Audi TT conversion

Have you made or bought a converted vehicle if so this is for you
TTmartin
Posts: 20
Joined: Fri Jan 06, 2012 10:10 am
Location: Bath

Audi TT conversion

Postby TTmartin » Sun Jan 08, 2012 1:42 pm

Can anyone clearly define the difference between an AC or DC system I'm in the process of converting a Mk 1 Audi TT to electric, but seem to be going around in circles as regards component choice. For now batteries will probably be lead acid 12x12 volt 150ah 144 volt pack I hope to design bat boxes to allow refit to lithium when prices are sensible!
My initial thoughts were to use DC Kostov 10" motor with Curtis or maybe zapi controller,but many people are advising going with AC motor/controller trouble is there doesn't seem to be much options out there for the DIY project.
As I see it the main difference is regen and slightly better efficiency with AC, is this correct?Also are DC motors ok for climbing hills compared to AC.
All I have really found available AC, is a USA AC-50 motor with Curtis 1238r controller but this is only 96 volt so I think under powered?
My goal is to make TT as light as possible have minimum 40 mile range to sensible DOD with acceptable performance around town driving and some hill climbing 50 to 60 mph top speed.
Looking for advice, guidance, thoughts, ANYTHING.

Measure twice cut once.

Martin.

User avatar
Night Train
Posts: 350
Joined: Sat Jun 21, 2008 11:55 pm
Location: Manchester

Re: Audi TT conversion

Postby Night Train » Sun Jan 08, 2012 2:13 pm

In real life terms there is little difference between AC and DC performance for the average budgeted DIYer.

AC costs more but the benefits of AC can be outweighed by spending the price difference on better batteries and controller on DC.

For a first project DC is easier to work with and can be up graded a step at a time later on.

DC motors are easily available, fairly 'bullet proof' and can be had on a low budget via a forklift truck breaker. The real clincher is in the controller, the controller makes or breaks the car I think. A really good DC controller can be bought, or built from a kit, with good performance whereas equivilent powered AC controllers are generally costly, very costly and silly money unless you are an electronics genius and can design and make your own.

For a first car, and given your budget (which I assume is limited as you are starting on lead acid) I would look at either the Paul and Sabrina Open Revolt Kit which is a proven and tested 144V 500A controller at the lower cost end of the scale and the Soliton 1 or Soliton Jr from EVnetics at the top end of the scale.

If you are keen on AC then Paul and Sabrina are/were working on an AC controller as discussed here on EcoModder but I haven't been keeping up to date with it so don't know where they are up to. Their DC controller is well documented on EcoModder too and the Soliton1 and Jr is well documented on DIY Electric Car dot Com.

You might also strike lucky and find an AC powered EV being broken for parts and then you could just transplant the whole system as Simon Rafferty did in his Land Rover Freelander.

It really is your call, based on your knowledge and skills ability and the size of your budget. My personal choice, due mainly to budget, would be to go with DC and while converting the TT save for a lithium pack rather then lead acid. You could test on a low voltage lead pack with second hand batteries but I don't think you would enjoy the performance limitations due to weight and range if you stayed with lead.

My own project is being designed around 120V DC but I will be hoping to get it road legal on 48-72V of lead from my electric tractor before I buy the lithium. The cell package sizes might reduce and I can then get in 144V by the time I am finished building.

I hope this helps.

User avatar
retepsnikrep
Posts: 1387
Joined: Sat May 26, 2007 4:50 pm
Location: North Yorkshire England
Contact:

Re: Audi TT conversion

Postby retepsnikrep » Sun Jan 08, 2012 8:35 pm

Personally I would not consider anything other than Lithium as the weight penalty is too high unless you are converting a van or pickup.

Controller the Curtis 1238 AC is pretty well thought of.

I would only use AC personally it's just much more advanced and refined.

You could canablise an old prius/or Honda IMA car and use the motor/s and drive pack out of one of those, I'm currently on with a stacked IMA motor long term project for an EV insight. Or as has been suggested strip an abandonded EV project.

Your available budget is the deciding factor :shock:
Regards Peter

Two MK1 Honda Insight's. One running 20ah A123 Lithium pack. One 8ah BetterBattery Nimh pack.
One HCH1 Civic Hybrid running 60ah A123 Lithium pack.

TTmartin
Posts: 20
Joined: Fri Jan 06, 2012 10:10 am
Location: Bath

Re: Audi TT conversion

Postby TTmartin » Sun Jan 08, 2012 9:43 pm

Thank you for your responses, to be honest about the only thing I've learnt so far is lithium is the way to go for a true fit for purpose electric car conversion, BUT :evil: the price I think is still just not right. Hopefully by the time I'm ready for ordering batteries they will have dropped enough for me to swallow that bitter pill. I probably will. :roll:
I want to get this (right first time) first desission is Motor and controller, from what I now know so far if I go the DC route, a Kostov 10" 144v or netgain equivalent will do the job ok hooked up with any one of a number of DC controllers. I can even have regen, the Kostov motor has interpoles if I use a zapi controller this does regen.
So all would be good I think?
Now AC ? Curtis 1238r 96v the only controller I've found so far is, I think to low a voltage for my conversion weight of finished car will be 1200kg maybe 1400kg? Strange that curtis don't do a bigger stock controller, they did say they can but not 1off for little old me.
All the motors I've found so far are only suitable for the above controller.
So my other option is keep looking or as suggested pick up old electric car/van and use parts, needle in hay stack comes to mind :( what's the downside if I go DC, brush change at 50,000miles ish :?: enough said sorry, trouble is I think if offered AC motor/controller fit for my project at sensible price that's the way I would go. Will have to make mind up soon engine etc now removed from donor.

User avatar
Night Train
Posts: 350
Joined: Sat Jun 21, 2008 11:55 pm
Location: Manchester

Re: Audi TT conversion

Postby Night Train » Sun Jan 08, 2012 11:21 pm

If you come across a suitable AC set up then, yes, it would be a good way to go.

Is there any reason for not going with DC, aside from a brush change? Also regen may or may not be of much benefit depending on the driving that you want to do and the terrain you are driving on.

What realistic range and speed are you looking to achieve? How critical is your journey time and what are your charging options at each end of your journey?

TTmartin
Posts: 20
Joined: Fri Jan 06, 2012 10:10 am
Location: Bath

Re: Audi TT conversion

Postby TTmartin » Mon Jan 09, 2012 12:17 am

The only reason I now am hesitating with DC is due to when enquiring about various components from various suppliers eg, motor and controller they respond by saying you should consider AC as all production cars are because there more efficient. If I am reassured that DC will perform (power wise) compared to AC as long as I can get respectable range with correct battery choice then brush replacement and regen are of no concern to me, only down side I guess is brakes will wear faster without regen but then again I've read quite a few articles where regen has been designed into conversions but turned off or way down due To un smooth operation or brush arching.
As regards actual driving requirements the car is hopefully realistically planned to be a second car for around town driving and work, 30 to 40 mph no motorways or racing! But I live in Bath so hills are an issue that's why I think minimum 144v, top speed is low priority 60mph. would like to aim for equivalent small diesel ICE performance acceleration wise.Charging probably only overnight.
Range! It's always about range, 40miles minimum with lead acid if I go there? Probably will even if it's for testing short term. In reality daily driving may only be 10 miles Sometimes. I think with lithium I would get good range and performance but empty bank balance.
Your thoughts much appreciated.

User avatar
Night Train
Posts: 350
Joined: Sat Jun 21, 2008 11:55 pm
Location: Manchester

Re: Audi TT conversion

Postby Night Train » Mon Jan 09, 2012 10:37 pm

In my opinion production cars do tend to use AC as it is the better system for a manufacturer to go for. They have the resources to develop suitable controllers, motors and transmissions to make a whole vehicle effective. Also they want to have easy regen to, on paper, improve the range.

I have read of a lot of conversions without regen and enjoying the increased range from coasting without power for long distances. The cars are often very free rolling with a low rolling resistance to take full advantage of this. It does change the way you drive though, pulse and coast being the norm so you only apply enough power to coast the car to then next stop or junction. Doesn't stop you having fun with it when range is not an issue though.



There are plenty of people who have DC conversions with no issues.

Have a look at these examples on another forum. The treads are well worth reading and also it is worth looking at some of the other threads started by the authors about ther cars and associated conversion issues and solutions.
BMW conversion in Ireland.
Renault conversion in Amsterdam.
BMW high performance conversion in Croatia.
Saturn conversion in USA.
Range Rover conversion in Finland.
One with issues:
Willys Jeep conversion in USA. worth checking his other threads as it is now commuting.

TTmartin
Posts: 20
Joined: Fri Jan 06, 2012 10:10 am
Location: Bath

Re: Audi TT conversion

Postby TTmartin » Mon Jan 09, 2012 11:40 pm

Thank you for your thoughts,
I find it's always good to throw ideas around and listen to other peoples views it sometimes clears the mind and you arrive at decisions. If an AC motor/controller fails to surface in the next month, (not going to happen) I will go with DC and place order for Kostov 10" 144v direct from Bulgaria as they offer good price compared to netgain. I can then look at making adaptor plate for motor/gearbox while deciding on controller.

Measure twice cut once :D


Return to “Conversions”

Who is online

Users browsing this forum: No registered users and 16 guests