Charging physics confusion

[daniel]

So...why not merely produce and distribute a switchable (to match available power source wattage) power inverter with power doubling/multiplying circuitry to step up or down the available power to match the Tesla's battery requirements?

I don't own a Roadster (just a lowly little Zap Xebra) but it seems to me that what you are suggesting is exactly what Tesla Motors has done:

The Roadster can accept power at whatever rate the available supply can provide. Your home, for example, or the plug at a charging station, provides power at a specific voltage, and has a specific maximum amperage. Maximum voltage (usually 110 or 220 in the U.S.) is determined by what the utility company will provide to you, and maximum amperage is determined by the size of your wires, since excess amperage will melt wires of a given size. In addition, the utility limits how much power you can draw, though typically you can pay for the privilege of drawing more power, which requires bigger stuff (wires, circuit breakers, etc.; just a question of how much you want to pay for.)

So your circuit (at your house or your charging station) can deliver only a certain maximum amount of power.

The Tesla Roadster is designed and built to accept as much power as the circuit it is plugged into will supply. In other words, it does precisely what you have requested. It cannot make something for nothing. It cannot pull 15 kW if it's plugged into a circuit that's only capable of providing 7 kW.

Your request has been granted even before you thought of it, because the Tesla engineers thought of it before you.

I think the characteristics of the batteries may put an upper limit on how fast they can be charged, but up to that limit, the Roadster adapts to the power source available. I wish my Xebra did that.

Daniel

 

[doug]

FYI: just-an-allusion turned out to be a troll playing the long con. His posts remain for historical value, I guess.

 

[JRP3]

Daniel,
If you read carefully what he was proposing you'll see it was not what Tesla did, or even possible:

power inverter with power doubling/multiplying circuitry to step up or down the available power

You can not step up the power available, i.e. take 240 volts and 100 amps and make it more than 24 KW.
And yeah, he was a troll.

 

[daniel]

FYI: just-an-allusion turned out to be a troll playing the long con. His posts remain for historical value, I guess.

Daniel,
If you read carefully what he was proposing you'll see it was not what Tesla did, or even possible:
You can not step up the power available, i.e. take 240 volts and 100 amps and make it more than 24 KW.
And yeah, he was a troll.

I (mistakenly) gave him the benefit of the doubt, assumed he was asking for a system that would allow the Roadster to charge from any available power source, and assumed that he did not understand the numerical explanations above.

I didn't realize he was asking for a magical box that would create power out of nothing. That's what he was SAYING, but I imagined he merely didn't understand.

I've only ever encountered two kinds of perpetual-motion advocates: People who do not understand the relationships between power and energy, etc., and jokesters.

In the latter category was a friend of mine who "invented" a perpetual motion machine based on the "fact" that six is greater than nine: You put a six and a nine on opposite ends of a bar that rotates around an axle. The nine, being greater, descends, but upon passing the meridian, the six becomes a nine and vice versa, and the rod continues to rotate. :biggrin:

 

[vfx]

The Tumanako Project is an Open Source development effort to produce Open Source hardware and software to drive and recharge electric vehicles.


Related:
SourceForge.net: Tumanako