Topic: Lithium-Sulphur Could Replace Lithium-Ion As Battery Tech Advances

[EV Dan]

But a hybrid does not suffer greatly from hauling extra weight around.

Thats because in a classic hybrid an engine and a motor can work in parallel to output required power and /or torque. So both can be made smaller and lighter.
In an ER-EV (aka Volt) the motor is on its own to cope with an applied load and the range extender needs to be as powerful to provide enough juice for the car to climb an indefinitely long and steep incline, fast.

[tpl]

But a hybrid does not suffer greatly from hauling extra weight around.

Thats because in a classic hybrid an engine and a motor can work in parallel to output required power and /or torque. So both can be made smaller and lighter.
In an ER-EV (aka Volt) the motor is on its own to cope with an applied load and the range extender needs to be as powerful to provide enough juice for the car to climb an indefinitely long and steep incline, fast.

If that was applied to trucking I guess we'd see rather more 1000 bhp trucks on the road?    Why not go more slowly up hill in an ER-EV or an EV.  Having spent some of my younger years driving old brit cars with sub 1 litre engines I can still remember how to manage my momentum in hilly country.

[Noto]

the A1 e-tron was pretty cool in that it used a tiny rotary as the generator power plant, minimizing weight.

...except rotaries are notoriously bad on gas as they simulate an always in-boost method - hence how they have such exceptional power-to-weight ratios, and hence why the 1.3L RX-8 twin-rotor used such an obnoxious amount of gas (my BIL averaged 13L/100km - there's so much better out there).

My RX is a heavy, heavy beast.  No question.  I'd love for it to be lighter, but I wouldn't love for it to have a rotary engine.  I'd sooner take VW or Nissan's route with the super/turbo hybrids.

Has anyone driven the Pathfinder hybrid yet?  I'm really, really curious as to how that'd play out, though logically, I'd think the electric motor's torque would make the immediate power (no lag) of the supercharger rather redundant.

[X-Traction]

But a hybrid does not suffer greatly from hauling extra weight around.

Thats because in a classic hybrid an engine and a motor can work in parallel to output required power and /or torque. So both can be made smaller and lighter.
In an ER-EV (aka Volt) the motor is on its own to cope with an applied load and the range extender needs to be as powerful to provide enough juice for the car to climb an indefinitely long and steep incline, fast.

True, but that's not what I meant.  In a non-hybrid, extra energy is needed to increase the speed or elevation of additional weight.  That extra energy is wasted eventually in braking or engine braking.

In a hybrid, that braking or engine braking recovers much of the energy that was used to increase speed or elevation.  So if you put a 300lb load in a regular car, it will just hurt mileage, plain and simple.  But put that same extra weight in a hybrid, and although it takes more gas to get it moving, and it also takes more braking to slow down that weight, the fact the braking is regenerative means much of the energy originally "invested", is recovered.

Accelerating a hybrid with extra weight in it is like putting money in the bank - you can get most of it back.  Accelerating a non-hybrid with extra weight is like throwing your money away.

[blur911]

Accelerating a hybrid with extra weight in it is like putting money in the bank - you can get most of it back.  Accelerating a non-hybrid with extra weight is like throwing your money away.

I think getting most of the accelerating energy back when decelerating would be very optimistic.  The efficiency of the regen braking system is likely below 75%, add in air-resistance, rolling-resistance and other losses and I bet it's below 50% for the total recovered energy.

[Noto]

I would think even lower than that, but I don't fully disagree with X-Traction.  My problem is, especially on the highway, that I often am "charging" an already full battery.  Then when I'm in traffic, I'm depleting the battery rather quickly.

the A1 e-tron was pretty cool in that it used a tiny rotary as the generator power plant, minimizing weight.

So I read an article today about the Mazda 2 range-extended electric (similar to the Volt's powertrain).  If that's what you were referring to, or if the A1 used the same layout, then yes, that is pretty cool.  Mazda claims that because the rotary will only be spinning at 2,000rpm (its highest efficiency zone) to generate (and never more/less), then it ends up being just as efficient as a petrol, but weighing far, far less.  If their claims aren't completely bogus, then that's a really, really neat application of the rotary.  Shame there are no plans to mass-produce it.  Imagine a plug-in BEV with that range extender - would make a fuel cell almost completely moot - only downside is that since it's still burning petrol, it will have emissions.  Still, the temperature and infrastructure limitations make me think that fuel cells will never take off.  The only positive I see about fuel cell tech is that producing the hydrogen required can be a really, really efficient process when coupled to recycling plants, algae ponds, or using excess energy that is otherwise given away (Ontario pays neighbouring states/provinces to take our excess electricity during low times) or grounded.

Still, I think the best gains will come from new battery tech.  Imagine a Tesla Model S with a small range extender (rotary) in the 'frunk'.  Now there's the perfect vehicle.

[X-Traction]

Accelerating a hybrid with extra weight in it is like putting money in the bank - you can get most of it back.  Accelerating a non-hybrid with extra weight is like throwing your money away.

I think getting most of the accelerating energy back when decelerating would be very optimistic.  The efficiency of the regen braking system is likely below 75%, add in air-resistance, rolling-resistance and other losses and I bet it's below 50% for the total recovered energy.

The fact that hybrids get about twice as good mileage as non-hybrids in city driving might indicate the energy recovery, even if it's "wasteful", is pretty good. 

On the other hand, to support your argument is that the Ford Escape Hybrid gets about 60% as good city mileage as a Prius.  Much of that shortfall is no doubt due to the larger frontal area and larger engine, larger tires etc, but a lot of it must be due to the greater vehicle weight.  It would be interesting to see what mileage a Prius would get if you loaded it up to match the weight of the Escape.

Additional weight, assuming it's inside the car, won't add air resistance.  The increase in rolling resistance from additional weight would be very slight.  You're correct that the hybrid's regeneration system wastes energy, but a non-hybrid wastes ALL that energy.  And this holds true for the additional energy involved with moving additional weight.

Despite all this, I believe my basic claim that extra weight doesn't penalize a hybrid's mileage drastically, holds true.

[EV Dan]

http://www.bmw.com/com/en/newvehicles/i/i3/2013/showroom/technical_data.html#m=i3
- use pull down menu to switch to i3 RE
This is a useful real life comparison of how even a moderate weight increase due to the RE affects the overall range and performance. I think rolling resistance and energy recovery % are to blame, as everything else is really the same for the two models.

[jyarkony]

the A1 e-tron was pretty cool in that it used a tiny rotary as the generator power plant, minimizing weight.

...except rotaries are notoriously bad on gas as they simulate an always in-boost method - hence how they have such exceptional power-to-weight ratios, and hence why the 1.3L RX-8 twin-rotor used such an obnoxious amount of gas (my BIL averaged 13L/100km - there's so much better out there).

My RX is a heavy, heavy beast.  No question.  I'd love for it to be lighter, but I wouldn't love for it to have a rotary engine.  I'd sooner take VW or Nissan's route with the super/turbo hybrids.

Has anyone driven the Pathfinder hybrid yet?  I'm really, really curious as to how that'd play out, though logically, I'd think the electric motor's torque would make the immediate power (no lag) of the supercharger rather redundant.

drove it briefly, although our focus wasn't the nitty gritty hybrid bits as it was thrown into a comparison. it is incredibly smooth transitioning between power sources so it was hard to pick apart the various elements in play. just feels like a smooth, powerful V6.

and as to the rotary in the A1, I believe because it was used as a generator, it was always at its most efficient/powerful high rpms - they didn't offer a lot of info on it as it was a bit of a sideshow to other vehicles at the event. later experiments with the A1 range extender ditched the rotary for a 1.5L 3-cylinder, so I guess Audi agrees with you on that one.