Author Topic: Fremont polices Tesla in high speed felony chase ran out of battery power!  (Read 985 times)

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Online nctnico

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Re: Fremont polices Tesla in high speed felony chase ran out of battery power!
« Reply #25 on: September 26, 2019, 04:29:18 pm »
But you can fill-up a gasoline car in less than 5 minutes and catch up again. A police car will have much less delays due to red lights and being slowed down by traffic.

I suspect that any cop in a high speed chase that pulls over for even a minute is no longer going to be in that chase.

I also wouldn't be surprised one bit if a Tesla has better range than say a Dodge Charger when it is hammered. EVs generally are more efficient than gasoline vehicles under high loads, especially because much braking energy can be recovered by regeneration.
Don't think so. ICE engines are the most efficient near maximum load versus RPM (this is not maximum power output). Or more precisely: when run at near full throttle. Besides that the Tesla has a serious weight disadvantage especially when needing to go through some fast corners; the regeneration tops out at 60kW so the rest of the energy will be burned by the brakes. Remember kinetic energy goes up square versus speed so any extra weight is a killer.
« Last Edit: September 26, 2019, 04:34:20 pm by nctnico »
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Offline tom66

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Re: Fremont polices Tesla in high speed felony chase ran out of battery power!
« Reply #26 on: September 26, 2019, 07:06:17 pm »
Engines are more efficient at high loads? That is not really correct. At around peak torque optimum efficiency is achieved, but this is far away from the "flooring it" type of driving that a police chase ensues, with the engine operating near to maximum rpm.

An electric vehicle will suffer a fall in efficiency at maximum power, but the decrease will be from around 90% to 60% (depending on resistive losses due to I^2 * R) whereas a gasoline engine will fall from a best-case efficiency of 25% to less than 10%. The relative drop is far higher for the ICE.

I have gathered some data from my Golf GTE's powertrain, comparing fuel input to power output, that demonstrates this.

The benefit an ICE has is that liquid fuel is easily stored so a police car might have extended fuel tanks, also the engine can generally get much hotter without risking catastrophic failure (just tends to shorten its lifespan somewhat.)
 

Offline duak

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Re: Fremont polices Tesla in high speed felony chase ran out of battery power!
« Reply #27 on: September 27, 2019, 04:19:11 am »
I've been helping a neighbor out with his race car, a 1960 Austin-Healey Sprite with a 1.3 litre engine.  Event by event, we've been making it reliable by breaking then finding and replacing the weak links.  On the first day of a two day event, we got it to where it was fast and about as bulletproof as it was going to get.  I didn't come to the track until the afternoon of the 2nd day.  When I got there, it was barely running and wouldn't even complete one lap.  The owner figured it was ignition and was making some new ignition cables.  I went over the symptoms and what he had done and then checked the fuel level with a stick.  Drier than a popcorn fart.  Even though we'd filled it up the previous day, because it had never lasted that long before we didn't think it would use all the fuel.  We figured it used up more than five gallons (Imperial) to go less than 40 miles for warm-up, qualification and one race.  Less than eight miles per gallon to put out maybe 75 HP at its peak?.
It's said that speed costs money - how fast can you afford to go?
« Last Edit: September 27, 2019, 05:16:53 pm by duak »
 

Offline benst

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Re: Fremont polices Tesla in high speed felony chase ran out of battery power!
« Reply #28 on: September 27, 2019, 11:01:58 am »
It looks like the original news article describing this was a bit of click bait. Here is an official response from the Fremont Police Department:

https://www.facebook.com/FremontPoliceDepartment/photos/a.210771958992325/2452175384851960/?type=3&theater

Ben
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Online james_s

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Re: Fremont polices Tesla in high speed felony chase ran out of battery power!
« Reply #29 on: September 27, 2019, 06:21:53 pm »
Let's not turn this into yet another general EV vs ICE threads please. This seems to happen in every single thread that has anything to do with EVs.
 

Online wraper

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Re: Fremont polices Tesla in high speed felony chase ran out of battery power!
« Reply #30 on: September 27, 2019, 06:42:51 pm »
Let's not turn this into yet another general EV vs ICE threads please. This seems to happen in every single thread that has anything to do with EVs.
You don't need to turn it into such. It already is such in the nutshell meaning from post one and clickbait news source it originated with. Some car ran out of charge/fuel, it's sure news worthy of global prominence  :horse:.
 
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