Improving functionality - Page 5

Chris H. · 07-20-2008, 11:37 AM

If the Roadster were capable of towing the generator, you could just get a few kWs into the battery and then drive away. The generator could continue to charge the battery as you drive to the nearest 70 amp charge station, charge up, and then return the generator to the service depot... Not perfect, but it should work.

vfx · 07-20-2008, 12:11 PM

"People expect Emergency recovery time scales to be far lower than typical recharge durations. That's the problem here. "

I see a traveling waiting room.

On the grand side, the rescue vehicle with the generator is a motor home. It has a plasma screen TV satellite receiver, and a supply of DVDs.

Throw in a laptop with internet and bunch of those old fashioned books or magazines. It will be just like your dentist or oil change place.

The super fancy version has the caravan back open down to ramp the car inside carrying the lot to the original destination while it's charging.

WarpedOne · 07-20-2008, 12:22 PM

Quote:

Originally Posted by malcolm

... Suppose we want to deliver 10kWh of energy to the exhausted car (for ~40 miles driving). Taking one hour at 240 V means 42 Amps. But we know 70 amps requires 17kWh for cooling, so the exhausted car will require a further 42.5 Amps for cooling.

Nah, it ain't so bad. Those 17kWh for cooling are needed if you charge for 3,5hours meaning the cooling system needs about 4kW of power to cool the battery at maximum charging rate of 53kWh / 3.5hours = 17Kw.

If you settle for "transfer" of 10kWh in 42 minutes (the roadster's max charging rate) you end up burning about 16kWh of your energy (10kWh transfered + 3kWh for cooling your battery + 3kWh for cooling recipient battery). It is not impossible, just not very practical.

Trailers are more promissing, we just need a smaller and lighter trailer-gensets than currently available ones.

mt2 · 07-20-2008, 09:18 PM

Another solution might be just to tow the car to the destination, assuming it wasn't home. Remember the town hall meeting where they had fun with the idea that the regenerative braking would recharge the Roadster if you towed it rather than haul it on a flat bed truck?

So here's the scenario; You and the spouse are on your way to a the Academy Awards, or some such. But you forgot to plug in last night and run out of juice half way there. You call a tow truck operator and have it towed to about three blocks from the shindig. Now you should have just enough juice to make a grand arrival and make a great presentation out of plugging it in.

Meanwhile, the tow truck operator is stranded and baffled why towing such a little car burned so much gas.

Not exactly Carbon Neutral, but great fun.

TEG · 07-20-2008, 09:59 PM

Quote:

Originally Posted by mt2

Remember the town hall meeting where they had fun with the idea that the regenerative braking would recharge the Roadster if you towed it rather than haul it on a flat bed truck?

Remeber this?:

Quote:

Originally Posted by TEG

TEG wrote on September 27th, 2006 at 11:48 pm
... Self-recharge mode when Tesla is being pulled behind an RV.
Lots of people who like to travel with RVs like to pull a small vehicle behind them for around town excursions when they park the RV somewhere for an extended stay.

malcolm · 07-21-2008, 02:48 PM

Oops.

Still a roadside 30 minute recovery recharge is a very tough challenge, since even the Tesla 15.4kW Fast Charger can only deliver a maximum of 7.7kWh in that time.

If I can get the maths right this time, 2.4kWh of that energy would have to be diverted to cooling, leaving the ESS with about 22 miles-worth of charge. (There is still some uncertainty as to whether the Roadster needs 3.5 or 4.5 hrs to fully charge from empty at the fastest rate - because of the additional energy consumption for battery cooling)

Is the ESS is designed to cope with a higher rated power supply? Are we stuck with 15.4 kW?

WarpedOne · 07-21-2008, 03:10 PM

Quote:

Is the ESS is designed to cope with a higher rated power supply? Are we stuck with 15.4 kW?

IIRC someone from TM mentioned that you could do a full charge in an hour of regen. To do this, ESS should be capable of recieving 50kW of "incoming" power. The charging interface is not capable of that, though.

malcolm · 07-21-2008, 03:19 PM

Quote:

Originally Posted by WarpedOne

IIRC someone from TM mentioned that you could do a full charge in an hour of regen. To do this, ESS should be capable of recieving 50kW of "incoming" power. The charging interface is not capable of that, though.

Which suggests the fastest emergency recharge system at the moment would be a flat bed truck equipped with a rolling road system. Half an hour of that and you'd be good for about 100 miles more.

tiptongrange · 11-21-2008, 08:10 PM

Quote:

Originally Posted by Chris H.

If the Roadster were capable of towing the generator, you could just get a few kWs into the battery and then drive away. The generator could continue to charge the battery as you drive to the nearest 70 amp charge station, charge up, and then return the generator to the service depot... Not perfect, but it should work.

Or, just have them bring a spare battery pack that fits in the trunk instead of a generator. Drive away off the spare and recharge it when you recharge your car.

Tesla Dave · 11-22-2008, 12:29 PM

The most common and easiest assistance for a dead battery is the already widely available flatbed tow back home. Unless you were seriously not paying attention, you're probably less than 20 miles away.

Hopefully we won't be eligible for a frequent customer discount from the tow company. Or have trouble finding one that won't snicker every time they give you a ride home.