Basic EV power explanation

I have created this basic overview for EV newbies. It is not intended to go into great detail or nuances but merely provide a basic overview of power sources, power storage, motor power supply and regeneration method and storage.

Energy in from charging

Alternating Current (AC)

When you connect an EV to an AC charging point which can be:

13a (2 -3kw) domestic charging cable
7kw home or public charging (fast)
11 or 22kw public charging (fast)

the cars inbuilt charger takes that AC input and converts it to DC (Direct Current) to enable that energy to be stored. The inbuilt charger will restrict the accepted AC input according to the cars design. Most common is around 7kw standard but 11kw is becoming more prevalent on newer vehicles

Around 7kw can be supplied as a single phase supply using a single phase 32amp cable
11kw upwards requires a three phase supply. A 32amp three phase cable type is required for 11/22kw charging. This cable can also be used on 7kw single phase chargers replacing the need for both types of cable.

The charge delivered at the car may be less than the advertised charging point delivery i.e 7kwh charging station could be measured for example at around 6.4kwh at the car, 11kw around 10 ish due to losses and inbuilt charger constraints.

The storage of that generated energy is held within the cars high voltage batteries.

Direct Current (DC) Rapid Charging (always tethered)

When you connect to a DC rapid or ultra rapid charger that energy is passed directly to the batteries in DC form, bypassing all of the limitations of the on-board charger and required AC conversion. The rate of DC charging is controlled by the cars battery management system design

Energy Storage

The stored energy is held in batteries in DC form. The battery types can materially be different but they fundamentally do the same job. You will see that advertised as Kwh for example 64kwh battery size. Almost all batteries have an upper and lower buffer so although, for example 64kwh is the headline figure, the usable figure will be slightly lower

Electric Motor

Most common EV motor types are AC. The stored energy (DC) requires conversion to AC to drive the motor. The car has an inbuilt inverter that takes that stored DC energy and converts it to AC for that purpose.

Regeneration

A feature of electric cars is energy regeneration. This is created using the momentum of the vehicle and the electric motor. Basically the motor reverses from drive to generation and feeds that generated energy back to the batteries. In most cases the inverter can take that generated energy and convert it to DC for storage within the batteries. The method of regeneration can vary but this is one of the most common forms. Regeneration can also occur when you use the brakes as blended braking uses the motor to slow the car down when braking normally and mechanical brakes when more force is applied. This blended braking allows regeneration during normal braking. Regeneration only occurs when the high voltage batteries have spare capacity.

12v Battery

The 12v battery is still a key part of an EV. It provides the power for the control systems and ancillary devices and without it the car is effectively dead. The 12v battery is charged from the EV HV battery using a DC/DC converter which drops the HV DC voltage down to around 14.5v. This is similar to how the alternator functions in an ICE car. The 12v battery is charged whilst in a ready to drive state, being driven and during the high voltage batteries charging or Vehicle to Load sessions. Some vehicles (including MG4) also have intelligent charging which can "top up" the 12v battery during periods of inactivity if required.

 

[tsedge]

Really good, depends how far you want to go with it, but may be worth mentioning differences between 16a and 32a charging cables and the fact that range will be lower in winter and maybe talk about the GOM and what it means?

Edit: just noticed you only want to talk about power, so can ignore some of my comments.

 

[the briggie]

I did not want to go to deep hence

Up to 7kw can be supplied as a single phase supply. 11kw upwards requires a three phase supply with appropriate cable type.

Do thing that needs to be more in depth rather that appropriate cable type?

 

[Ian Key]

I think a simple explanation of the salient points applying to the MG4 is all that's needed. For a more in depth explanation perhaps suggest they Google it.

Perhaps another post with the meanings of the common abbreviations used?

 

[tsedge]

I did not want to go to deep hence

Up to 7kw can be supplied as a single phase supply. 11kw upwards requires a three phase supply with appropriate cable type.

Do thing that needs to be more in depth rather that appropriate cable type?

Well, they might buy the wrong amperage, and you’ve been mentioning amps elsewhere.

You could say:

For untethered home charging, you need a single phase 32A cable to reach a maximum of 7.7kW.

For untethered public charging, such as supermarkets and workplaces, the same cable will work fine. However, if you car supports more than 7.7kW AC charging, you could buy a three phase 32A cable that supports up to 22kW. The same cable will work fine at home.

 

[tsedge]

If you just want to keep it as simple as possible, I don’t think you need to mention this.

 

[the briggie]

What about now re charging cables?

 

[tsedge]

Perfect

 

[Oberoy]

I have created this starter for ten to hang on hints and tips for EV newbies. Its focus is on power only in an attempt not to overcomplicate it. I would appreciate a review so that we can basically agree on it in its simplest form so please bear that in mind. I will hang it on with a slightly different title to remove comments and get alb to delete this one when required

Thoughts please

Energy in from charging

Alternating Current (AC)

When you connect an EV to an AC charger which can be:

13a (2 -3kw) domestic charging cable
7kw home or public charger (fast)
11 or 22kw public charger (ultra fast)

the cars inbuilt charger takes that AC input and converts it to DC (Direct Current) to enable that energy to be stored. The inbuilt charger will restrict the accepted AC input according to the cars design. Most common is around 7kw standard but 11kw is becoming more prevalent on newer vehicles

Up to 7kw can be supplied as a single phase supply. 11kw upwards requires a three phase supply with appropriate cable type.

The storage of that generated energy is held within the cars high voltage batteries.

Direct Current (DC)

When you connect to a DC rapid or ultra rapid charger that energy is passed directly to the batteries in DC form so the inbuilt AC charger is bypassed. The rate of DC charging is controlled by the cars battery management system design

Energy Storage

The stored energy is held in batteries in DC form. The battery types can materially be different but they fundamentally do the same job. You will see that advertised as Kwh for example 64kwh battery size. Almost all batteries have an upper and lower buffer so although, for example 64kwh is the headline figure, the usable figure will be slightly lower

Electric Motor

Most common EV motor types are AC. The stored energy (DC) requires conversion to AC to drive the motor. The car has an inbuilt inverter that takes that stored DC energy and converts it to AC for that purpose.

Regeneration

A feature of electric cars is energy regeneration. This is created using the momentum of the vehicle and the electric motor. Basically the motor reverses from drive to generation and feeds that generated energy back to the batteries. In most cases the inverter can take that generated energy and convert it to DC for storage within the batteries. The method of regeneration can vary but this is one of the most common forms.

Looks good to me, as a basic set of info.
EDIT:
though strictly a 32 amp cable isn't required for 11kW a 16amp one would get this speed, it makes sense to use a 32amp cable as this would also give 7kW on a standard home charge point
END EDIT
I see you say you want to avoid to much complexity. I think understanding amps is important as it's key to actually understand enough. I struggled get what caused the issues, why X input didn't mean X charging etc. until I saw an explanation of volts, and more importantly amps. The cable can become a bottleneck for 2 reasons single/three phase and amps it will pass. So giving a little more info is the key to actually understanding if that make sense.

 

[the briggie]

tsedge

There is also a thread on hints and tips called range where I added a basic explanation of gom. If you want to create a specific thread regarding that ala this type of explanation then

 

[the briggie]

Alb, thank you for moving this. Can you delete all the comments and just leave the original post. Many thanks in advance, Alan

 

[smokie]

I thought there was a "rapid" designation too...? (Maybe 11)

 

[the briggie]

11kw is still designated as fast. Rapid in all the definitions I have checked are DC 40kw and above

Understanding electric vehicle connector types | Charging guide - Zapmap

How long does it take to charge an electric car? Learn about charging standards, compatibility, and make informed decisions for your EV charging needs.

www.zap-map.com

 

[Ron61]

It might be worth mentioning that there is a loss of roughly 15% between what's put in and what the car gets. e.g. for ever 1.15 kWh reported on the charger the car will store 1kWh.

 

[the briggie]

Apologies but this is basic understanding. As stated I will not be delving into nuances or details just a primitive overview. I could go into energy losses between chargers and batteries and batteries to motor via inverter, temperature effects, battery heating, heat pump efficiency, regeneration settings, driving styles, cabin heating power draw, DC charging effects, battery longevity recommendations, estimated range...the list is almost endless and each subject could be worthy of its own thread but....

 

[Alb]

Alb, thank you for moving this. Can you delete all the comments and just leave the original post. Many thanks in advance, Alan

I've changed this to an "Article" thread as these are intended for exactly this type of use. It highlights and differentiates the original (article) post to keep focus on the information rather than replies. When comments get to page 2, you'll find the article repeated at the top of the page. See how that works for you

 

[Jomarkh]

I know this is kept basic for EV starter newbies but can we not call them AC chargers as they are just a switch to put mains 230v into the car.
The EVSE just lets car know how much power is available fir the cars on board charger.

 

[the briggie]

Is that not a touch pedantic given the overall context.....I am trying to differentiate between ac chargers and dc chargers and whether you regard it as a controlled switch is beyond this simple guide. Do a google search for EV AC chargers and EV 230v switch to put mains into a car and see what you get...

Trying explaining to a newbie that it is just a big fancy app controlled 230v switch in a box with control circuits on another thread if you so desire but please leave this simple