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OK, I need to explain something.
When I said Ryan's idea "sucks" it was supposed to be a play on the idea that you could suck more water (or electricity) out of the pipe than it can reasonable supply.
Bo knew that but he decided to go for the dramatic.
John C. Briggs
P.S. Ryan idea really isn't ... well his idea... eh the physics don't really support... sigh.
quote comment
The electrical wires are only rated for a certain amount of current, say for example 20A. If you put more current through them, say 40A, they will get very hot. The wires are insulated with plastic and the plastic will melt. Now the hot-uninsulated wire is in the wall next to the wooden studs. The studs get hot and catch fire.
To prevent all this, there is an appropriately sized circuit-breaker, say 20A, feeding the wire.
So if you want more juice to flow, you need more than a standard outlet with a bigger wire and bigger breaker.
Here is how it breaks down.
Standard outlet, 120V 20A = 2.4 KWH/hour, charging takes Tesla 22.0 hoursOven outlet 240V 50A = 12.0 KWH/hour, charging takes Tesla 4.4 hoursHouse Mains 240V 200A = 48.0 KWH/hour, charging takes Tesla 1.1 hours
We are a long way from the fabled 10 minute charge.
But Bo brings up a good point, if you have a smaller battery (presumably in a more efficient car) then charging is quicker. If the Aptera uses a 10KWH battery and we connect directly to the house mains then we could charge in 12.5 minutes. on the other hand, it would still take 4 hours on a standard 120V outlet.
As for Kim's idea of sucking the water out of the water pipe faster, this would not help much. Maximum vacuum pressure available is 14.7 PSI (pounds per square inch) and most homes have water at 80 PSI. So a suction system would provide only a modest 18% increase at best.
The alternative is high pressure, perhaps 160 PSI. Unfortunately this would burst the pipes in the house. So burst water pipes, or overheated wires, there is a general theme here. You need bigger pipes or wires to succeed in faster fills.
LaterJohn C. Briggs
After reading Dr. Briggs' clarfication, I'm starting to think maybe I WON'T go through with my plan tonight to ingest this entire bottle of prescription meds that I found on the sidewalk this morning...
If I'm not mistaken, the change was from 110V *outlet* to 220V *service*.
Which, if very broadly defined, could be the *entire* output of a step-down transformer, commonly mounted on a utility pole. Ordinarily, such a transformer would power some handful(s) of homes, depending on the maximum ability of the homes' service panel, typically a bare miniumum of 60 Amps, 100 Amps, these days 200 Amps, and greater in hot humid regions, where heavy duty Air Conditioning is required.
FWIW, Tesla's charging station is supposedly 70 Amps and requires installation by an electrician (as a *monster* circuit, in household terms).
So, maybe they're just trying like hell to squeeze it down to a magical 10 minute mark.
Which is also a bit silly. Because the average commuter is only going to need about 10 kWh, per day, rather than a full 50+ kWh charge. Few would ordinarily blow through a "full tank of gas", on most days.
GM's Volt has a Lithium battery with a "so-called" capacity of 16 kWh.
Unfortunately, in order to have a reasonable battery lifetime, GM is limiting it to between 30% charged and 80% charge - in short, only utilizing 8 kWh. (Just as others also do with Lithium batteries)
Using the *actual* capacity, of only 1/2, in reality doubles the $/kWh cost.
One of the marketing tricks of the the trade. :(
Nekote, Very interesting. At 70 Amps for the Tesla charging this is more than my electric oven/stove which is only 50 Amps. Tesla owners better have at least a 200 Amp service to their home. It would be interesting to know the installation cost of the Tesla charger.ThanksJohn C. Briggs
The reason plug-in conversion companies may want to cover the manufacturer's batteries under their warranty is that often switching to a plug-in battery pack voids the original manufacturers warranty. The plug-in conversion companies need to reassure the car owner that their product won't cause more problems down the road.
Perhaps this helps
nekote, I think the 1/2 figure is for the lead acid, 80% max discharge is for the lithium ion. There is no sense using the lithium ion if it has the same discharge capacity as a lead acid.
FYI, when I purchased (new) my 2008 Prius, it came with a standard Hybrid Battery warranty of 10 yrs / 150,000 miles. This applies to purchases in states that adopted the California Emmision Control Warranty (California, Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, New York, Oregon, Rhode Island and Vermont.) If purchased in another state, the warranty would have been 8 yrs / 100,000 miles.
The prospect of losing this warranty is one of the things that deters me from getting the Hymotion plug-in modification.
Steve
The problem with the water analogy is that electricity isn't water. The problem with charging up batteries rapidly isn't because there isn't enough electricity able to flow to them but that they encounter high resistance at the end of the charge cycle which slows the process down. Batteries charge very rapidly at the beginning of the charge cycle and then slow down at the last 20% and really, really slow down for the last 10%. That is why you often hear things like the batteries will charge up to 80% in the first hour. What happens is that it then takes an hour to charge up to 90% and after that it takes six or more hours to charge up that last 10% to reach 100%. Nano scale materials technology lowers the internal resistance of the battery allowing for much faster charging because there is much lower resistance. A regular AC outlet at 120 volts can pump up to 15 amps, which equals 1800 watts or 1.8 kilowatts continuously. That is a pretty big hose to use the water analogy. You would need 18 light bulbs on a single outlet to max out the amp out put of that plug. Theoretically if you add a 19th light bulb you should blow a fuse. Back to batteries, as long as the batteries can take the electricity they can handle all of the water coming from that circuit. So it is not the circuit that lowers the rapid charging it is the internal resistance of the batteries that prevents all that energy from being transferred rapidly to the batteries.
My pack is a 27 kwh pack for my electric car. (108volt system with 250 amp hour batteries) At 1.8 kilowatts continuously the only thing that is keeping me from being able to charge up my batteries fast is the ability for the batteries to receive the energy. Capacitors don’t have the problem of having to change chemistry while being charged up and they charge very rapidly. We still need a big hose to charge up vehicles, but the hoses we have are pretty big. A 120 volt 20 amp outlet = 2400 watts, a 240volt 30 amp circuit = 7200 watts or 7.2 kilowatts continuous. Big hoses.
Joe Lado (Joe the Analyst)
Joe, You have a few good point there.
Batteries certainly can be a limitation, there is no doubt. We are making the assumption that someone (e.g. Altairnano) can fix the battery charge acceptance problem and I think they already have demonstrated this technology.
One thing to keep in mind is that the CONTEXT for the discussion is a claim of a full charge from a standard outlet in 10 MINUTES. It is in this context that we are talking about small pipes (wires).
In your case, you have a 27 KWH pack. Assuming you have an outlet of 120Vx15amps, or 1800W. This can supply 1.8KWH each hour and it will take 15 hours to charge your pack, regardless of how fast your batteries can accept the charge. Even if you have an ultracapacitor, it will still take 15 hours.
In the context of a 10 minute charge, 15 hours is a long time, and a small hose (wire).
TIP: If the math is part of the problem here, assume you have a very small 1.8KWH battery pack and connect it to your 1.8KW outlet. How long will it take to charge the battery?
The answer is 1 hour.
Since your battery pack is much larger, it will take much longer than 1 hour to charge.
