# Converting an audi tt (is anyone else?)



## Technologic (Jul 20, 2008)

icebeater said:


> So it begins. I just picked up this audi tt (below) and plan to start converting it in 6 months +/- when I've pulled together the ca$h and parts and figured out the control system. I'd love to hear from anyone else converting a tt - there aren't any in the ev-album (or online in general.)
> 
> The plan so far:
> 
> ...


Don't take this as a shameless plug, because I'm not planning to sell these at all (only source/test them).

But you should follow my 0.35/wh lithium battery test thread. These batteries are $99 each for 3.2v x 90AH.
http://www.diyelectriccar.com/forums/showthread.php/just-received-quotation-lifepo-0-35-26535.html

Also you should take a look at these AC motors and controllers:
http://www.electricmotorsport.com/store/ems_ev_parts_motors_ac-induction.php

Those will give you regen outright without modifications. Any other questions let me know... I don't think you can hotwire an EMC in a car to do a controller's functions.

Lifepo4's can't be mounted sideways... must have their vents upwards.


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## DavidDymaxion (Dec 1, 2008)

I'm thinking of putting some Thundersky batteries in my car. I want to do severe autocross and maybe even road racing cornering. Would hard cornering be enough to be a problem for Thundersky batteries?


Technologic said:


> ... Lifepo4's can't be mounted sideways... must have their vents upwards.


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## Technologic (Jul 20, 2008)

DavidDymaxion said:


> I'm thinking of putting some Thundersky batteries in my car. I want to do severe autocross and maybe even road racing cornering. Would hard cornering be enough to be a problem for Thundersky batteries?


Probably not, but I'm unsure 100% on that.

In general what you want to avoid is long periods "hanging" sideways... the actual anodes/cathodes etc will start to sag inside of the battery over time it's thought.

mounting sideways is thought to reduce lifecycle by up to 60%


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## judebert (Apr 16, 2008)

$DEITY, I wish I had the money to convert a TT!

It wouldn't fill my requirements anyway. I have to take kids to school and haul groceries. But it's an awesome little car; I've always thought of it as the Karmann Ghia, Next Generation.


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## Greenflight (Sep 13, 2007)

Great to see someone converting one of these... I've always thought they'd make great conversions. Looks like you're going to do a good job too. Good luck!


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## Jimdear2 (Oct 12, 2008)

Icebeater,

This may help in your research. The TT is basically a spiffed up, rebodied New Beetle Chassis.

Audi and VW are trading off chassis. The New Beetle/Golf/Rabbit/A3/TT is one platform. Even the AWD is the same with different names. Another group is the Passat and A3.

So look for those cars when you research, you should be able to find useable information


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## icebeater (Jan 21, 2009)

Thanks guys! 
Techno - excellent info and suggestions ... and I am absolutely following your battery progress. Thanks! I'd be interested in a group buy if it comes together. More thoughts on your feedback below ...
Jim - I will look onto the VW conversions - good suggestion. 
jude - I'm obsessed w/it! If you're in Seattle, you'll have to come drive it.


I guess half the batteries are going in the back seats then. +2 seats aren't functional to start with and this is pretty much why I didn't choose the convertible! I'll end up with a v. large flat trunk like when the seats are folded down.
I can't find an AC setup for the power I want for under 3X the price of the DC system. With the WARP, I'm thinking that I could add regen for under $1000 using a small PMDC motor (etek or PERM) and controller. The regen motor would freewheel when not in regen mode (I'm not going to try push a WARP 11 with an etek.) A brushless motor/alternator may be optimal. If the 2 motors' max RPM were similar, they could be in series - else, the PMDC can run off a chain. Again - this regen idea is 50/50 - it adds more complexity than I like but it's worth it for 10%
You're right - the engine control module won't be hackable but its inputs and outputs will. I'll use either the input which comes from the accelerator or the output going to the injection system to drive the controller - I'm just not sure which. The accelerator would be simpler and it's awesome that the tt already has electronic acceleration but I'm concerned that the ECM/EMS may need the accelerator input - lots of unknowns (and work to do) here.


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## mill (Aug 22, 2008)

quattro or fwd?


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## icebeater (Jan 21, 2009)

QUATTRO 

Should have mentioned that - AWD was a big plus when choosing the tt. I figured that if you're gonna get 100% torque from zero RPM, it may as well go to 100% of the tires ;-)

The tt has an electronically controlled haldex coupling which can move the torque from 100% front to 100% rear in milliseconds. If I add regen I'll try to figure out how to ensure it uses all 4 wheels.


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## mill (Aug 22, 2008)

icebeater said:


> QUATTRO
> 
> Should have mentioned that - AWD was a big plus when choosing the tt. I figured that if you're gonna get 100% torque from zero RPM, it may as well go to 100% of the tires ;-)
> 
> The tt has an electronically controlled haldex coupling which can move the torque from 100% front to 100% rear in milliseconds. If I add regen I'll try to figure out how to ensure it uses all 4 wheels.


I dont mean to be a party pooper but unless you can build a control module to mimic ecm data (speed, calculated load, throttle position, engine rpm,ect) and transmitt that serial data over the CAN bus then none of that is going to work. the haldex control module uses signals from the ecm and abs control modules transmitted over the powertrain can bus and engages the rear when wheel slip is detected. this would require signal from the ecm with a running engine. i dont see how this can be done unless you are very experienced in programming automotive electronics. you may be able to mimic engine rpm using the crank position sensor on your electric motor and a similar pick-up wheel(or your old one), you will also have to have the electronic throttle hooked up doing nothing, and another key input is the mass airflow reading for engine load calculation. For that you would have to simulate its 0-5v signal but im not sure what you would base the signal off of. i dont think you need quattro, it really slows the car down, the fwd is notably faster once you get off the line and much easier to push into the shop than a quattro(we push'em in all the time) I think this would cost you considerable range.


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## madderscience (Jun 28, 2008)

Hi Icebeater-

Being in seattle you are lucky to have a pretty active EV community locally. If you haven't done so yet, consider coming to a few SEVA meetings (http://www.seattleeva.org/wiki/Main_Page) and bring lots of questions. You will get a lot of interest in your project as you are converting a newer "nice" car. 

Rich Rudman (of manzanita micro, maker of the PFC line of chargers) is selling Thunder sky LiFePO4 batteries as 12V modules WITH BMS included for what seems to be fairly reasonable pricing. They are packaged in such a manner to keep them from swelling up and have upgraded contacts and bus bars. He had several sample modules with him at the last seva meeting. I don't remember exact prices but 144V at 160AH would have worked out to about $15K including local sales taxes. Still pricey, but starting to get into the tempting range. 

The warp 11" is certainly a BIG motor but such motors are torque monsters and don't rev up as well. You might be better off with a warp 9" motor or anything of similar size that has gotten the Jim Hustead treatment. 

Good luck, and maybe see you at the next SEVA meeting!


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## icebeater (Jan 21, 2009)

mill - 



> I dont mean to be a party pooper


No worries - I came here for this kind of feedback! Thank you!



> but unless you can build a control module to mimic ecm data (speed, calculated load, throttle position, engine rpm,ect) and transmitt that serial data over the CAN bus then none of that is going to work. the haldex control module uses signals from the ecm and abs control modules transmitted over the powertrain can bus and engages the rear when wheel slip is detected. this would require signal from the ecm with a running engine.


The haldex uses signals over the CAN bus but they come from the accelerator pedal (via the ECM) and from the wheel speed sensors (ABS system.) I don't plan to mess with those and I won't be removing the ECM. This is actually a good reason the accelerator INPUT to the ECM shouldn't be hacked to drive the controller. And you've given me the idea to pull the accelerator signal for the controller from the CAN bus - sweet! So ... it looks like it can be done (he says, nervously.) If that fails though, the backup plan is to replace the halldex controller with the performance ones they sell for the track which have pretty simple electronic control for the AWD. 

I've taken a look at the list of actuators (outputs) directly controlled by the ECM and there isn't one I think I'll need. So, the ECM simply transmits some of its remaining (and simulated) sensor inputs to the systems that need it via the CAN bus. 



> you may be able to mimic engine rpm using the crank position sensor on your electric motor and a similar pick-up wheel(or your old one), you will also have to have the electronic throttle hooked up doing nothing, and another key input is the mass airflow reading for engine load calculation. For that you would have to simulate its 0-5v signal but im not sure what you would base the signal off of.


I realize I may need to simulate some of the ECM inputs that I will lose with the engine. I'm not 100% sure which of them. So far, all the engine sensors control the throttle valve and I won't need that but I'm sure there will be something (there always is.) I probably won't take an electro-mechanical approach to simulating sensors (beyond motor speed.) I'd rather program one of those processors they're using in robotics to do it. I'm no rocket scientist but programing is something I can do. This second, custom ECM could both simulate ECM inputs and translate sensor outputs for electric motor control. Yep, I'm giving myself a lot if time to figure this out. 



> i dont think you need quattro, it really slows the car down, the fwd is notably faster once you get off the line and much easier to push into the shop than a quattro(we push'em in all the time) I think this would cost you considerable range.


The beauty of the haldex system is that it IS 100% FWD when its not accelerating / cornering. This thing can entirely disengage RWD and so you only get AWD when you need it (which may actually increase range.) It's a small car - pushing won't be a problem. They only made the FWD tt with the 180HP engine (at least in the US.) Trust me, this car kicks the FWD's ass! ;-)


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## Technologic (Jul 20, 2008)

icebeater said:


> I can't find an AC setup for the power I want for under 3X the price of the DC system. With the WARP, I'm thinking that I could add regen for under $1000 using a small PMDC motor (etek or PERM) and controller. The regen motor would freewheel when not in regen mode (I'm not going to try push a WARP 11 with an etek.) A brushless motor/alternator may be optimal. If the 2 motors' max RPM were similar, they could be in series - else, the PMDC can run off a chain. Again - this regen idea is 50/50 - it adds more complexity than I like but it's worth it for 10%
> You're right - the engine control module won't be hackable but its inputs and outputs will. I'll use either the input which comes from the accelerator or the output going to the injection system to drive the controller - I'm just not sure which. The accelerator would be simpler and it's awesome that the tt already has electronic acceleration but I'm concerned that the ECM/EMS may need the accelerator input - lots of unknowns (and work to do) here.


I see... that's a possibility though you'd need to test the outputs themselves, found out their operating parameters and then adjust them through an external system... so the controller could use them (ie. if you're reading say 36v out to the controller input at 5% power... you'll need a voltage divider in series with the leads to the controller to keep this input correct like a pot would be).

About the regen part.

It's possible to do what you're suggesting... but I'm not sure most people realize how much power is generated via regen... which is why it's often done in a single large IGBT/MOSFET package that also controls the motor.

In general your 2600 lb (you should be around that... if you go with a moderate battery pack size), will pull around 100-300kw after efficiency losses while braking (briefly, but long enough the controller needs to take it). 
Also keep in mind... attaching an alternator to the permanently to a tire or set of tires and only activating it during braking will still add to the rolling resistance of the car. Ie. if you add 2 "alternator brakes" to the rear wheels, take that DC and convert it to pack voltage to charge the pack... these things will still functionally be resisting the forward movement of the car at rest as well. 
Likewise a BLDC motor that's capable of capturing that kind of braking energy will need to be rather large (think expensive) it will add something like 4-10lbs to rolling mass (think 80lbs of drag or so at highway speeds) and when powered on will need converted from AC to DC by a BLDC controller (think also expensive).

If I can help any further let me know... regen is an annoying mistress still.


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## Technologic (Jul 20, 2008)

icebeater said:


> I realize I may need to simulate some of the ECM inputs that I will lose with the engine. I'm not 100% sure which of them. So far, all the engine sensors control the throttle valve and I won't need that but I'm sure there will be something (there always is.) I probably won't take an electro-mechanical approach to simulating sensors (beyond motor speed.) I'd rather program one of those processors they're using in robotics to do it. I'm no rocket scientist but programing is something I can do. This second, custom ECM could both simulate ECM inputs and translate sensor outputs for electric motor control. Yep, I'm giving myself a lot if time to figure this out.
> 
> The beauty of the haldex system is that it IS 100% FWD when its not accelerating / cornering. This thing can entirely disengage RWD and so you only get AWD when you need it (which may actually increase range.) It's a small car - pushing won't be a problem. They only made the FWD tt with the 180HP engine (at least in the US.) Trust me, this car kicks the FWD's ass! ;-)


before you rip out the engine... take the time to map idle and max RPM inputs for the flow sensors so you can create a simple circuit to emulate their inputs... it sounds way harder than it is... and I or someone on the forum could easily help you with such a circuit. (you could even make a simple circuit that fed off of the throttle input and changed it's output accordingly... like an amplifier)

The RPM input is probably the easiest thing in all honesty. You can just drop a similar sensor (shouldn't be an issue to find one aftermarket) onto the electric motor's shaft... if the motor has a shaft extension out of the rear of the motor like some do... it'll be even easier


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## icebeater (Jan 21, 2009)

madderscience - 

warp9 vs warp11 is the other great debate for me. I had actually decided on the 9 for the RPM and then I read here somewhere that it doesn't handle more than 350A well ("saturates at 350" I think the post said) and I want the car to have good pull at highway speeds. So, now I'm thinking 160V and an 11 may be better. Good chance this decision will change again before I'm done.

Those TS's still sound too spendy for me though the local support would be great. For now, I'm hitching my battery hopes on Techno and China. I do want to ask the Manzanita guys what they think of BattCaps though - apparently they've tested them in an EV.

Thanks for the SEVA invite - I'll be there - though the tt may not be a "newer" car by the time I'm done ;-) SEVA sounds like just the place to work out this warp9 vs warp11 problem.


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## icebeater (Jan 21, 2009)

Techno - I'll eventually stop saying thank you for your advice but ... thank you!

The amplifier idea is definitely along the lines of what I was thinking. I'll measure everything and anything that has a current ;-) And yeah, lots of places to get RPM. 

on regen - Rolling resistance of a free-wheeling BLDC is something I need to do more research on. An electromagnetic clutch is an option for disengaging it but again, more complexity (and torque issues.) I don't want to brake the car using regen but rather thought I would draw the regen motor's max current (say 300A) whenever I can. I like the idea of regen whenever your foot's off the pedal for speeds < ~55 mph - above that, I think it may be optimal to only regen while braking. Under braking though, the disc brakes will still do most of the heavy work. Surely the controller can limit the regen power generated? Or no?


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## Longbow (Mar 15, 2009)

Hi folks,
Stumbled across your site and would like to point you towards another site that may be of interest. The answer to your thread title is yes - you are not alone in Modding the TT to run electric, take a look at this link:-

http://www.fraunhofer.de/Images/magazine1-2009_18_tcm6-108611.pdf

They are going hybrid rather than full electric and the Quattro platform is important in their concept.


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## oracle (Mar 16, 2009)

It would be cool if you ran the water cooling system to the rear and had the steam come out of the tailpipes.


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## JonasMeyer (Feb 28, 2009)

If regen is important to you, and you want to preserve the sporty acceleration, I'd go with a AC55 with a DMOC from Azure Dynamics. They run around $8500 shipped with all the wiring harnesses and such (I think the only distributor is electroauto.com). Everything I've read says that attempting to do regen on a DC motor is a recipe for crappier performance, a blown motor, or both. Just bite the bullet and go AC.

I don't know what the final drive ratio is on a TT, but if it is around 4:1, then you should be looking at around 824 ft lbs of torque at the wheels between 0 and 40 miles per hour, and a redline of 150 Mph. Of course, the real challenge is getting a battery pack that can put out the 400 Amps @ 320 Volts this thing needs to suck down to do that.


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## CroDriver (Jan 8, 2009)

JonasMeyer said:


> If regen is important to you, and you want to preserve the sporty acceleration, I'd go with a AC55 with a DMOC from Azure Dynamics. They run around $8500 shipped with all the wiring harnesses and such (I think the only distributor is electroauto.com). Everything I've read says that attempting to do regen on a DC motor is a recipe for crappier performance, a blown motor, or both. Just bite the bullet and go AC.
> 
> I don't know what the final drive ratio is on a TT, but if it is around 4:1, then you should be looking at around 824 ft lbs of torque at the wheels between 0 and 40 miles per hour, and a redline of 150 Mph. Of course, the real challenge is getting a battery pack that can put out the 400 Amps @ 320 Volts this thing needs to suck down to do that.


The strongest AD AC motor has a peak power of 59kW. That's not enough for 150mph. 

I don't think that there are any stronger AC systems on the market...

May be two of these 59kW systems would be a good solution... 

P.S. Don't even think about AC propulsion or UQM, they won't supply their system to anyone except OEM-s.


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## JonasMeyer (Feb 28, 2009)

CroDriver said:


> The strongest AD AC motor has a peak power of 59kW. That's not enough for 150mph.
> 
> I don't think that there are any stronger AC systems on the market...
> 
> ...


Yeah, especially since peak power is at 2100RPM, which would be around 40 MPH in a direct drive 4:1 setup. Still, 183 ft lbs of torque at 80 MPH is pretty respectable. The car might be wind limited rather than motor limited, but I think in a tt, that car should move. Put it this way:

A Tesla roadster does 0-60 in something around 4 seconds. It has an 8.28:1 drivetrain ratio. Judging from the graph on the "performance" section of their site, it is putting around 1700 ft lbs of torque to the wheels up to around 60 mph, at which point it begins to drop off. Now a TT is going to be heavier (not made of carbon fiber), and the motor is putting half as much torque to the wheels, but I'd still be surprised if it couldn't do 0-60 in under 8-10 seconds. Very respectable, considering it will probably cost our friend here under 1/3rd the amount of the roadster, and turn as many heads once he stencils a big lightning bolt on the side that says "Electric TT" on it. And now that I think about it, the weight will probably be similar to the roadster, since most people on this site can't afford a 52 KWh battery.


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## Metalman (Jan 21, 2010)

I am getting ready to convert a tt to electric, Who can I get a kit from?


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## Metalman (Jan 21, 2010)

I am getting read to conver a tt to electric, Who do I get a kit from?


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## Jimdear2 (Oct 12, 2008)

Metalman said:


> I am getting read to conver a tt to electric, Who do I get a kit from?


Metalman,

Look for VW Golf and New Beetle stuff, it is basicly the same drivetrain Even the AWD is from VW.


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## adragon (Jul 16, 2010)

Wish people would follow up...

This may be helpful. 

http://audihybrid.blogspot.com/


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## Joe Transue (Sep 1, 2011)

Is anyone still on this thread? My wife has a 2000 TT which I want to de-ICE. I know that there are a few people interested in this and I believe GA Tech did one as a project- this one I believe retained the Quattro (Haldex Coupling apparently has a tricky engine RPM sense which must be factored in). Cheers!
-Joe


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## efan (Aug 27, 2009)

is this conversion still happening? this is a great car to convert!


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## Joe Transue (Sep 1, 2011)

I never started mine. We are very near the point where we will either sell the car or convert it. The former option makes a great deal more sense for us financially. We might possibly cover it, add some fuel preservatives, and cancel insurance. The car is just too sexy to get rid of!


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## Kastagno (Sep 13, 2020)

Did u make it?



icebeater said:


> So it begins. I just picked up this audi tt (below) and plan to start converting it in 6 months +/- when I've pulled together the ca$h and parts and figured out the control system. I'd love to hear from anyone else converting a tt - there aren't any in the ev-album (or online in general.)
> 
> The plan so far:
> 
> ...


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## TassyTiger (Sep 17, 2020)

This guy converted one:





Electric Audi TT Coupe







audittev.blogspot.com


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