EV Public Charger Accuracy

[stevedee]

As a design engineer (in a previous life) of measurement equipment, I find it incredible that we've only just discovered problems with EV charger accuracy.

According to an RAC article:-

While petrol and diesel pumps are typically confined to an accuracy window of -0.5% to +1%, electric chargers are allowed a tolerance of up to +2%.
However, EVCI Global’s analysis indicates that nearly one‑third of chargers fall outside these standards.

Trading Standards people should be all over this ...if the poor blighters have not been pruned back to nothing by gov 'deregulation' financial cuts!

The full article:-

One in three public EV chargers are providing incorrect readings

There are growing concerns over the accuracy of public electric‑vehicle charging points, after an industry analysis found that 31.5% of chargers tested delivered energy readings that did not match the actual amount supplied.

www.rac.co.uk

 

[Rei]

Where is the measurement supposed to take place? There will be some loss in the cable, for example.

 

[stevedee]

Where is the measurement supposed to take place? There will be some loss in the cable, for example.

Naturally.

You plug the lead into a test rig and take readings.

Weights & Measures is about a transaction, where you agree to pay for something at an agreed rate. You should get the correct amount (by weight, volume, count or whatever) within agreed limits. If sold by volume or weight, the limits are typically based upon averages rather than minimums.

 

[Rei]

So the charger is supposed to account for the losses in the cable? That complicates things a bit.

 

[Everest]

I suspect that is not as easy to accurately measure as, say, a litre of petrol.

So the charger is supposed to account for the losses in the cable? That complicates things a bit.

For sure - obviously length, cross section and material of the cable should be calculable, but temperature will also play a part in the inductance of a cable.

Furthermore, it is non-trivial to measure AC power - and hence energy - when there will be different power factors of different vehicles, compounded by the fact that the grid supply is not perfectly sinusoidal. Modern EV's should have a relatively high PF, but even that will be charge-rate dependent.

 

[stevedee]

What utter nonsense!

 

[PeterHR2]

This RAC article seems to be a precis of the contents of the video on the Speak EV site.
And that video is on this YT channel.

 

[Everest]

What utter nonsense!

What is, exactly?

 

[Rei]

Are they talking about AC chargers, or DC rapids, or both?

 

[PeterHR2]

Are they talking about AC chargers, or DC rapids, or both?

Anything on the public charging network, but it seems mainly aimed at rapid DC chargers.

 

[stevedee]

What is, exactly?

"So long, and thanks for all the fish!"

 

[MG Clive]

"So long, and thanks for all the fish!"

Do you get those fish from "the restaurant at the end of the universe", because that really is utter nonsense.

 

[Bam Bam]

"So long, and thanks for all the fish!"

I don't think we need too much mystery on here!

 

[PeterHR2]

"When the seagulls follow the trawler, it's because they think sardines will be thrown into the sea"

 

[5teep]

Public EV chargers all have sealed calibrated energy meters in them when built, it's how they know what to charge you. I can't say if they are ever recalibrated during their lives.