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Laptop Batteries as Electric Vehicle Power Source

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LAN_403

Bust_A_Cap

Wed Jul 09 2008, 08:02PM

Registered Member #1561 Joined: Mon Jun 23 2008, 07:58PM
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Posts: 25

Alright so I'm sure everyone has heard about how the main problem with electric cars is the fact that the batteries are ridiculously heavy, and they don't store enough power, thus you end up with not very long range electric vehicles. So in response to this, people have started to use lithium ion batteries, problem here is that they have to be very carefully monitored, if you over charge them or put to much current into them, they can quickly get out of control, and fry...or much worse and more likely blow up and catch fire. But probably the biggest problem with Lithium Ion batteries is that they are really expensive and thus amateur's have a hard time piddling around with them and making any sort of advancements with the technology.

So forget the dangers for this second because i'm speaking only in THEORETICAL terms. Would it be possible to hook up straight up laptop batteries, to make a bank, which could be used in a car. For instance hook a bunch of them that are similarly rated in series so that you get a higher voltage and thus more power to the motor. Anyways the few laptop batteries that I've seen have more then just 2 pins on the back, which i imagine wouldn't be to hard to get around, but another thing is that they would be really easy to charge, because you could just hook up the normal laptop battery charger up to each individual battery and have them all charge at the same time.

Anyways let me know what you think, just tossing around ideas in my head.

Bust_A_Cap

Ken M.

Wed Jul 09 2008, 08:23PM

Registered Member #618 Joined: Sat Mar 31 2007, 04:15AM
Location: Us-Great Lakes
Posts: 628

The multiple pins are similar to cell phone batteries, where 2 pins are power and the other two are a "I.D. resistor" this I.D.R tells the power management chip and other power chips some info on the battery, or something like that, read about it breifly in Maxiims engineering booklet they mail out every so often.

Shaun

Wed Jul 09 2008, 08:35PM

Registered Member #690 Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616

Laptop batteries may make it easier to implement, but aren't laptop batteries INCREDIBLY expensive?

quicksilver

Wed Jul 09 2008, 10:03PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

Lithium Ion batteries are a bit expensive at the moment; but they're being used in power tools now quite abundantly. That's a good sign as that industry is getting very competitive and chances are the prices WILL drop!

Carbon_Rod

Wed Jul 09 2008, 10:53PM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
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Posts: 1155

Not all lithium batteries are the same:
LiCoO2 3.7V 140mAh/g
LiMnO2 4.0V 100mAh/g
LiFePO4 3.3V 170mAh/g
Li2FePO4F 3.6V 115mAh/g

Although some are used for vehicles... the usable life of Li cells still make them cost prohibitive.

AFAIK the industrial NiMH packs are still dropping in price (IIRC the last price was $8.5k), and companies like Toyota warranty the Prius power pack for many years.

The Biodiesel reactor currently costs consumers $0.63/l if they know were to look. Very few electric vehicles (Honda) can beat the total cost of ownership for a 6 cylinder turbo diesel on D100.

Andyman

Thu Jul 10 2008, 01:15AM

Registered Member #1083 Joined: Mon Oct 29 2007, 06:16PM
Location: Upland, California
Posts: 256

The tesla roadster's battery is basically a trunk full of lithium laptop batteries.

Firnagzen

Thu Jul 10 2008, 09:38AM

Registered Member #567 Joined: Tue Mar 06 2007, 10:55AM
Location: Singapore
Posts: 147

The problem with Li-ion batteries, as I understand it, is that the batteries degrade quite fast, and are considered by the industry unsuable by the time they're three years old. Also, heat causes the degradation to accelerate. Something else... Oh right. [Deviation]That's why I was so annoyed when I heard the iPhone's battery wasn't removable.[/deviation].

Steve Conner

Thu Jul 10 2008, 09:54AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Yeah, the T-Zero did this a couple of years back. It got something like 300 miles on a charge and could still beat a Porsche 911 Turbo down the quarter mile. The Tesla Roadster is basically the powerplant of the T-Zero, with the same 200hp induction motor and inverter, and a similar battery pack, stuffed into a Lotus Elise chassis.

As far as I know, the pack has about 6,000 of the 18650 cells used in laptop packs, connected in series-parallel to deliver 300V at a couple of hundred amps to the inverter. That's a lot of batteries (the average laptop pack has maybe 9 cells) and the main problems, as other posters have pointed out, are the cost, limited lifetime, and the risk of the whole thing "venting with flame" (Li+ battery manufacturers' euphemism for exploding) in a crash.

If you have $20,000 lying around, AC Propulsion will sell you the motor and inverter system that's in the Tesla Roadster. Wrightspeed put it in an Ariel Atom

There's also the Killacycle, a drag racing bike powered by A123 Systems' lithium-ion batteries. They're the exact same ones used in the new DeWalt cordless tools, just a heck of a lot of them.

Weston

Sun Jul 20 2008, 05:39AM

Registered Member #1316 Joined: Thu Feb 14 2008, 03:35AM
Location: Cambridge, MA
Posts: 365

For the prototype tesla roadsters they actually bought and cracked open laptop batteries for the cells.

Conundrum

Sun Jul 20 2008, 03:59PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061

Hi all. One alternative might be the packs currently being sold for electric drills, these are fairly high energy density and use the huge cells rather than 18650s.

Also, I have found that even broken packs might be useable as the main cause of failure is cell imbalance which results in the controller "bricking".

Regards, -A

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