[Newsbot]

Title: Battery breakthrough promises phone, car revolution
Category: Science
Posted By: bootlegga
Date: 2009-03-23 09:18:59

[martin14]

cool.. hopefully will change the battery equation around a bit.

[DrCaleb]

"In theory, a large battery that would be used to power a plug-in hybrid electric car could be recharged in just five minutes, compared to up to six or eight hours at present. But this would only be possible if a beefed-up electricity supply were available."

That's getting pretty close to Ultracapacitors.

You could supply such a battery from a downgraded 240V 3 phase. (I think, just back-of-the-hand power calculations).

[raydan]

DrCaleb DrCaleb:

You could supply such a battery from a downgraded 240V 3 phase. (I think, just back-of-the-hand power calculations).

Show-off...

[DrCaleb]

raydan raydan:

DrCaleb DrCaleb:

You could supply such a battery from a downgraded 240V 3 phase. (I think, just back-of-the-hand power calculations).

Show-off...

Occupational hazard.

[hurley_108]

So the capacity of the Prius' batter is rated at between 6.0 and 6.5 amp hours. If you were to charge that from empty to full in five minutes, would that mean you'd be running 72 to 78 amps?

[DrCaleb]

hurley_108 hurley_108:

So the capacity of the Prius' batter is rated at between 6.0 and 6.5 amp hours. If you were to charge that from empty to full in five minutes, would that mean you'd be running 72 to 78 amps?

If the batteries could handle that - yes. 78 Amps for 5 minutes is 6.5 amp/hours.

Most batteries could not handle that. Lithium ion for example. They would overheat and catch fire. Many Lead/ AcidGel batteries too, they could do perhaps twice that current, but only for a minute or two. 5 minutes would be too long and they would overheat.

The Prius uses Nickel Metal Hydride batteries, and those cannot be charged that quickly.

[hurley_108]

DrCaleb DrCaleb:

If the batteries could handle that - yes. 78 Amps for 5 minutes is 6.5 amp/hours.

Most batteries could not handle that. Lithium ion for example. They would overheat and catch fire. Many Lead/ AcidGel batteries too, they could do perhaps twice that current, but only for a minute or two. 5 minutes would be too long and they would overheat.

The Prius uses Nickel Metal Hydride batteries, and those cannot be charged that quickly.

I see. My concern was for the wiring. Ovens and clothes dryers bump the volts to keep the amps down, right?

[DrCaleb]

hurley_108 hurley_108:

DrCaleb DrCaleb:

If the batteries could handle that - yes. 78 Amps for 5 minutes is 6.5 amp/hours.

Most batteries could not handle that. Lithium ion for example. They would overheat and catch fire. Many Lead/ AcidGel batteries too, they could do perhaps twice that current, but only for a minute or two. 5 minutes would be too long and they would overheat.

The Prius uses Nickel Metal Hydride batteries, and those cannot be charged that quickly.

I see. My concern was for the wiring. Ovens and clothes dryers bump the volts to keep the amps down, right?

No, they increase the voltage and the number of phases per second so that the 'average' current is higher. In a dryer socket, it has higher current, higher voltage, and higher average (RMS*) current.

http://en.wikipedia.org/wiki/Three_phase

*It's called "Root Mean Square".

http://en.wikipedia.org/wiki/Root_mean_square

The three phase in your home will often be of higher voltage and current than a normal outlet. eg: a socket in the kitchen will be 120 Volt, 15 amp, single phase (60 Hz AC), but a dryer socket will be 240V, 30A, 3 phase 60 Hz AC. It could easily deliver 600 amps at 12 vdc if needed.

[mtpockets]

Great topic. One note though. 240V would be a single phase system.

[DrCaleb]

mtpockets mtpockets:

Great topic. One note though. 240V would be a single phase system.

I think you are right. I'm getting confused with my server rooms. They are all 240V, 20A or 30A, 3 phase.

(Edit, 20A, not 20V)

[PluggyRug]

DrCaleb DrCaleb:

[
No, they increase the voltage and the number of phases per second so that the 'average' current is higher. In a dryer socket, it has higher current, higher voltage, and higher average (RMS*) current.


The three phase in your home will often be of higher voltage and current than a normal outlet. eg: a socket in the kitchen will be 120 Volt, 15 amp, single phase (60 Hz AC), but a dryer socket will be 240V, 30A, 3 phase 60 Hz AC. It could easily deliver 600 amps at 12 vdc if needed.

An increase in RMS voltage (.707 of peak) for a higher mean value would require a frequency increase, similar to switching power supplies. Thats the problem with 60hz, most switching supplies are at 40khz. Hence closer to DC... I think.

[DrCaleb]

PluggyRug PluggyRug:

DrCaleb DrCaleb:

[
No, they increase the voltage and the number of phases per second so that the 'average' current is higher. In a dryer socket, it has higher current, higher voltage, and higher average (RMS*) current.


The three phase in your home will often be of higher voltage and current than a normal outlet. eg: a socket in the kitchen will be 120 Volt, 15 amp, single phase (60 Hz AC), but a dryer socket will be 240V, 30A, 3 phase 60 Hz AC. It could easily deliver 600 amps at 12 vdc if needed.

An increase in RMS voltage (.707 of peak) for a higher mean value would require a frequency increase, similar to switching power supplies. Thats the problem with 60hz, most switching supplies are at 40khz. Hence closer to DC... I think.

Ahh, but there is a frequency increase! The waveform is tripled, but the frequency of the waves is the same. The mean power is therefore also tripled.



Aircraft also use 300Hz AC for the reasons you suggest. It still overcomes the resistance of the wires, but is closer to DC when rectified.

[PluggyRug]

DrCaleb DrCaleb:

PluggyRug PluggyRug:

DrCaleb DrCaleb:

[
No, they increase the voltage and the number of phases per second so that the 'average' current is higher. In a dryer socket, it has higher current, higher voltage, and higher average (RMS*) current.


The three phase in your home will often be of higher voltage and current than a normal outlet. eg: a socket in the kitchen will be 120 Volt, 15 amp, single phase (60 Hz AC), but a dryer socket will be 240V, 30A, 3 phase 60 Hz AC. It could easily deliver 600 amps at 12 vdc if needed.

An increase in RMS voltage (.707 of peak) for a higher mean value would require a frequency increase, similar to switching power supplies. Thats the problem with 60hz, most switching supplies are at 40khz. Hence closer to DC... I think.

Ahh, but there is a frequency increase! The waveform is tripled, but the frequency of the waves is the same. The mean power is therefore also tripled.



Aircraft also use 300Hz AC for the reasons you suggest. It still overcomes the resistance of the wires, but is closer to DC when rectified.

Three phase is more efficient, but costs too much to install for domestic use. I use a single phase motor and capacitors (to produce a phase shift, 415v across two phases) to supply a 5hp 3 phase motor (vertical mill) from my homes single phase supply.

We need to convince the Hydro Co's to speed up the generators.