10-27-2017, 03:13 PM
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#11 (permalink)
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Thalmaturge
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Quote:
Originally Posted by Stubby79
Said chart is for a 32 kwh battery, and shows it can do 320 km(200 miles) on what it can get in 6 minutes.
Assuming it can safely charge 80% of the battery in that time, like the other rapid-charging of lithium batteries (might even be 90%, looking at the chart's 12 minute and 30 minute charge times), 80% of 32 kw is 25.6kw.
I doubt we're at the point where you can get 7.8 miles per kwh. Or even 6.25, if it got a full 32kw.
But, assuming it could suck in 25.6kw in 6 minutes, that's 256 kw...at 375v, that's still 682 amps...and more with losses.
Hmm. That's a lotta juice. Not impossible, but pretty out there. They'd seriously need to boost the charging voltage to make it reasonable and efficient. Some day, they'll have to have EVs running at thousands of volts rather than just hundreds.
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Tesla uses <400VDC for their superchargers, but Porsche is working on an 800VDC station!
That would be more like ~340A. My calculations say that could be handled by conductors 1cm^2 for a 2m long cable. It would be awkward and bulky as anything, but possible.
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10-27-2017, 03:24 PM
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#12 (permalink)
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Master EcoModder
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Quote:
Originally Posted by samwichse
Tesla uses <400VDC for their superchargers, but Porsche is working on an 800VDC station!
That would be more like ~340A. My calculations say that could be handled by conductors 1cm^2 for a 2m long cable. It would be awkward and bulky as anything, but possible.
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We have 00 gauge wires on our chargers at work for our battery operated equipment. They have ~3m long cables, and output "only" 120 amps. The wires generally stay cool, or only barely detectable warm, except sometimes near the connectors. They're generally only warm to the touch there, but when they get a bit of additional resistance for whatever reason...
I'd want something a bit better than those 350A anderson connectors, were I getting anywhere close to that kind of amperage. Something with a lot more surface area.
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10-27-2017, 05:41 PM
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#13 (permalink)
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Corporate imperialist
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Forklift chargers here use 4/0 cable and are 2m long.
Since there is no standard to rate EV range they could be driving 35mph on an indoor track with no stopping.
So they could get 5 or 6 miles per kwh depending on how Un realistic the range test is.
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10-28-2017, 10:51 AM
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#14 (permalink)
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Somewhat crazed
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Quote:
Originally Posted by NeilBlanchard
We are averaging between 4.5 and 5.5 miles per kWh, in 3 different EV's. So, that is between 182 and 223 wH/mile.
They might also be running a higher voltage battery.
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Only so many ways you can do 32kwh. 40 ah @ 800V. That's only about double what is in the ranger right now which would give me 80 miles range.
Maybe they were using a 50v rated brushed shunt wound motor. Pulse width would be incredibly short.
If you go up into the k volt range, motor currents are going to drop for a given hp, but the C of Drag has to be incredibly low and it needs to be very lightweight.
Sounds like unicorn corral material.
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10-29-2017, 05:21 PM
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#15 (permalink)
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Cyborg ECU
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Quote:
Originally Posted by thingstodo
... At 375V that's 1786 amps. ...
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Anyone else starting to imagine drivers getting electrocuted to death while charging their cars? Anyone else starting to wonder if self-service charging might get regulated out of existence? Is there a hardware/software fail-safe to prevent injuries? (Not that gasoline is safe, of course!)
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10-29-2017, 05:44 PM
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#16 (permalink)
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Corporate imperialist
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There was that stupid contact free inductive charging paddle for the ev1. It wouldn't electrocute you to death but it was limited by physics to charge slower than death.
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1984 chevy suburban, custom made 6.5L diesel turbocharged with a Garrett T76 and Holset HE351VE, 22:1 compression 13psi of intercooled boost.
1989 firebird mostly stock. Aside from the 6-speed manual trans, corvette gen 5 front brakes, 1LE drive shaft, 4th Gen disc brake fbody rear end.
2011 leaf SL, white, portable 240v CHAdeMO, trailer hitch, new batt as of 2014.
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10-29-2017, 08:15 PM
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#17 (permalink)
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Master EcoModder
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Quote:
Originally Posted by California98Civic
Anyone else starting to imagine drivers getting electrocuted to death while charging their cars? Anyone else starting to wonder if self-service charging might get regulated out of existence? Is there a hardware/software fail-safe to prevent injuries? (Not that gasoline is safe, of course!)
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The J1772 plug used on most EVs for L1 and L2 charging communicates with the car before flipping on the higher voltage. I'm pretty sure the other standards and fast charging standards do something similar. So the only time there's lethal current available is from a few seconds after plugging in and when you push the button to release the charger. I don't know what would happen if you were to cut a cord that was in use or if they fail-safe if there's a malfunction.
Considering that anything bad happening with an EV (particularly Teslas) is front page news, the lack of electrocution stories implies that everything is pretty safe, likely many times safer than gasoline.
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10-29-2017, 09:11 PM
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#18 (permalink)
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...beats walking...
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Unlike gasoline/petrol, electrons do not spill all over the place from a sloppily disconnected plug.
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10-29-2017, 11:24 PM
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#19 (permalink)
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Master EcoModder
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Quote:
Originally Posted by California98Civic
Anyone else starting to imagine drivers getting electrocuted to death while charging their cars? Anyone else starting to wonder if self-service charging might get regulated out of existence? Is there a hardware/software fail-safe to prevent injuries? (Not that gasoline is safe, of course!)
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I'm sure that someone will figure out how to hurt themselves, no matter what precautions are taken.
Someone successfully sued McDonalds for burning themselves , because their coffee was hotter than the coffee that other fast food places sell.
The ChaDeMo charger only has power to the 12V pins, does a handshake to verify that it is plugged into a car, then turns on a contactor to begin charging. There is a latch on the connector that shuts off the charging if the connector is removed from the car.
So .. not fail-safe or perfect, but good. Every charger or charging system released since is a bit more paranoid and has a few extra checks.
The engineers are *REALLY* trying.
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10-30-2017, 02:42 AM
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#20 (permalink)
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EcoModding Lurker
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The McDs coffee was recklessly hot.
6 minutes for a 200 mile charge sounds great! I wonder if you'll be able to upgrade the existing hybrids and electrics with these better batteries when available?
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