61–70 of 131 posts
Earlier quoted context omitted.
At some point the size of the connector TO the vehicle is going to be the limiting factor.
I was thinking of batteries connected in series with a mechanism to separate the connection during charging. The main connector would be the same. Perhaps this is just not possible with huge batteries? Edit: Oh I get it...the charging port is what you meant.
Earlier quoted context omitted.
All these EVs use roughly the same small cells, right? Essentially thousands of the same cells used in hobbyist RC aircraft (with which I’m fairly familiar)? Unless I’m mistaken, each little cell should theoretically be chargeable in parallel, limited only by heat, massively parallel wiring, and the one massive input carrying ridiculous current. In theory, if one cell takes 30 minutes to charge, all cells could be ch…
If all of them are connected in parallel, then you are right. It's like filling an array of glasses in the rain. However the superchargers connect to the vehicle through a power port, which is relatively small. So it may not have as many parallel connections. You could split the charging to individual cells inside the car, allowing for parallel charging of all the cells simultaneously, but that means that the superch…
What would prevent the battery from having a segmented design so that multiple segments can be charged in parallel? Is there something about the chemistry that requires the entire vehicle battery to be a single unit?
You can charge every single cell individually, simultaneously, if you design your connections to support it. IIRC our packs were wired to charge the internal cells in pairs.
If you think about it, though, with a given max current I = dQ/dt, you need the same amount of time to charge two cells each to a charge Q (mAh), no matter if you charge them simultaneously or one after the other. Because if you charge them simultaneously you can only supply I/2 each.
Earlier quoted context omitted.
At some point the size of the connector TO the vehicle is going to be the limiting factor.
In the case of a truck, that seems less likely -- surely they could come up with a design that hooks in 2, 3, 10 plugs the moment the truck is ready to dock.
Earlier quoted context omitted.
Wait, are you concluding that having batteries with more cells is not the same as increasing the capacity of the system? For any battery system, the capacity is the product of the number of cells and capacity per cell.
My point is that having a larger capacity battery automatically increases the wattage at which you can recharge. It's not like a gas tank where a 100L tank takes longer to refill than a 50L tank.
If I have a 250v, 25 kWh battery, I can charge it at 250 V, 100 Amps for 1 hour or at 250V, 1000 Amps for 6 minutes.
What charging rate I select depends on the voltage and chemistry in the battery. Can the battery support charging at such a rate. The charging current rate is limited to the max operating current of the battery.
If the above battery can supply a max current of say 50 amps, then you will have a max charge rate of 250V, 50 Amps for 2 hours.
Earlier quoted context omitted.
Did you seriously just compare rates by percentage across different batteries of probably different capacities? Anything to save face for Tesla I guess.
Of course I did. Why wouldn't I? They are all battery PACKS. Maybe I didn't make that clear but I think that is a well known fact that Tesla batteries are made up of a collection of cells. You have 100 of battery X and you go to 1000 of battery X you can charge 10X more watt hours but the same %.
I think most people are in agreement that the lithium ion battery is less-than-ideal technology that's due for replacement. And we have a number of innovations in battery technology vying for the opportunity. It's starting to feel a bit like Tesla's massive investments are only serving to further entrench the existing battery model. He's basically working to replace Big Oil with Big Lithium. There's no denying the be…
Electric cars need X kg of elemental lithium over the lifetime of the car. ICE cars need [on the order of] X kg of gasoline every 200 miles. This makes such a huge quantitative difference that comparing lithium mining to oil mining is almost pointless.
In addition, lithium can in principle be recycled when the battery wears out. Gasoline cannot be recycled, even in principle.
" Tesla offers free electricity to most of its Model S and Model X customers while paying almost $1 per kilowatt hour to produce it, Morsy said. That amounts to a subsidy of as much as $1,000 per car in 2017. " I realize that most people believe that Tesla and Uber will be able to continue subsidising their operations indefinitely, but it makes me very nervous.
The quote is wrong. First of all, supercharging was never 'Free' - it was a $1,000 addon option (at purchase, or $2,000 later) for a long while before finally being made standard. (The hardware was integrated into all models shortly after launch, but cost money to activate) Secondly, they killed the unlimited free charging program for new cars as of this year. (April, I believe was the cutoff for delivery of vehicles…
> To meet Tesla’s claim of 400 miles in 30 minutes for a semi carrying 80,000 pounds would require its new Megachargers to achieve output of more than 1200 kW 1200 kw is a lot of power. That's the average amount of power used by 600 homes, or half of the output of a large wind turbine here in the Midwest, to charge a single truck. If they use a 440 V supply to charge it, that'd be over 2700 amps.
The Tesla superchargers currently charge at around 2% a minute up until about 80% which is 40 minutes to hit 80%. Tesla is advertising 400 miles in 30 minutes which is 80% of the 500 mile capacity. What is so hard to believe about a 33% improvement over a couple year old tech that is a couple years from release? Here are current industrial/transportation/residential electric prices in US [0]. They think Tesla will pa…
Truckers are even required to take a federally mandated 30 minute break[0] during the day, during which the truck can be recharging. Industrial applications already consume much more power than an entire Megacharger site, so supplying the charger with power is an already solved problem. Getting power from the charger the truck is again, a solved problem in the industrial space. I can order an off the shelf industrial…
(I don't know the answer, but I strongly suspect that regulations are not going to be the driver of the adoption of this tech. Short haul or "hot shot" could be better suited for electric and autonomous. Show me some progress there first and I will buy into some actual disruption. If you want a research assignment, take to the interstate back and forth across a couple of flyover states and stop and see where the trucks actually are.)
