EV Voltage, Does it make a difference?

Every automotive original equipment manufacturer (OEM) has their own platform, or they have signed an agreement with another OEM to use their EV platform.

The following chart lists all of the current North American Automotive OEMs and the platform details that they have released.

While there are a few oddball platform voltages such as the Toyota/Lexus/Subaru platform with a 355-volt system or the Lucid with a 924-volt system, the bulk of the OEM auto manufactures have gone with a 400-volt or 800-volt system. Many of these OEMs are already planning or have moved to an 800-volt platform such as Tesla with the production start of their Cybertruck that is based on an 800-volt system running a 48-volt electrical system compared to internal combustion engine (ICE) autos that run a 12-volt system to run electronics while burning gas or diesel. 

While the chart above pretty much answers the question of what is the voltage as of today for every North American OEM platform, this still leaves the bigger question of does the voltage make a difference?

In short YES, voltage does make a difference in how the battery pack of an EV charges.

The transition of moving from 400-volts to an 800-volt EV charging system offers the following advantages:

• Weight savings
• Enhanced performance
• Increased efficiency and charging power

The largest drawback if you consider this a drawback is the need to convert existing charging stations to support the higher 800-volt specification and the need to redesign electrical components to support the higher voltage system. Lucid has one such platform as they say it can handle over 1000-volts though it is officially rated at 924-volts.

The current leaders of an 800-volt architecture are as follows:

• Porsche
• Audi
• Hyundai
• Genesis
• Kia
• Volvo
• Polestar
• Bentley
• Lamborghini
• Tesla Cybertruck only

What makes up an EV Charging system? For this I use a diagram from the ev charger design website.

The basics are pretty simple that make up the EV charging system:

• Battery
• Motors
• Controller
• Sensors
• Wires
• Electrical paraphernalia

As one can see above in the diagram you have two types of charging, DC fast charging which is a connection right into the battery pack delivering the largest and fastest charge possible. Second is the AC Charger, this can be from level 1 or 2 public chargers or from your own place of living, home, condo, townhouse, apartment and goes through an on-board controller and then into the battery pack.

Now that we have covered the basic of an EV charging system, let's take a look at what makes up the charging of a battery system. Charging of a battery system breaks down into a simple 4 stage system.

• Stage 1 Constant Current - Voltage rises at constant current
• Stage 2 Saturation charge - Voltage peaks, current decreases
• Stage 3 Ready mode - Charge terminates
• Stage 4 Standby Mode - Occasional topping charge

As the battery cells get saturated with power, the current drops off and this is why charging slows down as the battery pack fills up.

DC Fast charging will power up the battery pack till it reaches a preset charge level that is usually set by the EVs built-in software and then charging stops, and nothing is ever added as to why some public charging stations including Tesla stations now charge for connections that are not charging to an auto as they want to free up the charger for other EV users.

AC charging will charge up a battery pack to full but has the ability to sense if the battery level drops to top off the battery pack. This comes in to be very useful in extreme hot or cold environments where the battery pack needs to either be chilled or warmed up. End result is when you go to leave in your EV, you always have a full battery pack, based on the setting of the EV software. This could be 80%, 90%, etc. that you the end user chooses.

800-volts is the future replacement for the current 400-volt systems in use by the majority of auto OEMs. So what does this 800-volt system get us?

• Faster charging power
• Performance enhancement
• Efficiency
• Weight reduction

End result is that the 800-volt system reduces the amount of time it takes to charge a battery pack, getting one on the road that much faster. This equates to the minimal time it takes to fill a gas tank in a traditional internal combustion engine auto.

Currently the average gas fill-up takes approximately 5 minutes per the U.S. government.  This in comparison to the average charging time of an EV:

• Level 1 charging can take 2 to 3 days @ 110 volt
• Level 2 charging can take 7 to 15 hours @ 240 volt
• Level 3 charging can take 15 to 45 minutes to reach 80% state of charge on a current 400-volt system

The charging information above is based on a 60kWh battery pack from empty to full (80%) using a 7kW charging point. This can for level 1 and 2 change based on each EVs built in controller speed. See the chart above for controller charging speed by OEM.

If the EV built in controller was to handle 14kW, then the Level 1 charging time would be 1 to 1 1/2 days. Level 2 charging would be 3 1/2 hours to 8 hours. Reduced even further the higher the controller kW is capable of handling.

Faster DC charging also allows for EVs to have smaller battery packs (weight reduction) when you can quickly charge up the battery pack allowing for reduced battery pack size. Even with the average commute of auto owners being between 30 to 50 miles, range anxiety is an issue that has been blown up in the media depending on each media's agenda in support or against EVs. This is where weight increases have come from as people tend to have come to feel having 300 miles of range is a must in an auto.

This also brings up the future of Solid-state batteries that in early prototype have shown to be four to ten times energy dense as current lithium-ion batteries. This allows the OEMs to then reduce the overall size of batteries, thus reducing weight of an EV.

Another benefit that comes with 800-volt battery packs is the ability to charge in serial or parallel mode. This multi-charging system allows ease of working with all formats of 400-volt or 800-volt charging stations.

Per a Harvard research release, solid-state batteries will dramatically reduce charging times. Researchers have proven that Solid-state lithium batteries can last 20 years with minimal degradation while recharging in minutes. They used the example of a 110kW battery pack that would be equal to today's 60kW lithium battery fully charging in only 10 minutes at 800-volt and could be reduced even further if charging was pushed to 1,200-volts or higher.

Here we end up with smaller battery packs and faster charging by using 800-volt systems, add in solid-state batteries and you end up reducing the size and weight of the battery along with speeding up charging times.

Yes, there are plenty of writeups showing the pros and cons of 400-volt to 800-volt with the biggest con being that money has to be spent by the companies to upgrade their auto design, components, etc. to handle the higher 800-volt charge, yet if they want to be competitive, then they cannot sit on the sidelines.

End result is faster charging for all with an 800-volt system over the 400-volt systems allowing for a far superior experience by end users.

Auto EV Platform Info 2023.xlsx