400vs800volt battery poll

[rodhx]

The 800v charging will really become a necessity with the larger battery packs. Heavier trucks and SUVs may require over 200kWh batteries to make them viable substitutes for the gas siblings. So having a 800v 350kW charging will be necessary to fill up in reasonable time.

Exactly why I think the delay in opening Lightning ordering could hurt Ford. Well…not really “hurt” since they won’t be able to make enough for the Ford-only crowd, but hurt in the sense of conquest sales. The 800v Chevy will be unveiled and reservations start a few days before Ford opens the order banks. I am early on my dealer‘s list to order a Lightning when the banks open but I will be watching the GM announcement very carefully.

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[Sam2084]

Think wire size. It might not improve charge time but it removes some of the heat and loss at high current. Ohms law man. Do your engineering.

Yes, by going with an 800V system you can reduce your wire size and save some cash, and also increase efficiency a bit. Those aren’t crazy game changers though.

 

[Whatstreet]

Yes, by going with an 800V system you can reduce your wire size and save some cash, and also increase efficiency a bit. Those aren’t crazy game changers though.

100 amps at 0.1 Ohms is a 10V drop. Also, 100 amps with a 10V drop is 1000 watts of heat dissipation.

Now, let's say we double the voltage but maintain the same wattage, the current will be half as much as it was, because wattage is (V*I). In the first example, 100 amps will become 50 amps and so 0.1 Ohms will be a 5V line drop (I*R) and the wattage dissipated will be 250 watts.

Resistance becomes less significant as voltage is increased, and current is decreased. Power loss due to resistive heat will be less.

 

[Ride_the_lightning]

100 amps at 0.1 Ohms is a 10V drop. Also, 100 amps with a 10V drop is 1000 watts of heat dissipation.

Now, let's say we double the voltage but maintain the same wattage, the current will be half as much as it was, because wattage is (V*I). In the first example, 100 amps will become 50 amps and so 0.1 Ohms will be a 5V line drop (I*R) and the wattage dissipated will be 250 watts.

Resistance becomes less significant as voltage is increased, and current is decreased. Power loss due to resistive heat will be less.

Knowing Ohms law doesn’t make you an engineer, it makes you a high school physics student. Yes, that simple equation you posted is one part of many variables that go into an engineering decision. FYI I am an EE that designs DC fast charging projects for a living, so feel free to explain engineering to me.

 

[AZBill]

The current CCS chargers are limited to 500A current, so 400V systems cannot go above 200kW. That is a limitation that is hard to overcome due to heat in the cables, including internal to the vehicle. This is why GM is going 800V for their trucks. F150 will be a charging dog compared to GM trucks.

A video of the Lucid charging at 800V shows it can add 100 miles in 5 minutes. Lucid is the first vehicle to reach the 300kW peak charge rate, but now that Hummer is out it will hit 350kW.

 

[Dylancch]

I'd buy the hummer but 150k to expensive

 

[timbop]

Knowing Ohms law doesn’t make you an engineer, it makes you a high school physics student. Yes, that simple equation you posted is one part of many variables that go into an engineering decision. FYI I am an EE that designs DC fast charging projects for a living, so feel free to explain engineering to me.

Nice. Believe it or not engineering is often not the deciding factor that determines "winners and losers", despite what engineers think.

Being able to market 20 to 25 minute charging versus 40 minute charging makes a huge difference in what will quickly be a very crowded field.

Just like camera makers kept pushing more megapixels as the "critical metric" even though they had already pushed densities to the point that there was a negligible return, BEV makers need to address one of the biggest perceived concerns people have - which is having to sit and charge "often and forever". That perception is based on the previous generation of cars (and myopically the "new" Bolt BEV) with 50 and 70kw max charging that took an hour to "refill" for every 2 to 3 hours of driving.

 

[Ride_the_lightning]

Nice. Believe it or not engineering is often not the deciding factor that determines "winners and losers", despite what engineers think.

Being able to market 20 to 25 minute charging versus 40 minute charging makes a huge difference in what will quickly be a very crowded field.

Just like camera makers kept pushing more megapixels as the "critical metric" even though they had already pushed densities to the point that there was a negligible return, BEV makers need to address one of the biggest perceived concerns people have - which is having to sit and charge "often and forever". That perception is based on the previous generation of cars (and myopically the "new" Bolt BEV) with 50 and 70kw max charging that took an hour to "refill" for every 2 to 3 hours of driving.

I think you and I agree with each other. The earlier poster explained why 800V charging doesn’t actually provide faster charge speeds. My post was in regards to the poster who talked about charging losses (true but not the deciding variable).

I fully agree with you that faster charge speeds are needed. 800V alone won’t necessarily solve that though for all cars. That being said, I’m not against 800V. It’s the future. It just isn’t as simple as “put in 800V battery and charge 2X faster.” The lightning would benefit from it a lot more than the Mach E. The Mach E extended range would benefit more than my standard range. This is because they have much larger batteries that ARE being limited.

 

[tuminatr]

50kw was state of the art just a few years ago, but now they look like fossils. Unfortunately many states are still putting those in on highways, which does as much to inhibit BEV adoption as help it. At this point they're only useful as a backup option if faster chargers are unavailable.

True, unfortunately, there are very few CCS chargers in my state faster than this. And they are crazy expensive the owners need to take a reality check and adjust their rates. I would pay $10 per hour to use and not complain about it taking an hour to charge.

 

[Vaquero]

Of course I choose 800v charging system.
But I also think that a well implemented 400v system, where the charging curve and the cooling of the batteries is really good makes a big difference. I wish our MME had a good cooling system and from 0 to 80% the charge curve is always above 120kW.
Also LiFePo batteries would be a good option for safety.

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