800v charging capability, when?

[azbill]

I'm pretty sure you're charging at a V3 cabinet with a V4 dispenser, so your Hummer was charging at 400v instead of 800v.

That was my point, Tesla still does not have 800V chargers, even though they claim 325kw at those sites. They are pumping 900A out (at 400V) for the Cyber Trucks to make that claim.

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[pamalabama]

If you are comparing Lucid to Tesla use the Model S, which is a similar vehicle in size and comparison.

That is like comparing the Fiat 500 getting 4.8 miles/kWh to the Model 3 4.3 miles/kWh.

By the way, although the Lucid Air is significantly larger than the Model 3, it is in the same effeciency ballpark with a 4.3 miles/kWh.

The reason I'm comparing to model 3 is because model 3 LOSES to lucid in EPA testing.

If you look at real world efficiency of lucid it is close to model S

That motortrend article you linked only talks about EPA testing. The 5.0 mi/kwh of the lucid air pure is not something that a lucid owner will ever experience. The 4.3 number is with charging losses. That's an additional number not part of the EPA test.

Rivian efficiency is just bad. Not because it is 400v

 

[pamalabama]

The cost difference between 400v and 800v is nothing. Tesla uses dual 400v on the cybertruck. If it brought efficiency gaIns to use 800v then tesla would have already done it years ago. It would give them longer ranges with smaller battery packs

There are so many bogus threads on this forum blaiming rivian's poor efficiency for the terrible charging speeds. Rivian charges slow because the battery has improper cooling. Not because the vehicle is inefficient.

Inefficient vehicles have larger battery packs to achieve the ranges they need. Those larger battery packs don't necessarily charge any slower because the individual cell c-rates determine the max speed of battery charging

 

[SANZC02]

The reason I'm comparing to model 3 is because model 3 LOSES to lucid in EPA testing.

If you look at real world efficiency of lucid it is close to model S

That motortrend article you linked only talks about EPA testing. The 5.0 mi/kwh of the lucid air pure is not something that a lucid owner will ever experience. The 4.3 number is with charging losses. That's an additional number not part of the EPA test.

Rivian efficiency is just bad. Not because it is 400v

I have no complaints with my R1S, 38k miles 2.45 miles/kWh lifetime.

I did not buy a large SUV thinking it would be as efficient as a compact car.

 

[azbill]

You'd also notice that the Silverado doesn't charge at 500A or the 550A that a Rivian would at max rate.

I have a Hummer and it does pull 500A, both at 740V and 370V configurations. The peak voltage on the GM packs is 400V, not 450V like Rivian and Tesla. On the Ionna chargers (400kw), the GM trucks have achieved 370kw rates. I get 185kw at Tesla chargers, at 370V.

The thing about the GM trucks is that they maintain a very high rate for much longer than the Rivian. I am sure that is due to the better cooling. Last September on a trip I averaged 250kw from 30% to 80%. Just today I did a charge from 32% to 85% while eating lunch on my trip and it averaged 240kw. Even at 80% the charge rate is 180kw, and there is no sudden drop after 80%, it ramp linearly after that.

The other advantage of 800V systems, is that you can pull 175kw on chargers rated for 150kw. My Hummer does that all the time at EA 150kw chargers and the Hyundai's also get that same rate with their 800V systems. At the higher voltages you only need 250A to get that rate of charge.

 

[VSG]

My R1T gets up to 192 kW on EA 150kW chargers.

 

[KootenayEV]

For a given kW speed, 800v pack will see less current across all cells, assuming they’re in serial configuration. So less heat.

Sorry but that is flat out wrong. The individual cells have a voltage inherent to the electro chemistry of the materials. This cannot be changed. They are wired together in combination of serial and parallel to get the total pack voltage and amp-hour which gives total kWh. 800v or 400v pack made of the same cells will have the same number and each cell sees same voltage and current.

 

[Airnet]

I think the Osborne effect is the issue. Rivian might have the 2026 R1S 800v in testing now but the moment they announce it, sales of 2025 crash. Maybe they are planning 2027 for 800v, still crashes current sales.

We are ready to pull the trigger on a 2026 but no announcement probably due to the Osborne effect. Waiting.....

 

[DuoRivians]

Sorry but that is flat out wrong. The individual cells have a voltage inherent to the electro chemistry of the materials. This cannot be changed. They are wired together in combination of serial and parallel to get the total pack voltage and amp-hour which gives total kWh. 800v or 400v pack made of the same cells will have the same number and each cell sees same voltage and current.

Draw it out. Draw three battery cells in serial format, with each cell at 3.6v at 1A. Total power is 10.8W. (3.6V * 3 * 1A) Throughout the whole circuit, only 1A runs on the wires everywhere.

Next, draw the same 3 cells at 3.6v in parallel, also receiving 1A each. Also 10.8W total delivered to the cells. But, before the wires branch out to each cell, more than 1A (likely more than 3A) has to be flowing at some point in the wires. Which where the heat can build up. It’s not necessarily the cell-level, but at the entire pack level where the heat builds.

 

[KootenayEV]

Draw it out. Draw three battery cells in serial format, with each cell at 3.6v at 1A. Total power is 10.8W. (3.6V * 3 * 1A) Throughout the whole circuit, only 1A runs on the wires everywhere.

Next, draw the same 3 cells at 3.6v in parallel, also receiving 1A each. Also 10.8W total delivered to the cells. But, before the wires branch out to each cell, more than 1A (likely more than 3A) has to be flowing at some point in the wires. Which where the heat can build up. It’s not necessarily the cell-level, but at the entire pack level where the heat builds.

I was talking about the cells, where, as I understand it, the majority of the resistance is (ie the heat). Maybe it's in the wires though, or maybe the wires are enough to tip the balance so to speak. I'm not that interested in bothering to spend the time to math it out. Happy to be shown the math if someone else has the time.

 

[Joules Burn]

My bottom line. There hasn’t been ten minutes of difference in the ultimate 80% charging levels with any of my EV’s no matter what the provider. (okay, a couple quirks.) I have taken multiple cross-country trips with a Kia EV6 GT-L, Mustang GTPE, and Rivian R1S.

My charging stops were mostly regulated by the QUALITY of of the charger (PlugShare). NOT by the theoretical output.

RAN was number 1. Tesla a close second. EA was a WAY down third but ultimately the only option. My overnight “free” L2 at my hotels saved my financial butt.

800 or 400. The variables in the systems will give you a headache. Drive and charge and enjoy the trip and don't stress about minutia.

 

[Kaiju]

I'm afraid we've only scratched the surface on the actual nuances involved.

For the actual battery pack higher voltage has other consequences and the design is much more intricate than just stitching cells together in series or in parallel. For example, it's been said that for the same kW rating that 800V has about half the current draw as 400V. That's correct, at the charger. It can be more efficient there, though you can still size the conductors in either case to have the same resistance so efficiency is roughly the same. Whether or not it actually is comes down to engineering decisions and cost. So then it's down to whether or not you can get the full kW rating with amperage limits.

The thing is on the battery pack level, there may be no difference whatsoever between 800V charging, or 400V, or 100V. That's because all those 5V cells are most likely all wired in parallel and the actual charging within the pack happens at relatively tiny voltages. Series connections have dramatically more resistance and would require the conductors at the start of any given chain to be huge, because the total current for everything in the line has to flow through that one branch. Ohm's law favors dozens or hundreds of cells be wired up in parallel, or maybe in small clusters depending on where optimization break points were. Either way, the voltage seen at the level of actually charging cells within the battery is dramatically less than the input.

The real question is where voltage is stepped up and in how many stages. All of that can actually be external to the battery pack itself, as evidenced by some manufacturers using their motors to step voltage. Rivian could do '800V charging' by just adding a transformer just behind the charger interface and changing nothing else, but that would accomplish nothing if the pack was still limited to 220kW except adding the cost of a 220kW transformer and losing space to put it.

No matter what you do, trying to force 350kW vs 220kW into the same number of 5V cells means the current per cell increases, because you're still charging individual cells at 5V. That has all kinds of knock-on effects within the battery pack. More current means more resistance, chemistry of individual cells may be limited in how much they can actually accept, there may be a nonlinear relationship in the cells that creates diminishing returns and there are all sorts of problems associated with sinking 60% more heat in the same volume. Heat in the pack is always going to be directly proportional to the power input. This is also to the advantage of monstrous battery packs that simply have more cells, which is why some charging comparisons aren't apples to apples.

This is one reason why I've called it a marketing gimmick if the battery pack really can't take 350kW or can't handle it for very long. On a manufacturing end it doesn't make sense to eat the cost of upgrading everything if you can only hold the rate for a few minutes before having to throttle down due to overheating. If your active cooling setup can't keep up, then basically all the gains in charging time are limited to how much heat the battery can soak from its beginning to peak temp and gains become realized only in short charging sessions where you stop as or before it hits its temperature limit and the rate drops off to what's sustainable.

I personally get the impression that when dealing with these rather extreme kW inputs that the DCFC claims are basically all about the heat soaking ability of the main mass of the battery. So if you could hold 200 kW for 10 minutes, well, maybe a Rivian on the same thermals would only be able to hold 350kW for 5 or 6 minutes before throttling back. However it's not going to be strictly proportional because the higher charge rate is going to be less efficient. You would sink a bit more heat running your cooling that extra 4 or 5 minutes for the same power input. You've still charged faster- and if that's where you cut it off you've definitely charged way faster- but once it gets throttled on thermals neither 350kW or 200kW would make any difference so your net savings would be that initial 4-5 minutes on the whole session.

So how much money will people pay to save 5 minutes on DCFC vs how much it costs?

 

[DuoRivians]

I'm afraid we've only scratched the surface on the actual nuances involved.

For the actual battery pack higher voltage has other consequences and the design is much more intricate than just stitching cells together in series or in parallel. For example, it's been said that for the same kW rating that 800V has about half the current draw as 400V. That's correct, at the charger. It can be more efficient there, though you can still size the conductors in either case to have the same resistance so efficiency is roughly the same. Whether or not it actually is comes down to engineering decisions and cost. So then it's down to whether or not you can get the full kW rating with amperage limits.

The thing is on the battery pack level, there may be no difference whatsoever between 800V charging, or 400V, or 100V. That's because all those 5V cells are most likely all wired in parallel and the actual charging within the pack happens at relatively tiny voltages. Series connections have dramatically more resistance and would require the conductors at the start of any given chain to be huge, because the total current for everything in the line has to flow through that one branch. Ohm's law favors dozens or hundreds of cells be wired up in parallel, or maybe in small clusters depending on where optimization break points were. Either way, the voltage seen at the level of actually charging cells within the battery is dramatically less than the input.

The real question is where voltage is stepped up and in how many stages. All of that can actually be external to the battery pack itself, as evidenced by some manufacturers using their motors to step voltage. Rivian could do '800V charging' by just adding a transformer just behind the charger interface and changing nothing else, but that would accomplish nothing if the pack was still limited to 220kW except adding the cost of a 220kW transformer and losing space to put it.

No matter what you do, trying to force 350kW vs 220kW into the same number of 5V cells means the current per cell increases, because you're still charging individual cells at 5V. That has all kinds of knock-on effects within the battery pack. More current means more resistance, chemistry of individual cells may be limited in how much they can actually accept, there may be a nonlinear relationship in the cells that creates diminishing returns and there are all sorts of problems associated with sinking 60% more heat in the same volume. Heat in the pack is always going to be directly proportional to the power input. This is also to the advantage of monstrous battery packs that simply have more cells, which is why some charging comparisons aren't apples to apples.

This is one reason why I've called it a marketing gimmick if the battery pack really can't take 350kW or can't handle it for very long. On a manufacturing end it doesn't make sense to eat the cost of upgrading everything if you can only hold the rate for a few minutes before having to throttle down due to overheating. If your active cooling setup can't keep up, then basically all the gains in charging time are limited to how much heat the battery can soak from its beginning to peak temp and gains become realized only in short charging sessions where you stop as or before it hits its temperature limit and the rate drops off to what's sustainable.

I personally get the impression that when dealing with these rather extreme kW inputs that the DCFC claims are basically all about the heat soaking ability of the main mass of the battery. So if you could hold 200 kW for 10 minutes, well, maybe a Rivian on the same thermals would only be able to hold 350kW for 5 or 6 minutes before throttling back. However it's not going to be strictly proportional because the higher charge rate is going to be less efficient. You would sink a bit more heat running your cooling that extra 4 or 5 minutes for the same power input. You've still charged faster- and if that's where you cut it off you've definitely charged way faster- but once it gets throttled on thermals neither 350kW or 200kW would make any difference so your net savings would be that initial 4-5 minutes on the whole session.

So how much money will people pay to save 5 minutes on DCFC vs how much it costs?

Outside of the U.S., where 800v+ will be the standard soon, I don’t think it won’t matter to the consumers how much actual time is saved.

It’ll be a checkbox of what is offered, since the competition from China and Korea will offer them for cheap. And if a car doesn’t offer it, I think consumers will pass. Much like some version of adas will be a consumer requirement in the near future.

 

[CharonPDX]

Sorry but that is flat out wrong. The individual cells have a voltage inherent to the electro chemistry of the materials. This cannot be changed. They are wired together in combination of serial and parallel to get the total pack voltage and amp-hour which gives total kWh. 800v or 400v pack made of the same cells will have the same number and each cell sees same voltage and current.

This.

400V or 800V, if you're pumping 200kW into a vehicle, the *pack as a whole* may be only drawing 250A on 800V as opposed to 500A on 400V; but the individual cells are not drawing less current.

Let's invent a hypothetical 800 cell vehicle (HUGE cells.)And lets assume these are strange 1 volt cells (for simpler math than reality.)

You could have them all in series, which would produce an 800V vehicle. And if you feed 200kW, you're feeding 250 Amps to each cell.

Or you could have them in two 400-cell series, that are in parallel with each other, producing a 400V vehicle. If you feed 200kW at 400V, you're feeding 500A to the whole pack - by dividing it in two 400V segments, each drawing 250A. So each cell is getting 250 Amps.

 

[emoore]

The reason I'm comparing to model 3 is because model 3 LOSES to lucid in EPA testing.

If you look at real world efficiency of lucid it is close to model S

That motortrend article you linked only talks about EPA testing. The 5.0 mi/kwh of the lucid air pure is not something that a lucid owner will ever experience. The 4.3 number is with charging losses. That's an additional number not part of the EPA test.

Rivian efficiency is just bad. Not because it is 400v

Rivian poor efficiency isn't because of 400V vs. 800V, it's because it's a truck. Going to be a lot less aerodynamic than a car. Same goes for all ICE vehicles.

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