Three EcoModder-ish things I learned about the Tesla Roadster last night
 

http://ecomodder.com/forum/attachmen...1&d=1309267546


Went up to the EVCO (Electric Vehicle Council of Ottawa) meeting yesterday evening, and one of the presentations was by a local owner of a Tesla Roadster.

Three things I didn't know before:

1) Data acquisition/transmission capability

The car continuously logs all sorts of data about itself, which it saves in memory and periodically transmits to Tesla headquarters via the cell phone network. (Or not, if the owner has declined to participate.)

This is way cool. Real, in-the-field data about the way the cars are being used, and how they are behaving. Invaluable product feedback.

Most interesting... Owners can also copy the data file to a USB stick. The USB port is in the center stack, under the 12v power outlet.


2) Some owners are cracking their cars' data

It's apparently not pre-formatted to be immediately useful, so some owners have been working on decoding the data dump. The Ottawa Tesla owner says he thinks they've figured out about 80% of it.

He used his data to generate a graph showing SOC & Speed vs. Time for a trip he recently took to Toronto (to view the Model S at the company's showroom there).

(For those who realize that Ottawa is ~450 km from Toronto and beyond the car's usual range, he stopped once on the way for a big-amp top-up at a campground in the 1000 Islands, while enjoying a long lunch at a nice restaurant overlooking the St Lawrence River.)

3) The car has an instant & resettable average energy consumption display

This is sort of like the "ScanGauge" MPG reading, but for electricity consumption from the pack.

I doubt that most Roadster owners care very much about driving efficiently - without exception, they like talking about (and demonstrating) its rocket ship-like acceleration!

But I was happy to learn that in the event you want to nerd out and see how energy efficient you can be, OEM feedback is there.

---

One question I forgot to ask: what about gliding?

How easy is it to "glide" the car -- essentially coasting in neutral? (Critical for driving very efficiently.)

I think Prius owners used to call this mode "dead band", where the display shows no energy flow to or from the wheels.

The owner says the car's accelerator is mapped to provide both acceleration and regen when releasing back toward "0 TPS", making it possible to drive the car in traffic with just the one pedal. Regen is strong enough that when you release the pedal back to "0" the car's brake lights will illuminate for safety, even though you haven't touched the left pedal.

(A Solectria Force I have driven does this as well... but not sure about the brake lights part.)

But is there an easily modulated "glide" zone between accel and regen?

I'll ask next time...

Cool stuff. I probably won't be driving a Tesla anytime soon, but its still really cool to hear about the tech that goes into it.

A while back, when I was talking to a Tesla owner, I asked about the brakes and found out at that time that the regen WILL light the brake lights. I thought that was pretty cool.

Nice photo! I haven't seen the hard-top in place before.

About the data collection...
I recently found out that the Volt does the same thing. It uses OnStar to transmit the data. Some guys have started hacking them to collect and store data from their cars.

I already got some data from a Volt owner. I might be able to get more. It would be pretty cool to be able to pool data on Teslas or Volts and collect some real-world data right here on Ecomodder!

The other fun thing on the Tesla is the big dial right in the middle shows how much power you are using. To the right is power used, and to the left is regen. Straight up is zero energy use, like when sitting at a stop light. When I went for a ride, the driver hit the regen pretty hard to show me. I think the genenerated power went to something like 50,000 watts! :eek:

Another anecdote: Ottawa guy said that some countries' laws prohibit activation of the brake lights unless the brake pedal is physically pressed. That means potentially aggressive regen deceleration with no warning to following traffic!

Tesla owners in those countries have learned they have to tap the left pedal as a warning to avoid having people run up their tail pipes! (... I mean up their pattery pack cooling vents...)

That's about 67 hp. The brakes on any ordinary car brakes must dump 200 hp at least. I would think the Tesla could regen at close to the maximum motor output. I've heard the claim that the Ford hybrids (Fusion & Escape) can regen at 200 hp for up to 10 seconds. About 5 time the motor's continuous rating.

-mort

One minor problem with Tesla's regen is it's on the rear wheels! The harder you brake, the less traction you have at the back.

And I assume there's anti-skid logic in the regen code.

Yes, I forgot it was rwd for a sec. I guess the best that could be expected is about 30% of the braking being regen and 70% friction.
-mort