Slow vs "Fast" charging confusion

[tsedge]

I don't do calculations. I just expect a fast charger to be faster than a slow one. Surely that's not an unreasonable assumption to make?

Not unreasonable at all. But the world is not as simple as it should be.

There's basically 3 common types of Fast charge cables:

1. Single phase 32A - can charge up to 7kW minus losses, so you'll typically see 6.4kW or something at the car.

2. Three phase 16A - 3x 16A phases (3.6kW per phase), so connected to a suitable 3-phase Fast charger, you can get a total of 11kW, more typically 9.8kW or so at the car.

3. Three phase 32A - 3x 32A phases (7kW per phase, 22kW total), so connected to a 22kW Fast charge, you could get 20kW at the car, but only if the car supports it and the MG4 does not (max 11kW on 3 phase).

You have to match the charger's capability to the cable and the car, to get the speed you want. For example, a single phase cable on an 11kW 3 phase charger will only give you 3.6kW because that's all each phase gets.

Yes, it is complicated. CCS (Rapid) is simpler and it would be so much easier if we could all use that but then you need an expensive and bulky AC-DC converter, so that's why we have the AC solution at home.

 

[Anon70]

There is a spec sheet on the EV database website that night help

MG MG4 EV Long Range

All details and specs of the MG MG4 EV Long Range (2022). Compare price, lease, real-world range and consumption of every electric vehicle.

ev-database.org

With electric cars there is a learning curve as they are relatively new. If you have never owned an ICE car you would need to learn there are at least 2 types of fuel (diesel and petrol) the nozzle and aperture sizes are different, there are different octane ratings, the flow rate of the fuel is different at every pump and if someone is using the pump opposite you the flow rate can be affected, the auto cut off will vary between every fuel pump, the angle you hold the nozzle will impact the auto cut off and flow rate. It is possible to pour fuel down the side of the car and onto the floor if the if auto cut off fails for any reason.

So you probably just know all the complicated stuff for ICE cars and because electric cars are new you have to learn that stuff, which makes them seem overly complicated. Yes it would be great if all connectors and charge rates were the same, but the same can be said of ICE cars and their lack of single fuelling option.

 

[jeanloup]

Not unreasonable at all. But the world is not as simple as it should be.

There's basically 3 common types of Fast charge cables:

1. Single phase 32A - can charge up to 7kW minus losses, so you'll typically see 6.4kW or something at the car.

2. Three phase 16A - 3x 16A phases (3.6kW per phase), so connected to a suitable 3-phase Fast charger, you can get a total of 11kW, more typically 9.8kW or so at the car.

3. Three phase 32A - 3x 32A phases (7kW per phase, 22kW total), so connected to a 22kW Fast charge, you could get 20kW at the car, but only if the car supports it and the MG4 does not (max 11kW on 3 phase).

You have to match the charger's capability to the cable and the car, to get the speed you want. For example, a single phase cable on an 11kW 3 phase charger will only give you 3.6kW because that's all each phase gets.

Yes, it is complicated. CCS (Rapid) is simpler and it would be so much easier if we could all use that but then you need an expensive and bulky AC-DC converter, so that's why we have the AC solution at home.

Thank you that's the best explanation I've read yet. Still complex but it makes sense now. I just wish these things were better explained at the point of purchase so you could decide to spend an extra 30 quid or so for a 3 phase charging cable to make the most of fast chargers but I'm not sure dealerships even know about this...

There is a spec sheet on the EV database website that night help

MG MG4 EV Long Range

All details and specs of the MG MG4 EV Long Range (2022). Compare price, lease, real-world range and consumption of every electric vehicle.

ev-database.org

View attachment 25839

With electric cars there is a learning curve as they are relatively new. If you have never owned an ICE car you would need to learn there are at least 2 types of fuel (diesel and petrol) the nozzle and aperture sizes are different, there are different octane ratings, the flow rate of the fuel is different at every pump and if someone is using the pump opposite you the flow rate can be affected, the auto cut off will vary between every fuel pump, the angle you hold the nozzle will impact the auto cut off and flow rate. It is possible to pour fuel down the side of the car and onto the floor if the if auto cut off fails for any reason.

So you probably just know all the complicated stuff for ICE cars and because electric cars are new you have to learn that stuff, which makes them seem overly complicated. Yes it would be great if all connectors and charge rates were the same, but the same can be said of ICE cars and their lack of single fuelling option.

Again the analogy with ICE cars don't do it for me as the fuel types are clearly stated with each vehicle new or second hand (at least from my experience) and the difference of speed at which the tank is filled is negligible between models of cars, not so with EVs unfortunately

 

[fnegroni]

I don't do calculations. I just expect a fast charger to be faster than a slow one. Surely that's not an unreasonable assumption to make?

ok I don’t understand.
I take this is just a rant.
Honestly though, if you provide the info above we can help further. Otherwise so far I think you got more than 3.5 kW from a charger that was rated at 7kW so you are doing ok.
If you think you have not been informed correctly by the dealer when purchasing the car and you really need faster charging (faster than what you already get) from an AC outlet then that’s a different matter altogether

 

[jeanloup]

ok I don’t understand.
I take this is just a rant.
Honestly though, if you provide the info above we can help further. Otherwise so far I think you got more than 3.5 kW from a charger that was rated at 7kW so you are doing ok.
If you think you have not been informed correctly by the dealer when purchasing the car and you really need faster charging (faster than what you already get) from an AC outlet then that’s a different matter altogether

See my original post.

7 kW charging provides about 5.6 kW to the car which to me is reasonable enough

22 kW charging provides only about 4.2 kW to the car makes no sense. At least it didn't until people started explaining about 3 phase.

And yeah I get ranty when I'm confused, I like to understand things as much as I'm able, not gonna apologise for that

 

[fnegroni]

See my original post.

7KWh charging provides about 5.6KWh to the car which to me is reasonable enough

22KWh charging provides only about 4.2KWh to the car makes no sense. At least it didn't until people started explaining about 3 phase.

And yeah I get ranty when I'm confused, I like to understand things as much as I'm able, not gonna apologise for that

Got it.

So now you understand about the three phases etc.

You should still see about 6.5kW from both of those chargers you mention though, with your single phase 32A cable.

Hence my questions: is that the instant rate you saw while sat in the car? Was that an average over the period you were parked? Were you sat in the car while it was charging? Did you do any balancing of the battery?

Just to reiterate, your car will not charge any faster with a single phase cable. Your car can accept three phases, and therefore the cable you want is a 3P 32A cable. The fastest you’ll ever get with a single phase cable is 6.5kW.

 

[jeanloup]

Got it.

So now you understand about the three phases etc.

You should still see about 6.5kw from both of those chargers you mention though.

Hence my questions: is that the instant rate you saw while sat in the car? Was that an average over the period you were parked? Were you sat in the car while it was charging? Did you do any balancing of the battery?

Just to reiterate, your car will not charge any faster even with a three phase cable. Your car can only accept one phase, and therefore the cable you have is the correct one for your car. The fastest you’ll ever get is 6.5kW

No I wasn't sitting in the car, I only stay sitting in the car when I'm desperate for a rapid charge and there's nothing else to do. These are figures I would see while regularly monitoring the state of charge in the iSmart app, which I expect to be accurate enough.

As for battery balancing I have zero idea on how to do that, what the benefits would be or anything so no.

 

[PeteC]

Just to reiterate, your car will not charge any faster even with a three phase cable. Your car can only accept one phase, and therefore the cable you have is the correct one for your car. The fastest you’ll ever get is 6.5kW

Not necessarily true. Some of the early cars could use 3 phase charging. Mine will happily pull around 10kW on a suitable (22kW) charger. The op has shown a photo of his charge port which shows the bottom two pins being metal so his car should do the same.

 

[fnegroni]

Not necessarily true. Some of the early cars could use 3 phase charging. Mine will happily pull around 10kW on a suitable (22kW) charger. The op has shown a photo of his charge port which shows the bottom two pins being metal so his car should do the same.

I stand corrected and I will amend my other post.
When I first saw the picture on my phone I didn't see clearly. It makes sense to buy a 3 phase 32A cable. Or ask the dealer to replace it free of charge.

 

[siteguru]

@jeanloup's photo suggests that he has a MY22 (no rear wiper) long range (64 kWh) car as it appears to have metal clad pins on the L2 and L3 sockets. As such, if using a 3-phase 32A cable then he should get around 10kW charge rate from either an 11kW charge point or a 22kW charge point. (The rate is limited by the car's onboard charger).

Using a 32A single phase cable (which his other photo indicates) means a maximum of 3.6kW from an 11kW charge point, and 7kW from a 22kW charge point.

 

[fnegroni]

As for battery balancing I have zero idea on how to do that, what the benefits would be or anything so no.

That's all explained in the manual and on several threads on this forum, so not to derail from the topic I will not cover this here.

 

[jeanloup]

@jeanloup's photo suggests that he has a MY22 (no rear wiper) long range (64 kWh) car as it appears to have metal clad pins on the L2 and L3 sockets. As such, if using a 3-phase 32A cable then he should get around 10kW charge rate from either an 11kW charge point or a 22kW charge point. (The rate is limited by the car's onboard charger).

Using a 32A single phase cable (which his other photo indicates) means a maximum of 3.6kW from an 11kW charge point, and 7kW from a 22kW charge point.

I don't think I've ever even seen an 11kW charge point.

I'll get in touch with my dealership and ask if they'd be willing to swap my cable free of charge for a 3 phase one. I expect they won't but it doesn't hurt to ask, especially after a disappointing servicing last week.

Thanks for the info and advice everyone.

 

[fnegroni]

Using a 32A single phase cable (which his other photo indicates) means a maximum of 3.6kW from an 11kW charge point, and 7kW from a 22kW charge point.

He's getting far less than that though.
5.6 kW from a 7kW (single phase) charger, and 4.2kW from a 22kW charger. Those figures seem to indicate either some load is present (battery heater?) or the BMS is pulling less power (unlikely) maybe due to battery temperature or the unit is faulty or the charger was crippled by grid supply issues.

I don't think I've ever even seen an 11KWh charge point.

Those are normally installed at home premises that have a three phase supply from the grid, which is popular in some European countries. Public chargers tend to be 22kW.

 

[tsedge]

AC left on?

 

[jeanloup]

AC left on?

Ah ah if there's one thing that's almost always off it's the AC

 

[jeanloup]

A bit of an update on this topic. I went to charge at another 22kW AC charger yesterday and I was able to get about 6.5kW on average from this unit, which suggests the other unit I was talking about must either have technical issues or deliberate throttling or something as the unit yesterday was one of 6 and 4 of them were in use compared to being the only one to use a bay of 4 units earlier this week. It's still not the 10 or 11kW I would have liked but it fits the fact that with a single phase cable I can only draw up to 7kW. I'm gonna try to get a new cable from my dealership to correct that.

[ Edited Coulomb: "Charger" speed is in kW, not kWh. ]