Out: M.P.G. In: Kilowatt-Hours. Classic Cars Get an Electric Jolt. - The New York Times

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rcjordan

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Exclusive: Hands on With the World's First Electric Crate Motor | Digital Trends
 

Mike Perez

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Cool, but the problem with putting electrics in a GMC has never been the powertrain setup, it is the battery capacity. It is likely that my next personal car may be electric, so I've been doing some research. The problem is that even a super sleek model S at highway speed averages over 300 watt hours per mile. A GMC weighs a whole lot more and and is an aerodynamic brick in comparison. I would estimate the watts hours per mile would be at least 3 times as much. At 60 mph, you'd use 54,000 watts of power in one hour. That's half of the biggest model S battery. So you'd be out of juice in less than 2 hours or less than 100 miles.

We really need to get to where you can drive 300 miles, and recharge in less than an hour. When that becomes reasonably priced, count me in.

I'm cannibalizing a Nissan Leaf Battery to use as a house battery (it's a long story), and it will take more than half of an entire Nissan Leaf battery capacity to just run one Coleman Mach roof A/C for 8 hours. Now think of how much battery it will take to move a GMC down the road, run the dash A/C, the water pump for the cooling system, and possibly one of the AC units to keep the back cool.
 
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pvfjr

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At 60 mph, you'd use 54,000 watts of power in one hour.
I mean no offense, but the units here don't make sense. This is the reason I detest the "watt-hour" as a unit of measure. It causes a lot of confusion for folks, and gets people talking about watts when they're referring to energy capacity instead of instantaneous power consumption.

I think a better way to look at things would to be consider how many joules is in your gas tank (120 MJ/gal x 50 gal = 6 GJ ), take a guess at the typical efficiency factor for your gas engine (let's say 20%), and you'll instantly know how many joules your battery would need to hold for a similar range (you can correct by an electrical efficiency factor [maybe 85% if we're feeling generous] as well if desired). For example, (6 GJ x 0.2 / 0.85 = 1.4 GJ) Then a simple search for the energy density of your preferred battery technology (180 MJ/m^3) will give you the volume of battery required (1.4 GJ / 180 MJ/m^3 = 7.7 m^3 = 270 ft^3 = 2000 gallons). Then you can compare it to the volume of your gas tank, become extremely shocked, and give up on the idea until better technologies emerge.

Here's a neat graph showing various energy densities (not to be confused with specific energies--also shown). The generic lithium ion is pretty sad compared to gasoline. Even with over 4X the efficiency in our sample equations, it loses big-time to gasoline.
 

Mike Perez

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I mean no offense, but the units here don't make sense. This is the reason I detest the "watt-hour" as a unit of measure. It causes a lot of confusion for folks, and gets people talking about watts when they're referring to energy capacity instead of instantaneous power consumption.

I think a better way to look at things would to be consider how many joules is in your gas tank (120 MJ/gal x 50 gal = 6 GJ ), take a guess at the typical efficiency factor for your gas engine (let's say 20%), and you'll instantly know how many joules your battery would need to hold for a similar range (you can correct by an electrical efficiency factor [maybe 85% if we're feeling generous] as well if desired). For example, (6 GJ x 0.2 / 0.85 = 1.4 GJ) Then a simple search for the energy density of your preferred battery technology (180 MJ/m^3) will give you the volume of battery required (1.4 GJ / 180 MJ/m^3 = 7.7 m^3 = 270 ft^3 = 2000 gallons). Then you can compare it to the volume of your gas tank, become extremely shocked, and give up on the idea until better technologies emerge.

Here's a neat graph showing various energy densities (not to be confused with specific energies--also shown). The generic lithium ion is pretty sad compared to gasoline. Even with over 4X the efficiency in our sample equations, it loses big-time to gasoline.
Yes, but electric cars are measure in watt hours per mile and the battery packs are measured in watts. A Tesla Model S comes with either a 85,000 watt battery, a 90,000 watt battery, or a 100,000 watt battery. If the the car uses 300 watts per miles, it is really easy for most people to do the math. So a Model S with a 100,000 watt battery using 300 watts per mile will drive 333 miles before being empty or 300 miles with 10% reserve. A GMC using 900 watts per miles with the same size battery would be empty in 100 miles. So I think if someone want to figure out where to fit 300,000 watts worth of Tesla batteries in a GMC, then they may have something that could work. I'd do it, but I'm not up for spending $60,000 on batteries.

I don't think that battery energy density will ever get close to gasoline.
 

pvfjr

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Yes, but electric cars are measure in watt hours per mile and the battery packs are measured in watts. A Tesla Model S comes with either a 85,000 watt battery, a 90,000 watt battery, or a 100,000 watt battery. If the the car uses 300 watts per miles, it is really easy for most people to do the math. So a Model S with a 100,000 watt battery using 300 watts per mile will drive 333 miles before being empty or 300 miles with 10% reserve. A GMC using 900 watts per miles with the same size battery would be empty in 100 miles. So I think if someone want to figure out where to fit 300,000 watts worth of Tesla batteries in a GMC, then they may have something that could work. I'd do it, but I'm not up for spending $60,000 on batteries.

I don't think that battery energy density will ever get close to gasoline.
I'm not trying to attack you or be nit-picky, so I hope it doesn't feel that way. I'm just trying to dispel confusion and combat misinformation. You've certainly done enough groundwork and obtained enough understanding to see how limited this type of retrofit would be, and that's the most important thing. For the sake of other readers that may come across this, however, I'd like to clear a few things up.

You can't say "watts per mile" or "watts in a mile". It's dimensionally inconsistent units. It'd be like saying that New York is 3000 miles-per-hour away from LA. The stuff in green is fine, yellow is ambiguous depending on your intent, and red would lose all points on an engineering exam. Power is only an instantaneous measurement. It can be integrated over time, to become a watt-hour (which should actually be 3600 joules). Watt hours per mile is an acceptable measurement of efficiency that is comparable to MPGs, but it would be better as joules per mile.

If a Tesla has an 85,000 watt battery, that is not a measure of its energy capacity, but rather a measure of how much instantaneous power it can deliver in a given moment. You could have a 85,000 watt battery that has the same energy as a AAA battery. They're different measurements. How many watt-hours it can store is an entirely different question.

I understand that watt-hours are more relatable for the lay-person, but at what cost? It only causes confusion. I've been seeing it way too much for years now (even in magazine articles). I think if we all talked about joules more, people would have an understanding of what they mean. Another thing that sets people up for confusion is our monthly "power bill". We don't buy power though, we buy energy. You're charged based on the total energy used in a month. It has nothing to do with the amount of power consumed during any given instant. I don't know how this convention got started, but it sets up a flawed fundamental understanding of power in society. Everything gets dimensionally incorrect when watts and watt-hours get used interchangeably.

Either way, I think we can both agree that the feasibility isn't close yet. I don't have 270 ft^3 of space for batteries. I could use less space at the cost of getting less range, but then I have to stop more often and wait who-knows-how-long to recharge. None of this even begins to account for the weight of the batteries, or the expense. I'm WAY too cheap for that for the foreseeable future. Like you said, $60k in batteries is an enormous expense, and it could buy you a LOT of gas.
 

Christo

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I guess it's the same problem we ran into with the conversion from incandescent to LED light bulbs. People grok how bright a "60 watt" light bulb is, but that has nothing to do with light output, so we ended up with "60 watt equivalent" LED bulbs. And don't even get me started on all the wiggle room around lumens... ;-)
 

1976GMC

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I guess it's the same problem we ran into with the conversion from incandescent to LED light bulbs. People grok how bright a "60 watt" light bulb is, but that has nothing to do with light output, so we ended up with "60 watt equivalent" LED bulbs. And don't even get me started on all the wiggle room around lumens... ;-)
This is a perfect example. We, as a society, are all used to one way of "measuring" things, i.e. bulb brightness. In order for us simple folks to go on with our lives and be able to relate old habits to some new thing, the "smart" consumer relations departments figure out how they can label newish things with old, relatable terms. This is done with good intentions and in order not to confuse us (non-technical consumers) too much. It works to some extent, but eventually results in more confusion as soon as you actually start learning something or using your brain...

BTW, I agree with all of you here that EV technology is not there yet as far as reasonable battery capacity to move our GMC down the road. However, I am a total, absolutely off the charts optimist and I think we will see the day when it will be possible (with the caveat - if you got the $$$).

As far as places to stash the Tesla-like batteries... Two (maybe even 4) can go down where the fuel tanks are... then at least 3 - 4 more can be stashed into the space currently occupied by the 455 and transmission (this is assuming you got direct drive motors on the wheels). Unfortunately that whole setup will probably weigh much more than the hardware you'll be taking out, so the total weight of the vehicle will go up. Plus, now that I think about that, can front end handle that much weight concentrated above front wheels? I guess I should do some homework and find out how much those batteries weigh... ;)
 

pvfjr

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BTW, I agree with all of you here that EV technology is not there yet as far as reasonable battery capacity to move our GMC down the road. However, I am a total, absolutely off the charts optimist and I think we will see the day when it will be possible (with the caveat - if you got the $$$).
I'm optimistic about the future as well, but pragmatic about the present. The current offerings in lithium batteries are just too inadequate for me.

One scenario I can see becoming feasible is a heavily reduced range, offset by super fast charging times. I wouldn't mind only having 75 mile range if there were charge stations absolutely everywhere, and if the time-to-fill was just a couple minutes. You'll be stopping to pee that often anyway when traveling with a family. Assuming the charge stations were ubiquitous and quick, this could be doable.

If you want to feed your optimism some more, read up on the work John B. Goodenough has been doing. I can't wait for the day when his solid glass electrolyte batteries become available everywhere. Longer lasting, safer, quicker charging, etc.
 

1976GMC

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If you want to feed your optimism some more, read up on the work John B. Goodenough has been doing. I can't wait for the day when his solid glass electrolyte batteries become available everywhere. Longer lasting, safer, quicker charging, etc.
You are right - super interesting stuff. Talk about a deep rabbit hole once you get digging into the subject.

BTW, I was a little puzzled by your profile photo, but then realized what it was 😉 I started laughing because I had the same look on my wheels last year after driving our GMC from Oregon back to Washington last February during that massive storm that rolled through the area.
 

pvfjr

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You are right - super interesting stuff. Talk about a deep rabbit hole once you get digging into the subject.

BTW, I was a little puzzled by your profile photo, but then realized what it was 😉 I started laughing because I had the same look on my wheels last year after driving our GMC from Oregon back to Washington last February during that massive storm that rolled through the area.
Ha, must be a PNW thing. The pic is from September, driving over Willamette Pass in the Cascades after purchasing the motorhome in Phoenix.