Batery pack - optional upgrades

[WarpedOne]

That chart over www.pluginamerica.com really took my eye. I think offering a sellection of ranges for the same car model is the answer.

Why build only one package with 500miles range at ridiculus price with a ton of batteries if you can offer say a basic model with say 100miles range and then optionaly offer battery packs that give additional 100 or 200 miles. In this way the car becomes MUCH more accessable to 'normal' people.

You can advertise high maximum range (say 300miles or more with full battery pack) and also offer lower price for models with less batteries and shorter range. If battery pack design is modular, so you can just add one, two or three packs, this is almost trivial. I think   ;D

Having less batteries on board not only shortens your range and lowers the price, but also improves the performance. The car is lighter which translates into better acceleration, lower power demands, etc. If battery pack is placed centraly all this could be achieved with a single production model and little suspension tuning.

I think I've nailed it

 

[tonybelding]

I suggested earlier that removing some batteries might be a good thing for something like autocross competition. You're going to haul it to and from the track on a trailer anyhow, right?

I'm less sure about doing it to reduce the cost of the car. At least in the case of the Tesla Roadster. . . The batteries are something like $20,000 of the car's cost, so it's still an expensive car even if you were to cut out half of them. I could imagine, possibly. . . removing 200 pounds of batteries and replacing all the carbon-fiber body panels with cheaper fiberglass. So the car would end up about the same weight, but you'd save money on both batteries and body panels. That would be your economy model.

In the long run, the way to bring the price down is through mass production. When it's designed and built more like a Miata, then it'll be possible to price it more like a Miata. Of course you know, a Miata doesn't perform like an Elise -- but it does perform decently and is widely regarded as fun to drive.

 

[WarpedOne]

True, but for some time (5-10 years I'd say) the batteries will be expensive and relatively heavy. Why should I buy 700miles range if 200miles range will completly cover for my needs? On the other hand, if you only desing for 200miles you loose all those longdistance travelers.

I just think that having a range of battery-packs you can choose from is a good idea. The white star is supposed to cost around 50k USD. Current Tesla pack is already over half of that price. Cutting 10.000 USD from the end price is not a small thing.

 

[electrified]

You wouldn't get better exceleration from a smaller battery pack. If the present pack produces say 40kw, a quarter sized battery would produce 10kw, only enough to maintain 60mph, not get there in 4 seconds

 

[tonybelding]

You wouldn't get better exceleration from a smaller battery pack. If the present pack produces say 40kw, a quarter sized battery would produce 10kw, only enough to maintain 60mph, not get there in 4 seconds

I'm really unsure about that. It depends on the power density (not energy density) of the batteries and whether the current draw from them is the limiting factor. I sort of assumed it was not. . . but I could easily be wrong.

 

[electrified]

Read the current blog post:

Martin: As it turns out, when we designed a battery pack that delivers the desired 250-mile range, it happens also to produce enough power for the kind of acceleration we were after. In this sense, we lucked out with standard lithium ion batteries.


More batteries means more power as well as more energy. Each cell can only produce so much of each.

 

[Michael]

Of course, if the end result of reducing the number of batteries is a lessoning of the power available, a supercapacitor could always to utilized to increase the power available for the occasional bursts of speed needed.