Crown Bus Electric Conversion

[JoeNesquik]

You’re stuck in brand bias land. Like a truck owner. “My brand is better than brand b because of [unsupported false claim] and it’ll always be better.” Why Tesla?

 

[kazetsukai]

I think is doable a Tesla motor has 750 HP and I am planning to put 2.

What about actual torque? Do you know what a Tesla weighs? What a bus weighs? Have you thought at all about what your duty cycle might look like with an older, much heavier constructed bus weight versus the (by comparison) space-age lightness of a model S?


It seems to me you are dismissing anyone who challenges this idea from a pragmatic standpoint. You're not going to get far anywhere, with anyone, doing that. It has nothing to do with liking or disliking something, or "hate". We don't know what your expected/top end budget is, what performance metrics you're trying to achieve, anything. Most people, rightfully, are questioning whether there's any realism whatsoever in your question.


You can take the pragmatic challenges head-on like an engineer or you can ignore them like an academic romanticist.

 

[Sleddgracer]

What about actual torque? Do you know what a Tesla weighs? What a bus weighs? Have you thought at all about what your duty cycle might look like with an older, much heavier constructed bus weight versus the (by comparison) space-age lightness of a model S?


It seems to me you are dismissing anyone who challenges this idea from a pragmatic standpoint. You're not going to get far anywhere, with anyone, doing that. It has nothing to do with liking or disliking something, or "hate". We don't know what your expected/top end budget is, what performance metrics you're trying to achieve, anything. Most people, rightfully, are questioning whether there's any realism whatsoever in your question.


You can take the pragmatic challenges head-on like an engineer or you can ignore them like an academic romanticist.

I did read that the Tesla motor produces a large amount of torque , somewhere between 700 - 900 fp if I remember correctly

 

[kazetsukai]

I did read that the Tesla motor produces a large amount of torque , somewhere between 700 - 900 fp if I remember correctly

Lets be real: 750HP is 559kW, which means you need at least that in power draw even if the motor was 100% efficient. Now imagine pulling that at even 50% duty cycle with the most efficient motors available. Even at 600V that's well over 1000A! You'll be melting motors and cables.


Dyno TESTS are not real life. There's an assumed acceptable range for normal, day-to-day operation and these motors are spec'd with that in mind.

 

[Sleddgracer]

off the top I don't see any reason it couldn't be done - back yard mechanics are converting cars to electric for years - the electric motors have ample horsepower and torque to move a bus around, with acceleration better than gas or diesel - the big problems I see is the cost, range, and access to charging - there have been some commercial buses sold to school boards that didn't work out well - the technology is new and more failures than successes can be expected at first - but the time is coming that electric buses will be common

 

[kazetsukai]

the technology is new and more failures than successes can be expected at first - but the time is coming that electric buses will be common

This is entirely separate from the question as to whether one can slap A pair of model S (4300lb after 1000lb of ~80kWh batteries) motors into a 15000lb-25000lb (before adding batteries) vehicle and make it work, well.

Look at the torque /current curves for these motors as well- when you're not strictly maintaining speed you are munching >1kW/minute. You need a battery array measured in MW, not kW.

 

[Sleddgracer]

This is entirely separate from the question as to whether one can slap A pair of model S (4300lb after 1000lb of ~80kWh batteries) motors into a 15000lb-25000lb (before adding batteries) vehicle and make it work, well.

Look at the torque /current curves for these motors as well- when you're not strictly maintaining speed you are munching >1kW/minute. You need a battery array measured in MW, not kW.

it's obviously not impossible to do, seeing as there are electric buses on the road now with impressive range and power

 

[joeblack5]

prorally driver.. i took the liberty to look at flea bay auctions. There are several S motor out there. they seem to have two motors on each side of the transaxle. The transaxle has a single speed gear box ( all you need as i know from experience) I believe the ratio is about 1;10... about the same as i have in the solectria.



I would imagine taking a whole assembly like that and and locking the differential inside the transaxle. take an old tesla drive shaft and and mate it to the U joint to the differential.


If more power is needed then you just take a second transaxle with another two motors and connect that to the "other side "of the first transaxle.




It looks like the torque Tesla motors have is immense so my gut feeling is that it will hold up. Running the torque and Rpm numbers would make sense though.


Regarding you question about our BMS systems.


I am cheap and lazy so wiring up a BMS for 48 cells ( 192 Volt nominal) is a lot of work. I drove this solectria force with a split nissan leaf pack ) 2 sets of 48 serie cells in parallel, doubling the AH and halving the original voltage ( 384 Volt) of the pack. I adapted an original nissan leaf BMS to halve voltage and with an OBD2 on bluetooth can read out the individual cells . The BMS takes only care of the balancing. I am responsible for not discharging it to far. I re-programmed the Solectria charger to a max voltage of 192 volt ( 4.0 Voltage per cell) to stay on the safe side of the 4.2Volt..



A purpose bought BMS is fairly expensive and as I said a lot of work to hook up.


A normal 240 / 50 amp outlet will do a lot of charging overnight.
With one large tesla pack being 100KWH it would take above outlet about 8 hours to fully charge that.

It will depend on your mission what range and in what time frame you want to get there.




For our car I use a normal outlet 120 VAC . It take about 7 Amps.. and i am not in a hurry.



With tesla using a lot more cells in parallel it would be best to use their BMS charging elecronics.



Good luck,


Johan

 

[Kubla]

The problem is not the power of the motors, but whether than can dissipate the heat generated operating constantly at 6 to 7 times their designed running load, I think he should use the motors already in use in electric buses or trucks since they are designed for that load

 

[joeblack5]

Could be, hard to tell. If flat road running power requires 100hp and the motor is 90% efficient the you only need to cool 10hp or 7.6kw. That is not a lot and with some additional airflow or some copper tube around the motor pretty easily doable.

the availability and cost of industrial bus motors in this category is limited.
Using a whole Tesla package deal is very appealing. that the primary transmission is already included makes it even better.

The bus will loose a lot of weight without the old style diesel and transmission.

You will need an auxiliary heater to stay warm in the winter.. That 7.6kwatt of heat you need to shed is not enough to keep the windshield defogger.

Where are you located?

Johan

 

[prorallydriver]

So go buy 2 brand new tesla's of whatever flavor you choose. "Harvest" all applicable componentry that you'll need to attach to your bus.
That way you'll have the VIN'S to get factory support for your efforts?

Otherwise develop your own EV drivetrain based on a copy of tesla.

What are the other EV manufacturers using for real world recharging stations?
(assuming that is your issue?)

Buying 2 Model S P100D are around $100k+ each. If I buy the motor and the battery pack separately is $30k.

There are maybe 2 or 3 Max but they are not even near Tesla Technology.

 

[prorallydriver]

I do not have an opinion about your project it is your time and your money so rock on. As a question though, how do you plan to charge it?

I am thinking about the same thing. Because Tesla is not going to let me use its Supercharger Network that is for sure.

 

[prorallydriver]

What about actual torque? Do you know what a Tesla weighs? What a bus weighs? Have you thought at all about what your duty cycle might look like with an older, much heavier constructed bus weight versus the (by comparison) space-age lightness of a model S?


It seems to me you are dismissing anyone who challenges this idea from a pragmatic standpoint. You're not going to get far anywhere, with anyone, doing that. It has nothing to do with liking or disliking something, or "hate". We don't know what your expected/top end budget is, what performance metrics you're trying to achieve, anything. Most people, rightfully, are questioning whether there's any realism whatsoever in your question.


You can take the pragmatic challenges head-on like an engineer or you can ignore them like an academic romanticist.

Sure, you are right. But do me a favor read my question and read the comments is very easy to understand. Pragmatic? I don't mind at all but they are not right. I asked the question and I need a response from helpful experienced people.

 

[JoeNesquik]

Nobody has done this. You’d be better off buying a Thomas joules and adding an extra battery pack. Cheaper probably, easier, and no need to wreck a crown.

 

[prorallydriver]

off the top I don't see any reason it couldn't be done - back yard mechanics are converting cars to electric for years - the electric motors have ample horsepower and torque to move a bus around, with acceleration better than gas or diesel - the big problems I see is the cost, range, and access to charging - there have been some commercial buses sold to school boards that didn't work out well - the technology is new and more failures than successes can be expected at first - but the time is coming that electric buses will be common

You are on point. I would say Range and Charging infrastructure are challenging. It can be done that is 1000%. I'll keep you updated.

 

[prorallydriver]

it's obviously not impossible to do, seeing as there are electric buses on the road now with impressive range and power

Yes, They exist and they are doing incredibly well. Check Proterra 232-328 Miles of range that is beautiful!

 

[prorallydriver]

prorally driver.. i took the liberty to look at flea bay auctions. There are several S motor out there. they seem to have two motors on each side of the transaxle. The transaxle has a single speed gear box ( all you need as i know from experience) I believe the ratio is about 1;10... about the same as i have in the solectria.



I would imagine taking a whole assembly like that and and locking the differential inside the transaxle. take an old tesla drive shaft and and mate it to the U joint to the differential.


If more power is needed then you just take a second transaxle with another two motors and connect that to the "other side "of the first transaxle.




It looks like the torque Tesla motors have is immense so my gut feeling is that it will hold up. Running the torque and Rpm numbers would make sense though.


Regarding you question about our BMS systems.


I am cheap and lazy so wiring up a BMS for 48 cells ( 192 Volt nominal) is a lot of work. I drove this solectria force with a split nissan leaf pack ) 2 sets of 48 serie cells in parallel, doubling the AH and halving the original voltage ( 384 Volt) of the pack. I adapted an original nissan leaf BMS to halve voltage and with an OBD2 on bluetooth can read out the individual cells . The BMS takes only care of the balancing. I am responsible for not discharging it to far. I re-programmed the Solectria charger to a max voltage of 192 volt ( 4.0 Voltage per cell) to stay on the safe side of the 4.2Volt..



A purpose bought BMS is fairly expensive and as I said a lot of work to hook up.


A normal 240 / 50 amp outlet will do a lot of charging overnight.
With one large tesla pack being 100KWH it would take above outlet about 8 hours to fully charge that.

It will depend on your mission what range and in what time frame you want to get there.




For our car I use a normal outlet 120 VAC . It take about 7 Amps.. and i am not in a hurry.



With tesla using a lot more cells in parallel it would be best to use their BMS charging elecronics.



Good luck,


Johan

Thank you very much Johan for all the information very useful!. I want to put a P100D motor in the back and one in the front. That is more than 1400Hp. A complete Crown weight more than 6000 Pounds correct? Do you know what is the weight without the Mechanical components? Engine, Trans ...etc?

 

[prorallydriver]

The bus will loose a lot of weight without the old style diesel and transmission

Do you know the weight with the engine and transmission and without? Thank you Johan.

 

[joeblack5]

Sorry , I do not know enough about those buses or 2 stroke engines / tranny combination.


I read that they have the side windows lowering in between the wall as in a normal car. There are not many crowns in rust belt areas but i would think that they would rust pretty easy because of that. Not sure if you would want to convert to an rv but having the windows in between takes away from insulation possibilities.
Beside the good looks I think they are not very practical for rv conversion.
It is funny that they have wooden floors. Our transit has wooden floors as well. That most skoolies have a metal floor probably has something to do with fire barrier.


Looked at the wiki for tesla, very impressive stuff.

The D models have different motor assembly in the front . It seems that the rear drive consist of two motors and the front drive has one motor.
Since you would benefit from more battery capacity it would be better to use two vehicle s with only rear drive.... less expensive as a wreck and more likely that the software has been cracked since it is more available.
More power at the same time.


johan

 

[Ronnie-SKO]

Do you know the weight with the engine and transmission and without? Thank you Johan.

I just bought a 6-71 detroit like would be used in a crown and with a 5 speed manual trans it weighs right about 3000lbs. I took it over the scales on the way out, so that should be very close.