Why aren't diesel hybrids being used?

[nthach]

Originally Posted By: oil_film_movies
Cost, weight, and emissions control system complexity are too much with a diesel in car hybrid applications.
You do see hybrid transit buses using diesel engines.

And while those are expensive and not without issues, San Francisco's Muni is having problems with their BAE Systems HybriDrive-equipped New Flyers, the Allisons aren't perfect either. The Cummins ISB6.7 in those do spin constantly, since it's a series hybrid system in which the diesel engine drives a generator which in turn turns the motor for the drive wheels, but it behaves closer to Honda's IMA system.

The Allison system is closer to a Prius, in being a parallel-split hybrid system. I think SF is leaning towards those for their bigger buses to cope with heavy passenger loads.

 

[nthach]

Originally Posted By: PandaBear
Originally Posted By: mx5miata
I would like go see a hybrid with propane generator like the city transit bus


Last time I check bus use CNG instead of propane.

CNG hasn't caught on in the Bay Area, although I did see a SolTrans(Vallejo/Benicia) CNG MCI D4500 commuter coach pull into El Cerrito Del Norte BART a few weeks ago. But that bus is underpowered for a almost 60,000lb bus built for the highway with a 380HP Cummins ISL G natural gas engine, while the diesel versions come with a 425HP Cummins ISX12. MCI made the CNG concession to score orders from LA/Orange County and other CNG-dominant regions.

Sure, a 60-foot articulated bus makes do with a 300-330HP engine but city traffic is different than being able to comfortably cruise and accelerate when needed.

 

[Shannow]

Originally Posted By: KrisZ
Must be some funny/selective math going on with the 99% efficiency claims for li-ion batteries.


Yes, as I stated, the Tesla 100MW 129MWh Battery gives back 800KWh for every MWh that it takes in.

That's in a purely electric environment, no conversion to tractive effort.

Repeating a falsity (99%) over and over neither makes it the truth, or conjures it into being.

 

[OilFilters]

Originally Posted By: oil_film_movies
However, losses on the order of 10% do happen in the charging electronics & generator (kinetic energy to electrical energy conversion).

Therefore, as you drive a hybrid, every time you re-gen brake and/or drive a generator with an IC engine, you can assume around 10% loss there.
Input electrical wire energy to a Li-ion battery only loses about 1%, but note that is from the input wire to the internal battery guts.


There is no electronics in between the battery and charging. If you are feeding it direct DC, as comes from regenerative braking, then it goes straight into the battery. There is no 10% loss. The electronics monitor the battery for temperature and voltage, if either gets too high they shut it off. They are not burning 10% of the input.

If you had to convert from AC to DC and then back again, and change the voltage, yes, there would be more losses, but still not likely 10%.

Originally Posted By: supton
Li-ion batteries don't heat up when charging? Is that true for fast charge also?

I'm a bit dubious--if the battery has to have thermal management, then I question how efficient it is.


It depends on the charge speed and battery's state of charge. Hybrid cars don't run the batteries down to zero and then recharge them to full. They work roughly in the 40-80% range. This is where it is most efficient to charge them and creates the least heat. If you charge a lithium battery slowly, it does not heat up. It also does not get very warm until it's around 80% full. The losses get higher after this point. Regenerative braking can get away with higher charge rates because it uses quick pulses, and the battery stays cool.

I'm not sure why we're arguing about battery effectiveness on hybrids - it's already been proven by several manufacturers that gasoline hybrids with lithium batteries and regenerative breaking can make the car significantly more efficient. The battery side would be no different in a diesel.

 

[PeterPolyol]

Just a heads up Mr Filters there is still loss with DC-DC conversions, as well as the usual conductor and inductive losses. That implies that yes, there is certainly electronics between battery and charge source. Batteries are a funny thing and they need charge management, thus some type of regulator in the form of DC-DC converters. Indeed, batteries can only accept a certain amount of energy in a certain period of time before losses and thus efficiency skyrocket and plummet respectively, and the very circuitry responsible for managing charge input, the DC-DC converter is lossy too, on top of the heat lost by the battery cells during the (chemical) process of charging. Relatively speaking, the modern power converters are decently efficient.

 

[oil_film_movies]

Originally Posted By: OilFilters
There is no electronics in between the battery and charging. If you are feeding it direct DC, as comes from regenerative braking, then it goes straight into the battery. There is no 10% loss.
There is about a 10% loss in a generator, which you need to convert re-gen braking and/or IC engine kinetic energy to electricity. And, yes, there are signal conditioning and charging electronics on that path before it reaches the battery. Heat losses.

Still not understanding? Imagine you're pedaling a stationary bicycle, and you have a battery. You must have a generator between your bicycle and the battery, which has energy losses.

 

[OilFilters]

I understand the battery technology just fine...there is no 10% loss on from charging lithium batteries. Period. I am not talking about output losses. There is not a DC-DC converter being used during regenerative braking, but even if there was they are often in the 96+% efficiency range.

Again, even with any losses, hybrid technology has already proven to be more efficient than all the loses you find in a standard gas only car and drivetrain - that was more than a decade ago. New batteries, new electric motors, and new electronic controls are only getting more efficient. The first Prius used NiMh batteries, and older motor and electronics, which are less efficient, but still overall was a more efficient car.

Say you have 1000 watts coming in from regenerative braking. You will get 990 watts back out when you use lithium batteries. Way more efficient than any other type of battery system.

 

[PeterPolyol]

Originally Posted By: oil_film_movies

Still not understanding? Imagine you're pedaling a stationary bicycle, and you have a battery. You must have a generator between your bicycle and the battery, which has energy losses.


Sure man, there are energy losses all around; friction in joint cartilage, energy metabolism, all the bike bearings and chain

 

[nthach]

Originally Posted By: OilFilters

I'm not sure why we're arguing about battery effectiveness on hybrids - it's already been proven by several manufacturers that gasoline hybrids with lithium batteries and regenerative breaking can make the car significantly more efficient. The battery side would be no different in a diesel.

I don't know if the automakers will spring for ultracapacitors for electrochemical storage. Capacitors can charge and discharge quickly and they aren't as prone to the exothermic losses/dangers or cold weather sensitivity as Li-based technologies. But as we all know from Taiwanese capacitor syndrome, when a capacitor fails it fails slowly and silently but sometimes spectacularly like a lithium battery. Toyota's THSII(Hybrid Synergy Drive/Lexus Hybrid Drive) does have a few large capacitors in the hybrid inverter for "precharge" to get the IGBTs going.

It has been tried out in buses, as there was a system that ISE was marketing using the Ford Triton V10, a motor/generator pair supplied by Siemens and Maxwell(not to be confused with Hitachi Maxell) UltraCaps in a ultracapacitor bank. The ISE system was a flop, but it looks like BAE Systems is pushing the ultracap idea to the bus OEMs(and transit authorities as well).

 

[PeterPolyol]

EDLCs integrated into hybrid systems are the future. I remember posting about it ten years ago, then few years later Mazda is installing them in cars (i-Eloop). It only makes sense to use them in hybrid systems, beyond simple smoothing duties. They can potentially increase battery life (reduce short cycle throughput) and increase regen efficiency when combined with suitable logic control. Don't know why it's not more common?

 

[lovcom]

Originally Posted By: PeterPolyol
Originally Posted By: lovcom

Perhaps you fixed thousands of bum Toyota's, but if you look at the statistics over MILLIONS of them, you too will agree that they are the most dependable in the history of cars.

I too laugh...when people base their conclusions on a very small sample.


When it comes to Toyota, I too mindlessly and religiously subscribe to polls and "statistics" ignoring and disqualifying my own obvious sensibilities, because polls and "statistics" would never be used to influence public opinion- especially not when there is a 6B dollar campaign behind it all. Also, Hollary Clintron is doing a mighty fine job as President.....


Hehe. You guys can enjoy your delusions, just kindly please keep them to yourselves

Not all statistics are wrong.

You sound like the tobacco companies in the old days who maintained "the statistics that smoking can cause lung cancer are bias and flawed"...

 

[mightymousetech]

There are some.

https://www.caranddriver.com/reviews/2017-audi-q7-e-tron-tdi-plug-in-hybrid-first-drive-review