Electric car problems

I’ve been thinking about this for a while and it seems to me the biggest problem with viability of electric cars is the battery charging time vs. the potential distance per charge. If one can only drive 200 miles and then have to let the car charge for as much as a day and a half before driving another 200 miles the cars will never be good for much beyond local commuting. A battery needs to give at least 200 miles and maybe more like 300 between charges and would need to be charged in time comparable to filling a tank with gas to really take off in the market.

Since the charging time is more likely to be the primary issue - I can see technology extending the distance - I have a general idea that I think could work.

Why not exchange batteries instead of recharging them in the car? I picture a “universal” battery (probably different sizes for different types of vehicles, but standardized for sedans, suvs, trucks, etc.) that can be removed and replaced by a fully charged one, and then the depleted battery would be charged and used in a different car later.

The driver would pull a car into a specified dock at a service station. The car would slot in like a plug into a socket and the battery would be removed robotically and replaced with a full one. The spent battery would then be put into rotation for recharging and a new bar code would be attached showing the durability and life remaining on the battery.

Meanwhile, you would simply pay for the charging and replacement service, not for a whole new battery.

This way the time a driver would have to wait to take off again would come down to minutes rather than hours/days.

The batteries could, of course, be charged up overnight once the destination had been reached, but that would just be an option, not a requirement.

This is just an idea and I’m sure I’m missing a number of problems, but it seems like the most reasonable solution. Thoughts?

Same problem with exchanging propane tanks instead of refilling them. The only people who want to exchange are people with crappy, rusted tanks. See also: Gresham’s Law. Offhand, I can’t think of any successful large scale exchange programs.

The vast majority of drivers drive less than 40 miles a day. If you get a vehicle that recharges rapidly enough and goes 100 miles between recharges, you have a winner.

The difference is that not exchanging a propane tank is little hardship to the consumer - they just drive a little further to the place that fills the tank up, and save money on the bargain. Such a service as this would be providing a major benefit to the consumer, therefore is likely to have more participation.

There is, however, a degree of a market failure here. There would certainly be some effect of fear of getting a crappy battery. So the solution would be to minimize those costs - having replacement batteries cheap, and subsidized by the cost of the purchase of the car itself. However, that is the opposite to the market incentives for the manufacturers (assuming that the same person manufactures the cars and batteries). It is better for them to lower the price of the vehicle, and jack up the price of the replacement parts, once a customer is locked-in.

Many people have had the same idea, photopat.

The problem is that reliable, durable battery-changing robots would be way too expensive. Orders of magnitude more than a dumb mechanical pump.

standard batteries are also unlikely across manufacturers at this early stage. Maybe in 50 years.

Great minds think alike. Shai Agassi had the same idea, and went one vital step further - sell the car, lease the batteries. Supply customers an unlimited number of battery change-outs and all the electricity they can use for half to a a third of what they are paying per year for gas. At the same time, all those batteries waiting at the station ready to be switched into cars supply the missing part of any wind or solar system - storage.

I have to say, I’m a bit surprised that Dopers do not seem to be Wired subscribers.

The batteries I’ve seen are bulky and heavy and would take a fairly major effort to change. It’s not like swapping out a car battery today…and even that can be a pain in the ass sometimes.

I don’t think it would be practical to do, even if you could make it work economically…which I doubt because usually the battery is one of the most expensive components (I remember reading that one of the high capacity batteries being used cost over $10k…more like $20k actually).


There are many problems with battery exchange.

Storage - you have to provide above ground, highly accessable storage for all these batteries, currently fuel storage is in below ground tanks, with a pump to provide access.

Compatability - all batteries must be 100% compatible with batteries used in different models / makes of car. There are no compatibility issues with gasoline, all you need is the right size of filler neck…

Mechanics - you have to design the car so that a bank of batteries can be quickly and easily removed and reinstalled without damage to the car, batteries or connections. Batteries are very heavy, so it must be done with some sort of power equipment, and that equipment also has to be compatible with all cars.

Volume - this solution is designed to handle a problem encountered during long distance travel. Most electric car users will recharge overnight, only a small number will require a battery exchange, certainly nothing like the current need to refuel. How many shops can afford all of the expensive equipment on those volumes?

Repair/disposal - batteries wear down and become damaged, someone has to be responsible for repairing or disposing of batteries that are no longer useful. I assume that will become the job of the exchange depot, because anyone can drive in and exchange their dying batteries for a small fee.

I agree with Gozu here. The technology to design, build, and install robots that can change batteries has to be monumentally expensive. No doubt there would be competing designs, since it hasn’t been done yet, so we’d have to go through the winnowing process to determine which is best, if any. And there may be multiple designs (VHS vs. Betamax), so we’d be looking at years, if not decades, before a standard becomes viable.

I’d still like to see more electric cars on the road though, because if nothing else, it can be a bridge technology to Mr. Fusion or whatever else is on the far-flung horizon.

I’d say the effort would be better spent in designing a quicker recharge system than in some convoluted battery swap thingy. I can’t imagine that such a system would EVER be either practical or economical.


It’s a pain if you don’t design the car around the battery. These cars would have a standard sized battery pack attached to the frame from underneath, with standardized bolt patterns and power connectors. The customer pulls in, robotic mechanisms support the pack, release the bolts (or bayonet fasteners), drop it down, bring in the new one, lift it, connect it, test it, drive away. They plan for this to take less than five minutes.

See the article. Shai Agassi’s “flash of genius” (good movie, BTW) was to separate the cost of the battery and energy from the cost of the car. If you take the batteries out of the equation, an electric car is far more simple and cheap to build than an internal combustion one. Electric motors are far more reliable as well. From what I’ve read, the main reason Detroit has been so resistant to selling electric cars is that the repair parts business is more profitable than the new car market.

Correction: The Better Place business model is for metered usage, not unlimited. Which is better for those of us who would drive very little.

I’m skeptical, but even if you could design a battery large enough to give you the performance and charge needed AND to be easily removable, that still brings up how you would store enough batteries to make it feasible. How many people pop into a gas station a day? 100? 200? You’d need to have batteries on hand at every station (fully charged and ready to go…so, in actuality you’d have MORE batteries laying about than you’d need, because some would be in various stages of re-charge). Even if we don’t consider the cost of all the batteries, all the robotic equipment, testing equipment, training, etc…well, you STILL have the problem of storage of all those batteries and the logistics of getting the recharged batteries to the cars that need them.

This, to me, is pie in the sky…it will most likely never be feasible. Again, a better way would be to come up with quicker recharge technology…IMHO of course. Haven’t read the article on Wired yet…but Wired is usually pretty starry eyed when it comes to these kinds of predictions. I’d take most of what they predict or say with a very large grain of salt.

Who would front the capital for all those batteries then? I’ve seen similar plans in Europe for one of their all electric cars (the Citi…something like that), and it SOUNDS cool…for Europe. It might even work…in Europe. But here? I doubt it. The initial capital costs would be…well, very large.

As for why Detroit hasn’t sold electric cars, I think it has/had less to do with some loopy scheme to charge more for parts and more to do with the fact that there hasn’t been a MARKET for all electric cars that isn’t a niche.


Oxygen and acetylene tanks for welding, but there is a safety issue there. The tanks are tested to a pressure far higher than for propane tanks, and it is probably a lot faster to swap bottles than to wait for the tank and valve to be tested.
I’m going to go out on a limb and predict that IF battery powered cars ever take off, then the first large scale use will be in fleets (possibly as inner city rentals), and the batteries will be in large modules that can be easily swapped out. Possibly, a body panel will hinge out of the way and a standard sized pallet/module of batteries will be slid out and replaced. There will be a minimum of electrical contacts; the modules will attach with a minimum of fasteners, and the only specialized equipment needed will be something similar to a pallet jack.

They’re batteries; they shouldn’t take that much effort to replace.

A quicker recharge is limited by physics (although there is some impressive work going on). But why would I want to own batteries if I could lease them and be able to get fresh, fully charged ones down at the electricity station whenever I need? They have the multi-kilowatt connection to the grid needed to charge a large number of batteries at once and a sweetheart deal with the utility company to do most of their charging at night when electricity is cheap and not needed by most consumers. A similar system is in use in Chicago to store surplus electricity generated at night as ice to supply surrounding buildings with chilled water for air conditioning.

I’m honestly baffled when other people can’t see how a system like this could work. Cars are built mostly via robotics - how hard is it to believe that a well-designed system could change batteries quickly and economically?

There will be a production electric car from GM in 2010 with a 40 mile range. It’ll also have the capability to recharge while driving via an small gasoline engine to get a 370 mile range.


It’s not a question of whether it could work in principle, it is how much is it going to cost, how long is it going to take, and how do we start?

Lease batteries from who? Mr. Agassi? Will he allow competition in the field, or would this battery / robot technology be proprietary? What do I do with my car when his company goes bankrupt?

Cars are built by robots, one type of car at a time under very controlled conditions. There arent any robots that install parts on Toyota, GM, Honda, Ford, Chrysler, Hyundai, Mitsubishi, etc. where the bolts are rusted, the car is dripping salt, and just driven into position by an 86 year old grandma.

All of those manufacturers would also need to build their cars around Mr. Agassi’s battery design. I’m sure they’re going to love having their design options dictated by someone else. How do you handle batteries for sub-compacts vs SUVs?

Not only that, what do we do when battery technology advances? 10 years from now, batteries are 1/3rd the size they are today, am I still using the same design profile? Will my local exchange station have space to store 2-3 or more types of battery designs? 20 years from now, do I have to throw out my car because Agassi doesn’t want to support Battery v1.0 anymore?

Exactly. You’re thinking that is a problem when it is the backbone of the system. Every battery packs that is not currently in a car is part of the storage grid holding electricity generated by wind and solar or by conventional sources at times when it is the electricity is not needed by consumers and businesses. This is a service that has not had a business model until now. Suppliers of wind and solar have the obvious problem that their sources are not available 24/7. But nuclear plants had the opposite problem that their electricity is not needed 24/7 but it is generated 24/7. Every battery in the system contributes as part of a gigantic storage grid, and that cost is shared by the people leasing the batteries and electricity.

It’s a chicken and egg problem. But in this business model having the batteries “sitting around” has been made profitable.

I’m wondering if you could do me a favor and read the article, saving me the trouble of having to paraphrase every single point that has been raised and answered there? Thanks.

Reading through the Better Place website, it appears that they don’t wish to be a sole supplier of batteries, just to define the standard.

Cars are washed by robots. I can imagine a support system that doesn’t involve any bolts, that will allow release no matter how encrusted with dirt and salt. It’s not that difficult of an engineering problem. As for the 86 year old grandma - isn’t she currently driving her car into an automatic car wash that somehow manages to wash all makes of cars?

Um…you are aware that batteries come in standardized sizes, and different devices use different quantities of those standardized sizes right? A subcompact could use a single pack, while an SUV could use multiple packs.

The batteries would get smaller and lighter, and mileage would improve. I’d imagine the pack design would remain standardized even if the cells shrunk to one third of the size. The storage stations would handle the more compact batteries and there would be wasted space in the car. But still a fraction of the space currently wasted on inefficient engines and fuel tanks.

I’m headed out now to get lunch and attend the Wired NextFest in Chicago’s Millennium Park.