Greetings Earthlings

Just purchased a new to me 2011 SL with 12k on the clock. All twelve, yes all twelve, bars still present on the battery. Car is in great condition, the previous owner had the metal door sills installed, the blue center console and the organizing bin for the trunk. This is my first EV. I did look at the Kia Soul EV and even though the interior was much nicer I couldn't justify paying 20k more for something that doesn't have a significantly greater range. I already installed a dedicated outlet for the Juicebox that I ordered last week and am ready to be green! :mrgreen:

I am in the Roseville, CA area. Hope to get some good tips on maintenance and that sort of stuff. I have a decent automotive (gas powered) background but all this kw/h stuff is Greek to me. :?

Hi Maharaj, welcome to the forum, even if a little belated. Plenty of info here on whatever you need to know. Happy reading.

maharaj said:

... all this kw/h stuff is Greek to me. :?

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Welcome
Most of it is either kWh which is stored energy or kW the power flow rate.
Also the term miles per KWh for efficiency is used a lot.
Analogous to miles per gallon of gasoline.

TimLee said:

maharaj said:

... all this kw/h stuff is Greek to me. :?

Click to expand...

Welcome
Most of it is either kWh which is stored energy or kW the power flow rate.
Also the term miles per KWh for efficiency is used a lot.
Analogous to miles per gallon of gasoline.

Click to expand...

I like to introduce newbies to kWh (or kilowatt-hour)s as the rough equivalent of a pint of gasoline. i.e., each will take its respective (and LEAF-size) vehicle about the same distance. The big differences are in price (from say 5% to 25% of petroleum), source (many vs. "1", fully vs. partially domestic), and emissions (distant vs tailpipe, and cleaner almost regardless of the source).

I'm sure to get some push-back on this analogy (and let the arguments begin ;-)), but it's close enough for me!


Edit/ps. A fourth difference might be labelled conversion efficiency, or the percent of the stored "chemical" energy converted into kinetic energy and accessories. For batteries (kilowatt-hours) + electric motors, it is probably in the 90s or high 90s (percentile). For petroleum ("pints" of gasoline or diesel) + IC engines, it is what? 20-25%? This of course is why electricity is so much less expensive (above).

I like your comparison of a kWh to a pint of gasoline. However, I disagree with the efficiency claims. Fuel burned at the power plant has to go through electric transmission systems, including voltage conversions an power lines; that energy has to be processed through the charger (reported at around 85% efficiency), stored and recovered from the battery at the efficiency of that, converted to power the motor (some loss), then friction losses in the drivetrain. When you add it all up, it begins to look like the numbers for a gasoline engine car.

In my analogy, the battery is (like) the gas tank, so the kilowatt-hours I'm talking about (and the pints of gasoline) are the ones that have already made it to their respective "tanks", and irrespective of how they got there. Yes, there are losses along the way for "the electrons", but that is equally true, if not more so, for the pints of (refined) gasoline, which started as crude 100s or 1000s of feet below sea level, 100s or 1000s of miles from the station. And the efficiency of an electric motor vs a gasoline engine (~4:1) is measured this way, "indifferent" to how the fuel arrived. And the ratio only gets higher as your electricity sources become cleaner and closer ('to home').

So, no. I'd rephrase what you said and say just the opposite:

When you add it all up for both fuel sources, the efficiency numbers of electric vehicles DO NOT look like those for a gasoline engine car!

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That is, if you count "well to tank" for electrons, you need to count "well to tank" for gasoline too.

mbender said:

Yes, there are losses along the way for "the electrons", but that is equally true, if not more so, for the pints of (refined) gasoline, which started as crude 100s or 1000s of feet below sea level, 100s or 1000s of miles from the station.

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Right you are. The thing I neglected was the cos of getting the crude to the power plant, which also had to be counted. So, skipping the first part of the gasoline path gave some imprecise parity with skipping the oil/natural gas to the power plant.

alanlarson said:

I like your comparison of a kWh to a pint of gasoline. However, I disagree with the efficiency claims. Fuel burned at the power plant has to go through electric transmission systems, including voltage conversions an power lines; that energy has to be processed through the charger (reported at around 85% efficiency), stored and recovered from the battery at the efficiency of that, converted to power the motor (some loss), then friction losses in the drivetrain. When you add it all up, it begins to look like the numbers for a gasoline engine car.

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Hmmm Most of my electrons comes from 12kw in solar on my roof...

All of mine come from a hydroelectric plant 3/4 of a mile away.

mikesus said:

alanlarson said:

I like your comparison of a kWh to a pint of gasoline. However, I disagree with the efficiency claims. Fuel burned at the power plant has to go through electric transmission systems, including voltage conversions an power lines; that energy has to be processed through the charger (reported at around 85% efficiency), stored and recovered from the battery at the efficiency of that, converted to power the motor (some loss), then friction losses in the drivetrain. When you add it all up, it begins to look like the numbers for a gasoline engine car.

Click to expand...

Hmmm Most of my electrons comes from 12kw in solar on my roof...

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I could be wrong of course, but I'd guess that they actually don't. I bet your "roof's electrons" are actually sent to the grid and used by someone else. Later, when charging you LEAF, you are using electrons made by whatever mix of electric-generation fuel is used in your region.

Of course, it's possible that you charge during the day directly from your solar installation, OR that you have local battery storage that you tap into at night. If that's the case, awesome! But I covered that case above when I said that "the [efficiency] ratio only gets higher as your electricity sources become cleaner and closer ('to home')."

e.g., I occasionally charge at a public level 2 charger in a complex that has a large solar installation on the roof. And although I'm glad about that, I'm under no illusion (even during daylight) that the juice coming out of the charger was produced [nano]seconds earlier from the panels above. They were most likely produced by a nearby natural gas power plant. :-\

If the sun is shining when you charge at a solar-equipped facility, your charge is coming from the sun - electrons don't make round trips in the grid. If the sun is not shining, the power comes from the grid. Even then, if you are contributing power to the grid, you are making the grid cleaner, and that counts as well.

Back to the OP, not a lot of maint. to do. But it sounds like you want to be more in-the-know. I'd suggest some searching and reading on care-and-feeding of the battery. If I attempt to boil down what I've learned it is basically to try to minimize the number of hours that battery sits above 90% SOC or below 10% SOC. In other words, if you can avoid charging over 90% that's great. If you need all the range you can muster, don't charge to 100% the night before and sit at full charge overnight if you can instead get the last 10% in the hour or two before you leave.

Oh, and I'd suggest you edit your profile with your general location and vehicle type. This helps people take your statements in context of your location and provide more relevant info.