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Discussion Starter · #1 ·
Hi
I’ve owned several EVs and had my Ohme smart charger for a year now with no problems. Just got a Zoe and it won’t charge at all on the Ohme charger according to the schedule. It knows it’s plugged into the Ohme and there are no errors I can see but Ohme doesn’t deliver any charge at all and states it has an error is the car fully charged.

It must be something I am doing but for the life of me I can’t figure it out!! The schedule is right on the Ohme and the car is set to instant. The car charges fine in public charging so no issues there.

If any of you have any ideas I’m all ears!
 

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Tesla Model 3 LR AWD, Renault ZOE R135 ZE50 GTLine (Sold: R90 ZE40 i Dynamic Nav)
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You say it won't charge to the schedule. I assume it does charge if both the charge point and car are set to always charging?
 

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Discussion Starter · #3 ·
That’s what I’m just testing now but I think so based on the fact it will public slow and fast charge so I think it’s something to do with the delay between plugging in and charging starting
 

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As above, and is the Ohme registering the SoC in the new Zoe and not the previous car?
 
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Discussion Starter · #6 ·
So yes it all registered fine and no issues with them recognising each other. I’ve just jumped in the car and when I plug in it says earth insulation not appropriate and then keeps trying for a bit and fails? Charger was professionally installed and earth rods used and checked at the time
 

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So yes it all registered fine and no issues with them recognising each other. I’ve just jumped in the car and when I plug in it says earth insulation not appropriate and then keeps trying for a bit and fails? Charger was professionally installed and earth rods used and checked at the time

The wiring regs (well, really the On Site Guide to the wiring regs) only require that the value of Ra, the resistance of the earth electrode to local earth, be less than 200Ω. The Zoe needs the earth loop impedance that it measures before starting to charge (and which includes Ra as a part of that series earth circuit) to be less than 150Ω. This means that a Zoe can refuse to charge unless the earth electrode resistance is lower than 150Ω.

If you can see the earth electrode pit, lift the lid and pour some water around the rod. That should temporarily lower Ra and may get the Zoe to charge. The long-term fix is to get a better earth electrode installed. I recently installed a Condudisc for a hot tub and was impressed with the low Ra, much lower than would normally be seen from a rod electrode. Alternatively, it may be that the rod you have could be driven deeper, with an extension on top. Might be a simpler fix as long as the longer rod will drive in OK.
 

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Co-author of CanZE. Q210 nov 2013
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Please state your car type and if possible the software drop of the LBC, i.e through CanZE (SSP). What @Jeremy Harris said is true, but older drops in older model had 100 instead of 150 as the limit; you are looking at pre ZE50 cars with an LBC "soft" field value of lower than 0854.

If you have access to the rod, dump a bucket of water with some salt in it over it. No, that is probably not a permanent solution but if it solves things, you confirmed what the issue is. Thing is also, a dodgy earth connection, i.e. a single screw clamp not tightened properly, can wreak havoc but you would never know. So consider this problem irritating but a GOOD THING. Earthing, especially through local rods is close to a black art (hip hip hooray for TS-N-C grid networks), and ZOE is a charger tester on wheels first, a nice EV next. It will not compromise.
 

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It’s a ZE50 2021 model so should be 150 limit then. I will try the salt water now and see if that makes a difference

I'd just use tap water, definitely not salt water, as the rod earth electrodes we use in the UK are made of copper-coated steel, so salt water may cause corrosion of the steel in any scratched areas (and it will be scratched from driving it in).
 

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Renault Zoe Intens Q210 22kw 2013
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what if another earth lead was attached to that earth rod in the ground and brought right back to the main consumer box in the house on the earth busbar (assuming your house earth is TN−C−S where the earth goes on the N at the substation or in the meter box)
 

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Usual way to get Ra down is to just remove the clamp where the wire attaches, screw on an extension rod, drive that fully down, then re-attach the cable clamp and wire. Adding another wire has no real effect, as 99.99% of the resistance is between the surface area of the rod and the soil. That's why adding an extension rod works most of the time, as it increases the surface area.

If a rod can't be driven deep enough, perhaps because of underlying rock, then the best solution is to go for either a mat, like this: https://www.churchillsc.co.uk/product/earth-mat-lattice-copper/ or a Condudisc: ConduDisc - Earthing Services

The other way I've done it in the past is to dig a narrow horizontal trench, maybe 400mm to 500mm deep and lay a couple of metres of 25mm wide copper earth strap horizontally in the bottom. This trick often works well if the soil is reasonable and the problem is not being able to get enough depth. The DNOs do much the same now with underground cable joints, where they will sometimes add an intermediate using a copper strap in the bottom of the trench.

Must be the rod as just done the above with tap water and car charging with no problems. Contacted the installer. I’ve had the charger for a year but they should be expected to rectify the problem yeh?

Unfortunately the issue is with the Zoe (very sensibly) choosing to only accept a lower earth loop impedance than is required by UK wiring regs, so I doubt that this is something that falls within a charge point warranty. France has tighter regulations on earth loop impedance, as they tend to use TT earthing a lot, and EDF fit every installation with an disjoncteur différentiel (a big RCBO in English) on the incoming supply. IIRC, the limit for Ra under French wiring regs is lower than here, I think it may well be because the EDF RCBOs are set to trip at a higher current (500mA rings a bell, but I may be wrong).
 

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Tesla Model 3 LR AWD, Renault ZOE R135 ZE50 GTLine (Sold: R90 ZE40 i Dynamic Nav)
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I think one of @Jeremy Harris's suggestions should work for you.

However, if they don't, how is the incoming supply earthed? If it's TN-C-S (with earth and neutral combined in the incoming cable), as many UK properties are, then the charge point may have been installed with a separate TT earth (ground rod) and not connected to the incoming earth. If that is the case, then I think you could consider disconnecting from the ground rod and connecting back to the incoming earth. Have a PEN fault protection unit installed in front of the Ohme charge point. That should give a low enough ground resistance and meet the 18th edition of the regs. I'm not a qualified electrician and the above is just my understanding - you should get it confirmed.
 

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Co-author of CanZE. Q210 nov 2013
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It’s a ZE50 2021 model so should be 150 limit then. I will try the salt water now and see if that makes a difference
Got it. Nil my LBC firmware comments then, not valid for ZE50 anyway.

So definitely confirmed earthing. Good, at least a valid path now.

IMHO, but no sparky either, @cDy is on the spot. Assuming you are not connected through an ancient grid connection, it's likely you have a TN-C-S type. In far too simple terms it means that earth is provided by the grid operator through their cabling and in that case I think it is kinda weird to use a separate rod. If for some reason a rod is needed, yes, your sparky simply needs to do better. And indeed that can be a bit of a PIA. At least you have a temporary solution now, keep full bucket at hand ;-)
 

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Although this all appears to be understood and now resolved, I do find it slightly amusing that the solution to a charging problem is to pour a bucket of water on it. Context is everything in this case, but it does just sound so wrong when talking about EVs

Is this going to be the new standard call when it comes to Zoe's rather than the normal turn it off an on again 🙃
 

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Renault Zoe Intens Q210 22kw 2013
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if installer has run the cable from the consumer box anyway in that twin and earth cable (armoured/SWA/steel wire armoured) will be an earth back to the consumer unit anyway , and i should be earthed with the steel wire braiding as well as the green and yellow earth wire as well
 
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