Do We Really Need a 500 Mile Battery?

[DonC]

Charging needs make a 500 mile battery pack unworkable in anything but the far off future. A 500 mile battery at 350 wh/mile is a 220 kWh pack. At 90% charging efficiency that would require 243 kWh, which translates in time to over 72 hours at 3.3 kW, 36 hours with 6.6 kW, and nine hours with the maximum power supplied by the CHAdeMO standard, giving the term "roadside stop" new meaning.

The grid also likes predictable draws. To discourage large but sporadic draws, which messes up the grid design, power companies all have tariffs that call for demand charges. These demand charges are based on the highest power draw per unit time and would effectively preclude high wattage DC charging by making it far too expensive. You could charge one car a month and end up with a $4000 bill, giving "expensive fillup" new meaning.

Assuming you could solve the cost and packaging issues, which won't happen anytime soon, electrics still make no sense for long distance driving. The farther you need to go the less an option batteries are and the better fossil fuels or some other alternative are.

[saghost]

It's a matter of philosophy, and of selling things to people. Even the 95th percentile driver probably doesn't need more than 100 miles of battery on the average day. But occasionally, most drivers have a sudden need to drive several hundred miles, possibly a few times a year. So the question is: what do you do about those long road trips? Your two options are to build a battery that's far bigger and heavier (and more expensive) than anyone needs day to day to handle those extreme cases, or get the power for those trips from somewhere else (rent a car, onboard gas generator, towable power pack, fuel cell, swappable battery, electric highway quick charge.)

This is why I think the EREV approach will likely be around for a long time, and may evolve into battery + fuel cell instead of dying in the face of pure battery cars in the very long term. It allows all of the benefits of electric for the normal day, but effectively and conveniently (almost seamlessly) addresses the rare long trip.

Unless battery technology abruptly becomes an order of magnitude cheaper and lighter/more compact, it just isn't practical to make a battery car designed for the road trip case (and even then, there's the question of where you're going to find ~150 kWh of electricity overnight - you'd need 20+kW of power to recharge at the hotel or friend's house - 100 amps at 220V. I think the Tesla "twincharger" tech can deliver that kind of power, but house and hotel wiring will have to be upgraded.)

[Solarwind]

Although a 500 mile battery would be nice, I completely agree that it is overkill for 90% of potential buyers. It would be silly to offer a car with that as the only battery option. I think the Leaf is already in the right range for a single-option offering. I think the right approach is to over-size the main drive motor and sell bigger batteries that offer a combination of better performance OR longer range (depending on driving style). This value proposition better matches the way people historically value cars (V-8 costs more than V-6; everyone gets that). I think few people would be willing to pay for the incremental cost of range alone.

This is the way EV's should be sold 40, 80, 200, range ect. We are unable to use the full potential of our volt because all our travel is greater then 70 miles, and our electricity is free (solar)

[Zod]

DonC,

You're absolutely correct, but I think you're missing that fairly large group of people that take occasional (or sometimes regular) weekend trips on the 100-200+ mile range. In the hypothetical trip to the lake 200 miles away with no access to a charger, a 500 mile batter would do the trick.

But I agree, the thought of using an EV in the traditional ~1000 mile+ road trip is nonsensical, except maybe in the swappable battery paradigm (akin to propane tanks).

[Skotty]

I like to imagine that eventually batteries will be sold in smaller packs (maybe 8 kWh each), where the owner could load the car with anywhere from 1 to n packs, depending on the travel needs. A car might come with 1 or 2 packs to start, and the owner can buy more as needed. So you might have a car with 8 battery slots, but for your regular daily commute, you would only load up 2 or 3 of those slots. Then when its take to take a couple longer trips, assuming you have purchased the packs, you can load up 6, 7, or however many you think you will need, up to the maximum. This would also make it very easy to replace aging batteries. This would, of course, require one heck of a power management module. You might still have an extended range power source as well, unless effective fast charging becomes a reality.

That seems rather far fetched. More likely, I hope they at least offer superior battery replacements down the line for older models, either giving some additional range or reducing the weight (or both).

[Raymondjram]

Maybe no one will need a 500 mile battery because nobody will drive 500 miles in a day. But at the same time, having a large range battery allows someone who, due to long working hours cannot recharge every night, needs a capacity that can last five days. Then the battery can recharge for over 12 hours during the weekend.

This is similar to the gasoline tank capacity. I drive five days a week, and I fill up once every two weeks. If gasoline powered vehicles could swap out their large tanks for smaller ones, the weight loss (less gasoline being carried) will improve their MPG. But no one likes to get gas every night! I prefer to recharge at home while I am resting and the vehicle is safely parked, even if it had to be recharged every night. This is what present Volt owners have.

This new battery technology will allow both situations:
One for the daily traveler who cannot recharge every night, and needs a large 500-mile range battery,
Two for the short distance traveler who can charge every night, and can use a smaller 50-mile range battery.

I wish IBM much success for this research. It is a 100-year old company with many excellent products (especially the PC!) and has influence the lives of most Americans since its beginnings (it helped reduce the U.S. Census time to generate results after the counting since 1890), and it will continue to influence us for the new century.

[DCFusor]

An important point is being missed here. Even with the 40 mile battery in the Volt, I'm rarely charging it from flat to full. So, a somewhat larger battery would have to see empty->full a lot less often, and you'd be willing not to fully charge it most of the time - you'd just make sure you had enough for that trip, is all. It might take a couple days to go the full cycle - so what?

For me the ideal tradeoff would happen at about 100 miles pure electric range, which of course I could do with any battery bigger than that, and the main issue would be too big is too expensive in both bucks and pounds.

I have two errand loops and a visit loop. One of the errand loops is only 27 miles, and is the common one - almost daily. About once a week I have to do the 56 mile one (oops, doesn't fit) and perhaps a couple times a month, the 125 mile one (round trip numbers, no charger or time for that really, on the other end). So about 100 miles would suit me just dandy and really get me to 90% or more of my miles pure electric (solar!). If it was a 200 mile battery, I just wouldn't empty it before getting back on the charger, just like I do with the common trip/loop - and it would only take as long to hit full as it takes from what I'd used, not a full charge from zero each time - See my point?

[mikeg3]

An obvious reason for 500 mile batteries is to move almost all EV charging to the midnight hours, when the power stations and the power transmission network are way under-utilized. If the average EV can go a week without refueling, the power companies can even offer specials based on nights of predicted low demand. In the unusual circumstance where road charging is needed, the driver would only need enough power to get home, then fully charge that night.

Another justification for the 500 mile battery is larger vehicles. If we really want to bring oil prices back down under $10.00 per barrel, we need to move heavy vehicles off the gasoline habit.

A world with $10 oil is a world without terror.

[siromega]

I don't think they'll make a car that gets 500 miles per charge, mostly because of recharge issues. And I don't think the battery swap will ever work in the next 30+ years.

What you'll see is the 120-160 mile EV commuter car that is relatively inexpensive and either a car or crossover that works in multi-car households. Then the EREV models that get 40-50 miles per charge as a family's first car. Along with these two items, a proliferation of EV charging infrastructure in particular places where people leave their cars parked for an hour or more (shopping malls, movie theaters, etc) to extend that range further.

[sparks]

I will always want a range extender (in this lifetime, anyway), rather than rely solely on a battery, simply because I don't want to NEED a special charging system for long trips. I doubt that I will live long enough to see a public charging infrastructure anywhere near as ubiquitous as gas stations in my lifetime.

But this is not to say that a larger battery capacity would be useless. If you drive (say) 40 miles per day every day, and plug it into a 110 outlet each night such that the larger battery charges enough for 45 miles each night, you will pick up 5 miles per night, and in a week you will have a battery range of 40 + 35 = 75 miles, in two weeks, 40 + 35 + 35 = 110 miles, and so on, until the battery capacity is reached. All that on one ordinary outlet.