Performance Electric cars

[4pyros]

I don't know for sure either but given this.

,

I have my doubts he is talking about regenerative braking which in itself is easily accomplished with the drive motors and no extra mechanical systems are needed.

My interpretation is that he is suggesting using the power from the wheels to drive additional generators to recharge the batteries from the vehicle driving itself down the road on the power coming from its own batteries.

That or this is embarrassingly weak attempt on his part at trolling me.

No I just think he is not aware of all the losses involved.

 

[tcmtech]

That would not surprise me one bit. When I had my electric car it always amazed me how many people suggested that I just add a big alternator or two to the electric motor to extend my driving range.

 

[JimB]

TCMtech said:

I have my doubts he is talking about regenerative braking which in itself is easily accomplished with the drive motors and no extra mechanical systems are needed.
My interpretation is that he is suggesting using the power from the wheels to drive additional generators to recharge the batteries from the vehicle driving itself down the road on the power coming from its own batteries.

That is the impression that I was getting as well.

rc3po
Some of your terminology is a little bit vague and open to misunderstanding.
It appeared that you were proposing that by driving a generator from the wheels of the car as it was moving, that there was some "free energy" to be gained.
Please be assured that is not going to happen.
As they say where I originally came from: "Tha never gets owt fer nowt"

JimB

 

[rc3po]

I don't know for sure either but given this.

,

I have my doubts he is talking about regenerative braking which in itself is easily accomplished with the drive motors and no extra mechanical systems are needed.

My interpretation is that he is suggesting using the power from the wheels to drive additional generators to recharge the batteries from the vehicle driving itself down the road on the power coming from its own batteries.

That or this is embarrassingly weak attempt on his part at trolling me.

Trolling you?? I didn't ask you anything.
Your interpretation is correct though. It would only require a small amount of PSI to spin a generator. But there may be cheaper and simpler ways to accomplish the same thing.

 

[rc3po]

TCMtech said:


That is the impression that I was getting as well.

rc3po
Some of your terminology is a little bit vague and open to misunderstanding.
It appeared that you were proposing that by driving a generator from the wheels of the car as it was moving, that there was some "free energy" to be gained.
Please be assured that is not going to happen.
As they say where I originally came from: "Tha never gets owt fer nowt"

JimB

I really don't understand the problem. The mechanical advantage of a hydraulic system is great. 35 PSI in 4 tires will hold your car off of the ground easily - I really can't understand why that concept is so difficult...

 

[tcmtech]

Your interpretation is correct though. It would only require a small amount of PSI to spin a generator. But there may be cheaper and simpler ways to accomplish the same thing.

No it does not take a small amount of pressure to spin a loaded generator. That's your first misunderstanding. If you want to make a kilowatt of electrical or mechanical power at the output you need to put more than a kilowatt of power in first which in order to transfer energy with fluid power requires two things both a flow rate and a pressure. Without one or the other you have nothing. It's the same as with electricity. You need both volts (pressure) and amps (flow) to get power (watts).

I really don't understand the problem. The mechanical advantage of a hydraulic system is great. 35 PSI in 4 tires will hold your car off of the ground easily - I really can't understand why that concept is so difficult...

The 35 PSI that holds up your car is not the same as the fluid pressures operating in a hydraulic system. It has no flow rate behind it to add up to anything meaningful power or energy wise.

I think you need to take a number of basic physics classes or at least do a lot of reading first before getting into these subjects because right now it's clear you have a very poor understanding of the concepts terminology involved.

 

[ronv]

Hydrostatic drive systems variable displacement pumps and motors are a efficient way of creating a means to produce very wide gear ratios for either high torque or high speed with a smooth change from one end of the operating range to the other.

Contrary to popular belief in practical application a efficient electric motor does not produce the same mechanical power over its full operating range. 100% torque at zero RPM's is still zero power. Quick acceleration requires high initial torque from the wheels that rapidly changes to higher speeds with less torque but the total energy being transferred is still the same.

To get high torque at low RPM's from an electric motor either requires a large motor with a lower top end speed or a smaller high speed motor with a gear reduction. Using variable displacement hydrostatic pump and motor systems between the primary electric motor and wheels would simply allow for the electric motor to run at its maximum mechanical power point while providing continuously variable gear ratio transmission system between the motor and wheels.

Hydrostatics are not a magic bullet for making more energy from nothing. All they are is a way to produce highly variable and wide ranging gear ratio transmission with a high power to weight and mass ratio.

I see where you are coming from CVT's. I think in the case of the Tesla they just sized the motor for a respectable top end of 125MPH. With a 10 to 1 reduction ratio that makes the low end acceleration pretty exciting without any gears. It does cause some efficiency loss at low speeds, but the gear ratio helps that and there is not much resistance at low speed so not so many horsepower. Anyway this makes them killer quick, but not killer fast. So if your out in your Ferrari don't race one for a block but maybe a mile.
CVTs seem to make more sense for gas cars where the sweet spot is smaller, but the only one I know of is the Nissan Altima and It's mechanical.

Steve, your right you would need a power plant in your back yard to charge them like a gas car, but if they could get 3 times the power for the same price it might be getting close.

 

[3v0]

I am not sure if anybody has pointed this out. In the near term the sweet setup looks to be a small turbo charged gas engine with an electric super charger designed to make up for the turbo lag. In this video Jay Lenno drives a 1.1L ford focus and says it feels like a 2L or 3L engine. They mention selling a kit.

 

[tcmtech]

I see where you are coming from CVT's. I think in the case of the Tesla they just sized the motor for a respectable top end of 125MPH. With a 10 to 1 reduction ratio that makes the low end acceleration pretty exciting without any gears. It does cause some efficiency loss at low speeds, but the gear ratio helps that and there is not much resistance at low speed so not so many horsepower. Anyway this makes them killer quick, but not killer fast. So if your out in your Ferrari don't race one for a block but maybe a mile.
CVTs seem to make more sense for gas cars where the sweet spot is smaller, but the only one I know of is the Nissan Altima and It's mechanical.

That's exactly what I am talking about. With hydrostatic drive the power losses are about the same as with a mechanical system. At the point of the highest input to output ratio and highest load the losses are the worst but when in the range of minimal ratio change and light load the efficiency is very good. Most modern variable displacement piston pump and motor combination systems can easily run at >98% efficiency in light to medium load applications.

The bigger advantage of a variable displacement hydrostatic drive train is it's possible to have large gear reduction ratios that would be impractical to build into a normal mechanical transmission.

Very few vehicles get much over a 7:1 ratio in first gear but a hydrostatic system can easily run 3 - 4 times that ratio but then shoot up to a overdrive equivalent ratio that again unlike a mechanical transmission can go quite a bit further the other way. Granted with a electric motor the overdrive function is not needed but being able to shoot from a 30:1 or greater low to a 1:1 high ratio seamlessly while keeping the electric motor at it's peak power speed would allow for a smaller motor to appear like it has far more torque and peak power than it really has.

 

[tcmtech]

I am not sure if anybody has pointed this out. In the near term the sweet setup looks to be a small turbo charged gas engine with an electric super charger designed to make up for the turbo lag. In this video Jay Lenno drives a 1.1L ford focus and says it feels like a 2L or 3L engine. They mention selling a kit.

Back when I had my EV I often pondered on setting it up with a small diesel gen set that I could tow behind it for a similar effect but back then I didn't have any small diesel engines to play with. I figured that with a small 5 - 10 KW gen set I could have easily made my car into a far more practical daily driver being I would not have to plug it in when I went to town. I would have just let the gen set recharge the batteries while it was parked.

Oh well maybe on the next one but it will be a electric pickup next time. The two door hatchback concept just did not work well for me.

 

[rc3po]

No it does not take a small amount of pressure to spin a loaded generator. That's your first misunderstanding. If you want to make a kilowatt of electrical or mechanical power at the output you need to put more than a kilowatt of power in first which in order to transfer energy with fluid power requires two things both a flow rate and a pressure. Without one or the other you have nothing. It's the same as with electricity. You need both volts (pressure) and amps (flow) to get power (watts).




The 35 PSI that holds up your car is not the same as the fluid pressures operating in a hydraulic system. It has no flow rate behind it to add up to anything meaningful power or energy wise.

I think you need to take a number of basic physics classes or at least do a lot of reading first before getting into these subjects because right now it's clear you have a very poor understanding of the concepts terminology involved.

I know it would need to have high volume.
It doesn't matter anyway. They will chose the method that milks us for every dime they can. Some things never change.

 

[Nigel Goodwin]

Yes, that's what I mean - systems to use to charge the batteries while the vehicle is moving. Even if they can't keep the batteries fully charged even while you are driving, they could at least increase the range of the vehicle between plug-in charging.

Sorry, but that's an absolutely obvious 'stupid' idea - if you taking energy to charge the battery the energy has to come from somewhere - in this case it comes from the battery.

So you're taking extra power from the battery (for no reason) and returning a small proportion of it - result a fairly large net loss.

You're falling in the usual amateur 'perpetual energy' trap.

Where it can help a little is KER's systems, as on F1 cars - you recover a percentage of the braking energy, which is normally all wasted - but it's a complex system.

 

[skimask87]

Back when I had my EV I often pondered on setting it up with a small diesel gen set that I could tow behind it for a similar effect but back then I didn't have any small diesel engines to play with. I figured that with a small 5 - 10 KW gen set I could have easily made my car into a far more practical daily driver being I would not have to plug it in when I went to town. I would have just let the gen set recharge the batteries while it was parked.
Oh well maybe on the next one but it will be a electric pickup next time. The two door hatchback concept just did not work well for me.

You don't have any EV stuffs in the works do ya? Live in Logan. Not a lot of people around here into that sort of thing... You know how it is up here.
I've got an '88 Chevy Sprint (3cyl, 1.0liter, bazillion miles on the odo). I've had this idea in the back of my head (didn't say it was a good idea, but I've wanted to try it out since I got the car) of getting a rear axle from a small RWD or 4WD car, something like a Subara Brat or similar, swapping out my rear 'axle' for that and mounting a small-ish electric drive onto the input shaft, put a few decent batts in the hatch. More like a rear wheel assist than a full power drive unit. Fabrication isn't much of problem. Even control electronics aren't an issue. Figuring out how to mount IGBT's...that gives me a headache. (As a side note, no, I wouldn't rely on the ICE's alternator to charge the battery pack. That's just dumb. As dumb as buying an electric supercharger.)
As far as using a diesel gen set as a power booster, ya, I can see that happening. Most will disagree, but they likely don't take into account that a guy could run that diesel at it's optimal efficiency point 100% of the time. Can't do that with an ICE drive.

 

[cowboybob]

Welcome, skimask87!

The perennial "energy density" conumdrum: how much energy (E) can we pack into X space to be used to move Y mass for a distance of Z at maximum efficiencies?

Of course, fossil fuels are still king. Current hybrid vehicles are merely working the problem from the efficiency angles. Electrical vehicles merely transfer (with inherent losses) the energy need(s) back to the same source.

Until we (them, somebody) tames fusion (the "Flux Capacitor", perhaps?) our current (no pun intened) problem will persist.

That said, I applaud any and all efforts thus far attempted to reduce (however incrementally small) the reliance on fossil fuels, especially gasoline, since my 74' Vette needs it. Quite a lot of it. My crude estimates are that 20 Priuses even out my usage. Thus, net efficiency=100%.

 

[3v0]

The McLaren P1 technology is interesting.

 

[skimask87]

The perennial "energy density" conumdrum: how much energy (E) can we pack into X space to be used to move Y mass for a distance of Z at maximum efficiencies?

I'm lucky in that the vehicle doesn't have much X or Y, nor do I add much Y to it, and don't need to go much Z, therefore don't need much E
I've also have near the same conundrum by owning a '76 Blazer and '01 Ram 1500...both of which need only move about 50ft before completely offsetting fuel savings of driving my gas sipper for a whole month! (ok, maybe a bit less, but the point still stands)

 

[ronv]

The McLaren P1 technology is interesting.

I'd take one without gas or electric just to look at.

 

[rc3po]

Sorry, but that's an absolutely obvious 'stupid' idea - if you taking energy to charge the battery the energy has to come from somewhere - in this case it comes from the battery.

So you're taking extra power from the battery (for no reason) and returning a small proportion of it - result a fairly large net loss.

You're falling in the usual amateur 'perpetual energy' trap.

Where it can help a little is KER's systems, as on F1 cars - you recover a percentage of the braking energy, which is normally all wasted - but it's a complex system.

Some people said the earth being round was a stupid idea...

 

[Nigel Goodwin]

Some people said the earth being round was a stupid idea...

Presumably the same people who think you can 'magically' create energy from nothing

 

[rc3po]

Presumably the same people who think you can 'magically' create energy from nothing

I didn't say from nothing.