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Tesla Battery Pack for Roadster Meets UN Safety Requirements

Tesla Motors has met the UN safety requirements for delivery of the Tesla Roadster’s battery pack for use in consumer vehicles. The UN Testing Protocol for the Roadster’s ESS (Energy Storage System) included: (1) altitude simulation, (2) thermal cycling, (3) vibration, (4) shock, and (5) external short circuit.

The ESS development program, which to date has spanned more than three years, has included testing safety at both the micro (cell) and macro (module) levels. At the cell level, each of the 6,831 individual lithium-ion cells inside the Tesla Roadster’s ESS has passed both UN and UL 1642 testing criteria.

To deliver a safe and reliable high power pack, Tesla focused on developing a high level of redundancy and multiple layers of protection. The commodity cells Tesla uses in its pack all have an internal positive temperature coefficient (PTC) current limiting device, which limits short circuit current on an individual cell level. The device is completely passive.

The cells also have an internal Current Interrupt Device (CID) that will break and electrically disconnect the cell in the event of excessive internal pressure caused by over-temperature or other failures resulting in over-temperature. Tesla selected cells with packaging, materials and chemical factors that further augment the safety profile.

The Roadster pack comprises 11 battery modules, a main control and logic board, and a 12V DC-DC power supply. Each of the 11 modules carries a monitoring circuit board that communicates with the rest of the vehicle microcontrollers, broadcasting the voltage and temperature measurements of its module over a standard CAN bus.

Each of the cells has two fuses (one each for the cell’s anode and cathode). This allows the cell to become electrically separated from the rest of the pack if either of its fuses blow. In addition to cell fuses, each of the 11 battery modules has its own main fuse that guards against a short circuit across the complete module.

Tesla uses a 50/50 mix of water and glycol for cooling.

The microprocessors, logic circuitry and sensors continually monitor voltages, currents and temperatures within the pack, as well as inertia acceleration and vehicle orientation. The packs also include smoke, humidity, and moisture sensors.

Should any threshold be exceeded, high voltage contactors immediately disconnect the high voltage of the battery pack from the car. The pack design also incorporates an array of passive safety features as well as the active protection systems, which could fail in the event of severe damage, such as a collision.

ESS development and testing was performed by the Tesla Energy Group within Tesla Motors. The advanced technologies developed over the last three years have positioned the Tesla Energy Group to develop and manufacture battery packs for third parties.

Tesla Motors formed the Tesla Energy Group in December 2006 to develop and market custom designed battery packs for customers in a wide range of industries, utilizing Tesla’s patent-pending technology.

In May, the Energy Group, announced an agreement to supply Think Global with lithium-ion battery packs for their line of “TH!NK city” electric cars. (Earlier post.)

The primary focus of Tesla Energy Group remains the development and mass production of battery packs for the Tesla Roadster, to be released later this year.

Introduction of the Roadster is being slightly delayed due to a late change in transmission vendor, according to CEO Martin Eberhard.

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Comments

jack

That's good news. It'll be great to see these vehicles on the road in a couple of months.

Neil

Indeed!

This is great news. Major car manufacturers will have a harder time to discredit large lithium battery packs for PHEVs and BEVs.

Let's hope that real road usage will soon confirm the safety, security and endurance of the Telsa ESS.

Any news on the ESStor units?

Neil

I've been looking, but nothing yet. I don't expect to hear anything until later in the fall or even winter when they're supposed to be delivered to FGC. Even then there will probably be delays (good ol Murphy). If they're for real that is.

Matthew

When did the UN get involved in testing anything? And does their opinion of Tesla's battery packs have any legal bearing anywhere in the world?

John

Matthew: Apparently the UN is trying to standardize safety standards for goods shipped internationally. For an interesting read check out

John

John

whoops -

John

John

John

Sorry folks, fat fingers, fat head, whatever

http://www.teslamotors.com/blog4/

Ziv

The UN wants to standardize matters? So now we will have Sudans standards on human rights and Chinas standards on personal freedom? On a more positive note, we should be able to expect at least Saudi Arabian levels of religious tolerance!
Seriously, is allowing the UN to even begin to set some sort of standards for international trade a good idea?

jack

No, Ziv - we need to be very careful. The black helicopters will come for us before we know it.

DONALD TUCKER

will G.M.like these electric cars??

Kit P

Bravo Sierra alert, when Tesla discusses 'UN safety requirements' and fails to disclose test to common industry standards like ISO, ASTM, or IEEE; that is cause for concern. I expect Tesla to sneak off into the night without a press release after wasting millions of investor's money. It is just another toy for very, very rich boys.

Neil

"It is just another toy for very, very rich boys"

I don't know about the "very very" part. There are lots of sports cars sold that are way more expensive than this one. They've never claimed that the roadster would by itself change the world. You have to start somewhere.

The test is relevant due to practical implications for the cost of shipping the ESSs internationally.

sulleny

Apparently someone wants the UN to have a new role in technology. In light of their difficulties in other areas - it seems best to leave technological standards to organizations with years of experience ISO, IEEE, UL, etc.

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