate 5V supply.

The current state of play is that I have Home Assistant controlling the charge point, so I can turn it on or off, or set the charge current, from any device in the house that has a web browser. The next stage is to create a couple of Home Assistant automations, one to turn the charge point on and off at max power during the off-peak period, the other to automatically control the charge current when there is excess PV generation. I also need to 3D print a bracket to hold the ESP8266 board to the DIN rail.

Total cost of the bits I've used is around £140, but I think it should be easy to get this down to around £120, perhaps slightly less, by shopping around.

 

Thank you for your very comprehensive posts on testing and constructing a proper EVSE using off the shelf components.
I intend to go this route to migrate from my current so called Granny Charger.
Regarding RCD requirements you mention that you have not incorporated a RCD within the enclosure as the unit will be connected to a circuit protected by a DP Type B RCD. I think I read somewhere that a remote RCD should protect the EVSE only and not other circuits as well, so is that the case with your set-up?

 

This is the part of the regs that applies to RCDs etc for charge points:

Although each charge point has to be on its own dedicated circuit, with overcurrent protection, as long as the supply to that circuit is from a double pole Type B RCD then the requirements are met. This means that, for example, the set up I have is compliant. I have a sub-main that supplies a detached garage, and which does not export the protective earth from its supply. The garage has a small consumer unit, with a Type B double pole RCD and the protective earth is provided via an earth electrode. The small CU in the garage has three MCBs, one for sockets, one for lights and one for the charge point. This meets the requirements, as the charge point is supplied from a dedicated circuit, with its own overcurrent protection (as per 722.533.101) and the supply is protected by a 30mA Type B RCD (as per 722.531.3.101).

 

I had a search and found where I'd seen the bit about RCDs on the Hager website, which reads: Amendment 2 also introduced the requirement to individually protect the car charger with an RCD so this RCD should not serve circuits in addition to the car charger.
My arrangement is similar to yours except the garage is attached to the house and the cable run from the house CU to the garage is about 15 metres. The PE rod is near the main CU so if I have a charge point in the garage should I be installing another earth rod adjacent to the garage?

 

The quote I gave is verbatim from the actual regs, BS7671, Section 722.