VIDEO: Tesla Rolling Road

[e8_pack]

Is bhp really relevant on an electric motor, where's the torque output?

[kambites]

e8_pack said:

Is bhp really relevant on an electric motor

Yes, why wouldn't it be?

[bp1000]

I think there are a few vids of the rolling road results for the 690bhp car too

[Vixpy1]

Oo look, its me

[Xaero]

I've always wanted to see a Tesla on a rolling road. Makes a decent sound imo! Good result too. It's nice to roughly gauge what they can compare too now knowing that.

[anonymous-user]

Journo talks about electric car and gets the units wrong shocker(sic)!!


(kW is the unit of instantaneous Power. kWHr is a unit of energy. In this case the Tesla tested makes 428 bhp (320kW). So with a battery capacity of 85kWHrs, that means you could drive at full power for just 16mins before running out of electricity (assuming no other system losses and that you can use all of the battery capacity etc)

[R8VXF]

Vixpy1 said:

Oo look, its me

Reminds me that i need the get the GTS down to you soon to check stock output. Got any cheap Saturdays in April?

[PhillipM]

e8_pack said:

Is bhp really relevant on an electric motor, where's the torque output?

Yes. The same as for an IC.

[M11 MFP]

Max_Torque said:

In this case the Tesla tested makes 428 bhp (320kW). So with a battery capacity of 85kWHrs, that means you could drive at full power for just 16mins before running out of electricity (assuming no other system losses and that you can use all of the battery capacity etc)

A little under 16 mins at 100% motor efficiency and zero further loss to the roller. Assuming this 320kW is an at rollers figure and not a 'flywheel' or shaft kW fudge.
The AC motor is 90-95% efficient? And another 10% or so is loss through the short driveline and tyre contact. I reckon the Duracell bunny would be flagging by 13 min.

You know quite a lot about these systems Max. Could it sustain full power for that period, or would there be some thermal crisis and reign back before then?

Edited by M11 MFP on Tuesday 10th March 20:16

[R8VXF]

M11 MFP said:

Max_Torque said:

In this case the Tesla tested makes 428 bhp (320kW). So with a battery capacity of 85kWHrs, that means you could drive at full power for just 16mins before running out of electricity (assuming no other system losses and that you can use all of the battery capacity etc)

A little under 16 mins at 100% motor efficiency and zero further loss to the roller. Assuming this 320kW is a 'flywheel' or shaft kW fudge and not an at rollers figure.

The AC motor is 90-95% efficient? And another 10% or so is loss through the short driveline and tyre contact. I reckon the Duracell bunny would be flagging at 13 min.

Knowing SRR and vixpy, that will more than likely be a RWHP figure.

[kambites]

M11 MFP said:

You know quite a lot about these systems Max. Could it sustain full power for that period, or would there be some thermal crisis and reign back before then?

Almost certainly not if it's sat stationary on a rolling road with no air-flow over the radiator.

Could a typical internal combustion engine cope with running at full power stationary for a quarter of an hour? I certainly wouldn't want to try it with one I owned.

[R8VXF]

kambites said:

M11 MFP said:

You know quite a lot about these systems Max. Could it sustain full power for that period, or would there be some thermal crisis and reign back before then?

Almost certainly not if it's sat stationary on a rolling road with no air-flow over the radiator.

Could a typical internal combustion engine cope with running at full power stationary for a quarter of an hour? I certainly wouldn't want to try it with one I owned.

They have a VERY big fan at SRR, that is actually what most of the noise is from the vid, it drowns out Monaro and VXR8 engines

[kambites]

R8VXF said:

They have a VERY big fan at SRR, that is actually what most of the noise is from the vid, it drowns out Monaro and VXR8 engines

Big enough to move the air at whatever speed a Tesla would be doing if it sat at full power for a quarter of an hour on the road? You need a truly big fan to shift air at 150+mph and the people around the car might be having difficulty standing up if it was.

Usually on rolling roads, they point the fans straight at the radiator don't they? Where on earth is the radiator on a Tesla?

[SuperPav]

"Traditional" OEM's normally do Autobahn testing, which is largely what it sounds like - Vmax (or as much as possible given conditions) non-stop for several tanks of fuel.

Wonder how (or if!) this is done for a Tesla given ability to recharge is limited. There aren't many test tracks suitable for the autobahn test. Probably not the most representative test to start with for an EV.


My Leaf will sit at (limited) 100mph for about 40 miles, can then get a supercharge at services, and repeat.
But after 3/4 cycles, battery temp is off the scale (in the red, 11/12 bars).

[Vixpy1]

The noise you hear is the car only, did'nt bother with a fan.

This was done a few years ago mind!

[kambites]

SuperPav said:

"Traditional" OEM's normally do Autobahn testing, which is largely what it sounds like - Vmax (or as much as possible given conditions) non-stop for several tanks of fuel.

A great many powerful cars (including the Tesla) have speed governors limiting them to well below what their top speed would be if they were using full power, though.

What sort of battery cooling does the Leaf have? Are they water cooled like the Tesla?

[R8VXF]

Vixpy1 said:

The noise you hear is the car only, did'nt bother with a fan.

This was done a few years ago mind!

Thought something looked odd compared to the new place

[M11 MFP]

kambites said:

Could a typical internal combustion engine cope with running at full power stationary for a quarter of an hour?

Actually most I/C could with an appropriate cooling system. Most passenger cars are not a continuous duty type (excluding white vans), so are not set up for this. Any vehicle with very highly tuned specific output would probably not survive 15 min at WOT, but wouldn't ordinarily be asked to.

However, most trucks can easily cope given adequate radiator flow. Large diesels in tractors, combines, gensets etc operate for extended periods at 100% load with brief loads beyond 100%, and often in conditions of heat and dust more adverse than any encountered in a rolling road bay.

[SuperPav]

kambites said:

SuperPav said:

"Traditional" OEM's normally do Autobahn testing, which is largely what it sounds like - Vmax (or as much as possible given conditions) non-stop for several tanks of fuel.

A great many powerful cars (including the Tesla) have speed governors limiting them to well below what their top speed would be if they were using full power, though.

What sort of battery cooling does the Leaf have? Are they water cooled like the Tesla?

True, although more typical cars with <155mph will normally be running pretty much near full power when sat at Vmax. e.g. Audi A4 diesels etc. and they'd still be put through the same test.

I believe the above is the reason that GM didn't do a LS-engined Opel Omega, test cars would start to overheat before they'd gone through a tank of fuel on the autobahn, and to change the cooling pack meant a new bumper etc.


The Leaf battery is air-cooled. And performance degrades at high temperatures, so it all starts to compound somewhat when it gets hot.