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Q&A - EV charging and thunderstorms

  • 10 August 2020
  • 16 replies
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Userlevel 7
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Given the upcoming weather, and the fact all my ev charge plugs  and all public chargepoints all say "donnot use in thunderstorms" I was wondering:

A) Why

B) What is the real risk

C) Will anything prevent it actually charging

D) If you have a virtually flat battery in a storm, what should you do if you need to keep driving!

E) Is it (more?)dangerous with a v2g?

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Best answer by PeterR1947 11 August 2020, 14:57

@Transparent  Regulation 722.411.4.1 states that a PME earthing facility shall not be used as the means of earthing for the protective conductor contact of a charging point located outdoors or that might reasonably be expected to be used to charge a vehicle
located outdoors. 

It then lists three methods, any one of which could be used.  Fitting an earth rod is the most cost-effective and quickest way to comply with regulation 722.411.4.1.

Other methods include fitting a costly isolation transformer and incorporating special circuitry in the charger which monitors the incoming supply and disconnects the charger including the earth path if a fault condition is detected, the version 2 of my zappi charger has this functionality.

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16 replies

Userlevel 7
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I wasn’t aware that EV chargers advise not to be used in thunderstorms. I don’t see how the risks would be any different to using any other electrical device in the home during a thunderstorm. Moreover the car itself has better isolation due its rubber tyres.

Anyway, there are several other Topics here on the Forum where we’ve discussed lightning surge suppression and what is or isn’t present in the V2G Charger.

V2G Charger stopped working - No Power

OVO Smart charger stopped working

V2G charger tripping RCDs

Curiously Kaluza haven’t yet come back to us to confirm what surge protection is present in either of the Indra chargers they install. It would be interesting to hear from @Bobby_OVO about this.

Userlevel 7
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Maybe its a way to cover themselves. But I have charged my Leaf in all kinds of weather conditions and it’s still driving beautifully with above 95+ SOH battery. Zapping it with a few rapid charges has helped balance the battery too! Not sure if you knew this @Jequinlan 

Userlevel 7

Some good questions here, and I think we have the community members here to answer them all! 

 

Forgive the spam tagging but I’m going to mention all of our confirmed ‘EV volunteer’ badge earners for a bit of knowledge pooling:

 

@IbrahimEV @sylm_2000 @NeilG @jp1 @Andras @D10hul @DarrenG @Mikeyoung @Peetee @aaronr @PeterR1947 @Delboy 

 

Userlevel 6
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My guess is that it’s to prevent a lightening strike on the house (very unlikely but not impossible) travelling through the mains to the charger through the cable into the car blowing all the electronics and possible the main battery?

Obviously, when unplugged, the car is a Faraday cage and therefore safe?

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I am sorry but this is all a bit of an EV myth and totally incorrect.

  1. Charging a car whether at home or public charger in a thunderstorm is no less safe than actually you being out in that thunderstorm. Assuming you are physically outside then you are likely to be a preferred path to ground for lightning than the charger or the car.
  2. As above the real risk is that you are providing the prefered path to ground by being physically outside. 
  3. There is nothing to prevent the charging from occuring during a thunderstorm. That said lightning can disrupt power from the sub station if it is “tripped” due to a strike. It may also be possible for network connections to be impairred that could impact a public charger.
  4. If I had a low battery during a thunderstorm I would probably pull over and wait in the car till the storm passes. Cars act as faraday cages so are safe places to stay. Getting out of the car, say to charge, puts you in harms way. As previously stated that has nothing to do with car or charger just the fact you are physically out in the open. 
  5. V2G chargers have to pass the same stringent tests as anyother commercially available charger so should have the same level of safety.

They always say you should not drive a Golf in a thunderstorm as that is dangerous, or is that you should not play golf ……….  :-)

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Agree with much said above.  Electricity will find the least path of resistance, therefore, V2G chargers which I remember from my installation was tested for earthing.

I had an earth rod fitted at the time of installation of my first EV charger 5 years ago and it was the same earth which was used for V2G.

As part of the install, it is an essential safety check and that should put you at ease in using your charger during turbulent weather. Over the last five years I have used the EV charger come rain, snow or sunshine - no problems.

Humans on the other side are not “grounded” :)

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My thoughts are that charging is probably not the problem, but the earth connection It provides probably will be. Actually disconnecting the car would probably be. The connection to earth will mean the car is no longer insulated and isolated. The issue will be that if the local grid or car get struck, a very large potential will be placed across the network and as a result current flow and energy will be released…. the sensitive electronics in both car and charger will be toast! This is why pulling plugs from wall sockets is also advisable. A friend from work had a near miss strike few years back… a pole not far away was hit and he lost all the connected electronic devices in the house! Phones, TV, radios, etc..

 

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Indra does not list surge protection as a safety feature of the charger itself, but perhaps a separate device was installed??  From the specs:

Safety Features

  • Emergency stop button: Yes

  • Short-circuit protection: Yes

  • Over-current protection: Yes

  • Isolation system: Galvanic

  • AC earth leakage protection: Yes

  • DC earth leakage protection: Yes

Userlevel 7
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I think you’re on the right tack there @Andras 

There was a response here on the Forum in 2019 stating that the Indra chargers both contained surge suppression.

I then did some further research and discovered that integral surge suppression is part of the standard for the CHAdeMO connection. That’s not the same as having anti-surge protection devices for the charger itself!

 

The other puzzlement I still have is the ongoing debate about the need for chargers to have an earth connection “for safety”.

If your house is supplied with PME from the sub-station, then adding an earth is a no-no!

However…

… if the charger had integral surge suppression, then this may indeed require a path to earth because it’s got to find somewhere to route those pesky electrons.

At the moment I think there is a confusion being caused in the debate as to whether the charger itself requires an additional earth (stake), or whether there is a need for an earth connected (solely) to a pair of internal transient suppressors.

The hypothesis I’m putting forward is that perhaps an EV charger should have two separate earths. When being installed in a house that does legitimately have an earth stake, then those earths could be combined.

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@Transparent  Regulation 722.411.4.1 states that a PME earthing facility shall not be used as the means of earthing for the protective conductor contact of a charging point located outdoors or that might reasonably be expected to be used to charge a vehicle
located outdoors. 

It then lists three methods, any one of which could be used.  Fitting an earth rod is the most cost-effective and quickest way to comply with regulation 722.411.4.1.

Other methods include fitting a costly isolation transformer and incorporating special circuitry in the charger which monitors the incoming supply and disconnects the charger including the earth path if a fault condition is detected, the version 2 of my zappi charger has this functionality.

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Thanks for this @PeterR1947 ….

So presumably the suggested installation of an earth rod is instead of using the earth provided by the PME isn’t it?

Userlevel 6
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Thanks for this @PeterR1947 ….

So presumably the suggested installation of an earth rod is instead of using the earth provided by the PME isn’t it?


Hi @Transparent I’m not really sure, when I have nothing better to do, I’ll take of the front of my zappi and have a look!

Userlevel 7
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Thanks @PeterR1947 

To help others understand what we’re discussing, here’s the diagram which I pictured in my head when I suggested above that an EV charger could have two separate earths.

So I’ve conjectured that the case/electronics has an earth stake, and that there are internal lightning/surge suppressors to quench whatever nasties arrive via the live & neutral. These too need a path to earth.

I’m not saying this is how it should be. I’m merely putting the hypothesis forward for discussion.

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So, my install doesn't have sn earth rod, it has a "Matt:e" device inline, but my understanding from installers is it does a similar job. This was done due to the fact the cable can in theory reach a public lamp post and (I quote the engineers here) "Some idiot could put the connector to the lamp post" so I believe it essentially is the same as the rod and i guess for similar sudden changes in potential and the reason i know my voltage was often over 253V (after kaluza confirmed this issue) and hence my substation had to be adjusted is the device kept triggering normally! 

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Also, just checked this morning at the relatively new polar charger in devon and no comments about thunderstorms on that one. I think it may be just to indeed protect the v2g more (or just being overcautious, like the do not immerse laptop in water type warnings.)

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The Matt:E device is a different strategy. It has (relatively slow) over/under voltage detection. When such an event occurs, it disconnects the EV charger from the supply, including the earth.

I agree that this satisfies the requirements for connection in a property that has a PME supply (earth provided via the Neutral, which is connected to ground at the sub-station).

Using the O-PEN device, the isolation breaker must operate within 5secs. By that time, any self-respecting lightning strike will have long since done its damage and departed. :zap:

That’s why I’ve drawn a pair of Varistors in the above diagram. These should be conducting within a microsecond, thus offering a path to earth by the time the peak lightning pulses arrive.

 

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