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12 hours ago, MiWay0310 said:

That too, but I did some more snooping around, and I found out exactly where I got it from. Old news, but here goes:

https://www.busworld.org/articles/detail/1163

I'm surprised why parallel systems haven't gotten as popular as serial hybrids...I mean sure, a BAE is fine on downtown routes, but have you ever heard one of those things at 45+ kph? I haven't even mentioned the highway. Quite sure a parallel would be more fuel efficient, especially, say a parallel B500R at higher speeds.

In theory, a serial hybrid system will be far more efficient than a parallel one. Electric transmissions are always much more efficient than mechanical ones. The internal combustion engine is free to operate at its most optimal range of speeds, rather than being tied to a factor of the road speed of the vehicle.

 

The problem is with the components. Allison has been making transmissions for about a hundred years, so they have a very good handle on what needs to be done to make it reliable. (And the same goes for Voith and anyone else making parallel hybrid systems.) And adding two small electric motors isn't going to drastically change the construction, quality, form factor or utility of that transmission - at its core, it's still just a mechanical transmission.

 

Serial hybrids, however, are a much newer concept in the form factor required to fit a bus or motorcoach, and so it's been a tougher thing to design and fit the various devices into the spaces available - and more so still to get them mature enough to be reliable for every day use.

 

Dan

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2 hours ago, MiWay0310 said:

Won't parallel systems require some sort of plug-in capability, since the diesel motor isn't acting as a generator?

I believe parallel system hybrid buses that exist today are essentially traditional vehicles, just with a small battery for storing braking energy and a small electric motor to put the energy to use for acceleration. Its like a traditional Prius--not a battery electric vehicle.

Volvo does have plug-in hybrid buses in Europe, but I believe they use a series, not a parallel system. They are primarily electric vehicles.

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20 hours ago, MiWay0310 said:

I'm surprised why parallel systems haven't gotten as popular as serial hybrids...I mean sure, a BAE is fine on downtown routes, but have you ever heard one of those things at 45+ kph? I haven't even mentioned the highway. Quite sure a parallel would be more fuel efficient, especially, say a parallel B500R at higher speeds.

Who said parallels aren't as popular? Outside of Quebec and places like Toronto, NYC, San Fransisco, and Seattle, most hybrid buses that I know of use parallel systems. Think of how many smaller US systems have gotten Gilligs with the Allison System (not to mention the larger systems that have also ordered Allison Hybrid buses).

As you said, how a system plans to use a hybrid bus should be a factor in determining which system to buy (although this isn't always the case). Series hybrid buses are better suited for downtown or neighborhood routes with lower speeds and frequent stops. Parallel hybrid buses have more of an advantage when it comes to suburban routes with higher speeds and less stops.

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4 hours ago, WMATAC40LF said:

Who said parallels aren't as popular? Outside of Quebec and places like Toronto, NYC, San Fransisco, and Seattle, most hybrid buses that I know of use parallel systems. Think of how many smaller US systems have gotten Gilligs with the Allison System (not to mention the larger systems that have also ordered Allison Hybrid buses).

I have no idea why I didn't mention, or even acknowledge the Allison Ep Series (been kinda distracted recently), but yes, usually suburban-focused systems go with the parallels. Don't forget NYC on the list of series hybrids though. 

4 hours ago, WMATAC40LF said:

Parallel hybrid buses have more of an advantage when it comes to suburban routes with higher speeds and less stops.

Many drivers seem to like the smoothness of parallels at higher speeds. 

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4 hours ago, MiWay0310 said:

I have no idea why I didn't mention, or even acknowledge the Allison Ep Series (been kinda distracted recently), but yes, usually suburban-focused systems go with the parallels. Don't forget NYC on the list of series hybrids though. 

Many drivers seem to like the smoothness of parallels at higher speeds. 

I'm prepared to call bullshit on that. At higher speeds does the Allison Ep not operate in a strictly diesel mode, therefore, shifts like any other transmission, negating any benefits of a electric transmission? Certainly, at the lower end where the electic motor is in use for propulsion it's a bit smoother.

Anyone have a link to Voith's hybrid parallel products? I couldn't find one. Greatly appreciated.

Personally, I think the parelllel hyrbid is a crock of crap.

I get the series hybrid and think it's the best concept. and, indeed perhaps a bridge to fully electric buses (ie substitute the engine for more batteries). 

The series hybrid drivetrain is pretty much a diesel engine, battery pack, electric motor at it's simplest form. The problem I foresee with the parallel concept is you're now looking at diesel engine, battery pack, electric motors and a transmission device. Therefore, it seems more complicated than either a straight diesel or series hybrid, not withstanding the learning curve of designing a series hybrid in the first place. The question at the end of the day, for any hybrid bus, is are the (alleged) cost savings actually worth the capital cost? Ask Saskatoon how hybrid Allison's have worked out since they've retired at least one bus due to battery failure and them not wanting to put out the cost for a replacement....

It seems to me that BAE has been gaining market share from Allison.

FWIW, my personal opionon is that the parellel hybrid, as employed by Allison, was a ploy to stay relevent in a changing industry. In retrospect, hybrids haven't taken off like they were promised they would, and as a result Allison still provides a large amount of conventional transmissions.

I'm quite curious what could have become of Allison's Es Series hybrid concept, although, I suspect it never had much of a chance once they got the Ep series on the market.

14 hours ago, MiWay0310 said:

Won't parallel systems require some sort of plug-in capability, since the diesel motor isn't acting as a generator?

No. You're overthinking this.

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15 hours ago, M. Parsons said:

I'm prepared to call bullshit on that. At higher speeds does the Allison Ep not operate in a strictly diesel mode, therefore, shifts like any other transmission, negating any benefits of a electric transmission? Certainly, at the lower end where the electic motor is in use for propulsion it's a bit smoother.

Apologies, I could have clarified more. That statement was based off me asking multiple GO Transit drivers on their driving experience regarding the D4500CTHs, the 3xxx units. I found all round compliments, saying they were smooth on the highway. Obviously everyone's experience may be different in some way, but this was generally what I found. Perhaps other agencies have the system programmed differently, like the BAE HDS. 

17 hours ago, M. Parsons said:

Anyone have a link to Voith's hybrid parallel products? I couldn't find one. Greatly appreciated.

Wasn't able to find much in terms of a product site, except for this report from Voith itself. The DIWAh was tested by BOGESTRA AG of Bochum in Germany exclusively on Solaris 18s. 

http://www.voith.com/ca-en/insights/urbanization/a-report-from-germany-23347.html

Also a report from Autoblog containing some information on the specs of the system:

https://www.autoblog.com/2011/03/30/meet-the-articulating-solaris-urbino-18-diwa-hybrid-city-bus/

Just as a side note, that thing made nearly 400hp with an electrically assisted ISB. (!!!!)

17 hours ago, M. Parsons said:

I get the series hybrid and think it's the best concept. and, indeed perhaps a bridge to fully electric buses (ie substitute the engine for more batteries). 

The series hybrid drivetrain is pretty much a diesel engine, battery pack, electric motor at it's simplest form. The problem I foresee with the parallel concept is you're now looking at diesel engine, battery pack, electric motors and a transmission device. Therefore, it seems more complicated than either a straight diesel or series hybrid, not withstanding the learning curve of designing a series hybrid in the first place.

Agreed; however, the parallel is a very attractive option for agencies who'd like to equip their buses that run higher speed trips/highway routes etc. I'm almost certain a BAE HDS will not have the best highway fuel economy when compared to an Ep4/5/60, let alone a six speed Allison. We aren't even talking about driver and passenger experience here either. 

And yes, agreed, the parallels are likely to be more complicated. 

17 hours ago, M. Parsons said:

The question at the end of the day, for any hybrid bus, is are the (alleged) cost savings actually worth the capital cost?

I know that in Altoona tests, the hybrids only seem to score marginally better than their diesel counter parts, disregarding traffic and other real world issues, I don't think there is a huge fuel benefit when compared to a newer diesel. And I know the mid-life battery replacement is quite costly. 

17 hours ago, M. Parsons said:

No. You're overthinking this.

Supercapacitors!

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34 minutes ago, MiWay0310 said:

Wasn't able to find much in terms of a product site, except for this report from Voith itself. The DIWAh was tested by BOGESTRA AG of Bochum in Germany exclusively on Solaris 18s. 

Agreed; however, the parallel is a very attractive option for agencies who'd like to equip their buses that run higher speed trips/highway routes etc. I'm almost certain a BAE HDS will not have the best highway fuel economy when compared to an Ep4/5/60, let alone a six speed Allison. We aren't even talking about driver and passenger experience here either. 

I know that in Altoona tests, the hybrids only seem to score marginally better than their diesel counter parts, disregarding traffic and other real world issues, I don't think there is a huge fuel benefit when compared to a newer diesel. And I know the mid-life battery replacement is quite costly. 

My point for asking about the Voith is the fact I couldn't find any current information either. I remember when they brought it out many years ago towards the end of the start of the hybrid hype (if that makes sense- they were late to the game in North America). Me thinks it might have already been discontinued. I don't think it made it into any North American buses, save for maybe a manufacture demo or two, but I don't even recall any of those off the top of my head.

Agreed that a parallel might be better in higher speed operation than a series, but, I think again this is where you really need to see what the actual cost advantages are of a hybrid over a diesel.

It seems to me with the parallel you save fuel at the lower speeds, using electric propulsion to help get the bus up to speed where the transmission transitions to full mechanical operation from electric and blended modes. There fore, at higher operating speeds you're not necessarily saving fuel vs. a straight diesel. Sure, you'll save some during starting/ stopping, but, with a operation like GO, there's going to be less starting/ stopping during which to make use of the hybrid component. Add to that, you're now lugging around batteries and electric motors, so, I'd hazard a guess that if you were to compare a diesel to a hybrid at highway crusing speed, that hybrid could have reduced fuel efficiency on account of the extra weight vs. a diesel.

Given King County Metro's operation (lots of highway runs as I recall), I'm curious how those BAE hybrids are doing vs the older fleet with Allison parallel drives and what sort of decision went into choosing BAE, and how things like fuel economy will play out in the long run. I think BAE is offering more innovative features than Allison, or at least that's the impression I get from viewing their websites. Granted, BAE's bus industry applications deal only with hybrid drives, while hybrids are a small faction for Allison, and therefore BAE is probably spending more time, effort, and R&D on hybrids than Allision is. That's pure speculation mind you. 

ETS's testing was perhaps one of the better sets of testing out there as they compared series, parallel, diesel, and trolley and buses they owned (and leased in the case of the trolley). The testing should have included 2 types of series hybrid (BAE and ISE), but, the ISE's kinda shit the bed (and have since been converted to diesel). As I recall, for the diesel options, the BAE series was the most efficient, but, not anywhere near manufacturer claims.

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9 minutes ago, M. Parsons said:

My point for asking about the Voith is the fact I couldn't find any current information either. I remember when they brought it out many years ago towards the end of the start of the hybrid hype (if that makes sense- they were late to the game in North America). Me thinks it might have already been discontinued. I don't think it made it into any North American buses, save for maybe a manufacture demo or two, but I don't even recall any of those off the top of my head.

Yeah, I don't think it got as popular as Voith had hoped....which is too bad since it seemed like a great idea. I'm quite sure it is discontinued, because I never heard of it after the testing in Bochum. And I don't think it ever made it here either, which is odd considering how popular the DIWA transmissions are in North America, let alone hybrids.

13 minutes ago, M. Parsons said:

Agreed that a parallel might be better in higher speed operation than a series, but, I think again this is where you really need to see what the actual cost advantages are of a hybrid over a diesel.

It seems to me with the parallel you save fuel at the lower speeds, using electric propulsion to help get the bus up to speed where the transmission transitions to full mechanical operation from electric and blended modes.

You're right about lower speeds. I bet the Ep series get the same, or very close fuel economy readings on the highway as the B4/500Rs in sixth. Especially with an active limiter. 

And since you bring up fuel savings at lower speeds, I'm surprised more operators didn't go with the Ep rather than the HDS, considering the fact that the HDS generally starts to rev up at a lower speed than than the Ep systems. But again, this also depends on how the HDS is programmed. 

17 minutes ago, M. Parsons said:

There fore, at higher operating speeds you're not necessarily saving fuel vs. a straight diesel. Sure, you'll save some during starting/ stopping, but, with a operation like GO, there's going to be less starting/ stopping during which to make use of the hybrid component. Add to that, you're now lugging around batteries and electric motors, so, I'd hazard a guess that if you were to compare a diesel to a hybrid at highway crusing speed, that hybrid could have reduced fuel efficiency on account of the extra weight vs. a diesel.

And I'm quite confident that's the reason why GO never ordered more CTHs.

19 minutes ago, M. Parsons said:

As I recall, for the diesel options, the BAE series was the most efficient, but, not anywhere near manufacturer claims.

Not anywhere near manufacturer claims, and also disappointingly close to their diesel competitors. 

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