Advice for potential Roadster owner

[Alfred]

A good approach is to start from real consumption data for comparable cars. It might be impossible to drive a Ferrari to consume only 10liters /100 km (23mpg), nevertheless it is a nice round figure for starters:
The Roadster stores 53 kWh and consumes about 240 Wh/m (150 Wh/km or 15 kWh/100 km, normal driving, summer).
A medium sized (US) car tank holds perhaps 12 USgal (45 liters) and consumes around 23 mpg (10 liters/100km).
Take 10 kWh per liter of gasoline, or 38 kWh/USgal.
The petrol driven car stores therefore 7 times more energy than the electric roadster, but consumes also nearly 7 times more energy per mile or km.

 

[Eberhard]

I did 420km while consuming a little bit more then 50kWh = 121Wh/km. From Monaco to Bellinzona still had the reserve for another 40km.

 

[S-2000 Roadster]

Here's an idea: Run the battery coolant through a heater core and blow air through that into the cabin. That's how an ICE vehicle heater works. Would there be as much heat in the ESS? There's also the drawback that making the coolant system more complex opens it up to potential leaks in the heater core - something that is a real concern in 'normal' cars.

 

[Eberhard]

the problem is - in summertime, you have a surplus of heat. in wintertime, the waste heat from PEM and AC-Motor is only around 2-3kW compared to 50-70kW of an ICE vehicle

 

[Doug_G]

Here's an idea: Run the battery coolant through a heater core and blow air through that into the cabin. That's how an ICE vehicle heater works. Would there be as much heat in the ESS? There's also the drawback that making the coolant system more complex opens it up to potential leaks in the heater core - something that is a real concern in 'normal' cars.

Unfortunately basic thermodynamics rules that out. My battery doesn't go above 40C very often, and the coolant isn't going to be any hotter than the ESS. You can't get very efficient heat transfer with such a small delta-T. Coolant for an internal combustion engine is typically at 135C (water with antifreeze under pressure).

 

[S-2000 Roadster]

the problem is - in summertime, you have a surplus of heat.

That is not a new problem, not in terms of ICE vehicles or the Roadster (I'm not suggesting the removal of any existing Tesla cooling technology, just the addition of a heater core).

in wintertime, the waste heat from PEM and AC-Motor is only around 2-3kW compared to 50-70kW of an ICE vehicle

This is the real problem, as Doug also points out.


Here's a really bad idea: Run the ESS coolant through the seats, for direct contact. Anything above 37°C should feel quite comfy. I call this a bad idea because it would be far too easy to puncture the seat and lose battery coolant, plus there's the added mechanical complexity of diverting the coolant through a proportioning valve.

 

[fraccy]

Just for the sake of completeness, the potential owner has become an actual owner - I picked up my Roadster from Maidenhead in the UK yesterday.

I'm in love. :redface:

Haven't gotten round to swanky pictures, but its standard model, twilight blue, body colour top, silver forged wheels, and did I mention I'm in love with it? :love:

The two month wait nearly destroyed me. I have read every last scrap of material on the internet about them, and I have to say, even the very best reviews don't do it justice. This car is awesome in its own right, but it makes my brain fizz too. Its not just what it does, its how it does it.

I can now answer my own questions: Range immediately exceeded my expectations. I thrashed it around all afternoon and got home about 9pm with a sore neck and only having used about a third of the battery. No idea how far I went I just drove hard without thinking about it. My visions of it disappearing as soon as I floored it were completely unfounded.

An update on Mennekes: I've been shown physical evidence of a Roadster charging from the Ecotricity points at 30A here in the UK. The connector cable (I assume akin to the J1772 option in the states) is signed off and will be available soon, but they're looking at upgrading it already since these Ecotricity points (very usefully located up and down the M5 and M4) in theory have the ability to charge at 64A (but its not currently enabled on them).

The only catch so far has been the noise it made when I arrived home and plugged in (240v 13A), which was pretty loud in my tiny garage. It was the only blot on otherwise complete perfection. I guess thats less extreme if you haven't been driving hard just before, or is there any other way of quietening it? It stopped being so noisy after about 20 minutes though.

Er did I mention I'm in love? :redface:

 

[Dragon]

Congratulations. Nice first impressions. I'm going for a spin now!
Ah, one last thing: It seems you forgot to mention you're in love.

 

[NigelM]

The only catch so far has been the noise it made when I arrived home and plugged in (240v 13A), which was pretty loud in my tiny garage.

Congratulations. That feeling you have doesn't wear off. :biggrin:

The noise is the fans cooling the battery prior to charging. The length of time it runs depends on ambient temperature as well as how hard you drove (you may have pushed the temp up). I sometimes find that my garage gets hot as a result of the fans running so I leave the doors open for a few minutes after plugging in and most of the warm air generated dissipates.

 

[Alfred]

In cooler climes give the battery some time to cool down before starting to charge. If you have driven e.g. 100 Km you just need to replace about 20 kWh. At 13A that would take 7 hours. So starting your charge at 1 am will be enough to get you recharged fully again by 8 am. Mostly the fans will then not be needed anymore.

 

[hcsharp]

In cooler climes give the battery some time to cool down before starting to charge. If you have driven e.g. 100 Km you just need to replace about 20 kWh. At 13A that would take 7 hours. So starting your charge at 1 am will be enough to get you recharged fully again by 8 am. Mostly the fans will then not be needed anymore.

While it's true you won't get as much noise by waiting, it is also not as good for battery longevity. Best would be to charge it for a few minutes until the front fans go off which immediately cools the battery. Then it will be sitting at a cooler temp while waiting and cooling more to do a full charge later.

 

[kgb]

While it's true you won't get as much noise by waiting, it is also not as good for battery longevity. Best would be to charge it for a few minutes until the front fans go off which immediately cools the battery. Then it will be sitting at a cooler temp while waiting and cooling more to do a full charge later.

In various other threads, other owners have expressed the desire for a more "automated" charging system. We know that TM reads this forum, so pay attention, because this type of activity is exactly the type of activity that should be automated. Many other forum readers (and myself) have noticed that the owners find themselves taking an active roll in the charging process. The owners should be able to put some information into the car, such as, electricity rates and peak/off peak times. Then, the owner would only have to tell the car what time by which the vehicle should be charged. The car could then do things like (1) apply the fan briefly (which I understand it does regardless of whether it is charging or not) (2) it could charge the car from a particularly low SOC to midway immediately then save the rest for off-peak times or (3) something else. The car (TM) knows what's best for battery longevity, and the owner knows when he/she wants the car to be ready, the rest can be some automation algorithm that cares for battery health, charges at lower rates, and has the car ready in the morning.

 

[sauhlir]

In various other threads, other owners have expressed the desire for a more "automated" charging system. We know that TM reads this forum, so pay attention, because this type of activity is exactly the type of activity that should be automated. Many other forum readers (and myself) have noticed that the owners find themselves taking an active roll in the charging process. The owners should be able to put some information into the car, such as, electricity rates and peak/off peak times. Then, the owner would only have to tell the car what time by which the vehicle should be charged. The car could then do things like (1) apply the fan briefly (which I understand it does regardless of whether it is charging or not) (2) it could charge the car from a particularly low SOC to midway immediately then save the rest for off-peak times or (3) something else. The car (TM) knows what's best for battery longevity, and the owner knows when he/she wants the car to be ready, the rest can be some automation algorithm that cares for battery health, charges at lower rates, and has the car ready in the morning.

Yes, and take it a step farther. If you have more than one car and a limited supply of electricity, allow the drivers to explain what they want for the two cars (perhaps one really needs to be fully charged and the other doesn't, and one needs to be ready earlier than the other) and let the cars and the grid negotiate the best way to make this happen.

 

[fraccy]

Congratulations. That feeling you have doesn't wear off. :biggrin:

The noise is the fans cooling the battery prior to charging. The length of time it runs depends on ambient temperature as well as how hard you drove (you may have pushed the temp up). I sometimes find that my garage gets hot as a result of the fans running so I leave the doors open for a few minutes after plugging in and most of the warm air generated dissipates.

Thanks for this it helped. I also realised my tiny garage makes the sound seem a lot worse. I charged outside elsewhere at the weekend and it wasn't nearly as bad.

My only wish for improved charging software is to be able to quickly check the car's current charge status on a website from my phone.

 

[Doug_G]

My only wish for improved charging software is to be able to quickly check the car's current charge status on a website from my phone.

You want a Tesla Tattler.

 

[fraccy]

You want a Tesla Tattler.

I do. I do want a Tesla Tattler!

 

[hcsharp]

In various other threads, other owners have expressed the desire for a more "automated" charging system. We know that TM reads this forum, so pay attention, because this type of activity is exactly the type of activity that should be automated. Many other forum readers (and myself) have noticed that the owners find themselves taking an active roll in the charging process. The owners should be able to put some information into the car, such as, electricity rates and peak/off peak times. Then, the owner would only have to tell the car what time by which the vehicle should be charged. The car could then do things like (1) apply the fan briefly (which I understand it does regardless of whether it is charging or not) (2) it could charge the car from a particularly low SOC to midway immediately then save the rest for off-peak times or (3) something else. The car (TM) knows what's best for battery longevity, and the owner knows when he/she wants the car to be ready, the rest can be some automation algorithm that cares for battery health, charges at lower rates, and has the car ready in the morning.

I've implemented most of those features in my home-made HPC. In my climate we don't need to cool the battery down as much as warm it up. So I have a Quick Cool Down/Warm Up button. I'm kinda busy with work this week and next but at some point I'll post some pics...

 

[fraccy]

I don't know much about the Roadster yet, but I was wondering, the fact it aggressively cools the battery when you plug it in I assume is because it uses the information that you've actually plugged it in to know its going to charge and be sat still. I dont fully understand what temperature things need to be for charging versus driving etc.

Would it not be desirable if say, about 5 minutes before you get home (if you're not driving hard), you could tell it you were *going* to charge very shortly. The earlier it gets that information the more efficiently it should be able to act. It could then take that as permission to expend battery energy to start the cooling process (at least partially) before you get home? Where I live, the last couple of miles are always very slow through town and the car is cooling off a bit anyway?