# Hybrid school bus RV



## Jbear (Apr 14, 2019)

Hello all, I am new here but have been building EVS for the past 17 years with a total of 57 conversions under my belt. With that said I will have to add that I am an excellent machinist and fabricator having built ground up SCCA GT vehicles for many years and that balloned into EVS but, I am not an electrical engineer and my conversion have been simple conversions using off the shelf materials using special fabrications. Now, I have already converted one bus into an RV that we used to tour the USA and made it all the way to Panama in before selling it to an NGO as a mobile medical clinic. I am now looking at doing it again and want it to be hybrid. I am looking at a 72 passenger bus with a custom 7.3 litre turbo motor in it (est. 12 mpg) and am toying with the idea of making it part time 4wd, but, I would love for it to be hybrid. I know there was a guy on here awhile back that had grandiose (seemingly) ideas of a full electric bus/rv, but, that is not me, I am based in reality (mostly). I was thinking of something like two netgain 13" motors in series using the EMIS system netgain had developed but George tells me it is not available anymore. So I am asking you all if you know of an alternative to achieve my goals or if anyone here has the knowledge and fortitude to assemble such a thing and knows someone that can write the code, for payment of course. I look forward to hearing from one and all.


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## brian_ (Feb 7, 2017)

While novel designs make interesting projects, success is more commonly achieved by generous application of R&D... and by that I mean Ripoff and Duplicate. 

The hybrid medium-duty vehicle is a wheel that doesn't need reinventing.

From a previous (and highly related) discussion:


brian_ said:


> ... I assume that the hybrid E-450 is the Azure Dynamics adaptation of Ford's E-450 stripped commercial chassis to become a parallel hybrid, which they branded as "*Balance Hybrid Electric*". Apparently AZD mounted a 280 volt 130 hp AC (induction) motor in parallel with the stock transmission's output. From the diagram and some descriptions, it that is was a motor with a double-ended shaft, forming part of the propeller shaft (driveshaft) and so running at transmission output / final drive input speed. The final drive ratio (in at least some of them) was 4.56:1.
> 
> 
> 
> ...


Azure Dynamics is long gone, having joined the endless list of companies that have tried to build hybrid and electric commercial vehicles and crashed and burned. Their assets were auctioned off, and their motors are still found occasionally from resellers that got some of the auctioned material; complete vehicles are also out there may still be finding their way into salvage. There would be zero support for anything they did, but there must be knowledge about it somewhere.

At a larger scale, Allison still sells the H 40/50 EP™ Series transmission, which is their commercial version of the GM Two-Mode hybrid system; I'm sure that it would be prohibitively expensive new (if you could even buy it as an individual), but salvage from a scrapped transit bus (where it would typically be used with a Cummins diesel) might be possible. This hybrid transmission is designed as a direct replacement for a conventional automatic, so although it is normally used in "pusher" (rear engine) configurations it would also work in a conventional front-engine layout. The 2009-2013 Chevrolet Silverado and Tahoe (and GMC Sierra and Yukon) hybrids were the same system, but in a lighter-duty version which is probably not adequate for a school bus.


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## The_Sasquatch (Feb 11, 2018)

I am biased (I own one) but would suggest looking into the Smith Electric trucks hitting the market. The drivetrain would move a 57 passenger bus without a ton of added weight, and it would come with 80-120kwh of batteries to start the build with, a 12kwh charger, electro-hydraulic power steering pump + steering box... the list of useful parts goes on, and they are CHEAP right now. 

If I was concerned about range, I would add a generator capable of producing 50+% of my cruise power requirement... probably around 120hp. I am having trouble finding a good estimate of what the 45mph cruise power for a bus is, but 90kw should be a decent %. Add 120kwh of batteries and you will have at least 120ish miles of range, if not more.


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## Jbear (Apr 14, 2019)

Brian, I appreciate your response and the reference to the azure dynamics article, I am well aware of them and their products having used them in the past for two service vehicle conversions before they went tits up. I am not dismissing them out of hand and maybe it is the fact that they are no longer that makes me cautious about searching for anything from them. I agree that maybe re-inventing the wheel is not the best way, but I also would like something a bit more simplistic and home grown as I will be fixing any problems myself maybe in a muddy field in Guatemala (been there done that). What I maybe am looking for more to the point is a way to plug into the computer of the bus and control the controller so the electric motors dont overpower the engine/tranny or underpower them either.


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## Jbear (Apr 14, 2019)

I am not familiar with the Smith trucks, I will look them up. But I probably did not make myself clear in my original post, I am not looking to drive the bus on full electric persaybut am looking to assist the T444 engine from dead start to say 25 mph and possibly if I can work outthe electronics be able to bring the motors into play on long ardous hills.


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## brian_ (Feb 7, 2017)

Jbear said:


> Brian, I appreciate your response and the reference to the azure dynamics article, I am well aware of them and their products having used them in the past for two service vehicle conversions before they went tits up. I am not dismissing them out of hand and maybe it is the fact that they are no longer that makes me cautious about searching for anything from them. I agree that maybe re-inventing the wheel is not the best way, but I also would like something a bit more simplistic and home grown as I will be fixing any problems myself maybe in a muddy field in Guatemala (been there done that).


Even if you don't use any AZD parts (and I understand wanting to avoid any of their proprietary electronics), there won't be anything physically simpler than a parallel connection of a motor in the driveshaft like they used. If you don't want to make a double-ended motor work, you could use a divorced offset-type transfer case with the transmission output connected to what is normally the front output, and the transfer case left in 4WD. If you don't want to run the motor as slowly as driveshaft speed, you can run the transfer case in low range (if it is okay with that at highway speed, and straight-cut gears don't drive you crazy with noise).



Jbear said:


> What I maybe am looking for more to the point is a way to plug into the computer of the bus and control the controller so the electric motors dont overpower the engine/tranny or underpower them either.


That's pretty much what the AZD system does, right? It worked with Ford's engine, transmission, and controls. It should be possible to do this with custom code.


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## Jbear (Apr 14, 2019)

Brian, its been a long day for me, been up since 3 a.m. so I am a bit fuzzy at the moment. but first I want to thank you very much for contributing!! You state when you talk about the AZD system as in parallel, meaning I believe side by side (and I may not be thinking clearly at the moment) What I was envisioning was (if, and I think I will) I go 4wd, I do not want the front drive shaft to be to long and therefore potentially weaker (by mounting a divorced transfer case if I do not have to) So I will mount the transfer case to the 545 tranny and put the motor(s) in series off of the case. Am I making sense here and please tell me if I am not as I am working through it in my head first. And yes, thats what the AZD system does as far as the quote you put in. I just don't know how viable it is to recode their brains and whom I would actually get to do it.


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## brian_ (Feb 7, 2017)

The_Sasquatch said:


> I am biased (I own one) but would suggest looking into the Smith Electric trucks hitting the market. The drivetrain would move a 57 passenger bus without a ton of added weight, and it would come with 80-120kwh of batteries to start the build with, a 12kwh charger, electro-hydraulic power steering pump + steering box... the list of useful parts goes on, and they are CHEAP right now.
> 
> If I was concerned about range, I would add a generator capable of producing 50+% of my cruise power requirement... probably around 120hp. I am having trouble finding a good estimate of what the 45mph cruise power for a bus is, but 90kw should be a decent %. Add 120kwh of batteries and you will have at least 120ish miles of range, if not more.


With the added generator this is a series hybrid. While it would work, it would almost certainly be less efficient than a parallel hybrid, and probably less efficient than the original non-hybrid vehicle.

90 kW for 90 km/h is one kilowatt-hour per kilometre, which is about right. An engine designed for hybrid service (such as the pseudo-Atkinson variants in Toyotas, indicated by "-FXE" at the end of the engine model) kept at its optimal speed would be ideal. It would take a decent size engine (certainly more than the 1.8 to 2.5 litres of the four-cylinders used in Toyota hybrids) to be a peak efficiency while producing as much as 90 kW. Maybe the 2GR-FXE of the Highlander Hybrid?



Jbear said:


> I am not familiar with the Smith trucks, I will look them up.


Smith Electric was an old company that started when electric trucks were new (a century ago) and was eventually killed by trying to produce a modern battery-electric truck. They put their powertrain (a motor they bought from somebody and battery packs from somebody else plus their proprietary electronics) in "gliders" (new trucks without engine and transmission) from regular truck manufacturers. The Newton used a medium-duty forward-cab truck from a Czech manufacturer; there was even a school bus version.


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## brian_ (Feb 7, 2017)

Jbear said:


> You state when you talk about the AZD system as in parallel, meaning I believe side by side (and I may not be thinking clearly at the moment)...


Briefly reviewing hybrid terminology:
Hybrid configurations are classified by the path of the power, from source to wheels.

In a series hybrid, all power from the engine goes through the electric system: the power flows through the engine and electric motor in series. There is no way to get power from the engine to the wheels except by running the generator to produce electrical power for the motor.
In a parallel hybrid, the engine (plus transmission) and the electric system (battery and motor) are both mechanically connected to the wheels; they can deliver different amounts of power at the same time. That means that either one can drive the vehicle, separately or in combination.
There are hybrid vehicles which can switch multiple power flow configurations, and others that split the flow of power between a series path and a mechanical path (mixed-mode or power-split designs, such as the Toyota and GM Two-Mode designs).
There are many possible physical configurations, so without seeing what shaft connects to what, it can be hard to tell whether a particular configuration functions as a series or parallel or mixed mode hybrid.

Since the desire here is apparently to be able to operate on engine power without using the electric powertrain, a parallel hybrid is the target.



Jbear said:


> What I was envisioning was (if, and I think I will) I go 4wd, I do not want the front drive shaft to be to long and therefore potentially weaker (by mounting a divorced transfer case if I do not have to)


My divorced transfer case example was using a transfer case just to combine the engine and motor outputs, without building a custom gearbox; it wouldn't provide 4WD.



Jbear said:


> So I will mount the transfer case to the 545 tranny and put the motor(s) in series off of the case. Am I making sense here and please tell me if I am not as I am working through it in my head first.


That works. Keep in mind that inline with a shaft is not the same as a series hybrid. The motor could be on the rear output of the transfer case inline with the shaft to the rear axle (as long as the transfer case is in 4WD, even with the transmission or transfer case range shift in neutral the motor would still drive the front through the transfer case). As an alternative, with some transfer cases (generally all-gear offset designs) it could be at the PTO port (it would put power in where power is usually taken out to drive stuff such as winches or hydraulic pumps).

We have had some recent discussions of potential arrangements with transfer cases. I didn't realize until I did a search just now how often "transfer case" comes up in DIYElectricCar discussions, and some of them are hybrid proposals... but few if any are actually built. In _Planning 1975 Volvo c304 electric expedition camper_, if you jump into the middle at post #35 (to avoid a bunch of fascinating but irrelevant stuff about obscure Volvo trucks) you can follow a few posts of transfer case discussion.



Jbear said:


> And yes, thats what the AZD system does as far as the quote you put in. I just don't know how viable it is to recode their brains and whom I would actually get to do it.


I agree: unless you have good documentation and the software tools used by the AZD developers, making it work differently from the original would be a problem. If you are not able to do that, you can only copy the general configuration, not the actual electronic components.


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## Jbear (Apr 14, 2019)

Brian,


Thank you for the lesson and food for thought, I was contemplating in regards to the 4wd only driving the rear wheels hence the motor(s) being mounted after the transfer case but upon reflection.. why not divorce the transfer case which minimizes the troubles possibly having to manufacture a engine/transmission mounting plate, possibly eases the pain of having to drop a broken transmission by not having to unmount the transfer case with it and since it is part timefour wheel drive the front shaft will not be turning all the time with the hubs unlocked so shaft length is not hyper critical. that way the motor(s) can be mounted between the trans and transfer cases so they can be utilized in both 2wd and 4wd modes but in order to keep my path the shortest I am going to have to switch to AC motors in a pancake design. hmmmm.. but now I am still back at controlling them in unison to the transmission speed which means that I do not have to utilize the ems system but the transmission control algorithim/shift points instead. I love how you all are making me think and re-think this, I am still just not well enough versed electrical engineering wise to know how to go about that problem though....


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## Jbear (Apr 14, 2019)

Brian, question, after the rig reaches motor cut out speed say... second gear (20 mph +) the motors will be able to act as generators to recharge the batteries correct (being rotated by the ICE)? But if so, that begs the question of would the drag being generated by charging negate the benefits of uzing motors to start the rig from a dead stop?


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## brian_ (Feb 7, 2017)

Jbear said:


> Brian, question, after the rig reaches motor cut out speed say... second gear (20 mph +) the motors will be able to act as generators to recharge the batteries correct (being rotated by the ICE)? But if so, that begs the question of would the drag being generated by charging negate the benefits of uzing motors to start the rig from a dead stop?


Yes, motors work about equally well as generators. In a non-plug-in hybrid, all of the energy comes from the engine, so all of the energy that goes into the battery (other than a bit from regenerative braking) comes from running a generator (normally a motor as a generator) with the engine. Since there is inefficiency (and thus energy loss) in every stage of generating, storing the generated electrical energy in the battery, getting the energy back out of the battery, and running the motor, this is all pointless and just causes more fuel consumption *unless* the hybrid system helps the engine run more efficiently. This more efficient engine operation can be due to:

meeting high power requirement with the help of the battery and electric motor enables the use of a smaller engine which runs more efficiently during moderate power requirement situations (cruising), or
running the engine at a more consistent and moderate power level, instead of running at high power to accelerate and just idling when decelerating.
I think a more sophisticated control method than just "on while accelerating at low speed" would be required to achieve either of these improvements. Certainly you don't want the motor to switch to generating while still accelerating, just because you passed a speed threshold. Even in the most advanced production vehicles, hybrids generally help fuel economy only in urban conditions; in highway use, the extra weight and moving parts approximately negates any advantage of better engine operation.


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## Jbear (Apr 14, 2019)

So, what I am taking away is that my idea (done my way) is just not beneficial in the long run. I wonder if that is why the EMIS system from NetGain Tech stopped being as that is where i was getting my idea to emulate.


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