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How to drive past electric car range limits for long range trips

Recently Consumer Reports bought a Ford Focus Electric and towed it to their testing grounds, when they could have stopped at charging stations along the way and driven it all the way to their office without towing.

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A couple weeks ago Consumers Reports bought a Ford Focus Electric for testing that will result in a future review of that car. Getting it to their office meant a 100 mile journey from Westchester County, NY to their offices in Connecticut. Along the way they had a little misadventure in planning long range trips with electric cars that illustrates a common misconception about electric cars. That they can only be driven around town, because the short electric only range is useless for road trips. At first blush an electric car with a 76 miles driving range might look useless to reach a destination 300 miles away, or even 100 miles away, but with some planning it can be done.

The Consumer Reports blog entry says they'd picked up the car in Rye, NY, and stationed "a tow vehicle and trailer at about the half way point" on the way back to the company's testing grounds. Their website doesn't clearly say where the testing grounds are, but according to Google Maps the location is in East Haddam Connecticut. The preferred route to there from Rye, NY, is 110 miles, on I-95 and I-91.

There have been several news items referring to CR's trip as proof that electric cars are a failure, because Consumer Reports had to tow their new Ford Focus Electric to their office. As we'll see, this is more about the failure of Consumer Reports' staffers in understanding how to take a longish trip with an electric car. This a teaching moment opportunity, demonstrating how we can take longer trips using an electric car.

The first step to driving a long trip with an electric car is to understand the range of your car. How far you can go in one charge, and the effect of mountains on the range, is only partly captured by the EPA range estimate. It's best to spend a while driving your car, recording the energy used to go different places, to gain a better understanding of its capabilities.

Because it was a newly purchased Ford Focus Electric, CR's staffers couldn't do that. The best they could do is trust the EPA range estimates and then be really conservative about the distance they'll drive in each segment of the journey. Which leads to the next step.

Divide your journey into segments based on the distance you're comfortable driving. The goal is to avoid getting stuck on the side of the road with a dead battery. How far can you drive and leave yourself enough charge in the battery pack in case there is a problem? For the Ford Focus Electric, each leg of the journey should be 50-60 miles. While the rated driving range is 76 miles, being conservative on the length of each leg helps to avoid running the battery down to dead, and gives some leeway in case plans have to change.

Next use an application like ReCargo to browse the charging stations along the route you'll be driving. There are several smart phone applications that show the charging station networks, and ReCargo is one, and another useful app is PlugShare. These applications do not help with route planning, so it is useful to map each leg of the trip in an a regular map application. You have to look for charging stations within the driving distance for each leg of the journey. It's useful to have alternate locations in case one of the charging stations is down or occupied. We want each leg of the trip shorter than the total driving range, just in case you have to seek out an alternate location. It's not helpful if your car is on its last electron, only to arrive at the charging station to find that it's broken. Some of the charging station app's allow you to query charging station status ahead of time.

For the trip CR's staffers took with their Ford Focus Electric, there are several charging stations along the route. These include the Summer Street Garage in Stamford, the Yankee Doodle and Maritime Parking Garages in Norwalk, a Whole Foods near Fairfield, several parking garages in New Haven. Unfortunately the list of charging stations grows sparse after that point, but the Hartford Amtrak station has a public charging station. Therefore, the CR staffers could have driven directly from Rye, NY to West Haven (47 miles), charged, then from there to Hartford, charged, and then on to their office, with no need for a tow vehicle. The charging session in West Haven should be a full recharge, and because the Ford Focus Electric has a 6.6 kilowatt charger the charge time would have been close to two hours. The charging session in Hartford should be just enough to have the range to get to CR's office, so an hour of charging should be sufficient.

The rule of thumb for electric cars with 6.6 kilowatt chargers, is that each hour of charging adds 22-25 miles of driving range.

For a slightly tougher request, let's consider someone living in Kansas City, MO, visiting relatives in Wichita, KS. According to Google Maps the distance is 200 miles, and according to the ReCargo application there are public charging stations in Olathe, Lawrence, Topeka, Emporia, El Dorado, and Wichita. The distance between each of these is short enough to allow an electric car to make the journey, hopping from station to station along the way. Unfortunately getting much further west in Kansas than Wichita or Salina is not terribly doable, because of the lack of charging stations.

The basic principles are: a) divide your trip into legs based on how far you can drive, b) map out the available charging stations, c) have alternates in case a charging station is down, d) drive an electric car with a fastest charger you can find, so that you'll be waiting the least amount of time possible.

Several on-going or recent long range electric car trips demonstrate these cars don't need to be limited to short hops around town. One is a Tesla Roadster owner from Spain who is chasing a pair of Frenchmen driving a Mitsubishi i-MiEV around the world. Another is a Frenchman driving an electric Citroen postal van across rural Africa. In June, a San Diego man drove his Nissan Leaf from Baja CA to British Columbia (BC to BC). A week ago I drove my electric car, a Karmann Ghia conversion with a 50ish mile range, about 150 miles per day for a couple days in a row, using these same techniques.

With all this in mind, it is best to remember that the auto makers have designed the current crop of electric cars with around-town driving in mind. The 300 mile range electric car is quite possible, and Tesla Motors is making it, but the price is not in the realm the average consumer can even dream of spending. Until battery technology improvements come along the electric cars for the rest of us will have a driving range of around 100 miles. The pragmatist should recognize that it's best, now, to use the electric car for the primary trips around town, and relegate a gasoline car to those longer trips. If you rarely take longer trips, all the better, because you could completely fore-go owning a gasoline car, and rent one when needed for a long trip.

Trips slightly beyond the rated driving range of the electric car are completely doable using the steps just outlined, and Consumer Reports could have taken their Focus Electric home without towing it.

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Nicolas Zart    August 6, 2012 - 2:36AM

Unfortunately CR doesn't really make sense a lot of time. They consistently put certain products over other of lesser quality. They defend themselves by saying the rate things as the best bang for your buck, but that doesn't always jive.

Sad to say but I never too seriously what CR does, at least not when it comes to cars and computers.

Aaron Turpen    August 6, 2012 - 2:51PM

In reply to by Nicolas Zart

CR has two major advantages over every other car test/review magazine out there:

1) they use scientific methods that are as closely tuned to reality as possible;

2) they buy their cars and aren't beholden to advertising or other possible sources of influence - most magazines/websites at least have a "don't talk too bad about them so we don't piss them off and stop getting cars" policy.

That, for me, means they're more reliable than others. I suspect you don't like their computer reviews because they don't pander to Apple. ;)

Don Bain    August 6, 2012 - 1:35PM

Any place you can plug in an RV, there's a good chance you can charge your electric car with the appropriate patch cord. Tesla drove a roadster two or three years ago from their California headquarters to the Chicago Auto Show by merely stopping at KOAs along the way.

It's just that most Americans are not to interested in hanging around these charging places so much. They want to drive to where they're going and then recharge, both self and car.

Aaron Turpen    August 6, 2012 - 2:47PM

Somehow, I doubt that CR was interested in spending hours of employee time sitting around waiting for a car to recharge. The fastest, surest way to get the car to their facility was to tow it. If I purchased an EV in Denver, I'd tow it back to my home over 100 miles away too. It just makes sense and means you don't waste most of your day sitting at recharge points.

Paul Scott (not verified)    August 6, 2012 - 7:10PM

In reply to by Aaron Turpen

I'm not sure the cost of an employee waiting for a total of 3 hours would be that much more than a tow truck driving 100 miles. I think the intent of this article is to let you know that this kind of a drive is completely doable in a car like the Focus. Had the driver used hypermiling techniques as I do, he/she could have driven the full 100 miles on one charge. I have been averaging over 100 miles per charge in my LEAF for the past 17,000 miles. It's quite easy, and it's the safest way to drive.

CR missed the boat on this completely. They should instruct their drivers to use efficient driving techniques for all of their testing. Dumbing it down for the "average" driver doesn't help get the point across that we are a very inefficient country in need of a wake up call before the effects of peak oil are truly upon us.

Aaron Turpen    August 7, 2012 - 10:48AM

In reply to by Paul Scott (not verified)

ASSUMING they could gain access to a 220V charger, then maybe 3 hours or so. Maybe.

As for driving like the average "dumbed down" person.. Isn't that the whole point of doing car reviews and evaluations? To see it from the perspective of the AVERAGE?

Maybe you hypermile, but 99% of Americans don't. You can blame that on whatever you'd like, but not everyone is a single guy in a small car going an average of 20 miles per day at mostly low speeds and in perfect LA weather. Most of us are in variable weather conditions, have families, drive a lot of distance and/or have a lot of us in the vehicle, and do things ranging from hitting the hardware and lumber store to packing everyone up for camping, shopping, etc., etc.

I've driven a Leaf, Focus Electric, Roadster, Volt, etc. and not a single one of them would be viable or realistic for my family and where I live. Until car makers and EVangelists realize that not everyone lives in LA and NYC, EVs are not going to sell. Until EVangelists realize that there are people with families, car seats, dogs, groceries, etc. who are driving in wind, snow, rain, sleet, as well as sunshine.. those cars aren't going to be mainstream.

This Focus, like most current EVs, is nothing more than a California compliance vehicle. I'm actually amazed that CR is wasting budget on buying one. I guess reviewing it might help them sell magazines, but realistically, Ford isn't going to make enough of these for most consumers to ever even see one, let alone buy it.

Aaron Turpen    August 7, 2012 - 3:44PM

In reply to by David Herron

Look at it from CR's perspective, David. 1) maybe hit a charging station and get the car charged while spending 3+ hours of employee time . 2) Have a tow ready to carry the car the rest of the way, thus guaranteeing the car arrives, employees don't go into overtime, and nobody gets stranded or stuck.

Let's assume $15 an hour for two employees, including benefits cost. That's basically minimum wage, for those of you wondering. Now those two employees get into a car (again, assuming they're driving to and back) an drive 100 miles. At an average speed of 60 miles per hour, they've made the trip in about an hour and forty-five minutes. Arrive, get the EV, sign paperwork, etc., etc. Assume an hour for that. Now the return trip, halfway through which they'll have to stop to recharge the EV. So another hour on the road, then they stop for 3 hours, then continue and arrive back at CR. Total trip time: 2 hours 30 minutes driving, 1 hour at dealership, 3 hours charging = 6.5 hours at $30 = $195 in just employee expense. Add to that the gasoline, charging cost, and so on.

Triple that wage to a realistic number (I highly doubt they're sending minimum wage interns to pick up brand new cars) and the employee expense jumps accordingly. At $45/hour for two employees for three hours, you're looking at $270 for just sitting around waiting for the car to charge.

David Herron    August 7, 2012 - 3:56PM

In reply to by Aaron Turpen

Aaron, I agree with what you're saying. Let's back up a second to get a bigger perspective. I purposely wrote this piece in a way that's not pointing a finger of shame at CR, but using what they reported as a teaching moment to say what is possible. There were several reports starting from "CR had to tow the Focus EV" and coming to the conclusion that EV's are a failure. In truth CR could have done a calculation of the sort you just made, come to the conclusion it's cheaper to tow the thing, etc. And that it's not about EV's being a failure, but CR being pragmatic about how to get the vehicle to their office. What I attempted to do is explain the process you'd go through to drive a Focus EV over that route without burning gasoline. And BTW I had a chance last week for a three day test drive of the Focus EV, and I know first hand what it's capable of.

Paul Scott (not verified)    August 7, 2012 - 2:18PM

In reply to by Aaron Turpen

Aaron, the OEMs will be making cars that serve your purpose eventually, but for now, the commuter EV is what they are making since it's the easiest one to build. It's the fault of the media, and certain individuals who constantly harp that this car or that one will not do what I want it to do. Over 58% of Americans households have two or more cars. Certainly one of them can be a BEV with a 100 mile range. The other one can be a PHEV. The PHEV could easily be an SUV or truck.

We are a wasteful nation and our energy policy is largely responsible. That, and an uncaring populace. We need more people to become better drivers. It has nothing to do with being a single guy driving 20 miles to work. Anyone can hypermile, and all who do will realize significant gains in efficiency.

There are consequences to using filthy energy like oil and coal. These involve using our military to secure access to the world's oil with hundreds of billions of dollars and dead soldiers being the result. Our environment is heavily polluted and our economy is wrecked.

If you, or any other American chooses to drive an inefficient vehicle, and to drive it without regard to efficiency, then you are responsible for more of those negative consequences than you should be. That is your choice. That does not make you a good person, quite the contrary.

Aaron Turpen    August 7, 2012 - 3:32PM

In reply to by Paul Scott (not verified)

We own two of the most efficient practical gasoline vehicles on the road, neither of which is new and one of which is high mileage. Most of the people I know own practical, relatively efficient vehicles as well. Nobody likes wasting money on gasoline. Neither do they like wasting money on cars that won't do the job. But a car that is impractical costs more than a car that isn't. Since EVs are aimed squarely at the demographic I mentioned earlier, they're going to sell to a very small portion of the total population. Which makes them a curiosity akin to high-end sports cars and purpose-built vehicles.

So people like me who pay taxes into the system have to wonder why our tax dollars are being spent to subsidize both the R&D and the sales of these cars when, frankly, the only segment of the population that can own them can easily afford them without our help. If I buy a high-efficiency TDI, which is much more useful where I live, or a (currently unavailable) practical-sized CNG car, I don't get $7,500 to help pay for it. Yet those two fuels are much more common and readily available (without buying any accessories such as charging stations or building infrastructure) and are far greener than gasoline or even BEVs when you consider sources.

Oil, for a very long time, was a cheap, plentiful, ready resource. Still is, though we've managed to regulate our way out of getting most of it. Obviously it's not good for the environment, but twenty, thirty, fifty years ago, those were not concerns. Now they are, but we aren't going to get off our dependence on oil in a few years or even a few decades. Every study I've seen shows petroleum being a primary energy source for the next fifty years and beyond.

But instead of dealing with reality and figuring out how to make our use of petroleum as efficient as possible, California and its followers are instead forcing unrealistic solutions that are accomplishing nothing but hype and wasted resources.

David Herron    August 7, 2012 - 4:01PM

In reply to by Aaron Turpen

I would suggest that because diesel and TDI is already popular, that makers of those vehicles don't need help. The situation with CNG is a little different because while natural gas is "everywhere", it isn't widely available in a form suitable for refueling a CNG car. In fact the CNG refueling infrastructure is much worse off than the EV refueling infrastructure. The DoE recently floated some grants (?loans?) to several companies to build better CNG refueling infrastructure.

As for the future availability of fossil oil ... er ... world oil supplies have already hit peak oil ...

Paul Scott (not verified)    August 7, 2012 - 5:21PM

In reply to by Aaron Turpen

First of all, thanks for using efficient vehicles. I wish more people would do that.

I'm curious why you have a problem with someone being encouraged to buy a plug-in car by being able to keep more of his own money instead of paying it in taxes, but you seem to have no problem when our military spends $80 billion per year protecting access to the world's oil (I have the link, but this site will not allow links to be posted).

These costs are exclusive of the wars we fought for oil. The Iraq war has cost over $1.5 trillion and thousands of dead soldiers. This is a huge cost and one we would not have paid had Iraq no oil.

Further, there is much medical research that concludes thousands of Americans die prematurely every year from the effects of internal combustion pollution. Hundreds of thousands suffer ill effects but don't die. Many are children who, through no fault of their own, happen to live proximate to freeways or downwind from refineries.

The environmental degradation from extracting, shipping, refining, distributing and burning of oil is enormous. The Gulf oil spill caused the loss of thousands of jobs, and is still causing major problems there. Oil spills in pristine rivers happen all the time the world over.

None of these costs are in the price you pay at the pump. You are being heavily subsidized by our treasury, the lives of our soldiers and fellow citizens, and the environmental damage done by the fuel you use. Seems if you were a fair minded person, you would take those things into consideration.

You are also still claiming these cars are impractical. Over 80% of Americans drive less than 40 miles per day. Please explain why you think a car that can drive 100 miles on a charge, and be charged from any plug anywhere, is impractical.

Aaron Turpen    August 7, 2012 - 7:59PM

In reply to by Paul Scott (not verified)

Two things: the subsidy for EVs is a direct subsidy - a payment for a specific activity, rewarding said activity. If the excuse that buying an EV eliminates foreign oil imports actually sound (it isn't), then my earlier statements about subsidizing natural gas and diesel/biodisel would still be sound as well. Those aren't made from foreign oil either. In fact, most of our motor fuel is NOT from foreign oil imports, it's from North American domestic stock. The majority of imported oil is used to make plastics and other petroleum-derived products, such as about 50% or more of that electric car you drive. Further, our net import is 45% of total use and just over half that is from this hemisphere (mostly from Canada, Mexico, and Venezuela). The Persian Gulf area makes up about 22% of our overseas imports, most of that Saudi Arabian oil (note we haven't gone to war there). These are all EIA numbers.

Now let's look at that "80%, 40 miles" number people love to throw out there. That's one of those urban legends that's been repeated so often, it must be true. The number is actually 78% drive 40 miles or less and it comes from a Bureau of Transportation OmniStats publication in 2003. It says that 77% of the population drives less than thirty minutes a day for about 15 miles one-way. Get this: the survey had a sample size of.. only a thousand people. A thousand. Wow. Highly representative, is it not?

Paul Scott (not verified)    August 7, 2012 - 8:47PM

In reply to by Aaron Turpen

I noticed you completely ignored all the external costs I discussed. The $80 billion figure comes from RAND, so it's sound. If you think oil didn't play a part in the Iraq war, you're pretty ignorant. Even the military leaders know that we fought that war for oil. They are some of the most ardent supporters of plug-in vehicles, both for civilian use, and their own use.

You seem to be straining to find fault with my comments. If the figure is only 77% instead of 80%, what's your point? My point is that EVs work for the majority of American's daily driving needs. That's pretty clear to the most casual observer.

You seem to harbor a hate for EVs. I really have no idea where that comes from. If you don't want one, then don't buy one. Why would you want to stop others from getting them? About 30,000 Americans have bought plug-in cars in the past two years. We all deserve the choice to drive on renewable electricity. The carmakers are finally giving us that choice.

You should be happy other people are choosing to drive without oil. For every EV that replaces a gas burner, your air gets cleaner, your nation safer, and your economy stronger. What's not to like?

Aaron Turpen    August 7, 2012 - 9:15PM

In reply to by Paul Scott (not verified)

I didn't ignore your comments, I brought up that oil doesn't have to come from the Middle East. We get only 22% of our oil from there. That's not a hard number to tackle. But anti-oil types seem to want to make the impression that every gallon of gasoline, every drop of petroleum, comes from evil cartels in countries we want to bomb. Frankly, the fighting in the Middle East has little to do with American national security and a lot more to do with multi-national energy cartels wanting to control supply to everyone else. Note that as soon as Iraq was "stabilized," they immediately started auctioning oil futures to foreign governments - mostly China. These wars have a lot more to do with global economics than they do with oil specifically.

I don't hate EVs - I have websites devoted to alternative energy sources for automotive. I see battery electrics as one small part of a larger, overall solution. My problem with BEVs is that they seem to get all the glory when they're really just a tiny portion of the overall. I don't think battery electric cars will solve our problems. Not near-, mid- or even long-term. I notice that you've now twice ignored me when I wonder why other, just as clean alternatives are ignored in favor of EVs when it comes to subsidies and tax breaks.

Howard Marks (not verified)    August 7, 2012 - 5:29AM

The article says
With all this in mind, it is best to remember that the auto makers have designed the current crop of electric cars with around-town driving in mind. The 300 mile range electric car is quite possible, and Tesla Motors is making it, but the price is not in the realm the average consumer can limit even dream of spending. Until battery technology improvements come along the electric cars for the rest of us will have a driving range of around 100 miles."


The ONLY limits to affordable long range EV driving IS corporate policy NOT science and engineering !!

David Herron    August 7, 2012 - 2:15PM

In reply to by Howard Marks (not verified)

Howard - it is a combination of corporate policy AND science and engineering. Tesla proves with the Model S that it's possible to build a 300 mile electric car that can be recharged in an hour. However, look at the cost for that vehicle. This is where the science and engineering come in, to develop the batteries that cost less for the same energy capacity.

Howard Marks (not verified)    August 8, 2012 - 12:26AM

In reply to by David Herron

You are wrong. The RAV4-EV would have a range using NiMH Panasonic batteries that would match the best TESLA at an affordable price by now. CHEVRON has kept the NiMH battery in a prison for ten years. Meanwhile the RAV4-EV drivers who got to buy their cars avoiding the otherwise crushing of them have driven between 100Kmiles and 200Kmiles on the same 1997 NiMH PANASONIC EV95 battery. A battery that drove the RAV an SUV 120miles in 1997 the same battery drove the EV1 160miles in 1998. That battery was due for a 50% upgrade by 2005 but CHEVRON intervened. Now Ford and Nissan sells 76mile cars in 2012.


David Herron    August 8, 2012 - 4:49PM

In reply to by Howard Marks (not verified)

Generally speaking lithium ion batteries start at twice the energy density of nickel chemistry batteries.

Yes I know quite a bit about the first generation RAV4 EV, and the patent issues concerning NiMH batteries. But if you do the math, lithium batteries will go quite a bit further than nickel batteries because lithium batteries are in a different realm of energy density.

Yes it is corporate policy - because they're targeting a desired price range and do not want the Leaf or Volt or Focus Electric price to be unaffordably high.

It also has to do with science and technology because lithium batteries are still being developed.

Aaron Turpen    August 9, 2012 - 2:45AM

In reply to by Howard Marks (not verified)

NiMH suffers from serious drawbacks:
1) Lower voltage
2) Shorter lifespan (# of charge cycles)
3) Less tolerant to temperature changes
4) Low shelf life - sitting unused, they lose up to 25%/month
5) GM patent issues (controlling interest in Ovonics patents - Toyota pays GM a premium for every Prius made with a NiMH battery)
6) Generally slower charging/discharging than Li-ion

Don't believe everything you saw in Who Killed the Electric Car. There was a lot of propaganda in that film.

Howard Marks (not verified)    August 9, 2012 - 5:41AM

In reply to by Aaron Turpen

You are WRONG on ALL counts. I can assure you that I and my colleague have done more research and crunched more numbers on this than you and maybe anyone other than CHEVRON's own scientists who informed their executives that the ONLY doable mass market battery is NIMH and that is why CHEVRON put it in a prison.

You wrote

NiMH suffers from serious drawbacks:
1) Lower voltage
2) Shorter lifespan (# of charge cycles)
3) Less tolerant to temperature changes
4) Low shelf life - sitting unused, they lose up to 25%/month
5) GM patent issues (controlling interest in Ovonics patents - Toyota pays GM a premium for every Prius made with a NiMH battery)
6) Generally slower charging/discharging than Li-ion

You are so utterly wrong on every point !!

1) By 2005 the EV95 would have matured into a battery 50% better than 1997.
NiMH has greater power density than Li-on.
2. Shorter lifespan ? ARE YOU RAVING BLOODY MAD !! Get this into your ignorant head. The RAV4-EV owners have been driving around on the original
1997 PANASONIC EV95 NiMH battery for over 14 YEARS !!!!! I know a woman in
Northern California who owns two of them with a combined mileage of over
275,000miles on ORIGINAL batteries !!
3. Less tolerant to temperature you are nuts it is Lithium that requires a far more
complex Battery Management System precisely due to the temperature volatile
lithium lack of tolerance. The PANASONIC EV95 circa 1997 that the following temperature range approx minus 30centigrade to plus70centrigrade while the average professional lithium powertool battery for gear used in factories has a temperature range of only Zero C to plus 30C.
4. The NiMH in the Prius is not relevant as it is so small CHEVRON does not object.
5. Slower or faster is not the point far more important is that NiMH is better at deep discharging and you can use more of the total available power.

Aaron Turpen    August 9, 2012 - 6:15AM

In reply to by Howard Marks (not verified)

Thanks for the insults. I'm sure your "scientific" methods are sound and everyone is now going to believe your every word because you've proven yourself to be so professional.

I love the capitalized references to "Chevron." How many times have you seen that propaganda movie (I mean "docu-film") again? Sheesh.

For the Tesla Roadster to hold its current range, it would have to employ a NiMH battery of about 1,000kg in weight compared to the 400kg its current Li-ion battery has. Maybe in your dreamy sub-reality of "by 2005" nickel batteries would have improved to that point, but I highly doubt it. If NiMH were really that great, everyone and their brother would be researching and working with it. Instead, they're working on lithium. Of course, you obviously have a convoluted conspiracy theory for that, which helps you justify your self-touted "research" time, culminating in your very academic response herein.

Sorry, Howard, but your approach, attitude, statements, and obvious bias are showing. Anyone who's spent time here at TN knows that I routinely call out EVangelists when I see their zealotry showing. You, sir, need to hitch your pants up.

David Herron    August 9, 2012 - 11:29AM

In reply to by Howard Marks (not verified)

Howard, You are one of the NiMH zealots .. you have made your points .. thank you.


1) What Aaron meant by "lower voltage" is that the per-cell voltage of NiMH is 1.2 volts while the per-cell voltage of lithium ion is typically 3.3 volts, but this depends on the specific chemistry. This means a lithium pack requires fewer cells to reach the same voltage, fewer cells means better reliability.

2) shorter lifespan - I don't know enough to comment, other than there are many lithium suppliers claiming 3000 charge cycles. The thundersky's in my car are rated for that number of charge cycles. And, yes, I know many people who own NiMH RAV4 EV's and have had amazingly long useful lifetimes

3) I agree with you that most lithium batteries have a narrow enough temperature range to be a problem. See the concerns over cold weather or hot weather impacts on the Leaf. However, A123 recently developed a variant of their battery that has better temperature range.

4) low shelf life - sounds as if Aaron was referring to the self discharge rate. I don't like AA NIMH cells for my portable gizmos because of this, but a couple years ago found some AA NiMH cells that do not self discharge. That's a good thing. It means that NiMH can be designed to not self discharge.

5/6) Charge and discharge rate is extremely important. The discharge rate governs how fast the vehicle can go, which is very important when merging onto a highway and a big truck is barrelling down on you. The charge rate directly determines the effective speed because it determines how quickly your car recharges while on a trip.

Howard Marks (not verified)    August 9, 2012 - 5:46AM

In reply to by Aaron Turpen

PANASONIC official data released 1998 on the EV95 Battery guaranteed a minimum of 1000 full deep charge/discharge cycles. Please not these days many lithium manufacturers or the car makers who use them are claiming 3000 chaerge cycles for lithium but this is based on tests that are often as little as 50% discharge. Like so many things nowadays the numbers are not honest. PANASONIC today in making lithium cells since being prohibited from making high density NiMH cells no longer assured full deep discharge cycles above 300.