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Electric vehicle safety

1200px-Volvo_C30_Electric_WAS_2011_852

Frontal crash of an electric vehicle at 64 KPH

Vehicle safety used to be a back-end job, with engineers toiling in the crash lab analyzing, testing and validating different materials for their crash absorption characteristics. Now, it has become a sign of pride for most of the OEMs.

Differences in architecture between EVs and ICEs:

One might assume that electric vehicles would perform in a similar way to conventional ICEs (Internal Combusion Engine s) but this is not true. In comparison to ICEs , EVs (Electric Vehicles) have a different drive-train layout & the power source i.e. battery pack is very different to a conventional cylindrical fuel tank. Even the HVAC (Heating Ventilation And Cooling) system in modern EVs are taking a different shape and size. The only systems resembling ICEs seem to be the suspension systems for now but even this is beginning to skew towards a different technology Literature.

Built-to-crumple:

Modern vehicle body-in-white structures are no longer heavy and bulky built, instead ‘impact energy absorption’ has become a methodology for success. A normal crash test team goes about determining load-paths for a vehicle during crash in order to best divert forces away from the passenger compartment and for an EV, they also try and keep the forces away from the battery pack. Since Li-ion batteries have a state of instability which could lead to fires under high impact conditions or thermal runaway, safety of the battery pack is of high priority.

A load path and stress distribution chart are what crash engineers rely on.

Legal standards:

Crash legal requirements & consumer ratings are set by agencies such as Euro-ncap,Us-ncap, Japenese-ncap, Iihs etc. and they give a rating in terms of stars with 5 being the most safest. A technical evolution in these tests is that they rate the vehicles not just in terms of passive safety but also crash avoidance systems, high-voltage protection, post-crash safety and many more. Some examples of crash test standards are FMVSS 208, FMVSS 214, FMVSS 301, ECE R94, ECE R95, TRIAS 47 etc. How to read the stars NCAP

Comparison in safety:

Yes depending on the vehicle class and one can verify this with a number of studies Study on crashworthiness of electric. Moreover, the improvements in EV safety are happening at such a rapid pace, vehicle homologation agencies are not able to keep-up. Just as an example, the underbelly of EVs used to be a major concern during fast collisions with road-lying objects. This part of the vehicle has been improved so much more in terms of crash safety that software updates are sent to the raise the vehicle using its suspension system in rocky areas.

On a more economics note, there are different body structures that deliver better profits to the OEMs and this is a work under process, especially for electric vehicles. Volume sales, body architecture and profitability are crucial variables in vehicle safety for any vehicular platform.

By

Ashwin Shreshta

Solar & automotive technology consultant

Email:  creativedzns@automotron.in

www.automotron.in

 

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