Tesla sometimes has been mocked as a bunch of hackers that simply wire-up a load of laptop batteries, whereas other serious and professional carmakers are looking into serious and professional batteries to power their future EVs. If egmcartech is not mistaken, then some of the serious and professional carmakers just had a sudden change of heart.
The price of the battery is the big bugaboo in the EV business. Carmakers apparently are running out of brilliant ideas to drive that price down. That’s why Toyota, Daimler, and BMW are seriously looking into using the cobbled-together lithium-ion laptop batteries Tesla is using. Well, Toyota and Daimler have shares in Tesla, so no surprise there. Daimler also has teamed up with China’s BYD, but what with the recent series of mishaps at BYD, Daimler is probably reorienting. Or maybe not, see below. BMW? They are looking for “something new.”
Custom made EV batteries cost about $700-$800 per kilowatt hour to produce. Mass-produced packs using strung-together laptop cells cost only $200 per kWh, says egmcartech. There are 6,831 laptop cells in a Tesla Roadster. For the foreseeable future, laptop batteries probably will have more volume than those made specifically for EVs. If you think that laptop-powered EVs catch on, then buy stock in producers of laptop batteries: Sony, Sanyo, Panasonic, or … BYD.
are laptop batteries really good in heat and cold and very high current (acceleration)? All schemes of use for a laptop seem different from a car. the typical laptop user doesn’t use 100% current at 0°F or 100°F. Also the typical laptop battery loses significant capacity after 2-3 years.
Yes they are cheaper because they are made in the millions. but sometimes you get what you pay.
laptops have 4 to 12 cells usually. Cars need hundreds (hybrid/small EVs) to thousands (large EV or fast EV) of cells. More cells = less stress per cell = longer usable life.
some actual numbers for the Prius are
1997 Prius 240 cells
2000 Prius 228 cells
2004 Prius 168 cells
2010 Prius 168 cells
Another thing to consider is that with a laptop once the battery dies you can’t use the PC. With a Hybrid you can rely on Gasoline. This means the Hybrid doesn’t need to stress the cells by depleting them fully and it doesn’t have to be too aggressive during charging as there is little downside to having inadequate charge. Avoiding excessive depletion and being gentler on the charging cycles extends life as well.
Now for a Pure EV you are dealing with usage more comparable to a laptop in that if the battery goes dead you can’t use the vehicle any more but you still have the advantage of way more cells.
Tesla claims about 6800 cells in the roadster.
Nissan leaf is apparently only 192 cells.
How you recharge the pack will affect its life. Nissan has said it expects to Leaf drivers to have around 70 to 80 percent capacity left in the pack after ten years. What will get drivers to the upper or lower end of that range? The amount of fast charging one does. With regular Level 2 charging, drivers should expect 80 percent live left in the battery. With a lot of Level 3 charging – two or three times a day – the pack will only be at the 70 percent level.
So again we see that the faster you charge the less overall life the battery will have.
Thermal control is a serious issue. More and smaller cells are easier to control. An overheating cell can be taken offline while affecting overall battery output less than if a design had fewer and larger cells. At least this is true of the admittedly very few systems I’ve seen – which were involved in propulsion.
The most common, reliable lithium cell in the world is the 18650 (18 mm diameter, 65.0 mm long). It is used in laptops and the Tesla. It provides the best energy density for the money, and billions of them are produced every year.
Flatpack cells are not as energy dense or cost effective, nor are other cylindrical cells. The problem is a matter of economies of scale – the 18650 has developed a monopoly.
I help develop portable electronic devices for my company, and this is a constant problem. When we want to make a smaller product with a different form factor or energy requirement than the 18650 offers, we pay more money and have a less-reliable supply chain. Anyone who investigates this in detail will find the same thing.
The custom batteries used in the Volt and the Leaf must be very expensive per kWH, since they are only produced in the tens of thousands. The trick Tesla has accomplished is an elegant means of manufacturing and controlling all those cells.
“The trick Tesla has accomplished is an elegant means of manufacturing and controlling all those cells.”
Tesla does not do any battery manufacturing. They just buy commodity cells from others.
Tesla did develop technology for individually heating and cooling each cell. But it’s simple, brute force technology. They have some patents on that. The patents seem pretty worthless.
Tesla also has a good battery management system. But again, it’s nothing particularly innovative. Just good, solid engineering. Anyone skilled in the art can do it.
The problem with lithium batteries (unlike the nickel metal-hydride batteries in the Prius) is that they lose capacity. It’s hard, maybe impossible, to avoid losing about 2% per month.
Some people say they have solved that problem. I’m skeptical. Some of the Tesla Roadsters have been on the road for over 2 years. I’ll bet they have lost about 1/2 of their battery capacity. But I’d love to know the truth.
What is the truth? Tesla isn’t telling.
@Daanii2: I meant to say “assembling” rather than “manufacturing”; I know very well that they’re using someone else’s 18650 cells.
I disagree that anyone skilled in the art of battery management can do what Tesla has done. If that was true, someone else would have done it sooner. Just going from a single cell to two cells in a pack becomes a special problem. Having nearly 7k cells is most impressive.
You don’t need Tesla to tell the truth about their battery capacity; there should be owner testimonials about it. The keys to improving lithium ion cell life are temperature management, charge and discharge rates and times, and means of isolation from bad cells, among other factors. All EV mfrs have to work with these issues so that their packs won’t lose capacity too quickly. As a result, I doubt that Tesla’s products are dying at the same rate as a laptop battery.
I didn’t mean to quibble about your comment on Tesla manufacturing. My point is that Tesla does little with the batteries. Someone else makes them. Unskilled labor assembles them in a pretty simple way. Essentially, Tesla just connects together 8,000 batteries. Not much to it. You can read their battery patent portfolio. Pretty sad.
And other people have indeed thought of this idea. In fact, Martin Eberhard said that he took the idea from AC Propulsion, who built their tzero with just such a battery pack.
As for the performance of the Roadster, nobody seems to be telling. I’ve asked a few owners. They don’t know. Their mileage gauges have gone down a little. That’s all they know. I’ve tried to find any information — good or bad — on the Roadster’s owners’ forum, without success. No owner testimonials that I could see. If you know of any, please post a link here.
Even Elon Musk said early on that he expected many owners would want to replace their battery packs within two years. As you say, a lot of things can affect battery life. But in practice lithium cells have always shown from 1% to 2% loss of capacity per month, even in good conditions. I’d be surprised if Tesla has found a way to stop that. If so, as I said, Tesla isn’t telling us that.
I’d be surprised if Tesla has found a way to stop that. If so, as I said, Tesla isn’t telling us that.
is like owning an exotic car, owners put up with them even with high maint & unrelaibility until one day they either ran out of mulla/ no money no funny honey , had enuf time in the shop or hit the wall so they just take a bit of the bullet sell her cheap!
Now is too early to admit the un-speakable truth yet.
then if its so good u think they would not be gloating all about it?
my car runs on nothing, 150 mpg, zero maint. wave my digital salute to the Arabs.