The EV Musings Podcast Nov 24, 2025

277 - The Charger Accuracy Episode

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Hi, I'm Gary in this episode 277 of EV Musings, a podcast about renewables, electric vehicles

and things that are interesting to electric vehicle owners.

And on the show today, we'll be looking at how accurate EV charges are in terms of giving

you what you're paying for.

Now, our main topic of discussion today is charger accuracy.

Now, I don't know whether you know, but there is a department in each local authority that

is responsible for ensuring that goods sold to the public meet certain standards when

it comes to contents, ingredients and volumes.

This is the department that evaluates waste scales, for example, so that if you go to the

local butcher and ask for a half a pound of sliced ham, you actually get a half a pound

of sliced ham and not a third of a pound of sliced ham.

When it comes to petrol stations, this department will regularly go around with their measuring

cans and dispense a litre of petrol or diesel into them.

If the pump reads more than a litre, when the litre measure is full, that's an issue

because it means you're not getting what you pay for.

However, at the moment, there is no such thing for charging stations, and that's a problem.

But it's a problem in two stages, one which is physics and can't be overcome, and the

other one of which is, well, we'll come on to that shortly.

From a physics point of view, the issue is inefficiencies.

For example, if I plug my car in at a 7kW charger and start a charge, the charger

will, in theory, provide 7kW of energy from the unit.

It will travel through the circuits in the device, down the charging cable to my car, through

the inverter in my car, and into the battery.

As that happens, the amount of energy in the circuit will decrease.

The charger may be pushing out 7kW, but the car may be receiving 6.5kW.

I'm paying for charging at 7kW, but I'm not getting 7kW of charging, and more importantly,

and this is where the difference is, after 10 hours on the charger the device will

require payment for 70kW of energy, but the car will only have received 65kW of energy.

5kW of energy has disappeared in the process.

There is a whole discussion to be had about who should pay for that 5kW.

From a CPO point of view, they've provided 70kW through the device and want to be paid

for it.

From a customer point of view, they've only received 65kW, and that's what they

want to pay for.

The key here is that charger has actually dispensed the amount of energy it says it has dispensed

and charged you for.

If I go back to our ham slicing example, you'd only want to pay for the ham you received,

not the ham that the butcher sliced up, any bits and pieces that didn't make it across

or through the slicer, and not your responsibility, right?

But the sort of losses I'm talking about and what I want to discuss in a bit of

detail today are actually related to a different sort of loss in charging.

It's the equivalent of putting the finger on the scale when measuring the ham.

It's when the charger dispenses 60kW of energy, but charges you for 70kW of energy.

How much of that 60kW you receive is not the question.

It's how much the charge has told you it gave you.

And this is the same as when a petrol pump tells you that it's charged you for a litre,

but it's only actually given you 9 tenths of a litre.

The measure is inaccurate.

Now you would think that because everything is electronic and there's no way of physically

underreporting actual electric current that this wouldn't happen, but you'd be wrong.

So let's talk to someone who can tell us more about this.

Hi, my name's Craig Marsden and I work at EVCI Global.

Now when we met at a conference recently I was fascinated when you shared a couple of stats

about charger inaccuracies and I want to talk about two things with you today.

The first one is what are these inaccuracies?

What do you mean when you talk about charger inaccuracies and how do they occur?

And secondly, I want to talk about EVCI Global, what you're doing, how you're gathering

data and what you're wanting to do with it.

So let me start with the first question.

Tell me what exactly we're talking about when we're talking about the inaccuracies that you're

looking at because I know we talked on this podcast before about charger losses in cables.

So the charge point puts out a certain number of kilowatts.

The car receives a slightly less number of kilowatts and the difference is in the charger

cable, but that's not what you're talking about, is it?

What we're talking about is what's delivered on the display of the charger versus what's

actually been delivered to the vehicle.

So any losses that occur on the vehicle side, we don't measure in any way, shape or form and

I understand that that's down to the vehicle, that's nothing to do with what's been delivered.

What we're measuring is what the charge point is delivered and saying it's delivered

versus what's actually delivered.

So we have a very, very precise bit of equipment that is accurate to 0.1% and is itself calibrated

and it tells us what's been delivered versus what the charger's told us has been delivered.

So if I give a specific example, I could plug in a charger and I can charge for 10 or 15 minutes

and the charger says, we have actually sent you 20 kilowatt hours of energy, but what

actually happened is the charger has sent might be less than that or it might be

more than that.

Is that what we're actually talking about?

Absolutely correct.

So in massive extremities that we have, the biggest under delivery we've ever had

was minus 37%.

So essentially you paid for 10 kilowatts and you've got 6.3 and the biggest over delivery

we've ever had was 30% where I paid for 10 kilowatts and I got 14 in a bit.

When you say kilowatts you mean kilowatt hours, don't you?

Kilowatt hours, my apologies.

So why are you thinking then?

At the end of the day, I'm not here to work out the how, why's and when's.

At the end of the day, the system was put in at speed, I'd say.

So the charges and the charge point operators, to be fair, weren't ever told that they had

to be accurate to any degree, but if it was wet fuel, for example, diesel or petrol, if

you have an under delivery of anything more than 0.5%, weight and measure would close

that fuel station down and if it has an over delivery of more than 1%, then that

would be closed down as well and until they were recalibrated by the fuel pump manufacturer

then that would stay closed.

So sort of piggying back on that, how are you measuring the differences?

Because you mentioned wet fuel and in the old days the guys from trading standards would

come around with a litre or a gallon can and they'd pump a gallon in and then they'd

look and see what was actually showing on the display and if there was a difference

then that was an issue, as you said, but how are you actually doing that with electric

vehicle charges?

So what we have is a unit called a man in the middle unit and what that does is we'll

plug your charger point into our very, very, very accurate metering equipment and then

we'll then plug that into either the vehicle that we use sometimes or we'll put it into

a lower box and another thing that we use if it's AC is electric fans as well and

what we do is we just will literally measure the amount of kilowatt hours that's been delivered

to us versus the kilowatt hours that's shown on the screen.

Now the government have something called the office for product safety and standards.

Why is this not their job?

Well, it should be their job to be fair but it's a mystery to me as to why it's

not.

At this moment in time we're at the second stage of the grant with the National

Physical Laboratory so that we can put together a framework with them to measure the differences

in EV charger outputs across vehicle to grid, across the HTVs and the wider charger network

and they'd then fire the information through to OPSS who would then make their decisions

on it and then put that through to waiter measures but why it's not measured at this

moment in time is beyond me to be fair.

So the question that jumps out when I'm talking about this or when we're talking about this

is, you know, in practice you're getting, you may be getting something you're not paid

for but generally I believe you're going to be not getting something that you have

paid for.

There's going to be an under delivery.

You're paying for more than you've actually received.

Is this fraud?

I couldn't tell you whether it was or wasn't.

I'd definitely say that it wasn't deliberate in any way shape or form.

I think the place that we're at is the government wanted charge points put into the ground as

quickly as possible and that's what we've got and the reasons for why they're inaccurate

isn't down to me.

I can just tell you whether they are or whether they're not.

So if you think of our company and our services, we're more like the MOT station and then

the charge point providers would go back to the manufacturers I would guess as the

suppliers of the equipment to work out why they're not working the way they should.

In your experience, do charges generally over dispense, i.e. you get more than you pay for

or under dispense, you pay for more than you get?

It depends on the margin of deviants that you're talking about.

If you go into our 2%, I'd say that a lot of the charges that we've tested have passed

that 2% but I'd say that more under deliver than over deliver and generally you're looking

around 15% of the marketplace that we've measured and by all means we haven't measured anything

like 80,000 charges but a third of those will definitely not pass our certification if you

like a 2%.

Now, I know you've already said it before, just tell me again, what's the most egregious

differences that you've seen?

So minus 37% is the largest under delivery I've ever seen and plus 30% is the biggest

over delivery I've ever seen.

So an under delivery B will be you haven't received electricity you've paid for and an over delivery

means you've had a lot more than you have than you've paid for.

Okay, so I've got two questions that follow up from that and I'll give you some provisos

around these in a second.

Is this a CPO issue or is it a charge and manufacture issue?

There's a question for you.

I would say that there's a number of different things that influence whether they're accurate

or not.

So for example in California they're saying that your charger needs to be 1% accurate as

it comes off the production line but then 2% accurate wants it to put into the ground

and it's being commissioned.

So there's a number of different things that can make the charger drift over time

for example or down to the way that the design was made in the first place or down

to weather factors.

So there's a whole host of different reasons as to why they may or may not be accurate.

Generally stuff that's come out of Germany and Zeichrich is pretty good but not everything's

perfect so this is why we set up what we set up so that people can find out both charge

point operators and then end users and what the charge points are actually putting

out.

And that leads me very nicely on to this second part of my question.

Now I know you're confined I think by NDAs with the charge point operators that you're

working with and I'm speaking with Vicky Reid from Charge UK in a couple of weeks as part

of the end of season round table and I'll bring this topic up with her but are you

seeing any patterns appearing?

I mean you've already talked about the German hardware being a little bit better than

some of the other ones.

The discrepancy is that you're seeing more of a certain CPOs that are coming

up with red flags or is it just certain hardware?

Is it certain DNOs?

What kind of underlying factors are you seeing that play into this?

I'd say that there's a number of different factors and some charge point providers I'm

looking at have seemed to come up with consistently fantastic results.

Some charge point providers have got better as they've progressed and some charge point

providers have got worse as they've gone along so I think I'd like to say there's

so many different factors that come into this and we've only been testing these for a year

and a half now and I think the longer that we test the more information we'll gather

and the more of an accurate forecast we can give over which charges or charge points

are given what they should be given.

So leaning on from that talk to me a little bit about what EVCI Global are planning

on doing moving forward because you've talked to me already about the fact that you're

going out you're putting your what's the phrase you used a man in the middle piece

of tech in there and that's capturing data.

What are you going to do with that?

Well the plan long term is for us to accredit sites with our diamond standard

accreditation so charges and therefore charges sites the pass are I think

it's a pretty fair and lenient pass rate of plus or minus two percent will

gain our diamond standard accreditation bias that they'll be able to

display on the front of the charges any network equipment that they've got

should be able to get that and the totem pole will also be allowed to

display our logo as well so people will know without guessing which charges

are in fact accurate and that's our way forward we're also in with national

physical laboratory we're trying to put the framework together that we talked

about earlier so that long term we'll be testing all of the charges

in the marketplace and as I thought we won't be the only company that will be

doing that we're just the only company that are right now.

So when companies such as yourself that are reasonably new to the market I mean I

know you said you've been around for you know doing this for a year year and a

half but when you're approaching CPOs what sort of pushback are you

getting is your business case strong enough to encourage CPOs to pay for

the service because I know you and I have had conversations and you did

speak to one particular CPO and ask them whether they thought their charges were

accurate and they said yes absolutely we're very very happy about that and then

you went on went on and measured one of those and found out that it was over

delivering by 30% so what sort of a reaction are you getting from the

charge point operators? Every charge point operator has voted who wants to

deliver an accurate amount of electricity I've not had anyone that wants to

present it with the fact say that they want to do anything different so

I'd say from a CPO point of view they're very proactive on having this sorted out

one way or another. Now I know you talked about this a few seconds back but

just talk a little bit more about the diamond certification what what do you

expect in a charge point operator to do with this certification I mean yet

it'll look good on the website you've already talked about maybe putting it

on the the totem outside on the individual charges but is this

something that you'd like to see incorporated into things like oh I

don't know that map for example so drivers can sort on charges with a diamond

rating for example. Yeah that's exactly where we'd like to be so you can then

choose which ones are diamond standard accredited so that you know for sure that

you're getting exactly what you paid for so you can trust and know that the

charger that you're going to use will be fair. Cool now is there a way to get

this mandated by the government like we've already discussed you know the

trading standards people go out to wet fuel stations and they use their

measuring equipment there is that something that can be mandated by the

government for charges or is it going to rely on companies such as

yourselves to go out and actually do the measuring. My understanding is that

it will be mandated by the government in around 2027 but we all know what

these things are like so it may or may not come to fruition then. Talk to

a little bit about what you're offering is to the CPO because we've said okay

you go in and you'll speak to the CPO and you'll go out and do some

measurements but how does it actually work? Do they say there's a charge

point operator say right can you go out and check all the charges at this

site or all of our charges in this area or are you allowed to sort of

randomly choose charges regardless of which CPO you're working with and

then go back and confront them with the results what actually happens what's

that process. We don't really confront anyone with the results so what we

do is we invite people to work with us we'll offer them a pilot site where

we'll go out and test an entire site present them with the results and we

take it from there depending on how they do or don't like the results. Playing

devil's advocate because I tend to like to play devil's advocate and you

told us that you've encountered sites that have got large amounts of under

delivery. I also know from conversations that we've had that you don't

feel that it's right to actually name those. Is that ethical? You know you're

taking these measurements and there are charges out there that you know are

delivering less than people are paying for. Is there not an ethical

statement to say you should be publicising those results? No I don't

think publicising results helps anyone I think the thing to do is tell the

charge point operator that the charges aren't measuring the electricity

correctly and then give them a chance to sort it out. Ultimately once it becomes

regulation by the government then that'll be a different kettle of fish but

we're only here to celebrate the good charges that have passed at this

moment in time that's our job. So you don't feel worried about the people

who are using the charger that's under delivering by 30%? I wouldn't go so far

as to say I'm not concerned about them because I'm one of those people

myself but at the end of the day this isn't something that's regulated by

the government at this moment in time so until it is

there's nothing we can do with that data other than feed it through to the

CPOs and generally like I say they're massively receptive to that.

80 what do you say 80 or thousand charges across the UK

how many people you've got working on going around and evaluating these

charges? We have two full-time members of

staff and three part-time members up there. And presumably for this to be

something that is both valuable and accurate you would need

every charger to be evaluated at least once

and then on a regular basis thereafter. Is that feasible with the headcount that

you've got at the moment? Yes. Over what period of time? Well I'd say over 12

months. So we can ramp up at the end of the

day it takes normally about a week for us to

train someone up and then for them to get the certification that they

require to go onto fuel pump stations

and so on it goes. It takes us about three months to have our

equipment built so I'm not really concerned about

whether or not we can make those targets or not we'll be okay.

Is there anything else you'd like the listeners or the people who are

watching us on YouTube to know about EVCI Global or the

work that you're doing before we close? I'd just like them to give

that out for our diamond standard certification and

they'll know what the charges bear. Wonderful thank you very much Craig

Marston. Thanks for your time, much appreciated.

You're most welcome. So a couple of takeaways from this discussion.

Charger misreporting is a real issue it's widespread

and it's an issue that isn't getting a great deal of attention.

The charger that I referenced in this discussion was part of a conversation

that Craig told me about that he'd spoken with Instavolt

and he point blank asked them if their charger misreported

and they said they don't. So he checked the charger and he posted

that anyone wanted to get free electricity should basically go to this

specific Instavolt charger because when you paid for 100% of the

charge you actually got 130% of the charge that you

paid for because it was overreporting or underreporting

whichever but he did also tell me that a lot of charge point operators he

spoke to will test their hardware in their workshops or office

and they are accurate when they they're put into the ground but just like petrol pumps

things happen that can affect the accuracy which is why chargers and petrol pumps

need to be rechecked on a regular basis.

Now one thing that I think has come out of this and Craig did mention it there

is the concept of FOMO. Over time there will be a number of

charge point operators whose hardware will end up with a diamond

certification. Now if you go to a location with

several CPOs only one of which has a diamond certification to indicate

it's accurate. Are you going to use their charger

or are you going to use the other charger without the diamond?

More importantly are you going to put out on social media that you've seen an

uncertified charger? Will this help CPOs decide that they want

their chargers certified if they get bad publicity?

We'll see. Shortly after this episode is published

I'll be spending a day on the road with Craig. We'll be going to a number

of different charge point operators and sites and I will be asking senior

management at those CPOs beforehand if they feel that their charges

are misreporting at all. Be interested to check the results against

the management expectations so stay tuned to my social media for

results. Now it's time for a cool EV or renewable

thing to share with your listeners. Italy has launched a 600 million euro bonus

to pay people and small businesses to buy new electric vehicles.

Private buyers can get up to 11,000 euros depending on income

and a small business can get up to 20,000 euros but applicants must

scrap an older Euro 5 or worse car and apply before buying.

The scheme targets residents of cities of 50,000 plus people

and aims to replace about 39,000 combustion vehicles by mid-2026.

Well done Italy.

The EV Musings podcast is sponsored by ZAPMAP, the go-to app for EV drivers helping

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charging card. Join over a million EV drivers

download ZAPMAP and charge with confidence.

I hope you enjoyed listening to today's show. It was put together this week with

the help of Craig Marsden. Many thanks for your time, Craig.

Excellent discussion. If you have any thoughts, comments,

criticisms or other general messages to pass on to me I can be reached at info

at evmusings.com. On the socials I'm on Blue Sky at evmusings.bsky.social.

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Hashtag if you know you know nothing else. Thanks as always to my

co-founder Simon. You know he's got big plans for next year,

a world electric unicycle day, a personal electric transport week

and a Nobel Prize for the best use of an electric vehicle.

I told him there's a lot to think about with that and he said

at the end of the day I'm not here to work out the how, why's and whens.

Thanks for listening. Bye.

About this episode

The discussion dives into the accuracy of electric vehicle (EV) chargers, revealing that many chargers either underdeliver or overdeliver energy compared to what they display and charge for. Craig Marsden from EVCI Global explains how they measure charger output with precise equipment, uncovering discrepancies as large as -37% to +30%. The lack of government regulation means these inaccuracies persist, but EVCI Global aims to introduce a diamond standard certification to help consumers identify reliable chargers. The episode also touches on the challenges of enforcing accuracy and the potential impact on charge point operators and EV users.

Dodge Charger

Original notes

In this episode of EV Musings, Gary Comerford discusses the accuracy of electric vehicle chargers with Craig Marsden from EVCI Global. They explore the discrepancies between what chargers report and what is actually delivered, highlighting the lack of regulation compared to traditional fuel stations. Craig explains the testing process and the potential for a diamond standard accreditation for accurate chargers.

Guest Details:

Craig Marsden : I lead the technical and operational strategy at EVCI Global, specialising in the accuracy of electricity delivered, future compliance, and trustworthiness of public EV charging. My work focuses on real-world testing and independent verification, ensuring every kWh billed is every kWh delivered. With experience across the UK and Ireland, I work directly with charge point operators, regulators, and fleets to raise standards and future-proof infrastructure. I head the development of the EVCI Diamond Standard – the UK’s only accreditation for EV charger accuracy, aligned with MID Class A (±2%) thresholds. My goal is simple: build a charging ecosystem drivers can trust, operators can market, and regulators can stand behind.

Craig's Website

The EV Musings Podcast is sponsored by Zapmap, the go-to app for EV drivers, helping you find and pay for public charging with confidence.

Links in the show notes:

Italy launches electric vehicle bonus - electrive.com - Cool Thing

Episode produced by Arran Sheppard at Urban Podcasts: https://www.urbanpodcasts.co.uk

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The EV Musings Podcast

Gary Comerford

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