Science Forums 2

[CraigD]

Originally Posted by GAHD

Pheonix motorcars
Zenn
…
Yes these manufacturers have STREET LEGAL ready to sell vehicles.

It depends on what you mean by “street legal”, and what you mean by “ready to sell”.

According to ZENN’s (annoying, effectively unlinkable flash-based ) website,

In accordance FMVSS 500, the ZEN has a regulated top speed of 25 MPH (40 km/h).

, meaning that it’s a “neighborhood electric vehicle”, meaning that it’s legal only on low-speed roads, varying by state and local jurisdiction. In some states this means having a posted speed limit no greater than 35 MPH.

According to Phoenix’s website,

Phoenix Motorcars will release a consumer version of its zero-emission, freeway-speed, green vehicle in 2010.

, so it’s not quite “ready to sell”.

IMHO, however, these are mere quibbles. The real engineering notability of these and similar EVs are their energy storage systems.

Originally Posted by GAHD

YES they have designed the 5 minute charging ability!

For vehicles planned by Phoenix and ZENN, this is potentially true (the manufacturers usually list 6 or 10 minutes as the charge time), due to their licensing of two distinctly different electric storage system.

ZENN plans to use the EEStor “ultracapacitor”. As the term suggests, these are not batteries, which store charge through the movement of ions between poles in an electrolyte, but very large capacitors, which store electrons directly. The greatest concern about the EEStor is that it may be a hoax. Its energy density is orders of magnitude higher than previous ultracapacitors, and has not been demonstrated to work to any third party observer or standards agency. EEStor announced in 8/2008 that despite “having taken longer than intended” to develop, the company is working toward a commercial product as early “as soon as possible in 2009”.

Current ZENN vehicles use lead-acid batteries, requiring about an 8 hour charge to go 35-50 miles.

Phoenix plans to use a Lithium-titanate battery patented and manufactured by Altair Nanotechnologies under the tradename “Nanosafe”. These batteries are variations of conventional lithium ion batteries in which the graphite anode is replaced with “nano-titanate”, apparently a titanium salt (Altairnano is fairly secretive about the precise composition and manufacturing techniques used). They exist, and have been used in experimental applications such as electric dragsters. IMHO, they’re the product of a legitimate technical breakthrough, and are likely to win the marked from conventional li-ion batteries in many applications, not just vehicles.

Due to the difference in anode composition, they can charge and discharge about 30 times faster than graphite anode li-ion batteries, without heating excessively. They should also last about 10 times as long, 9000 vs. 750 charge-discharge cycles.

This PDF document by Altairnano is the best I’ve found on the Nanosafe. In short, its higher current, lower heat, and longer life are due to the molecules of its anode physically moving less during charging and discharging than those in a graphite anode.

Therefore, I amend my withdraw by previous claim

Originally Posted by CraigD

Practically speaking, there’s no current market-ready technology (at least none I know of) that will allow a car-size battery, such as the lithium-ion batteries in the Tesla roadster, to be recharged in 10 minutes. The Tesla, for example, requires at least 3.5 hours (210 minutes) to recharge its 53 kWh battery system, and is capable of this rate only because it has a motor driven liquid cooling system. It’s wise, I think, to assume that electric car recharging will remain an overnight processes for some time to come.

I now do know of a market-ready (or very nearly ready) technology that will allow a large battery system to be recharged in 10 minutes – though a powerful cooling system is still required, not only for the battery, but for its supply cables.

Were I a betting man, my money would be on Li-titanate, or some similar “nano-structured” lithium batteries.