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Novice to EVs but a question?

DucRider

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I wrote that in December 2019 and only a bit more than a month has passed but in that time I have learned that Tesla does exactly that with the Semi (more than two chargers though) and, as they are now producing less capable EVSE (48 A max) it seems that they will almost have to offer dual charge ports on the CyberTruck (or the 3 motor long ranfge version at least) given its high energy utilization. As its consumption and battery size are similar to the Rivians' it would make sense for Rivian to do this too and I wouldn't be surprised if they did this or at least offered it as an option. Thinking further about the kluge aspect: it really wouldn't be so bad. Just a couple of contactors or solid state relays (and some software, of course). One would need two EVSE to support this but as homes are going to have multiple BEVs in the near future mutiple EVSE are going to be commonplace.
To even need to do this at home, you would have to regularly do back-to-back 400 mile days while returning home in between. This would be a rare case and not likely something Rivian would design for.
And it is much more than relays, it would require two EVSE's, two charging ports, two chargers (or at least 2 inverters). Not likely something Rivian would design for. you would also have the potential added expense of sufficient electrical service to the home. Tyical new homes generally have 200A service (older homes often have 100A). Adding 2 60A EVSE circuits would likley require a serious upgrade to the homes electrical system. And all this would get you to about 22 kW charging.
The Rivians will DCFC at 160 kW, and the thousands of dollars required to equip the Rivian with dual charging systems would pay for a lot of public DCFC sessions.

If you are consistently driving 200 miles a day, you will easily be able to easily leave every morning with a full "tank" with a single 48A EVSE.

Tesla discontinued dual chargers (this used to be an option n the S/X). The Semi example is charging about a 1 MW pack in a DCFC application while on the road. When charging from DC, the charger is in the service equipment and not built into the vehicle. Rivian has filed a patent to take advantage of 800V DCFC equipment by essentially splitting the pack into two and then splitting the 800V into 2 400V circuits internally. This will effectively double their DCFC rate by "adding a couple of contacotors or relays", but won't do anything for home charging (unless you happen to have 3-phase 480 V service at your house and want to drop as much on a DCFC unit as you spent on the Rivian)
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ajdelange

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To even need to do this at home, you would have to regularly do back-to-back 400 mile days while returning home in between. This would be a rare case and not likely something Rivian would design for.
Actually, I don't even need a truck. But I have ordered one each from Rivian and Tesla. I do not need the largest battery in each but I have ordered the largest battery for each. People don't need solar cells on the roofs of their trucks but when they are offered people buy them. I don't need 72A charging for my Tesla X100D but I have it and I use it. IOW, with BEV, especially trucks, there are many things that we do not need most of the time (how often will I be hauling manure) but that we find useful, perhaps infrequently, to the point we are willing to pay for them and these things are gold to the manufacturers. Consider FSD in the Tesla. It may actually be available some day but people shell out thousands for it today.


And it is much more than relays, it would require two EVSE's,
Certainly two EVSE are required. I mentioned that in my last post where I pointed out that 2 EVSE is hardly rare today and is certainly going to be more common in the future as mom and pop each replaces his ICE car with a BEV. That fact is one of the big selling points of the dual port/dual charger approach.

two charging ports, Not likely something Rivian would design for
The test models they took to South America already have this. Hardly a big deal.

two chargers (or at least 2 inverters).
Not likely something Rivian would design for.
They may already have this. Tesla does and while we have, of course, no knowledge of what Rivian is doing in this regard common sense says that a 24 A rectifier module is a good idea. Why? You can put two of them into a car that does Level 2 charging from a single phase system to get 48A (what Tesla does with its current line in the US or you can put 3 of them into a car that charges from 3 ø mains as Tesla has done for Europe to get 72 A equivalent. Or you can put 3 of them in a biphase car as they did in my X (option no longer available). Modularity definitely confers advantages to the manufacturer as the modules can be used in different vehicles in different markets and, in the case of the Tesla modules, even in the SC network. The overall point being that adding a second charging path would be a simple thing to do involving the addition of the second plug, additional rectifier modules (see below) and some wiring. On further thought no switches or contactors would really be required.

You are a little confused on the architecture of a "charger". It converts AC from the mains to DC and then raises that DC to the higher voltage necessary to actually charge the battery. The Tesla approach is apparently (I cannot confirm) to use a bridge rectifier followed by a high frequency chopper (you could call this an inverter if you like) followed by a step up transformer and another bridge rectifier.

you would also have the potential added expense of sufficient electrical service to the home. Tyical new homes generally have 200A service (older homes often have 100A).
I wouldn't know about that. I have 400A service in an older home but it had been added on to. The NEC has requirements for the service size for new homes. As the use of electricity in homes is increasing with wider adoption being part of that I expect larger services are being installed. I believe California now requires a circuit for BEV charging in new construction. If one is going to buy a BEV or 2 electrical service is a consideration for sure and depending on what you have in your house at the moment it can cost you.

In proposing dual charging ports I am asking myself if I think its something that I would like to have, IOW if Rivian comes to me and says "$4000 for a second charging port - double your charging speed- interested?" I would doubtless say yes because none of the argument you have advanced phase me in the least. I have sufficient electrical service and, when I get the Rivian, I will be a two BEV family. I am guessing that there are enough like me that this is a potential money maker for Rivian as the engineering required to add such an option is trivial. That's what the manufacturers love best. Sell something they already have as an extra feature. Lots of profit in that.


Adding 2 60A EVSE circuits would likley require a serious upgrade to the homes electrical system.
It might or might not. Anyone new to BEVs who has to make a decision about how much infrastructure to add to support it would be, IMO, very unwise to not size his installation for at least 2 vehicles because I think that many, if not most, people who trade in and ICE vehicle for a BEV will be trading in their other ICE vehicles reasonably soon. Think of such an installation as supporting two 48A chargers be one in each of two vehicles or both in one vehicle. The dual port option in the Rivian thus really imposes no additional burden on the house electrical system. One could, of course, install 3 EVSE and dual charge the Rivian and a 3rd BEV but that would require extra energy - or would it if you stagger the charging. This can go on for pages but be aware that modern EVSE (e.g. the new Tesla HPWC) can (or will, when the software is available) be able to charge up to 16 cars at a total of less than X amps where you specify X). You could, then, with 3 EVSE, dual charge a Rivian and a Tesla without having to add more service capacity than needed for 2.

And all this would get you to about 22 kW charging.
You need to start thinking in terms of miles added per hour of charging. 11.5 kW will get me 23 miles per hour in the Rivian. That's 10 less than I can get with the X now but nevertheless enough most of the time. But there are times when I "need" or at least want, more. And consumers are bound to say "Gee, I used to get more than that with my old X". The dual charge port could be Rivian's instant rebuttle. That's why I think it may be a potential money maker for them.


The Rivians will DCFC at 160 kW, and the thousands of dollars required to equip the Rivian with dual charging systems would pay for a lot of public DCFC sessions.
At EA's rates I'm not so sure. Anyway this is hardly a consideration. Convenience is. There are some who will be motivate by this factor but I guess I believe that convenience will come first for most. I preferred home charging even when I had free DC charging and convenience was definitely the reason.

If you are consistently driving 200 miles a day, you will easily be able to easily leave every morning with a full "tank" with a single 48A EVSE.
In fact I charge at 20 A most of the time but at 72 A when I need to.

Tesla discontinued dual chargers (this used to be an option n the S/X).
I explained the Tesla architecture above. The triple module option was available up until the end of last year.


The Semi example is charging about a 1 MW pack in a DCFC application while on the road. When charging from DC, the charger is in the service equipment and not built into the vehicle.
The architecture when SuperCharging is in fact the same, to the point that the rectifier/convertrt is rumored to be the same except for being in the SC cabinet rather than in the wheel well. That's why it would be so simple for Tesla to put dual Level II charging ports on the CT especially as they have already done it on the semi.

Rivian has filed a patent to take advantage of 800V DCFC equipment by essentially splitting ...
The "pack" consists of 385 V (or thereabouts) modules which are wired in parallel when the vehicle runs or is being charged from a 400 V chargers. When 800 V available they would use a couple of switches or contactors to rearrange the modules into a parallel/series configuration (i.e. two groups of paralleled modules connected in series). This will add some nuance to the equalization algorithms but not much I wouldn't think. While that is interesting, of course, it has no relevance to the discussion at hand.

All the things mentioned are things that need to be thought about. You just need to broaden your perspective a bit and think a bit about load sharing, understand the architecture of the chargin circuits a little better etc. My gut feel says that Tesla will do this (add the second port) to the CT but, of course, I could be dead wrong. An additional consideration that has not been brought up is towing. Most people who buy a Rivian or Tesla will never tow with it or if they do tow only modest sized camping trailers. But the fact is that even a modest size trailer requires energy to move it. A few calculations suggest that a Rivian towing such a trailer may have double the energy consumption that is, around, 1 kWh per mile. Now the single on board charger is only good for about 11 miles per hour. With the trucks charger limited to 11.5 kW what's the only way to get that up to something reasonable? Add a second charger. Is that easy to do? Yes.
 
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CappyJax

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The faster you charge your battery, the lower the expected lifespan. EV manufacturers don't put in higher rate chargers because they want most people to charge at home from a 12kW service so their batteries last longer.
 

ajdelange

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Were that the reason they would simply have the car limit the rate at which it accepts charge. As further evidence that this isn't the reason consider that Tesla has sold cars with 80 A, 72 A and 48 A chargers with batteries no bigger than 100 kWh capacity but are now limiting the charging capacity of their Level 2 HVSE to 48 A even though they will soon be releasing cars with batteries twice that capacity. The real reason for limiting the capacity of EVSE lies in the NEC. Up to 60A life is relatively simple and you have a fair amount of flexibility with respect to what you can do and be code compliant. Above that level things get a bit more complicated not to mention that No. 6 is (what you need for a 48 A installation) is nasty enough. A third consideration is that 24 A is a convenient rectifier/converter size. Building for the US market you use 2 for 48A charging and for the European market where the mains are 3ø you use 3.
 
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CappyJax

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Were that the reason they would simply have the car limit the rate at which it accepts charge. As further evidence that this isn't the reason consider that Tesla has sold cars with 80 A, 72 A and 48 A chargers with batteries no bigger than 100 kWh capacity but are now limiting the charging capacity of their Level 2 HVSE to 48 A even though they will soon be releasing cars with batteries twice that capacity. The real reason for limiting the capacity of EVSE lies in the NEC. Up to 60A life is relatively simple and you have a fair amount of flexibility with respect to what you can do and be code compliant. Above that level things get a bit more complicated not to mention that No. 6 is (what you need for a 48 A installation) is nasty enough. A third consideration is that 24 A is a convenient rectifier/converter size. Building for the US market you use 2 fro 48A charging and for the European market where the mains are 3ø you use 3.
No, because then they would have to advertise a 6 to 9 hour recharge time. No one would buy them if they couldn't fast charge. But they want to limit fast charging as much as possible and hope most people charge with 12kW at home rather than with superchargers.

The NEC says nothing about having multiple EV chargers in the same home. You could have two chargers and two ports on the EV which is exactly what this thread is about in the first place. Most EV manufacturers don't want to allow high speed charging at home. Also, for 99.9% of people, it isn't needed.
 

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ajdelange

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No, because then they would have to advertise a 6 to 9 hour recharge time.
I gather you have no experience with BEVs so the following may be of interest to you (and to others here for whom their R1T or RIS will be their first). I don't have any experience with Rivian because at the moment I don't have one. So I'll tell you about Tesla and I think it is safe to assume that Rivian's level 2 charging will be similar. I don't, for example, think it coincidence that Rivian and Tesla have 48 A chargers on board. These deliver a bit over 10 kW and, as such, will charge a vehicle with a 100 kWh battery fully in 10 hrs, That amounts to about 30 - 35 miles per hour and Tesla tells you that in their manual. A Rivian will have a 180 kWh battery and thus will require 18 hrs to charge fully. That amounts to about 22 miles per hour.

Tesla ships with a travel EVSE which can deliver at most 32 amps implying about 7 kW and it would take it, thus, about 14 hours to charge a 100 kWh battery corresponding to about 21 miles per hour added range. And Tesla tells you that in its manual. Thus they have no hesitation in telling you that charge times are long.

No one would buy them if they couldn't fast charge.
But they can't and they do.

But they want to limit fast charging as much as possible and hope most people charge with 12kW at home rather than with superchargers.
The only people they want to charge at home rather than at super chargers are the ones that have free supercharging.


The NEC says nothing about having multiple EV chargers in the same home.
As I gather you do not own a BEV I also gather you do not have a copy of the NEC. It has quite a bit to say about multiple EVSE. Multiple EVSE are no longer a rarity.

You could have two chargers and two ports on the EV which is exactly what this thread is about in the first place.
That's true and I believe Tesla will do that as they do it on the Semi.

Most EV manufacturers don't want to allow high speed charging at home.
Most EV makers couldn't care less about how fast you charge at home. The fastest rates, under 20 kW, are way too slow to adversely effect battery life to any degree and the only concern the manufacturer has about battery life is that it exceed the warranty period.

Also, for 99.9% of people, it isn't needed.
Except when it is.

So at this juncture I lean back and ask myself "What in heavens name is this guy trying to say?"
 
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CappyJax

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Airplanes are a different matter. They will be powered by liquid fuel for some time as it is the mass of the fuel being thrown out that makes the thing go.
Whatever, smartguy.
 

ajdelange

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