Chevy Volt - Electric Car

Duh, now I see that they intend to discharge down to 30% with Li-on

That will be fun to watch

 

They have already done it. As I said 100% DOD 0% SOC and the cells can be cycled 4000 times.

80% DOD, 20% SOC they can be cycled 7000 times.

And as I said I think they are changing their mind and targeting 50% DOD/SOC now.

And I am working on this stuff too, that is why I know all this random trivial nonsense.

http://www.gm-volt.com/2007/08/24/n...when-battery-power-hits-50-stops-again-at-80/

 

xxx, I think 80% discharge (so 20% is left) is not equal to 50% discharge either way.

 

50% and 7000 cycles sounds much more reasonable.

Looking forward to the new toys, exciting times coming

 

Ah, just noticed this information about Volvo's PHEV concept car.

Differences to the Volt:

Li-poly batteries instead of Li-on.
60 mile range on batteries instead of 40 miles.
Diesel engine/generator instead of Petrol.
Acceleration/top speed performance roughly equivalent to the Volt.
Wheel motors (does the Volt have these?) = regenerative braking.

Sounds interesting. Anybody know the advantages/disadvantages of Li-poly over Li-on? If I remember correctly, in other threads, various people have stated wheel motors ought to be a benefit.

 

I believe you don't want your motors in the actual wheel, because of the 'unsprung' weight.

 

Depends on the weight of the motor. You can avoid using CV joints and axles by putting the motor there.

 

There are advantages and disadvantages. You have far better control, traction control with no differentials etc...

 

I believe these (or close cousins) are the wheel motors used in the Volvo concept:

http://www.pmlflightlink.com/archive/news_generator.html

45kg each. Light enough or too heavy, I wonder?

 

Uhm, that's not a motor, that's a generator. There are motors on that page too, but not what you linked.

 

Ah crap. That'll teach me to make posts when half-asleep.

Just had a quick look around and found the following information about the weight of the motors used in PML's Mini hybrid concept. The quote comes from a sales manager which is perhaps why it is chock full of exclamation marks!

Similar motors should be used in the Volvo so it certainly doesn't sound as though the wheels should be particularly heavy in comparison to a standard car.

 

That's illegal around here. No road license for that car. But it's a minor thing to correct the chassis, otherwise it looks interesting.

 

Didn't read the rest of the same paragraph, did you?

 

Oops, missed that about "drawing attention"

But as said, that's a minor thing which is easy to correct anyway.

 

Regenerative braking only..........No thanks.

 

That does seem a bit dangerous.

 

I cannot speak on this with any sort of knowledge, so maybe here xxx can tell us something, but it doesn't seem all that terrible to me.

I am sure people said the same thing in the past about hydraulic brakes etc...

If we are moving to drive by wire systems then the brake will be disconnected from your foot anyway.

And yes I realize we have a mechanical emergency brake still. I wonder if they even have that?

It seems a fail safe would not be hard on this to lock things down more or less in the absence of signals to the wheel motors, but it would also make it difficult to control when stopping.

 

Perhaps they'll provide an anchor to throw out the window in case of emergency?

Volvo have a hard-won reputation for the safety of their vehicles so I'm sure they will have paid some attention to the safety implications of using regenerative braking only.

 

It's not all that dangerous, as the energy needed to brake is generated inside the wheels. If you remove the batteries, you can still brake. And you have about 3000Nm to do it with. So I guess it's probably even safer than hydraulic braking, where you can lose braking power completely when there is a leak or the pump malfunctions.

 

What are the reasons not to switch to all electric right away?

1. It's new and scary. The big car companies don't like it, and the consumers don't like it.

2. The volume is very low, so they are very expensive in purchase.

3. The oil companies don't like it, as they run on selling gas.


The first one is being adressed by the specs of the new breed of all electric supercars. Although the design and marketing are still way beyond the regular supercars. But, given the same manufacturing and marketing budget, the electric one easily outperforms any ICE car in existance.

The second one is the classic chiken-and-egg one, and can only be adressed by simply waiting (so the other producers who want efficient batteries make the volume rise), or some big volume contracts from large car manufacturers.

The third one is probably the hardest one: the oil companies are very rich, which is why they demand some solution that uses a fuel that can be pumped at the gas station, which they can produce. A liquified gas is fine.