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I’ve got a 2016 Zoe and often use a free Podpoint charger at a local retail park, but after attempting to charge it several times, it won’t charge, and the car keeps saying Check Connection. I've tried both side of the charging point. It charges fine at home and everywhere else, but not here. A Tesla has also just plugged in next to me and is charging fine. I’ve rang Podpoint each time, and they reset the Podpoint, but still nothing. I rang them again today, and after another reset, it's still not working; they said the unit was charging fine this morning, so it’s not the charging point, but there are often issues with Zoe’s and Podpoints.
Any ideas?
 

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Possibly just that Ra is too high at that charge point. The Zoe does an earth loop impedance check before it starts to charge, and if the measured value is too high (>150 ohms) the car won't charge. The UK requirement is for Ra to be below 200 ohms for a TT installation (and a public charge point will almost certainly be connected as TT), so it's possible to have an installation that complies with UK wiring regs but which doesn't pass the Zoe pre-charge test.

This will possibly be worse in dry weather, when Ra tends to rise as the soil dries out, so you can get a fair bit of variability. If you can see the earth electrode pit, then pouring water around it may get Ra down enough to get it to pass the test. Electricians have been known to pee around earth electrodes before now to get a good reading . . . .
 

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Thanks, but I'm not electrically minded in any way! From you message, it sounds like Zoe's are known to have issues with Podpoints. Why would it have worked at this point before?
Is there anything I can do to mu car?
 

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Thanks, but I'm not electrically minded in any way! From you message, it sounds like Zoe's are known to have issues with Podpoints. Why would it have worked at this point before?
Is there anything I can do to mu car?

No, nothing to do with the make of charge point. The Zoe is sensitive to earth loop impedance, that's all. It's the only EV I know of that does this safety test before it starts to charge, and a very good test it is too. The snag is that it refuses to charge if the impedance measured is greater than 150 ohms, but that here in the UK the normally allowed value for the resistance of the earth electrode is not greater than 200 ohms. That means that any installation that has a high, but acceptable (in UK regs terms) value of Ra (the resistance of the earth electrode) may cause a Zoe to fail to charge.

It doesn't happen often, as most installations tend to have a value of Ra that's well below the nominal 200 ohm limit. For example, the charge point I installed for my wife's Zoe has an Ra of 24 ohms, well below the maximum.

The weather can cause the resistance to change, simply because very wet soil tends to be more electrically conductive than very dry soil. So if the soil around the electrode dries out a bit, the resistance tends to rise a bit.

There's nothing that can be done to change this in the Zoe, it's a key safety check, and is fixed at 150 ohms.

Out of interest, is this location likely to be on sandy or gravelly soil? Very free draining soils can cause the resistance to increase a fair bit when they dry out.
 

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Thanks, but I'm not electrically minded in any way! From you message, it sounds like Zoe's are known to have issues with Podpoints. Why would it have worked at this point before?
Is there anything I can do to mu car?
Renaults are known to have issues with many charge points, it's not limited to Pod Points. As has been said, Renaults are rather fussy about the earth connection, more fussy than the UK wiring regulations. I think the French wiring regs are fussier than the UK.
Yes, certain charge point installations may raise issues with Renault vehicles (the Twizy is as bad as the Zoe in this respect), and the one that you have encountered happened to be made by Pod-Point. The fact that there's a Pod-Point there is irrelevent. It's down to the electrician who did the install and whether they achieved a good earth connection, or a really good earth connection.
As Jeremy suggested above, if a earthing rod was installed in soil that drains well (e.g. sandy soil), then the earth rod won't be as effective as one that is surrounded by water.
 

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I've also had issues with free vend PodPoints - RSPB Minsmere never works, Sheringham Park failed to start and Felbrigg sometimes works. I know not to rely on them which was a problem when I had a Zoe 22.
 

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I've also had issues with free vend PodPoints - RSPB Minsmere never works, Sheringham Park failed to start and Felbrigg sometimes works. I know not to rely on them which was a problem when I had a Zoe 22.
I've been to two of those sites, and both of them have very sandy soil, so it would be difficult to install an earthing rod that would meet Renault's expectations.
I wonder how the installers cope in France, where they have fussier electrical installation regulations? Much longer earthing rods? Multiple earthing rods?
 

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I've been to two of those sites, and both of them have very sandy soil, so it would be difficult to install an earthing rod that would meet Renault's expectations.
I wonder how the installers cope in France, where they have fussier electrical installation regulations? Much longer earthing rods? Multiple earthing rods?

Just use a mat or grid, or even a condudisc or just a lump of conductive concrete. The issue is getting enough surface area, and this is easy enough to get if you break away from the UK domestic obsession with banging rods into the ground. Every sub-station, mobile mast and other big comms installation will have earthing mats with a very low value of Ra. This site, for example, lists some affordable ways to get a good earth electrode installation for a charge point installation: Earthing Materials – Churchill Specialist Contracting
 

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No, nothing to do with the make of charge point. The Zoe is sensitive to earth loop impedance, that's all. It's the only EV I know of that does this safety test before it starts to charge, and a very good test it is too. The snag is that it refuses to charge if the impedance measured is greater than 150 ohms, but that here in the UK the normally allowed value for the resistance of the earth electrode is not greater than 200 ohms. That means that any installation that has a high, but acceptable (in UK regs terms) value of Ra (the resistance of the earth electrode) may cause a Zoe to fail to charge.

It doesn't happen often, as most installations tend to have a value of Ra that's well below the nominal 200 ohm limit. For example, the charge point I installed for my wife's Zoe has an Ra of 24 ohms, well below the maximum.

The weather can cause the resistance to change, simply because very wet soil tends to be more electrically conductive than very dry soil. So if the soil around the electrode dries out a bit, the resistance tends to rise a bit.

There's nothing that can be done to change this in the Zoe, it's a key safety check, and is fixed at 150 ohms.

Out of interest, is this location likely to be on sandy or gravelly soil? Very free draining soils can cause the resistance to increase a fair bit when they dry out.
Wow some fantastic info there out of interest how do you measure the Earth impedance? So no greater than 200ohms interesting
 

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Wow some fantastic info there out of interest how do you measure the Earth impedance? So no greater than 200ohms interesting

The classic way (and the way I still do it, being old school) is to use a three or four terminal earth electrode tester. This uses additional earth spikes that get put in the ground some distance from the earth electrode. It runs a current through the electrodes and allows the true resistance of the electrode to earth to be measured. This is the true value of Ra that should go down on the installation certificate.

Nowadays, few bother to do it properly, and just use the Ze measurement function on a multi-function tester (MFT). This measures the earth loop impedance, so the impedance from the supply back through the earth electrode, through the ground and back to the local substation. This is close to being the same as Ra, but is technically an indirect measurement, but most will still put that measured value down as Ra on the chit, and it's generally accepted as being close enough, as the impedance of the supply cable will usually be very low in comparison to the electrode resistance (typically a couple of tenths of an ohm or so).

The Zoe measure Zs in exactly the same way as an MFT. It pulses a current from the supply to earth, for a short enough period of time to not trip an RCD, and uses that short current pulse to measure Zs. It's Zs, rather than Ze, as the Zoe measures it at the car, not at the incoming supply (Zs includes the impedance of the cable etc).

The regs imply that a value of Ra up to 1667 ohms is actually OK, as they define Ra as being the resistance needed to ensure that the touch voltage of any exposed conductive parts doesn't exceed 50 VAC before any residual current/earth leakage protection device trips the supply off. This RCD trip current is not greater than 30 mA, so from Ohms law, 50 V / 0.03 A = 1,667 ohms. In practice, allowing Ra to be this high when tested, given that it will vary a fair bit with whether the soil is wet or dry, means that a lower limit has been set in the guidance to applying the wiring regs, the On Site Guide. That suggests that 200 ohms is a safe maximum when testing, to give a large margin for variability.
 
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