DIY charge point

[NewbieT]

When I saw this thread I was nearly inspired to build an EVSE with a Raspberry Pi for Agile charging (to bypass the API).

Whilst I’m capable of building an EVSE, I’m not sure I can be bothered. Similar reason as the OP re: maintaining code plus I already have a PodPoint. You can see why Tesla came up with the granny cable & adapters.

 

[Glan gluaisne]

This is my portable box build years ago

I set myself a challenge for the first portable charge point I built, fit the entire thing, minus the protection components, inside a Type 1 connector. I used an 8 pin PIC on a tiny, slimline, PCB, with a small encapsulated power supply and separate 16 A relay. The only giveaway from outside that the EVSE was inside the connector were the two small LEDs fitted to it. I fitted a long (around 15m) mains cable to this EVSE in the connector, with and RCD inline at the plug end. I used this for around 5 years to charge my PHEV Prius without any problems. It wasn't compliant with what was then the IET requirement for any OLEV funded charge point, the requirement that's now been included in BS7671:2018, but the garage supply I plugged it into was wired as a TT installation anyway, so the only real risk was DC blinding of the RCD. As it was only me using it I just accepted that risk at the time.

I made a second one of these, with a much longer cable, to charge the car when away from home, as it was easier to use than a conventional brick-type granny lead. As the PHEV Prius only charged at 10 A maximum, the lead didn't need to be very heavy duty, which made it easier to lug around. I think I still have the remnant of that EVSE around somewhere, although I think I stripped the power supply out of the connector to re-use for something else. I found a copy of the PCB layout for it (for scale it's about 20mm wide and 60mm long, all through hole components):

 

[Glan gluaisne]

Got distracted by going flying yesterday, but finished off the box and tested it fully this afternoon, so it's now ready to install. I just need to swap over the tethered lead from the old box it's replacing and tidy up the run of NYY-J* cable that supplies it, that will also be swapped over to this box:

* I ran NYY-J cable, rather than SWA, to this charge point location as the run is in a conduit along a low fence, and didn't need the added mechanical protection that SWA offers. It's also a great deal easier to work with NYY-J cable than SWA, so nine times out of ten I'll choose to use this for outdoor cable runs that aren't likely to get cut through by something. NYY-J cable is as tough as old boots, anyway, and is fine for most runs that are just clipped to outside walls, IMHO. I've never really understood why so many electricians use SWA in installations where it's not really needed.

 

[pdk42]

Has anyone got an OpenEVSE box? Wondering if there are any compatibility issues with a Model 3...

 

[Glan gluaisne]

Has anyone got an OpenEVSE box? Wondering if there are any compatibility issues with a Model 3...

Answered in the other thread, but the Open EVSE works just like every other charge point that's IEC61851 compatible, so is fine with all EVs, including Teslas. Not sure if it has DC tolerant RCD protection, though, and I'm certain it doesn't have open PEN protection, so the Viridian module is a better bet in that respect.

 

[pdk42]

Answered in the other thread, but the Open EVSE works just like every other charge point that's IEC61851 compatible, so is fine with all EVs, including Teslas. Not sure if it has DC tolerant RCD protection, though, and I'm certain it doesn't have open PEN protection, so the Viridian module is a better bet in that respect.

I have a TT installation so the open PEN protection isn't an issue, but I guess the DC protection is still an issue (but then again, the professionally-installed EVBox I have now doesn't have DC protection either and they didn't fit a suitable RCBO).

 

[Neilman]

@Glan gluaisne , you mentioned a "charge point test simulator box" earlier in this thread.
Is this something you can use on any charge point to test it and, if so, do you have the plans available for one?
Not sure I'd build one but I'm certainly interested in it.

 

[Glan gluaisne]

@Glan gluaisne , you mentioned a "charge point test simulator box" earlier in this thread.
Is this something you can use on any charge point to test it and, if so, do you have the plans available for one?
Not sure I'd build one but I'm certainly interested in it.

Yes, it will test any charge point. It's not possible to do a charge point installation in accordance with the regs without one, as it's needed to both functionally test the charge point and allow a connection point downstream of the charge point contactor to allow proper testing. Easy enough to build one, just a box with a Type 2 connector and a handful of passive components. Mine has a 13 A outlet on the front that allows a normal multifunction tester, as used to test the rest of an electrical installation, to be plugged in. It also has break out connections so that the control pilot and proximity pilot lines are available easily:

 

[Glan gluaisne]

I've just scribbled down a rough schematic for what's inside this test box. It follows the vehicle end diagram that's in IEC61851 and J1772, with test buttons to simulate fault conditions and switches to simulate the vehicle being plugged in and requesting a charge. The test equipment connection points aren't needed, I fitted them mainly so that I could hook kit up to the control pilot to see what it was doing. For normal testing they aren't needed.

The charge point should behave like this when plugged into the box:

All switches off, charge point plugged in, no charge power and charge point should sit in the idle state, with the contactor open and no power at the 13 A outlet.

Plugged in switch on, charge request off, charge point should be in the "ready to charge" state, with the CP at 1 kHz, duty cycle indicates available maximum current. Contactor should remain open, with no power at the 13 A outlet.

Plugged in, switch on and charge request switch on, charge point contactor should close, switching power on to the 13 A outlet and illuminating the "charging" panel light.

Pressing either of the fault condition test buttons should cause the charge point to trip out, cutting power.

 

[dakaix]

Has anyone got an OpenEVSE box? Wondering if there are any compatibility issues with a Model 3...

I built an OpenEVSE charger in the summer, I tested it on a temporary 16A commando and it worked perfectly with my Model 3. Just waiting on the final external cabling run to finish the installation now.

Which reminds me:
@Glan gluaisne: Are there any regulatory issues that I would need to be aware of with using clipped H07RN-F for the final 10m around the wall of a house? My 6mm SWA will be terminating into a small enclosure (for the Type B RCD) at the back, but it needs to negotiate one 90 degree corner to reach the drive, NYY-J and SWA all have too large bend radii.

 

[Glan gluaisne]

@Glan gluaisne: Are there any regulatory issues that I would need to be aware of with using clipped H07RN-F for the final 10m around the wall of a house? My 6mm SWA will be terminating into a small enclosure (for the Type B RCD) at the back, but it needs to negotiate one 90 degree corner to reach the drive, NYY-J and SWA all have too large bend radii.

As it will be protected by an RCD at that point, then there's no problem at all with running heavy duty flex for that final run. The only issue is really an aesthetic one, in that flex that's clipped direct often looks a bit untidy. An alternative might be to run 20mm conduit around that sharp bend and up to the charge point, and then use 6mm² equipment wire inside the conduit.

 

[Bernard_S]

My 3 year old Rolec charger has tripped the RCBO a couple of times in the last few months. I suspect it might be the low quality part that they fitted. It is the later blue one but I suspect it's Chinese. What's the best (but not over top expensive) supplier and part number to use ? I may as well replace the contactor while I'm at it.

 

[dakaix]

As it will be protected by an RCD at that point, then there's no problem at all with running heavy duty flex for that final run. The only issue is really an aesthetic one, in that flex that's clipped direct often looks a bit untidy. An alternative might be to run 20mm conduit around that sharp bend and up to the charge point, and then use 6mm² equipment wire inside the conduit.

What a happy co-incidence then that the enclosure ended up where it has! It was only the possibility of needing a future garden/workshop supply which decided it... along with the side effect of allowing an earth rod in the garden instead of drilling through the tarmac on the drive. Thanks for confirming, and the idea of using equipment wire in conduit - that wasn't a possibility I had considered. Would look substantially neater too, albeit with the downside of being slightly more effort to remove for any future house move....

 

[Glan gluaisne]

My 3 year old Rolec charger has tripped the RCBO a couple of times in the last few months. I suspect it might be the low quality part that they fitted. It is the later blue one but I suspect it's Chinese. What's the best (but not over top expensive) supplier and part number to use ? I may as well replace the contactor while I'm at it.

Garo make reliable and decent quality RCBOs that are a drop in replacement for the SP+N ones normally fitted to Rolec units: Garo RCBO 1+N 40A char B 6kA Type A

The contactor is usually OK in the Rolec units, at least I've not heard of them failing, and they don't have a hard life anyway, as they only get operated a few dozen times a year, usually.

 

[Bernard_S]

Garo make reliable and decent quality RCBOs that are a drop in replacement for the SP+N ones normally fitted to Rolec units: Garo RCBO 1+N 40A char B 6kA Type A

The contactor is usually OK in the Rolec units, at least I've not heard of them failing, and they don't have a hard life anyway, as they only get operated a few dozen times a year, usually.

The installer only used 4mm^2 cable, is 40A rating ok on that ? Or should I use 32A ?

You are right about the contactor of course, I thought while Ive got the cover off......

Thanks

 

[Glan gluaisne]

The installer only used 4mm^2 cable, is 40A rating ok on that ? Or should I use 32A ?

You are right about the contactor of course, I thought while Ive got the cover off......

Thanks

It should be wired with 6mm² really, but 4mm² is just about OK. Clipped direct 4mm² is rated at 36 A, but the supply cable isn't protected by the RCBO in the charge point, it's protected by the MCB at the supply end but using a 32 A RCBO would be a better bet: Garo 32 Amp RCBO, 2 Module, 2 Pole, Characteristic C 6kA Type A .

IIRC, Rolec charge points are set to 30 A maximum charge, rather than 32 A. They normally use the Mk 1 version of the Viridian EVSE controller module usually, sometimes re-badged Rolec, this unit: Viridian EV EVSE Protocol Controller Tethered

 

[MrBadger]

IIRC, Rolec charge points are set to 30 A maximum charge, rather than 32 A.

We get 32A on one installed early this year.

 

[pdk42]

Slightly off topic question... I have a dumb charger and would like to add some simple timing capability. I'm considering swapping the unit for either an OpenEVSE or maybe another commercial unit, but a thought crossed my mind, based on an application note for the QUBEV charger. That has a timer option shown that works by simply putting a timed switch into the CP line. So in other words, it simply leaves the CP open circuit until the allocated time.

Looking at the IEC spec, that's not how it should be done, but I guess it ought to work. Given the expertise of the contributors here, what are your thoughts?

I can see that there will be questions about whether the car will wake up or not (I'm talking about an ID.3), but I'm wondering if there are other gotchas.

 

[MrBadger]

Slightly off topic question... I have a dumb charger and would like to add some simple timing capability. I'm considering swapping the unit for either an OpenEVSE or maybe another commercial unit, but a thought crossed my mind, based on an application note for the QUBEV charger. That has a timer option shown that works by simply putting a timed switch into the CP line. So in other words, it simply leaves the CP open circuit until the allocated time.

What about adding it via the API ? TeslaFi does it off the shelf under settings/notifications and I am sure others would too. Or custom script - I'm sure you would be able to find something even if you didn't write it yourself.

The only thing that the API cannot help with is setting charge rate.

 

[pdk42]

What about adding it via the API ? TeslaFi does it off the shelf under settings/notifications and I am sure others would too. Or custom script - I'm sure you would be able to find something even if you didn't write it yourself.

The only thing that the API cannot help with is setting charge rate.

Thanks, but I'm doing this to work with my wife's new ID.3, not the Tesla. That doesn't yet support scheduled charging (supposedly due in Jan/Feb), so I'm looking for an interim solution.