# Hybrid transmissions - DIY E.V. future?



## bigmouse (Sep 28, 2008)

That's a very nice rundown of hybrid transmissions. Thanks for putting it together!

One challenge with many Toyota/Lexus transmissions is the MG1 gear ratio when the input shaft is fixed. On the ones I've looked at (2nd gen Prius and Camry Hybrid) the vehicle speed is limited to unreasonably low speeds (around 40mph I think) by MG1's speed rating. I think the Camry was a bit more reasonable. The IS300h transmisison looks very promising if MG1 speed isn't an issue.

Others (jddcircuit) have welded the power split planetary gears to lock MG1 and MG2 together, but you lose the gearing advantage when doing this. Also, I don't like the idea of opening up the transmission in the first place. All my required modifications are external and reversible (not that I'd ever want to reverse them).

In the GS450h, MG1 has a very high speed rating that will allow the car to go 100mph with the input shaft locked. MG2's two-speed reduction allows for maximum performance off the line.

Another issue with hybrid transmissions is the relatively low continuous power rating. I expect I will need very good cooling on mine in order to drive it up long hills, but it should be doable. Race track use is out of the question. It should be fine for every day driving, drag racing, and autocross. The heat transfer is limited by the design done at Toyota. Nothing we can do will make it any better. Our best bet is to put the most effective cooling in place as it practical.

These motors (at least the Toyota/Lexus ones) are wound for very high voltage. The boost converter in the inverter is a severe bottleneck for EV use. A high voltage battery is required. This presents its own difficulties.

Finally, a high voltage inverter is required. I'm making a custom control board for my GS450h inverter.


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## nimblemotors (Oct 1, 2010)

I am using a prius transaxle in my http://the-indy-one.com​
When you have a 1200 lb vehicle,
the prius transaxle sans generator and gas motor has plenty of power,
some might even say it is overkill for such a light vehicle.
For your typical 3500 lb car, not such a grand idea.

I only starting working on this idea about 5-10 years ago


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## ETO (Jan 5, 2016)

Hi, I am new on this forum, but I have some experience in electro-mechanical equipment.
I am interesting in this transmission, because Poland very close to my place and price amazing.
But I just not shure if this monster will fit in classic car with aft wheel drive, like Ford Mustang or similar coupe from 80's?
Like KIT this set very good and cheap.
Also your software and PCB going nice. If print will be available for free usage it become a masterpiece of DIY EV sets.

How about Outlander EL motor from Phev? I fond one on ebay
Looks like can fit with some gearbox FWD wheels and maybe AFT
use CAN and price good


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## Chris Pincetich (Nov 30, 2015)

Great list! 
too bad there aren't any true transaxles yet, with the output being to CVs/axles instead of to a driveshaft.


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## bigmouse (Sep 28, 2008)

Chris Pincetich said:


> Great list!
> too bad there aren't any true transaxles yet, with the output being to CVs/axles instead of to a driveshaft.


RX450h rear motor fits that description, as does any pure EV drive motor.


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## Matej (Dec 4, 2015)

Has anyone made progress in this field?

I ask because I have an opportunity to pick up one of the GM hybrid RWD transmissions for quite cheap. The nice thing about them is that unlike the Toyota/Lexus transmissions, both of the motors are the same. I assume this would be beneficial if someone wanted to lock them together and control them with two identical controllers/inverters.

Although I do not have the knowledge to do anything with it, at least not yet.

Could the two motors perhaps be hooked up to two Curtis 1239 controllers? I know the Curtis controllers are made for lower voltage motors, but I am curious if they could at least spin the motors to half their max speed, for example. Or would they require a completely different type of setup?


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## mira9_cz (Feb 27, 2013)

Hi, honestly I don't know. Bigmouse might proceed with his BMW conversion, but both Damien and me we have done nothing yet. But few days ago I have placed the request for 2ML70 Tahoe hybrid drivetrain from US. And now you are writing that you can have this gearbox, nice. I have planned to control it by Chevy Volt controller through UMC Drive by Eldis: http://www.diyelectriccar.com/forums/showthread.php/any-ac-motor-any-inverter-umc-152234.html


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## Matej (Dec 4, 2015)

mira9_cz said:


> But few days ago I have placed the request for 2ML70 Tahoe hybrid drivetrain from US.


That is the one. A variant of it was also offered in the 2009-2010 BMW X6 hybrid and the 2009-2010 Mercedes ML450 hybrid, which may be easier to find in Europe.

Please keep us updated if you are able to do anything with it.


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## bigmouse (Sep 28, 2008)

Matej said:


> Has anyone made progress in this field?
> 
> I ask because I have an opportunity to pick up one of the GM hybrid RWD transmissions for quite cheap. The nice thing about them is that unlike the Toyota/Lexus transmissions, both of the motors are the same. I assume this would be beneficial if someone wanted to lock them together and control them with two identical controllers/inverters.
> 
> ...


Video proof that hybrid transmissions are amazingly capable: http://www.diyelectriccar.com/forums/showpost.php?p=828074&postcount=198

My car has more torque than I can use and the transmission and inverter combined cost around $2500. No modification to the transmission required! That's pretty hard to beat, if you're able to figure out how to control the inverter. The only downside is the requirement to run a high voltage system (600+ Volts) to achieve full performance. Slight modifications to the inverter are also required.

Full build thread linked in my signature.


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## Matej (Dec 4, 2015)

bigmouse said:


> Video proof that hybrid transmissions are amazingly capable: http://www.diyelectriccar.com/forums/showpost.php?p=828074&postcount=198


That is fantastic. You should consider modding and reselling the inverters for a plug-and-play swap.


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