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Discussion Starter · #1 ·
Today I had my first computer glitch.

I'm not sure if this is why I got my first glitch, but I was fussing about with the navigation system (which I must agree is truly terrible) and used it to store a location. Not too long afterward (but after the car was parked for a bit), the "system status" "energy flow" screen had blotches in place of several of the letters in the words "STEALTH MODE".

Also, later today (around 5 PM), some big thunderstorms rolled through and the power glitched at the apartment I'm living in until the house is done. Several clocks (microwave and oven) lost their times; one electric pump (in the cat fountain) quit; several GFI outlets required resets; and in the garage, the Karma's convenience charger recorded some kind of power error (I didn't check what kind) and stopped charging the car.

Disconnecting the convenience charger from the 120V (and GFI, which in this case had not tripped though) outlet and reconnecting it made everything happy again, even without first disconnecting the J1772 connector from the Karma. So that was good.

One other noteworthy item: the speed limit on I-15 through Utah varies from 55 mph up to 80 mph. There is a long stretch where the 80 zone begins just south of Nephi, where the navigation system believes that the speed limit is 55 mph. Yesterday, we had to turn off the built-in Nag Lady in the nav system. (Maybe the Nag Lady setting is part of the glitching. At some point yesterday, during or after turning off the Nag Lady, some of my other settings reverted. However, my girlfriend was looking for this in the settings while I was driving and might have inadvertently touch-screen-changed a setting or two.)
 

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Electricity is a strange thing. For us old petrol heads we have a whole new paradigm shift. Perhaps a few short courses in electrical engineering is in order!
 

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Discussion Starter · #3 ·
TIMCANTWELL said:
Electricity is a strange thing. For us old petrol heads we have a whole new paradigm shift. Perhaps a few short courses in electrical engineering is in order!
I really like the "water" analogy for electricity because it works well (at least when thinking about direct current; and batteries are all DC).

The way the analogy works is to think about electric energy—not "electricity" per se; the distinction gets really important at times—think about (electric) energy as being "like" water.

As with water, you need a bucket of some sort to hold it. The available buckets today are batteries and super- or ultra-capacitors. The important difference between the two is that capacitors can't store much, but can be filled and drained very rapidly; batteries can store a lot more, but are slower to fill and drain. (Using a lot of batteries lets you store and drain energy "fast enough" but someday we might want some sort of hybrid mix of batteries and ultracapacitors for efficiency-vs-price optimization.)

Also like water, the way you use the energy is to drain it out of the storage tank. It has to flow to do work (flowing water does all kinds of work, including such things as mining gold and digging the Grand Canyon). When it does flow (in a pipe, for water, or in a wire, for electric energy), you get two things you can control: the "width of the pipe"—the cross section—and the pressure inside the pipe.

Pipe width is of course a lot easier to see with water. Just think of the difference between a squirtgun nozzle, a garden hose, a sewer pipe, or the Mississippi River. The wider the pipe, the more water you can get into it even if it's moving very slowly (low pressure). With a skinny/narrow pipe, you have to push hard (high pressure) to move the water through fast, and even then not very much water comes out of the end of a squirtgun.

The thing is, electricity (electric energy) works the same way. The "width of the pipe" is the amperage or "amps", and the pressure in it is the voltage ("volts"). The rate—the speed—at which energy flows through the "pipe" (wire) is the product of the two. With 120 volts and 13.75 amps, you get 120 x 13.75 = 1650 watts. Raise the pressure to 240 volts while keeping the same 13.75 amps, and you get 240 x 13.75 = 3300 watts.

Again, that's a rate of flow. It's the "speed of the energy". It doesn't sound like it because of the word "watts" (or kilowatts) but it's a speed, like "mph" or "km/h". It looks more like speed when it's expressed with a different unit: "joules per second".

One watt is one joule per second. When you see "watts" think "gpm" or "mph". It's a speed. It's how fast the energy is moving, the same way you might measure the water flow rate through a pipe.

(The other problem here is that "one joule" is an itty bitty teensy weensy, very tiny, amount of energy. The Karma's batteries hold about 20 "kilowatt-hours". That's a lot of joules: 72,000,000 to be exact. 72 million joules, or "megajoules" or MJ. Hardly anyone uses "joules" in practice because they're so small. One "kilowatt-hour", 1 kWh, is 3.6 MJ. So kWh is a lot easier to work with.)

Practice thinking "gallons per minute" or "miles per hour" or "km/hr" or whatever speed units you prefer, whenever you see "watt" or "kilowatt" (but not when you see "kilowatt-hour" or "kWh", as on your electric bill; that's got the "hours" multiplied in, so it's actual energy, rather than a speed-of-energy). Your light bulbs walk along at a speed of 60 or 75 or 100 watts, and your hair dryer—if you still have hair—probably runs at a faster pace of about 1200 or 1500 watts. That's your homework for the first lesson. :D
 

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Discussion Starter · #5 ·
EVer1 said:
LOVE IT! I'm giving this to my boys to read.
Another fun thing to remember, once you start thinking of "kilowatts" as "speed of energy", is that "kilowatt" and "horsepower" are the same basic unit (slightly different scale, it's about 4-to-3). So the 403 horsepower (or 401, or whatever it is) in the Karma equals 300 kilowatts.

The maximum speed at which the Karma can use energy to propel you forward is 300 kilowatts. The batteries can only supply about half of that, so to push out energy at max speed, you have to go into "sport" mode.

One of these days I want to have someone record the energy flow screen and see what it reads when the accelerator pedal is floored. :D
 

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Discussion Starter · #6 ·
OK, so today (or maybe yesterday) I had my "RKE" and accessory-delay settings mysteriously revert. I like to unlock the entire car at once so I keep RKE set to Global, but it went back to drivers-door-only. Also I let the accessories run for 1 minute after system-off but that reverted to 0 minutes.

I don't normally use the radio so I'm not sure if anything reverted there...
 

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You are not alone.
Thi happens to me every one or two weeks
It also resets to give me the horn while locking the car, which is not allowed by law in Germany and disturbed my 'lovely' neighbors...




Stefan
 
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