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EV Charger relay strange behaviour

Snagsy1980

New Member
Hello,

I have a Shell NewMotion Advanced EV chargepoint installed at my house. It's wired into a GARO unit which has an RCBO B40AS and a GK40 4NO relay before it hits the main fusebox of the house into a fusebox B32 MCB.

The problem i'm seeing is the relay in the GARO unit, it's energising and de energising at seemingly random times. So for example if the RCBO is tripped on the GARO and the MCB is tripped, MCB powered on then RCBO powered on the light comes on but it doesn't energise the relay, if i do it again a few moments later it may energise the relay when that's done.

The GARO unit has been changed 2 times now but this weird behaviour isn't going away. can someone help me to troubleshoot it?

I didn't install this btw, it was done by a firm who specialise in EV charger installs. I am not an electrician but i do understand electrics, i'm a former RAF avionics engineer who served 10 years and left in 2007 so electrical theory and repairs was a LONG time ago :D
 

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rjenkinsgb

Well-Known Member
Most Helpful Member
That DUA55 unit is monitoring the mains supply voltage and switching on if it is within a set tolerance of whatever the installers configured it for.

The plate at the bottom should unclip and allow you to see the setting switches.

Data sheet here:

I'm guessing it's set to 230V +/- 10% as that is what the Newmotion charge point data says it requires.

The formal permitted range in the UK is 230V +10% / -6%, to include the traditional UK 240V system.

If the voltage relay is correctly set for 230V 10% then you need to contact your electricity supplier and complain that the voltage is going out of specification.

(Or you have something causing heavy interference / voltage spikes?)
 

Snagsy1980

New Member
That DUA55 unit is monitoring the mains supply voltage and switching on if it is within a set tolerance of whatever the installers configured it for.

The plate at the bottom should unclip and allow you to see the setting switches.

Data sheet here:

I'm guessing it's set to 230V +/- 10% as that is what the Newmotion charge point data says it requires.

The formal permitted range in the UK is 230V +10% / -6%, to include the traditional UK 240V system.

If the voltage relay is correctly set for 230V 10% then you need to contact your electricity supplier and complain that the voltage is going out of specification.

(Or you have something causing heavy interference / voltage spikes?)
My friend, you are a legend. I popped the cover off and it was set to 230 v so i've upped it to 240 +/- 15% voltage window and the relay seems to be holding so far
 

Nigel Goodwin

Super Moderator
Most Helpful Member
My friend, you are a legend. I popped the cover off and it was set to 230 v so i've upped it to 240 +/- 15% voltage window and the relay seems to be holding so far
Presumably you're in the UK? - the mains here is 240V, so it should be set to that, not to 230V.

The 230V is really just an equipment specification, so that any products intended for use in the EU will work on either 220V or 240V, although I believe some countries have actually changed to 230V.

Historically, European equipment tended to fail a lot in the UK, due to the slightly higher mains voltage - and mains transformer failure was common.
 

Snagsy1980

New Member
Presumably you're in the UK? - the mains here is 240V, so it should be set to that, not to 230V.

The 230V is really just an equipment specification, so that any products intended for use in the EU will work on either 220V or 240V, although I believe some countries have actually changed to 230V.

Historically, European equipment tended to fail a lot in the UK, due to the slightly higher mains voltage - and mains transformer failure was common.
Yep Nigel, i am UK based. I'm surprised that the installers haven't seen this before mind you but I was happy to give it a go myself and it seems to have worked!.
 

rjenkinsgb

Well-Known Member
Most Helpful Member
it was set to 230 v so i've upped it to 240 +/- 15% voltage window and the relay seems to be holding so far
OK, but that means your mains supply is going out of the range the electricity companies are permitted to supply.

If it's excessive, it may damage the charger, vehicle or other equipment; 230 +10% permits up to 253V and if it's shutting off at that, the voltage could be far higher...

The new setting will permit up to 276V !
 

Diver300

Well-Known Member
Most Helpful Member
OK, but that means your mains supply is going out of the range the electricity companies are permitted to supply.

If it's excessive, it may damage the charger, vehicle or other equipment; 230 +10% permits up to 253V and if it's shutting off at that, the voltage could be far higher...

The new setting will permit up to 276V !
It is incredibly rare for the mains voltage in the UK to go very high, and hardly any appliances have over-voltage protection because it is not needed. Your last sentence makes it sound as though excursions to far too high a voltage are common.

The upper limit that the voltage relay is set to is now nominally 276 V, but the voltage is not going to get there, and even if it does, the vehicle will most likely just work fine, or it might shut down.

230 V +10% should be the upper limit to the supply voltage, but it seems silly to set a cut-out at exactly that limit, as there will be tolerance in the sensing relays. I've just measured the voltage in my house in the UK, and it's around 245 V, but I am not going to get paranoid about the fact that my laptop charger is rated for 100 - 240 V.
 
Last edited:

Nigel Goodwin

Super Moderator
Most Helpful Member
It is incredibly rare for the mains voltage in the UK to go very high, and hardly any appliances have over-voltage protection because it is not needed. Your last sentence makes it sound as though excursions to far too high a voltage are common.

Yes, the UK has probably the best electrical infrastructure in the world, and faults (particularly high mains voltage) are incredibly rare. I don't think I've ever seen an appliance with over-voltage protection?, presumably the EV charger has it because it's a world-wide product, and some countries have abysmal quality mains.

Historically (going back decades) we used to get occasional mains issues at work - one was low mains, and this was as a result of a new housing estate been built where never planned, and taking the mains from the feed to an existing street, which was only sized to feed that street. Eventually, they dug the road up, and upgraded the main feed down the road.

Another, one of, was a house with high mains - his (valve) TV was 'doing funny things' and when our engineer went out he checked the mains and found it to be excessive. We rang the Electricity Board (that's how long ago it was) and they came out and fixed it the same day.

The vast majority of issues though is idiots in diggers going through under ground cables!.
 

rjenkinsgb

Well-Known Member
Most Helpful Member
230 V +10% should be the upper limit to the supply voltage, but it seems silly to set a cut-out at exactly that limit,

I've seen several places with extreme voltage variations; typically near large industrial sites, that have high consumption and variable loads.

230 +/- 15% would be a rather safer setting; 240 +/- 15% seems extreme, and if it's getting anywhere near that, you have grounds to complain to the distribution company.

Technically, if a fault does occur with the charger or the vehicle charging system, the warranty may be void if it was connected to an out-of-tolerance system.

Voltage limits are set in stone by UK statute law:
 

Nigel Goodwin

Super Moderator
Most Helpful Member
I've seen several places with extreme voltage variations; typically near large industrial sites, that have high consumption and variable loads.

230 +/- 15% would be a rather safer setting; 240 +/- 15% seems extreme, and if it's getting anywhere near that, you have grounds to complain to the distribution company.
As UK mains is 240V it seems silly setting the centre voltage to 230V?. If you want a lower top voltage, then reduce the tolerance.
 

Diver300

Well-Known Member
Most Helpful Member
As UK mains is 240V it seems silly setting the centre voltage to 230V?. If you want a lower top voltage, then reduce the tolerance.
In the legislation rjenkinsgb quotes, the supply is 230 V +10% -6%. However, that is "Unless otherwise agreed" and for new installation only, and as the terms and conditions for electricity supply will be many pages, it could well be that many supplies are allowed to go well over 253 V and still be within the whatever is agreed.

I've spent about 10 minutes looking for what the agreed voltage is on my energy supplier, and I can't find it. I also couldn't find what voltage range my EV is rated at, but energy suppliers and car manufacturers are both good at having pretty websites with no information.

I think that damaging an electric car through overvoltage when plugged into a standard UK domestic supply is a danger so unlikely that it doesn't need worrying about.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
In the legislation rjenkinsgb quotes, the supply is 230 V +10% -6%. However, that is "Unless otherwise agreed" and for new installation only, and as the terms and conditions for electricity supply will be many pages, it could well be that many supplies are allowed to go well over 253 V and still be within the whatever is agreed.

I've spent about 10 minutes looking for what the agreed voltage is on my energy supplier, and I can't find it. I also couldn't find what voltage range my EV is rated at, but energy suppliers and car manufacturers are both good at having pretty websites with no information.

As I've said already, the target mains voltage in the UK is still 240V, as it's always been - the supposed 230V and offset tolerance is simply to 'pretend' that's it's 230V, which is only really an equipment specification. Likewise it's the same on most of the continent, where their -10%, +6% 'pretends' their 220V is 230V.

I think that damaging an electric car through overvoltage when plugged into a standard UK domestic supply is a danger so unlikely that it doesn't need worrying about.

Why would you imagine it might damage an electric car? - surely the VERY, VERY expensive charger would take account of that anyway - it's not just sticking raw mains straight across the batteries.

The protection in the charger is to protect the charger, when used in areas with really poor mains supplies.
 

Diver300

Well-Known Member
Most Helpful Member
Why would you imagine it might damage an electric car? - surely the VERY, VERY expensive charger would take account of that anyway - it's not just sticking raw mains straight across the batteries.
I think that there is a terminology problem here. By "electric car" I was including the AC charger that is inside the car somewhere. I guess that the AC charger inside the car would be the first part to be damaged by an overvoltage if that happened during AC charging.

The DC high power chargers at motorway service areas are different.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
I think that there is a terminology problem here. By "electric car" I was including the AC charger that is inside the car somewhere. I guess that the AC charger inside the car would be the first part to be damaged by an overvoltage if that happened during AC charging.

The DC high power chargers at motorway service areas are different.

I was presuming that there's considerably more in an electric 'charger' at home, than just a mains connection - there's certainly a degree of feedback to control the charging current. If charging from a 13A socket, then of course it's just a wire, with the only charger in the car.

Funnily enough I was watching a video on YouTube about a guy trying to control his home charger from an Arduino or something?.
 

Diver300

Well-Known Member
Most Helpful Member
An EVSE (Electric Vehicle Supply Equipment) is a switch that turns the power on and off. It only turns on when requested by the vehicle. The EVSE also measures a resistor in the lead which indicates the current rating of the lead. It then tells the vehicle how much current it is allowed to take, depending on that resistor and what size supply it is connected to, which is pre-programmed on installation, or set for the plug on the end if it's a portable EVSE.

So the EVSE can't control the charging. It can only request that the vehicle limits its charging current to a certain current, but unless the vehicle does something it shouldn't,

The connection to the car is AC plus some signal voltages at less than 12 V.

Portable EVSEs will usually measure the temperature of the plug where they plug into the wall, so they can reduce the power or turn off if the plug gets too hot.

It is quite easy to emulate the signal voltages to get the vehicle charger to alter the charging rate. The Arduino control would be like that. It's probably not inherently dangerous as it would all be low voltage, and cars can rarely take more than 32 A at 240V, and domestic EVSEs will normally be rated to that, so it's difficult to overload anything. The vehicles will, of course, stop the charging when the batteries are full.

The DC chargers at motorway service areas are serious cost, size and weight. One that I charged at would do two vehicles and it said it weighed 350 kg or something like that. It makes much more sense to rent space on one them than it does to carry one around in a car. Also, they can deliver much more power than domestic electricity supplies can deliver, making the idea of having one in a house completely useless. The really big ones have water cooling of the vehicle plug.

The DC charger connects to the battery using different pins (usually) than are used for AC. The vehicle signals what charging voltage / current is requested, but the vehicle cannot actually control the charging.

The YouTuber "Technology Connections" explained EVSEs quite well.
 

Snagsy1980

New Member
UPDATE. The DNO have been (Southern Electric) they caught the voltage going from 248 up to 251 and that was enough to recommend a voltage monitor being fitted for a week (no date for that yet). The chap who was here said the permitted range is 216-253v but he said the main problem they have is houses with solar panels when it's v sunny vs v cloudy as they have trouble balancing the load. I have a house opposite in front and at the back of my property that have solar panels so i guess that may be where the issue lies. He said they'll normally come and fit a step-down transformer depending on how close we are to the main one for the street.

Since reading through the replies on this thread i changed the dip switches so it's 230 V + or - 15% and yesterday the relay de energised a couple of times, once in the morning and 2 times later in the day/evening which supports the solar panel theory but also that the voltage is going above 264.5 which is kinda worrying. I'd love to know what it's topping out at but i dont have a meter and we won't know until the voltage monitor is fitted...

Developing story :)
 

Diver300

Well-Known Member
Most Helpful Member
It's good that you've found a probable cause. You don't know how accurate the voltage monitor is, and the tripping out voltage will not be exactly 264.5. I would guess it would be within about 5 V of that. Also the monitor may be sensitive to fast voltage spikes.

The EVSE and the charger within the car are unlikely to be damaged at voltages like that. Other electronics is more likely to be damaged, but I still think that it's not a real problem.
 

Snagsy1980

New Member
It's good that you've found a probable cause. You don't know how accurate the voltage monitor is, and the tripping out voltage will not be exactly 264.5. I would guess it would be within about 5 V of that. Also the monitor may be sensitive to fast voltage spikes.

The EVSE and the charger within the car are unlikely to be damaged at voltages like that. Other electronics is more likely to be damaged, but I still think that it's not a real problem.
Yeah it's being supplied and fitted by the DNO so you'd hope it's decent..

The spikes, if i think about the relay behaviour, are not fast, they can last a while so that shouldn't be a problem.

That makes sense and so far (fingers crossed) there isn't anything that's gone in the house. the things that run in the day are computers (because we are working from home) and the washing machine.

I've not long had my fusebox upgraded as well so it does have surge protection, if that's helpful at all.
 

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