On Sat, 13 Oct 2012 00:57:33 -0400 (EDT) relng...@aol.com wrote: I don't recall discussions about this topic before.
Manufacturers of smaller electric vehicles such as electric bicycles, scooters, and mo torcycles similarly struggle to manage the thermal demands of increasingly energy dense batteries with high discharge rates. Whether protecting car batteries parked all day in the scorching Phoenix sun or electric bike batteries baking inside a metal case exposed to direct sunlight, AllCell's PCM composite can protect the expensive lithium-ion battery cells from overheating, dramatically extending battery life.
............... One thing I question is how much thermal capacity the material will have. Baking in the scorching Phoenix sun all day while sitting in a parking lot and then having to supply high discharge rates to satisfy some "lead foot" could certainly exceed the thermal capacity of the material. Craig .............. Gerry wrote: ".....Batteries provide the "fuel" that drives electric cars - in effect, the vehicles' lifeblood. If batteries are to have a long service life, overheating must be avoided. A battery's "comfort zone" lies between 20°C and 35°C. But even a Sunday drive in the midday heat of summer can push a battery's temperature well beyond that range. The damage caused can be serious: operating a battery at a temperature of 45°C instead of 35°C halves its service life........." "......Thus far, conventional cooling systems have not reached their full potential: either the batteries are not cooled at all - which is the case with ones that are simply exchanged for a fully charged battery at the "service station" - or they are air cooled. But air can absorb only very little heat and is also a poor conductor of it. What's more, air cooling requires big spaces between the battery's cells to allow sufficient fresh air to circulate between them. Water-cooling systems are still in their infancy. Though their thermal capacity exceeds that of air-cooling systems and they are better at conducting away heat, their downside is the limited supply of water in the system compared with the essentially limitless amount of air that can flow through a battery.....snip
http://www.fraunhofer.de/en/press/research-news/2012/july/keeping-electric-vehicle-batteries-cool.html "..... there is a debate raging, over whether automakers should turn to air or liquid to regulate battery temperature, and the choice has provided fodder for some green car makers to toot their own horns or slam competitors. Tesla Motors CEO Elon Musk has derided Nissan's battery pack, which uses an air cooling system, as "primitive" compared with the sophistication of even Tesla's first prototype, which uses liquid cooling. As a result, the LEAF pack will have temperatures "all over the place," claimed Musk, causing it to suffer "huge degradation" in cold environments and basically "shut off" in hot environments. General Motors for its Volt and Ford's line of hybrids and EVs, have also opted to use liquid for battery temperature regulation.....snip http://gigaom.com/cleantech/electric-car-101-liquid-vs-air-battery-cooling-systems/ _______________________________________ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
