Do Hybrids Really Make Sense?

[P-hack]

Originally Posted by GreenHornet

anything that can run off the engine can run more efficiently off an electric motor

For some reason, I feel compelled to mention that this is generally true over a wider dynamic range, but (not unlike the manual vs cvt vs??? discussions) a direct connection has better peak efficiencies, so efficiency gain is relative to driving (operating) conditions vs the operating conditions considered during design (and the drivers ability to replicate those conditions).

i.e. it might not make sense on a plane or boat that rarely stop and go, but cruise within a fairly narrow band, or for a driver who does mostly the same (or can toggle between those conditions and "off").

[oil pan 4]

I guess it makes sense if you don't think about it and so long as you don't have to replace the hybrid battery pack.

[P-hack]

yes not thinking is the key to it making sense

[RedDevil]

You cannot replace the belt driven fan by an electric one, do a PS delete, do FAS, P&G and other stuff and then claim hybrids don't make sense - as you are then driving a hybrid yourself, albeit mainly a 'manual hybrid'...

[oldtamiyaphile]

Originally Posted by GreenHornet

Every car that has an alternator in a sense is a hybrid albeit to weak of a hybrid to exhibit any of the strengths we have come accustomed to in todays world such as start stop, regenerative braking, or power assist abilities.

Everything is moving to electric hybridization with the ICE as support only. Take for instance Power steering, What about electric water pumps, or even electric AC, or even electric super chargers :-) anything that can run off the engine can run more efficiently off an electric motor and this is why you now see the shift from the car manufacturers.

About half of all non-HEV's already offer stop-start and regenerative braking.

Running everything off the battery is only efficient for accessories that have a low duty cycle. Burning petrol to charge a battery is very inefficient and as you switch more accessories to electric recovering enough energy under regen becomes problematic.

[oldtamiyaphile]

Originally Posted by RedDevil

You cannot replace the belt driven fan by an electric one, do a PS delete, do FAS, P&G and other stuff and then claim hybrids don't make sense - as you are then driving a hybrid yourself, albeit mainly a 'manual hybrid'...

If I can do it myself, that's precisely why I don't need one

Every car I drive becomes a hybrid (99% of cars already have electric fans [jury is still out on if this really saves fuel- fwd's went to electric fans for packaging reasons, not efficiency], and probably 80% EPAS).

[GreenHornet]

Originally Posted by oldtamiyaphile

About half of all non-HEV's already offer stop-start and regenerative braking.

Running everything off the battery is only efficient for accessories that have a low duty cycle. Burning petrol to charge a battery is very inefficient and as you switch more accessories to electric recovering enough energy under regen becomes problematic.

Currently yes but in the future car manufacturers will begin to solve the regenerative braking problem with Boost caps instead of batteries which has all ready started to happen.

They have also started to tackle accessories that have a higher duty cycle like AC with solar panel support. Better window glazing, better cabin insulation, and more efficient design will all help to reduce cabin temp fluctuations.

Burning Petrol period currently is inefficient so we have to be creative and selective in when and how we use the resource for maximum efficiency gain with in an entire system strategy.

GH

[Ecky]

Just like to throw out there that I drove 50 miles today to see a cabin for my in-laws to rent next month, and averaged almost 95mpg @ 50mph without doing any P&G or EoC.

I'm sure one could make belt-driven fans, water pumps, power steering, and alternators considerably more efficient without moving them over to electricity, but electricity seems to be "easier" in some ways, and probably more reliable. Rather than a belt, which is a wear item, and a clutch, which requires its own wiring, and possibly even gearing (e.g. to allow a water pump to run at different speed than engine RPM), having an electric motor do the job sounds like a more elegant solution.

The Honda S2000 has electric power steering and an electric fan - how much of a hybrid does that make it? How about a diesel that has electric power brakes, rather than a belt-driven vacuum generator?

Now that you've added a high efficiency motor/generator to replace the alternator and allow for stop-start at redlights in your new car, why not allow that motor to provide a little bit of assist when accelerating, allowing you to downsize the ICE, and improve fuel economy when cruising? Maybe increase your battery size just a bit to give it some extra time to assist? The hybrid battery in Honda's older hybrid system is not actually all that much bigger than some of the 12v batteries you find in trucks and SUVs, it's just higher voltage.

[oldtamiyaphile]

[QUOTE=GreenHornet;473773]Currently yes but in the future car manufacturers will begin to solve the regenerative braking problem with Boost caps instead of batteries which has all ready started to happen. [QUOTE]

My Fiat (ICE) manages to keep up with electrical consumption using regen only, however, it's battery is charged as soon as it gets home. Saying that the water and vacuum pumps are still mechanically driven.

Capacitors can help, but they get large quite quickly, a 'D' cell sized cap only has as much power in it as 'N' size NiMh.

I also wonder how much energy there actually is available in a typical hypermiller braking event. Unless a light changes on me, I usually only brake from around 16mph.

They have also started to tackle accessories that have a higher duty cycle like AC with solar panel support. Better window glazing, better cabin insulation, and more efficient design will all help to reduce cabin temp fluctuations.

Burning Petrol period currently is inefficient so we have to be creative and selective in when and how we use the resource for maximum efficiency gain with in an entire system strategy.

GH

A whole car roof covered in panels has about enough power to run the ventilation fan, but it's a long way short of the 2-3kW required by the A/C compressor.

I've only seen 'improved' A/C efficiency in HEV/EV's because the economy hit from running the A/C kills economy/ range on those vehicles (more so than an ICE it would seem).

Since the efficiency of HVAC isn't part of the EPA tests, OEM's have little interest in making improvements. Mercedes have had double glazing for at least a decade but it's never made it's way into the companies' more basic models. There's also a fair weight penalty there. Of course you can get thermally efficient glass without double glazing, but it's really only a half measure.

[jamesqf]

Originally Posted by oldtamiyaphile

I also wonder how much energy there actually is available in a typical hypermiller braking event. Unless a light changes on me, I usually only brake from around 16mph.

I suppose that depends on what you think of as typical. Your 16 mph with traffic lights sounds like (sub)urban driving, and probably in flat terrain. For me, typical brake/regen is descending a couple thousand vertical feet of mountain roads, with 6% grades or steeper.