Electrically assisted bicycles have been available for some time, but because you often have to carry your bike, with lead acid batteries they were somewhat impractical. Lithium-Ion batteries with their 4 times the energy density have changed this completely. Now, Lithium Ion technology is available for your car.
As of January 2010, a lithium-ion battery has been available as a $2320 cdn option for Porsche GT3s and Boxster Spyders. This made Porsche the first manufacturer to offer one. Porsche quotes a 22 pound weight savings. When you buy this option, the car is also delivered with a standard battery, because Porsche feels that the LI battery does not have the stuff to start the car below 0C
At the SEMA show in Las Vegas this November, there were at least two aftermarket manufacturers promoting LI batteries for Automotive use: …
Both advertise weigh savings of up to 60 pounds. The Braille 490R has 1525 Pulse Cranking Amps, the Lithionics G49, 1250. Pulse Cranking amps is the current available in short 5 sec bursts. The Braille claims 32 Amp-Hrs, the Lithionics 23.4. They both claim that LI battery Amp-Hrs are the same as twice the lead-acid equivalents. In comparison, a typical Type 49 lead-acid will do 950Amps at 0 C, and has a capacity of 100 Ah.
I contacted Steven Tartaglia of Lithionics, and asked him some questions.Here are his responses:
Could one use one of your batteries in a street car reliably? Yes, the use of our batteries in a street car is most reliable. The ONLY problem that can occur is non-use, allowing the lithium battery to go to low or to zero volts over about a 60 day time frame. If a car is not used, the battery should receive a charge current every 3 to 4 weeks. In a few weeks, we are introducing a low-voltage cut-off system inside our battery to make our battery foolproof. But, if a car is driven at least once per week, the battery should last for years.
Down to what temperature? Our batteries perform with the same cranking AMPS from -20C to +60C. Below -20C, any battery is affected, but, lithium will still work. At very cold temps, the user will crank the car, and although it won’t start immediately, the battery is warmed up by the starting attempt. Then, in 30 seconds, the battery should start the car.
What is the maximum motor size, compression ratio, etc?In a test using the Alex Job Racing Porsche 911 GT car, we measured the strongest Bosch starting motor at 280 AMPs. The highest number of cranking amps we have measured is for a CAT diesel RV engine…365 CA. But, it’s the VOLTAGE SAG that matters! Our smallest lithium batteris will start most engines, but, we size the battery to prevent the voltage in the system from falling below 10.8 volts. Our largest pack…at 1500 AMPs, was used to start an Aston Martin LeMans V12 engine, to keep the voltage sag above 10 volts. That’s the key!
Any limitations/caveats you can think of? Lithium is superior to lead-acid in every respect. But, like lead-acid, you should not let it become fully discharged. That is why we have filed for patents for, and expect to have in production soon,low-voltage cut-off protection. Then, lithium is vastly superior in every possible way. We absolutely know this…an alternator and the starter motor do last much, much longer when mated with a lithium battery.
Can a car with a lithium battery be jumped started? Yes.
Storage? A lithium battery, if unplugged from a parasitic draw, will maintain its charge for about 2 years.
Anything else you can think of? Yes…the Muscle Milk Porsche Cayenne-based LeMans car reported to us that the cranking RPM’s of its engine spins at 325 RPM’s during cranking versus 225 with a lead-acid battery. This is due to the superior lower internal impedance. That means faster starts and more pure electricity for all your vehicle electrics and electronics. There is no comparison…lithium provides HUGE improvements all around.
( If there are any pioneering souls who go this way, let us know how it goes! OWM )