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Comment: Re:Might have bottomed out (Score 1) 72

by WalksOnDirt (#49531225) Attached to: I predict that by next Earth Day Bitcoin will ...

Banning the trading of certain goods which aren't inherently harmful by themselves seems like a dangerous precedent to set.

The precedent was set by the outlawing of gold bullion ownership. I'm glad that's over, but governments have not promised to never try such a thing again. The control of the money supply is important to them.

Comment: Re:Tesla's battery is around $400/kWh .. (Score 1) 330

by WalksOnDirt (#49406009) Attached to: Inexpensive Electric Cars May Arrive Sooner Than You Think

The difference between the 60kWh and 85kWh Tesla Model S cash price is $10,000 or $400/kWh so I'm not sure about the article's conclusion that the battery costs $300/kWh.

In addition to the other points mentioned elsewhere, the 85 kWh Tesla includes access to their charging stations, which is valued at $2,000.

Comment: Re:Nice idea but (Score 1) 185

I'm very suspicious of the idea of used battery packs being used for grid storage.

However, lithium is cheap and is well understood. I think Tesla could devote some of their production into non-cobalt based cells, and possibly non-nickel too, and use them for stationary storage.

Comment: Re:Do the math, that cannot charge a car... (Score 1) 441

by WalksOnDirt (#48828129) Attached to: Why We Have To Kiss Off Big Carbon Now

FYI, a kilowatt is a unit of power, i.e. a rate of energy transfer per time. 21 kilowatts means you can move around 21,000 joules of energy per second.

A 'full charge' depends on the amount of total energy the battery can store, i.e. units of simply joules. Joules are pretty small and energy for batteries is often expressed as kilowatt-hours; 1000 watts * 3600 seconds = 1 kilowatt-hour = 3,600,000 joules.

So, 86 kilowatt-hours is about 310 million joules. If you charged a 86 kilowatt-hour battery with a 21 kilowatt power supply, it would take 86 / 21 = 4 hours to charge.

I was going to point this out, but Mister AC beat me to it. You rarely run a Tesla down to empty in a day of local driving. Also, most places in the US get between 5 and 6 hours of sunlight per day, although it can be much less in winter if you're anywhere near Canada.

The solution of this problem is trivial and is left as an exercise for the reader.