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Towing and off-road

Anything to do with the electric or hybrid world

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Kevin Johnson
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Towing and off-road

Post by Kevin Johnson » Wed Dec 04, 2019 4:55 pm


gruntguru
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Re: Towing and off-road

Post by gruntguru » Wed Dec 04, 2019 7:03 pm

Kevin Johnson wrote:
Wed Dec 04, 2019 4:55 pm
Not surprising when you think about it. Very high conversion efficiency (onboard energy store -> wheels) is one of the big advantages of EVs and this efficiency stays high under all driving conditions.

However this becomes a chink in the EVs armour when it is used for heavily loaded operation because it suffers in comparison to combustion engine vehicles where conversion efficiency IMPROVES as load increases. For example:

In the video it is apparent that towing the horse trailer at highway speeds requires about three times the energy as the unladen Model X. For the BEV this means 1/3 the range.

For a gasoline vehicle, the conversion efficiency of the ICE would improve from say 25% to 35% comparing unloaded to loaded so the range would reduce to 1/3 x 0.35 x 0.25 = 0.466 ie 46% or about 1/2.

In addition, the video uses a sedan with low aerodynamic drag. This suffers dramatically with the huge frontal area and poor Cd of the trailer. Something like a large pickup truck would get poor highway mileage in the first place - the energy required might only double when adding the trailer. Furthermore the truck (due to its poor economy) will have large fuel tank. This vehicle is designed to tow and is a good choice for towing.

The takeaway is - this is the wrong marked for rolling out EV technology. The prime market for EVs - especially at the "emerging technology" stage, is inner city commuting.

Unfortunately the world's biggest economy has a huge market for SUV's and pickup trucks, so EV startups in the US are in many cases trying to penetrate that particular market - which is unfortunate.

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