[Omkar]

Times are changing fast and we’re surrounded by more electric vehicles than we would’ve expected a few years ago. While we know most things about IC engine cars - how they work, what systems are involved, the standard set of do's and don'ts etc., we tend to overlook a lot of similar things in electric vehicles probably because they're pretty straightforward to drive. However, IMO, EVs are far from that. There's a lot of technology involved and the level of complexity is also high. With such an influx of EVs in our market, it’s about time we also got ourselves acquainted with the technology to make better decisions. To be specific, I am referring to electric vehicle architecture.


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Before we get to the specifics of the architecture, quoting the basics of an electric vehicle from one of our official reviews -

There are 3 main components in an EV – the battery, the motor and the controller/charger. The battery is what stores the energy and the motor is what uses that energy to drive the wheels of the car. The controller/charger converts the energy from the battery into a usable form to power the motor. In more technical terms, the power grid from your house or a charging station is usually an AC. The lithium-ion battery can store electric energy in DC form. So while charging, there’s usually an AC/DC converter that will convert the power grid's AC into DC and store it in the car’s battery. The DC fast chargers that you see, usually have the AC/DC converter inbuilt, which is how they can charge the car’s battery faster. The controller typically sits on top of the motor.

Now coming to the electric vehicle architecture, if you have been following the news, you might have noticed that some of the manufacturers are now opting for an 800V battery architecture. This is obviously in the premium EV segment, not the budget segment, but some manufacturers have made the change. Most of our budget EVs come with a 400V battery architecture. Let’s take two Hyundai EVs for example – the Kona EV and the Ioniq 5. Just look at some of the stats below and something seems a bit odd. How does the Ioniq 5 manage to charge in a similar time as the Kona while having a battery that’s almost twice as big? The simple answer is that the Ioniq 5 has better EV tech, which is what we'll dive deep into. The Kona EV has a 400V architecture while the Ioniq 5 has an 800V architecture.



Tech talk

To understand how voltage works and how it affects the charging time and even the way an EV drives, let’s jump into some technical details. I’m sure there are quite a few members on the forum who’ve worked closely with EVs and will be able to shed more light on the same. As is with some electrical engineering concepts, you can use the hydraulic loop analogy to understand the concept better. There’s a reservoir, a motor/pump and pipes. The voltage is equivalent to the pressure in the pipes. So, if you use a more powerful motor/pump or a larger reservoir, the pressure in the pipes will increase. Remember Ohm's law?

Voltage = Current x Resistance

The current would be the diameter of the pipes. Hence if you increase the diameter (i.e. current) the pressure will drop (i.e. voltage). Manufacturers try to keep the resistance minimum hence they must play around with the other two factors that are inversely proportional to each other.



So, what does all this mean in EV terms? A higher voltage architecture will need less current to push the same amount of power to the motor. How does that help? Lower current means manufacturers can use lighter wiring harnesses. Also, current is one of the primary reasons for heat generation in electronics. Low current means less heat generation, ergo longer lifespan for electronics and batteries. Also, heat generation during fast charging is usually the limiting factor for charging speed. Putting it all together, high voltage, low current and less heat means that the charging speed can be much higher. Circling back to the Kona vs Ioniq 5 example, the 800V architecture in the Ioniq 5 allows it to charge faster. More importantly, it also allows the Ioniq 5 to use fast charging options like the 150kW charger that can charge the battery from 10-80% in ~ 25 mins or even the 250kW fast charging that can charge the battery from 10-80% in ~ 18 mins. In comparison, the Kona EV can only go up to 100kW charging that will charge the battery (10-80%) in ~48 mins.



Additional benefits of high voltage architecture

As mentioned earlier, the high voltage architecture means lesser wiring, reducing the complexity of the system. Lower heat generation means that the loss of power due to overheating is almost eliminated. The system is more efficient in terms of power delivery. You don’t have to worry about your system being overworked. Even if you’re doing back-to-back drag races, or pushing the car for a long period, the system won't overheat easily and the battery drop won't be drastic. Think of this as redlining your IC engine car. You cannot over-rev the engine for a long period as that will strain it and probably blow it up if you overdo things. But with a high-voltage architecture, you can get the maximum rated power output over and over again without putting the system under immense pressure.


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What's the current scenario?

It was Porsche who first brought the 800V architecture to its road cars with the Taycan. They had used the tech earlier in their Le Mans-winning 919 Hybrid race car. Some of the cars that use the 800V system are the Audi E-Tron GT, Kia EV6, and Hyundai Ioniq 5. The Mercedes EVs like the EQS sedan and the EQE SUV are currently using the 400V system but are rumoured to be receiving the 800V system soon. Most of the other EVs are still using the 400V system, but as time goes by, they might also consider shifting to the 800V system.



How does it matter?

Some of you might be thinking, "Long wait times don’t bother me as much. Why should I spend the extra amount? How does any of this matter?" That’s totally fine as well. High voltage architecture like the 800V system is more efficient and doesn’t face overheating issues. Along with the temperature management systems in place, you have EVs with longer life. For someone who’s in the market for an EV and who likes to keep their cars for a long period, investing an additional amount initially makes more sense than having an outdated car 3-4 years down the line. Because as it seems, manufacturers will start offering 800V systems soon enough. The Ioniq 5 is the most affordable car with the 800V system and in the coming years, technology will become more accessible and affordable.

People used to say that EVs are the future. Well, the future is here, so why not prepare for the future that is to come? Do share your thoughts on the same.

Sources - 1, 2, 3

[Omkar]

Thread moved out from the Assembly Line.

[chinkara]

Thanks for the excellent thread. One correction.
High voltage Harnesses are more robust than LV harnesses. This is because power (V*I) is more and designs are failure proof. Most normal wiring harness manufacturers in India struggle with HV harness. Also, the system is more sophisticated - greater safeguards needed to prevent electric shock etc.

[DIY410]

Originally Posted by chinkara

Thanks for the excellent thread. One correction.
High voltage Harnesses are more robust than LV harnesses. This is because power (V*I) is more and designs are failure proof. Most normal wiring harness manufacturers in India struggle with HV harness. Also, the system is more sophisticated - greater safeguards needed to prevent electric shock etc.

No Indian manufacturers do not struggle, the criteria for automotive wires are the insulation rating, designed to handle the high ambient temperature of engine bay area which is much higher then EV powertrain area, vibrations and flexibility. So the material used is different then the house hold wires.

Even your basic no name cheap household wire will have a insulation voltage rating printed on them, which is typically 600v for the basic ones, irrespective of the current they pull.

Finolex, Polycab etc even their basic household wire have a rating of 1100v, irrespective of the current draw.

Your spark plug wire insulation is rated to handle 40000v.

So if you use a basic finolex household 1100v wire of 2.5sq.mm rated at 18A, it can in theory pull close to 20kw of power(V*I) before its insulation starts to fail under standard test condition.

But the same wire if used in a 12v DC of a vehicle, you can pull only around 220watt. So that is why Elon Musk is switching to 48v, which can also result in switching to aluminium core wires instead of expensive copper.

Same applies to HV cables.

Indian manufacturers even export automotive wires to Russia besides other nations.

[chinkara]

Originally Posted by DIY410

Finolex, Polycab etc even their basic household wire have a rating of 1100v, irrespective of the current draw.


Indian manufacturers even export automotive wires to Russia besides other nations.

Aren't you confusing HV cables with HV harness? Finolex, Polycab AFAIK do not manufacture Harness.
Of course Motherson Sumi is a global leader and has the technology. But smaller manufacturers still do not have ready harnesses.
There are many factors - terminal design, insulation, impact resistance etc. which make automotive harnesses more complex than household cables.

[DIY410]

Originally Posted by chinkara

Aren't you confusing HV cables with HV harness? Finolex, Polycab AFAIK do not manufacture Harness.
Of course Motherson Sumi is a global leader and has the technology. But smaller manufacturers still do not have ready harnesses.
There are many factors - terminal design, insulation, impact resistance etc. which make automotive harnesses more complex than household cables.

HV harness means a bunch of HV cables in a wire loom with connectors. Anyone can make a harness. Substitute the HV cables with automotive grade HV cables you get a HV harness for automotive use.

There are plenty of harness makers in India, who buy automotive grade wire from Indian manufacturers.

If Indian manufacturers are able to supply for extremely harsh operating environment of defense applications from aircrafts, missiles, submarines. A EV HV wire is the most basic of the basic, a welding cable handles 400A DC or more and its available of the shelf in India from any big wire company.

Same goes to DC solar panel wires which is exposed to 8 hrs of sunlight UV rays etc and the operating voltage rating is 400v to 1000v for roof top applications.

Its all in the material of the insulations that determines the application from Temperature, Current, Voltage, Flexibility, Abrasion Resistance, UV, Gases etc.

[Omkar]

Originally Posted by chinkara

Thanks for the excellent thread.

Thanks chinkara!

One correction.
High voltage Harnesses are more robust than LV harnesses.

Don't think I've mentioned anything that contradicts your statement .

What I have mentioned though is that the high-voltage system allows manufacturers to use lighter wiring harnesses. This was in context of actual weight reduction. In the Taycan, Porsche was able to shed ~30 kilos by making the switch to an 800V system (Source)

[srini1785]

A few technical points that come to my mind.

1. Harness is a bunch of wires with pre linking and connectors which is easy to use in automotive wiring. I don't think we lack the capacity to manufacture HV harness of any voltage. There are Indian companies which make UG cables which can go up 33Kv. The insulator is usually XLPE (cross linked poly ethylene) with either a wire or sheath armor.

2. When you say a 250kW system charges in 10 mins while a 100kW charges in 40mins, what we are talking about is essentially battery capacity to receive energy (measured in kwHr). The charging system can push an even higher energy to the battery in a even shorter times but the charging current would fry the battery and battery would go boom. As on date the battery tech is able to cope with only so much energy. In future, i'm pretty sure that we would be able to charge the battery in lesser time as we take to fill up a tank.

[ohaak]

A key aspect often overlooked in electric vehicles is their reliance on the traditional 12-volt electrical system, a standard that has remained unchanged for around a century. The Tesla Cybertruck marks a significant shift in this trend, adopting a 48V system. This transition brings numerous benefits, including enhanced efficiency, lighter and smaller wiring, improved performance of electrical components, more effective regenerative braking, and a smoother integration with the vehicle's high-voltage systems. This integration simplifies voltage conversion processes.

Furthermore, the problem of electric vehicles failing to start after being parked for extended periods (several weeks) due to the draining of the 12-volt battery highlights the importance of rethinking the low voltage system architecture. A more robust system not only contributes to the vehicle's efficiency but also enhances user convenience and reliability.

[Rocketscience]

While understanding all this is a bit out of my zone and will to invest time researching about it myself, but this seems to be the opposite approach to what is happening in mobile phones. (about which I know a fair bit)

Chinese manufacturers who are the best when it comes to charging speeds used to use lower voltage charging with obviously thicker wires so that the heat can be kept away from the phones and stays in the charger.
This way they could deliver fast charging without generating much heat in the device and maintaining the battery health for long and also delivering much faster charging speeds than the competition.
The phones I have used (iPhones) never adopted this technique and instead used higher voltage for fast charging (9 volts as opposed to lets say OnePlus's initial days 5 volts), here they could get away with similarly thick cables but the phones did heat up a lot as a result while still charging slower than OnePlus, the battery health when using fast charging vs without it was affected in hot places like Delhi and the phones in my family used to completely stop charging at around 80% because of high temperature unless they were kept in an air conditioned room.

I don't know why Apple didn't engineer it differently but this is true even in my latest iPhone 15, maybe they benefit from batteries dying faster as firstly they sell their batteries at a ridiculous premium and their batteries cost as much as what complete entry level phones do, or even better for them the people will be compelled to sell their perfectly fine working phones instead of replacing the batteries, either way they win.
(My iPhone 11's battery lasted me 4 full years as opposed to 2.5 years in my sister's iPhone 12, the difference being me using slow charging and her using fast charging)

Won't batteries heating more be an issue here as well or is it something different?

[niranjanrvce]

Originally Posted by Omkar

Voltage = Current x Resistance

The current would be the diameter of the pipes. Hence if you increase the diameter (i.e. current) the pressure will drop (i.e. voltage). Manufacturers try to keep the resistance minimum hence they must play around with the other two factors that are inversely proportional to each other.

Thanks for the super informative article Omkar.
One clarification on the above statement is that voltage is directly proportional to current (not inversely). But since power = voltage * current, it is preferred to achieve the same power via higher voltage while keeping the current low to reduce Joules heating effect.

[chinkara]

Originally Posted by niranjanrvce

Thanks for the super informative article Omkar.
One clarification on the above statement is that voltage is directly proportional to current (not inversely). But since power = voltage * current, it is preferred to achieve the same power via higher voltage while keeping the current low to reduce Joules heating effect.

I think what was meant that to deliver the same power, voltage and current are inversely proportional. While V = i * R, if resistance is the same, effectively you are tweaking the system resistance at design stage to deliver same power at a higher voltage. And as Joule's equation suggests that heating is proportional to R but proportional to i^2, this also reduces the cooling arrangement needed. In fact, bulk of the savings come in cooling needs rather than just light-weighting.

Some OEMs are also working on 960V systems AFAIK.

[Jeroen]

Thanks for putting up this thread. I see some comments about wiring harnesses and so on. I would say that on all ICE cars one of their weak points is ultimately the quality of all the wiring used. As cars age, the wiring does degrade. Or rather in most cases the insulation. Which becomes brittle, starts to crack and so on. On cars over say 20 years old this is very often a problem, it’s not the car electronics, more often it is the wiring and wiring components such as connectors that are becoming problematic.

Time will tell how EVs which rely even more on wiring in various shapes and formats will stand the test of time. Already we know that battery aging is not an issue. But it will be a couple of decades before wiring issues show up.

And trust me, some of the big A brands have had horrible wiring issues that are rearing its ugly head now after 20-30 years. E.g. most Jaguars, quite a few Range Rovers, and also certain type of BMW and Audi.

My Jaguar X308 is famous for its low quality wiring installed. Won’t give you any problem for the first 15-20 years, but plenty later on in life.

Aging is a real issue on all wiring and cables.
Time will tell who got the quality wiring and cables installed.

Jeroen

[thtechnician]

Originally Posted by Rocketscience

this seems to be the opposite approach to what is happening in mobile phones. (about which I know a fair bit)

Chinese manufacturers who are the best when it comes to charging speeds used to use lower voltage charging with obviously thicker wires so that the heat can be kept away from the phones and stays in the charger.

This way they could deliver fast charging without generating much heat in the device and maintaining the battery health for long and also delivering much faster charging speeds than the competition.

(My iPhone 11's battery lasted me 4 full years as opposed to 2.5 years in my sister's iPhone 12, the difference being me using slow charging and her using fast charging)

Won't batteries heating more be an issue here as well or is it something different?

The same applies to mobile phones as well. Lithium batteries get degraded by heat, not because of fast charging. Here's a great video by MKBHD :

https://m.youtube.com/watch?v=UpqaQR4ikig

You sister's phone possibly lasted less because of :
A) More charge cycles
B) Completely draining the battery down to 0% and charging upto 100%
C) Using the phone while charging which generates more heat

Thicker wires are required for carrying more current. Heat will be generated both in the phone and the charger, thicker wires can't "carry heat" away from the phone. There's not enough direct contact between them.

The heating effect of electricity is given by (I^2 x R), which means dissipated heat increases with the square of current passing through it. You always want to have highest voltage with lowest current to avoid heating, and also lower current requires thinner wires.

[Rocketscience]

Originally Posted by thtechnician

The same applies to mobile phones as well. Lithium batteries get degraded by heat, not because of fast charging. Here's a great video by MKBHD : https://m.Youtube.com/watch?v=UpqaQR4ikig

You sister's phone possibly lasted less because of :
A) More charge cycles
B) Completely draining the battery down to 0% and charging upto 100%
C) Using the phone while charging which generates more heat

Thicker wires are required for carrying more current. Heat will be generated both in the phone and the charger, thicker wires can't "carry heat" away from the phone. There's not enough direct contact between them.

The heating effect of electricity is given by (I^2 x R), which means dissipated heat increases with the square of current passing through it. You always want to have highest voltage with lowest current to avoid heating, and also lower current requires thinner wires.

MKBHD's video is gross generalisation of the entire fast charging scene, it is an entertaining and well produced video but that's about it.

Thicker wires don't keep heat away from the phone but 5v charging does, thicker wires are required because more current needs to transferred at lower voltage for same wattage (As compared to 9v charging),
The charger will generate more heat this way (again as compared to same power at 9v vs 5v) but the phone's internal circuit will need to do lesser of the heavy lifting, since it will not need to step down 9v to lower voltage for charging the battery.

Have been going through in depth tests by chinese dedicated websites over the years, one of them being chongdiantou.com

Sister's phone was used roughly similar to my phone with the battery cycles being dramatically lesser than mine while degrading much faster.
(Her battery cycles were roughly 650 while mine were 1100+ both with 78-79% battery health)
Her phone used to heat up more because of fast charging, this is an different issue than Oneplus's vs Apple's charging approaches for example.

Here I slow charged it 99% of the times with Apple's 12w charger and she used Apple's 20w charger.

My phone didn't heat up at all while her's used to be considerably hot because of fast charging and that naturally degraded the battery.

Curiously both were 2 amps charging and voltage was the only differentiating factor between the 2, 12 w charger charges at 5 volts and 20w charger at 9 volts.

So yes, heat killed her battery much faster with much lesser cycles but fast charging and 9v charging was the reason for this extra heat and not using the phone while charging or running it down to 0% and charging it all the way to 100%.