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Discussion Starter #1 (Edited)
I have been thinking for a while about recharge rate. Does anyone know what the peak power at which the batteries can be charged? I assume no one has those exact specs, but from what I can get out of the FAQ and the About links, I gather the peak steady output to be around 45kW. Let's say this is the peak for steady input, that leads to 8kWh/45kW = .1777 hours or just under 11 minutes. That seams really short. Does anyone know what the peak steady input should be if the peak steady output would be 45kW?

If that 11 minutes is close then it would be nice for GM to provide an additional charging port for this.
 

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I have been thinking for a while about recharge rate. Does anyone know what the peak power at which the batteries can be charged? I assume no one has those exact specs, but from what I can get out of the FAQ and the About links, I gather the peak steady output to be around 45kW. Let's say this is the peak for steady input, that leads to 8kWh/45kW = .1777 hours or just under 11 minutes. That seams really short. Does anyone know what the peak steady input should be if the peak steady output would be 45kW?

If that 11 minutes is close then it would be nice for GM to provide an additional charging port for this.


Quick-charging is a whole different ballgame. It will require a special charging port that I happen to feel should be automated so that people are not touching it. Moving that much energy through a connection point is dangerous and nothing you want grandma or the kiddies near.

As I just wrote in another thread the quick-charge station will have an energy storage system like a bank a batteries that will be charging all day and night using standard industrial power feeds. When a car comes in, a battery-to-battery energy transfer will happen. Massive substations directly fed by the grid or a hand-held plug are not going to cut the mustard. I hope people understand how much energy we are dealing with. Don't worry, it's all very doable.
 

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Quick Charge

That seams to be the thing people do not think about Texas. To supply 45 kW, it would take over 200 amps at 220 volts. You won't pull that off many supplies and certainly not at my house.
 

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Not terribly dangerous

With sound engineering I don't see why people couldn't do the charging themselves. You just have to make sure it's well insulated and that the contacts aren't exposed until the plug is in the receptacle. Even at say 3k volts so long as the there's a descent amount of insulation it wouldn't be much of a hazard. I mean a lineman works on exposed 7k volt line with nothing but rubber mats and gloves.
 

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I agree it can be done safely. We need a universal vehicle charging connector for high voltage and amps, one used by all not just GM. This would benifit all and simplify future charging stations.
 

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This doesn't have to be just a dumb plug and socket, like our household 120VAC wall receptacles. The high-voltage/high-current power could be automatically switched, turning on only after a proper connection has been established. Yes, this would cost more, but it would be infinitely safer.
 

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Altazi,
Check out this post
http://www.gm-volt.com/forum/showthread.php?t=1138
Yes it is already been thought over and codified on a national level.
I just want a connector that is used by all manufacturers to simplify connecting if you buy a Fisker, a Volt or any other vehicle. Just like all 110 volt recepticles are the same in the U.S., all vehicle high voltage plugs should be the same configuration.
 

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The issue is not safety. The issue is power from the pole. 200 amps at 240 is all I have for my whole house. I am not going to shoot it into a car for 10 minutes. I might turn the AC off and shoot 50 amps into it for 50 minutes, but not 200 amps.
 

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You can't quick charge batteries and hope to have them last. Think about it. If quick charging were an option for Li-Ion batteries, wouldn't somebody have made a quick charger for our laptops by now? How about camera batteries? One tiny little battery and with all the power in your home, we should be able to zap that baby full in about 30 seconds right? This technology does not exist. So why do we want to believe that we could charge our car this way when we can't even do simple little household appliances now? For what ever chemical/physical reason, batteries need to be charged slower than they discharge.

Capacitors are a different matter. This is why there may be a marriage of capacitors and batteries in the future. One for quick charge and one for storage
 

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You can't quick charge batteries and hope to have them last. Think about it. If quick charging were an option for Li-Ion batteries, wouldn't somebody have made a quick charger for our laptops by now? How about camera batteries? One tiny little battery and with all the power in your home, we should be able to zap that baby full in about 30 seconds right? This technology does not exist. So why do we want to believe that we could charge our car this way when we can't even do simple little household appliances now? For what ever chemical/physical reason, batteries need to be charged slower than they discharge.

Capacitors are a different matter. This is why there may be a marriage of capacitors and batteries in the future. One for quick charge and one for storage



The technology exists but it's still new:



http://www.physorg.com/news116591313.html

There are a few companies claiming they can do it but we will have to wait. Also, if you believe EEstor they can also take just about anything that you can throw at it (I'm not holding my breath).

Finally, who said safety is not an issue? Also, to the person that said that it is codified at a national level. That was not for the amounts of energy we are talking about. Think 53 kWh in 5 minutes (filling up a Tesla) kind of power flows. Ouch! We will have to wait to see what DOT, and all the other agencies allow. I can almost guarantee they will not let an untrained person anywhere near a high voltage line. Grandma pulling an electric hose capable of delivering that kind of power out of a cabinet and into her car and hitting the start button? Even if she was strong enough to carry the cable weight I am confident that is never going to happen.

Again, serious power flow and serious amounts of energy. The charging system will have to be very well designed and fool proof. I stand by that it will require automation or a trained and certified attendant. Probably both in the beginning. THIS IS NOT CHARGING UP YOUR CELL PHONE!!
 

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Discussion Starter #11
For what ever chemical/physical reason, batteries need to be charged slower than they discharge.
Yes, but by how much? This goes back to my original question of peak regenerative rates. If it is only 50%, that still is worth going down to the shock shop and getting a cup 'o' jo, or plugging in at the local sonic for a cheese burger, fries, and a Jolt.

As it stands, My laptop recharges at a fairly decent rate. As does my cell phone and iPod, and I think some of these rates are limited by the charger and not the battery.
 

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Heat is one big problem. When you dump that much energy into something in a relatively short time, you would have a tremendous heat build-up. In a perfect battery, all of the energy would go into reversing the chemical reaction and restoring the reactants to their original state. We do not have perfect batteries, so at least some of the energy used for recharging will create waste heat. Fortunately, battery technology is improving.
 

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Finally, who said safety is not an issue? Also, to the person that said that it is codified at a national level. That was not for the amounts of energy we are talking about. Think 53 kWh in 5 minutes (filling up a Tesla) kind of power flows. Ouch! We will have to wait to see what DOT, and all the other agencies allow. I can almost guarantee they will not let an untrained person anywhere near a high voltage line. Grandma pulling an electric hose capable of delivering that kind of power out of a cabinet and into her car and hitting the start button? Even if she was strong enough to carry the cable weight I am confident that is never going to happen.

Again, serious power flow and serious amounts of energy. The charging system will have to be very well designed and fool proof. I stand by that it will require automation or a trained and certified attendant. Probably both in the beginning. THIS IS NOT CHARGING UP YOUR CELL PHONE!!
Even I can design a safe way to plug in that kind of power. Grandma Moses could use it if she could pick up the charging cable. Just run 2 sets of sensing wires. One is the charger saying "Am I plugged in yet?" and the other is the Volt (or whatever) saying "You are good to go." Untill the charger gets both siginals back, there is no power supplied to the plug except the 5V sensing from the charger.
 

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Even I can design a safe way to plug in that kind of power. Grandma Moses could use it if she could pick up the charging cable. Just run 2 sets of sensing wires. One is the charger saying "Am I plugged in yet?" and the other is the Volt (or whatever) saying "You are good to go." Untill the charger gets both siginals back, there is no power supplied to the plug except the 5V sensing from the charger.

Brilliant! <cough> And can you tell me what voltages you plan on using? Please assume a quick charge for a Tesla in 5 minutes. That's 53 kWh. Wire gage size? Remember that there are going to be regulations. For example, they are not going to allow kV lines running from the island to your car where little Johnny can touch them. Think about this! I think when you calculate the currents and voltages needed you will see the light. Still easy? DOT and everyone else happy? Good luck!

The real world where everyone is going to be near the station and in your garage by yourself with a few welding cables are two different realities. ;)
 

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"Yes We Can!!!"

. . . find a way to make things happen, Texas. Don't you want to find a way to make this work?

This is just a technical problem. There is no reason something like willdryden's approach wouldn't work. We can expand on it - make it so completely monitored and double-checked that not so much as a stray milliamp could travel down an unintended current path - like your "little Johnny". Think GFCI, only more so. What's wrong with sending a few kV down the wires - it's not magic, after all. The only trick I see is the higher the voltage, the more expensive the conversion and charge-control circuitry.

It is possible to make good insulation with guard layers that could detect damage, leakage current, etc. We can make it so damned safe that it almost won't work, if that's what you want.

There's no reason a massive power cable would have to be much stiffer or difficult to handle than a current gasoline hose. It is possible to make limber wires, depending upon the material and the size and number of the strands, and the type of insulation. If it's too heavy, then put the plug on a spring weight assist, or make the whole thing into an articulated arm like the movable light at the dentist chair. There is a way!

As to the delivered energy per unit time, of course there will be practical limits - limits imposed by the charge acceptance rate of the battery, the capacity of the charging electronics, the gauge of the connecting wires, or the energy available on the AC powerline.

Stopping at a fast-charging station, so what if it might take 20 minutes to "fill" my Tesla, while your Volt charges up in five minutes? That's just the way it is. I'll grab a snack or hit the restroom with the extra time I have. Whatever solution we get, we'll deal with it for the time being, and maybe see if something better comes along soon. And all the while, we can rejoice at the money we are not sending to unfriendly oil-producing countries!

Of course, the quicker, easier, and safer this all is, the more expensive it will be. Be prepared to fork over. . .big time.
 

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. . . find a way to make things happen, Texas. Don't you want to find a way to make this work?

This is just a technical problem. There is no reason something like willdryden's approach wouldn't work. We can expand on it - make it so completely monitored and double-checked that not so much as a stray milliamp could travel down an unintended current path - like your "little Johnny". Think GFCI, only more so. What's wrong with sending a few kV down the wires - it's not magic, after all. The only trick I see is the higher the voltage, the more expensive the conversion and charge-control circuitry.

It is possible to make good insulation with guard layers that could detect damage, leakage current, etc. We can make it so damned safe that it almost won't work, if that's what you want.

There's no reason a massive power cable would have to be much stiffer or difficult to handle than a current gasoline hose. It is possible to make limber wires, depending upon the material and the size and number of the strands, and the type of insulation. If it's too heavy, then put the plug on a spring weight assist, or make the whole thing into an articulated arm like the movable light at the dentist chair. There is a way!

As to the delivered energy per unit time, of course there will be practical limits - limits imposed by the charge acceptance rate of the battery, the capacity of the charging electronics, the gauge of the connecting wires, or the energy available on the AC powerline.

Stopping at a fast-charging station, so what if it might take 20 minutes to "fill" my Tesla, while your Volt charges up in five minutes? That's just the way it is. I'll grab a snack or hit the restroom with the extra time I have. Whatever solution we get, we'll deal with it for the time being, and maybe see if something better comes along soon. And all the while, we can rejoice at the money we are not sending to unfriendly oil-producing countries!

Of course, the quicker, easier, and safer this all is, the more expensive it will be. Be prepared to fork over. . .big time.

Altazi, Maybe you should read what I wrote before commenting on what I think. Just on this thread I wrote:


"It will require a special charging port that I happen to feel should be automated so that people are not touching it."


"I hope people understand how much energy we are dealing with. Don't worry, it's all very doable."


"The charging system will have to be very well designed and fool proof. I stand by that it will require automation or a trained and certified attendant. Probably both in the beginning."


Does that sound like I don't think it will work or I don't want it to work? Many people think it can be done with a standard extension cord or that its going to be easy to have everyone sign off on this. I don't. You might not think it's not that much voltage but 1kV will kill you and knock you right out of you shoes. Why not just automate the process or have trained operators do it? Why don't you propose a design and show it to the DOT? I'm sure they will give you their professional opinion.
 

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Brilliant! <cough> And can you tell me what voltages you plan on using? Please assume a quick charge for a Tesla in 5 minutes. That's 53 kWh. Wire gage size? Remember that there are going to be regulations. For example, they are not going to allow kV lines running from the island to your car where little Johnny can touch them. Think about this! I think when you calculate the currents and voltages needed you will see the light. Still easy? DOT and everyone else happy? Good luck!

The real world where everyone is going to be near the station and in your garage by yourself with a few welding cables are two different realities. ;)
You can not protect idiots regardless of what you do. If little Johnny takes a hacksaw to the armor sheath, it is not a lot different to taking a knife to the hose on a gas pump. Wire gauge is determined by the current in the cable and voltage is negotiable. We were talking about making it safe under normal conditions with reasonable care.

I know the wire gauge is going to be large. That is why I said if Grandma Moses could lift it. It took 3 people to pull a 150 ft run of 500mcm cable for a telephone swith I helped install.
 

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I bow. . .

Altazi, Maybe you should read what I wrote before commenting on what I think. Just on this thread I wrote:


"It will require a special charging port that I happen to feel should be automated so that people are not touching it."


"I hope people understand how much energy we are dealing with. Don't worry, it's all very doable."


"The charging system will have to be very well designed and fool proof. I stand by that it will require automation or a trained and certified attendant. Probably both in the beginning."


Does that sound like I don't think it will work or I don't want it to work? Many people think it can be done with a standard extension cord or that its going to be easy to have everyone sign off on this. I don't. You might not think it's not that much voltage but 1kV will kill you and knock you right out of you shoes. Why not just automate the process or have trained operators do it? Why don't you propose a design and show it to the DOT? I'm sure they will give you their professional opinion.
. . . in apology! Sometimes I don't re-read the entire thread. My bad!
 

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Texas,
I apprieciate your input on this blog, always insightful. This is in responce to your post.

I also did a little pondering on this problem and this is what i think for common application of EV charging,

If to charge 50% of a 16kwh battery (like the Volt's) will take 8kw for 1 hour or 8kwh then;

240volt/50amp circuit = 12000w or 12kw

3/4 of 1 hour @ 12kw per hour = 8kwh


This is not a 5 min. charge but it is a 45 min. charge and using a common voltage at most residences, like for a welder in the garage. A commercial grade cable that can handle this load is not too heavy for even a grandma. The load can be doubled and the time cut in half which brings it down to 22.5 min. to charge a volt ( if the batteries can take a charge this powerful and fast).
This is quick enough for me. And this application has been codified up to 600 volts in the NEC (see article 645.4). So this tells me it will be safe, if done to code including Interlock and Automatic De-Energization of Cable.
The Lightning will accept a quick charge, maybe the Volt will get there too.

The future will be great!
 

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Texas,
I apprieciate your input on this blog, always insightful. This is in responce to your post.

I also did a little pondering on this problem and this is what i think for common application of EV charging,

If to charge 50% of a 16kwh battery (like the Volt's) will take 8kw for 1 hour or 8kwh then;

240volt/50amp circuit = 12000w or 12kw

3/4 of 1 hour @ 12kw per hour = 8kwh


This is not a 5 min. charge but it is a 45 min. charge and using a common voltage at most residences, like for a welder in the garage. A commercial grade cable that can handle this load is not too heavy for even a grandma. The load can be doubled and the time cut in half which brings it down to 22.5 min. to charge a volt ( if the batteries can take a charge this powerful and fast).
This is quick enough for me. And this application has been codified up to 600 volts in the NEC (see article 645.4). So this tells me it will be safe, if done to code including Interlock and Automatic De-Energization of Cable.
The Lightning will accept a quick charge, maybe the Volt will get there too.

The future will be great!

Thanks Jim, That all sound very good. However, I hope you can agree that there is a huge difference between providing a 20 mile charge in 22.5 minutes and charging the Tesla (200 miles) in 5 minutes. The first application has almost no use if people are going to be driving long distances. When we talk about quick-charge stations I think the point is that people will be able to go to the station, charge up like they do for gas, and head out to the next quick-charge station until they reach their destination. They are not going to be very happy if that driving distance is 20 miles and they have to wait 22.5 minutes each time. Right? Now please redo your calculations for 53 kWh and 5 minutes using 600 volts. Granted, 600 volts is much better than 250 volts but the resulting cable size and weight will surprise you. Here is a quick calculation:



I = P/V
I = 53000 Wh/600V*(60min/5min)
I = 1060 amps


AWG: 1
mils dia: 289.3
Carrying current: 119.6
Feet per pound: 3.947


Thus, we would need 1060 amps/119.6 = qty. 9 of AWG 1 cables. Yes, 9 welding cables!
The weight for let’s say a 15 foot cable bundle would be: 15 feet *9/3.947 feet per pound
Weight of bundle: 34.2 lbs! That’s a lot of wire, even if it’s festooned. Grandma do? No way!

Don’t forget that you want control lines and great all-weather non-cut outer covers. You may also want to add more cables because the cable will get very hot if ran near capacity. Don’t forget that there are also regulations for the temperature. You wouldn’t want Johnny bumping into a hot cable would you? Add cooling lines? Add to the weight and diameter. Oh the lawsuits.

Well, there you go. I hope everyone can now agree that this is not a simple situation. No working system even exists that is anywhere near ready for a consumer to touch that will be able to charge a Tesla in 5 minutes. Can we all agree on that simple fact? I’m sure there are many people out there working on such an animal and I will be very excited to see a working prototype. If anyone knows of one, please post it here (no, not the university ones that only supply a fraction of what I just discussed or the ones that a regular consumer would not be allowed to touch - think grandma and your little sister).
 
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