REPORT: Panasonic to follow the Tesla model of laptop batteries in cars
Tesla Roadster – Click above for high-res image gallery
While the lithium ion battery technology that everyone expects to be at the heart of the upcoming generation of electric vehicles was initially used in consumer electronics devices, only one company so far has committed to using laptop-style cells. Tesla Motors builds a battery pack for the Roadster that consists of 6,831 cells of the type used in portable computers. Virtually every battery maker developing lithium ion for automotive applications is creating larger format cells that have what is referred to as a prismatic (flat rectangular) shape.
Interestingly, one company seems to be taking a different approach. Panasonic – which has a joint venture with Toyota to produce nickel metal hydride and lithium ion batteries for hybrid and plug-in vehicles – reportedly intends to produce automotive battery packs using laptop cells. The company claims to have developed a new method for connecting the cells which will bring the cost down by half compared to the larger format cells. The savings are claimed to come from using existing production facilities and tooling to produce cells.
However, critics suggest that while it may be true that producing cells on existing equipment will be cheaper than building new lines for prismatic ones, the quantity of cells required if EV sales approach projections over the next decade could quickly outpace this approach. Using larger format cells means far fewer interconnects are required and the complexity of building packs from the cells is greatly reduced. Because of the size of packs needed for car applications, the prismatic cells also provide greater density and improved thermal management.
Gallery: Jason Calacanis' Tesla Roadster
Photos copyright ©2009 Drew Phillips / Weblogs, Inc.
[Source: Reuters]
Reader Comments (Page 1 of 1)
Jon 4:14PM (10/05/2009)
My laptop battery is a year old and now iStat tells me it has 22% health. It only holds a charge for about an hour on minimal use when before it would last 4 hours with moderate use. I've been taking good care of it, etc.
What does this mean for electric cars running on these type of batteries?
When you buy the car it'll have a range of 200 miles but a year later it could potentially only range 50?
Reply
Mark Kiernan 4:23PM (10/05/2009)
You have probably over charged your batteries at times. I have a Dell Insiron from 2004 and the battery still works pretty much like the first day.
Jon 4:34PM (10/05/2009)
I know this is a little off topic but please enlighten me.
I only have 128 cycles and have only ever charged it when the battery goes down to 10% or below. Then I charge it to a hundred a leave it plugged in (assuming that it's only taking power from the AC and not the battery once it reaches 100) and only take it out when i need to, and let it go down to 10% again and recharge to 100. Is that not how you're supposed to do it?
paulwesterberg 4:37PM (10/05/2009)
Over draining your battery can also harm it. Laptops are build to be disposable and the single battery is under a lot of strain. Bev battery packs use sophisticated battery management systems to balance the load, slow discharge and charge rates and keep the pack from being overcharged or overused.
That being said, there will probably be some manufacturers that cut corners and don't use bulletproof management software and use substandard batteries.
Alan 4:46PM (10/05/2009)
As I understand it temperature management is also important in preserving battery life, something cars will do to varying extents and laptops don't. Basically BEVs are not going to be built and sold where the battery reduces to 25% capacity in a couple of years, if they do they'd better be up front about it and if they are I doubt anyone will want one! Even the Nissan Leaf batteries seem to lack some longeviety, however I've only done 60000 in my current car in 10 years, so if they have 80% capacity after 60000 miles I'll be happy.
PopSmith 4:44PM (10/05/2009)
What people don't realize about Lithium-ion batteries are a couple of things:
1) The batteries in the Roadster, as well as the Model S, plus up coming models from other manufactures, are ACTIVELY cooled with both fans and a liquid coolant, such as antifreeze. This maintains an optimum temperature for the pack which keeps it from massively loosing range as your laptop looses time.
The lithium-ion batteries in laptops are passively cooled. They are also exposed to the heat from other components in your laptop, which further heats them and lessens their life.
2) In general the batteries in cars are NOT allowed to charge past 90% capacity or drain below 10% capacity. Fully charging and fully draining a lithium-ion battery has a negative effect on it's lifetime and future capacities. If you keep a lithium-ion based battery in the 80% range, as well as actively cooling it, you keep the battery "happy" and it will maintain its capacity for a long, long time.
Jon 4:47PM (10/05/2009)
so i should just charge it to the 80% range, unplug it, and keep charing to maintain in in that range?
makes sense about the cars. glad they're foreseeing all this and taking measures to prevent batteries from dying out.
john 5:00PM (10/05/2009)
My laptop battery didn't last long either, and it's not even a lithium ion! It's a NiMH type. In my experience MiMH AA, AAA, and 9V batteries have been very reliable, but for some reason the battery in my laptop didn't fare so well. I suspect it's due to poorly thought out battery management software. Guess laptop manufacturers tend to cut corners like this. It sure doesn't raise one's confidence in electric cars which use the same type batteries - I'm entering the electric car market with a bit of apprehension about how long the batteries will last. On the other hand, some Tesla Roadster owners have already had a year to experience their cars and they still have nearly the same range as when they were new.
Sean 6:29PM (10/05/2009)
@Jon
You got a dud. Call tech support while it is still under warranty. Get a friend who knows about computers to check if yours has heat issues.
No one I know has seen battery degradation anywhere near that bad.
kert 7:30PM (10/05/2009)
Another point : there is no such thing as a standard lithium-ion battery. There are different chemistries, with different characteristics for shelf and cycle life, different sensitivities to charge and discharge patterns, different C ratings etc.
What you have in your laptop are most likely lithium cobalt oxide cells. I dont think many manufacturers will go for this in BEVs because
a) cobalt is expensive
b) they are prone to thermal runaway
c) cycle life characteristics arent that great
Dave R 5:08PM (10/05/2009)
@Jon - Batteries do not enjoy the following - lifetime degrades as a result of the following:
1. High temperatures
2. Charging to maximum capacity
3. Discharging to empty
4. Calendar time (Lithium only - NiMH are OK)
Your use case of discharging to nearly empty and then charging fully results in #2 and #3 occurring frequently. Ideally, you'd be able to set adjustable low/high charge thresholds in order to maximize battery life based on how much run-time you need.
In addition, batteries in laptops frequently get very warm - also not good for life. Best to remove the battery when not in use (charged to about half-way).
Batteries in EVs and hybrids are coddled. Tesla does not recommend you regularly charge/discharge the pack fully unless you need to. All hybrids keep charge levels between 40-80% (and as close to the middle of that range as possible). And both have some sort of active cooling to limit battery temperatures.
Reply
paulwesterberg 5:11PM (10/05/2009)
Laptop batteries are built to maximize runtime with very little regard for longevity because the company wants good specs on the box and will be happy to sell you a new battery.
EVs built by quality manufacturers and backed by a decent warranty will have much more planning put into maximizing battery life while providing an acceptable range.
Reply
paulwesterberg 5:19PM (10/05/2009)
Also when you drive an EV you will be driving to a destination. Where you will turn the car off and let it sit while you go and do stuff, so in your daily routine you will not be running down your battery to empty like you do with a laptop or cell phone. So if you buy a 100mile range max EV you likely wont be driving it 100miles every day(if you need to do this then you should probably buy a 200 mile ev or move closer to work.)
Efried 7:15AM (10/06/2009)
Sanyo has introduced their ENELOOP technology with electric bicycles, would that be an issue for larger vehicles too?
Reply
KK 1:07PM (10/06/2009)
Frankly I'm confused by Sanyo's use of the Eneloop brand name. It used to be the name of their low-self-discharge NiMH batteries. With the Eneloop bicycle, they seem to be implying that "loop" refers to a sort of closed-loop power system, in the sense that some of the energy output is recovered through regenerative braking and looped back to the battery. But these bikes do use NiMH batteries.
Li-Ion batteries have very low self-discharge to begin with. So that shouldn't be a major issue for electric cars.
Paul 2:06AM (10/07/2009)
Who are these know-all 'critics' you reference?
There is no negative side to the story in the original Reuters blurb!
Nothing like an anonymous critic!
Reply