# Kit Car 0-100km/h 2-3 sec.



## Lipo Louis (Oct 29, 2012)

Hi People,

In the past I have finished several projects, 30KW electric outboard motor a lot' s of really fast ebikes etc. So I have lot's of experience with Batteries, BMS's Controllers etc.

Now my wish is to build a car that will do 0-100 km/h in 2 or 3 seconds.
The only way to build this for a descent price is to go with a very light car, so I think the only option is a 500 KG kit car like the MEV Sonic 7









So I was thinking to buy a finished kit car, so I don't have to build a complete kit car and the car is at legal license plates.

And then I do not exactly know what motor would be best for the power/price ratio. A Netgain Warp 11 motor maybe ?

And a Soliton 1 Controller ?

For a 0-100 km/h in 2 or 3 sec at a 500 kg car I think a 200-250KW burst is enough.

I think I read somewhere that a modified Warp 11 can handle 340v at 1000A for a few seconds ?

As for the battery, 180 x A123 20ah pouch cells from Victpower for 15 usd per cell, And build a 90S2p 288V 40ah pack which is 324V fresh of the charger so the Soliton 1 can handle it.

40Ah pack and I believe the A123 can handle 20C burst, which would be 800A x 288V = 230 KW

So I have the following in mind :

Kit car 10.000 USD
Warp 11 3000 USD
Soliton 1 3000 USD
A123 90s2p 2700 USD

Shipping. cables, connectors, throttle, charger etc is what I need.

But I was hoping you guys can think with me.
Is this setup something you would choose ? Is it realistic or do I need other parts, I am totally new to EV cars but I prefer to buy some overkill parts instead of have regret because I have not enough power for my needs.

Do I need a gearbox or would a direct drive be better ?
Would a motor like a Warp 11 fit inside a kitcar ?


Thanks, I hope I will learn more from this great forum !


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## major (Apr 4, 2008)

Lipo Louis said:


> Hi People,
> 
> In the past I have finished several projects, 30KW electric outboard motor a lot' s of really fast ebikes etc. So I have lot's of experience with Batteries, BMS's Controllers etc.
> 
> ...


Looks similar to this  http://www.diyelectriccar.com/forums/showthread.php?t=72681


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## Chad (Aug 1, 2008)

Direct drive is better (IMO) a gearbox is likely necessary, (could just be a diff) but a transmission is not. (basically, you shouldn't need to change gears)

If you are going to get a kit, make sure it is built well. Do some research on this! I would also recommend Factory 5 kits as they seem like the best.

I wanted to do a 33 as an electric. http://www.factoryfive.com/kits/33-hot-rod/

I love the kit car idea. Brand new rolling chassis without the ICE parts to be removed.


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## MN Driver (Sep 29, 2009)

The Warp 11 HV is rated for 288v and the Kostov 11 or 11Alpha probably could take the same voltage too(don't take my word for it though, please check). I'm not sure what you can stretch it to, but with a Soliton 1 and battery sag, I don't think you'll get past 288v under load anyway unless you've got an extremely stiff pack.

Not sure if either of those setups will get you there that quick even with perfect traction, speaking of which, traction is a big part of this too. I don't know the dynamics/calculations to know how much torque and power you will need to make your goal. Good luck!


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## Bowser330 (Jun 15, 2008)

So when the Warp11HV first came out it was rated for 336V and then it was quickly downgraded and rated to 288V...

My understanding is that the interpoles allow for higher voltage handling capability...but how high is my question...why 288V and not 340V?


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## Lipo Louis (Oct 29, 2012)

Thanks for the replies people.
I love the factory5 '33 Hotrod ! What an amazing ride, but I think it will be too heavy and much more expensive. 

On the other hand, a descent roof would be nice to, an open kit car is light but at a rainy day in Holland also very wet.

Maybe there are 500 kg Kit cars with roof ?


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## Duncan (Dec 8, 2008)

Hi
100Kph = 28 meters per second
so 2 - 3 seconds means 1G acceleration (10m/sec/sec)
Need sticky tires!

Assume 500Kg car 
Power required
Force x Distance/time

At take off power = zero
as you accelerate you need more power
at 100 Kph
500Kg x 10 x 28m/sec = 140Kw

So you need 140Kw - you won't be able to use all of it until 100Kph

Sanity check
Kinetic energy = 1/2mass x velocity squared

1/2 x 500kg x 28 x 28 = 196Kjoules

Power from zero - 140Kw = average 70Kw
70Kw x 2.8 seconds = 196Kjoules

So you need 140Kw


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## Duncan (Dec 8, 2008)

major said:


> Looks similar to this  http://www.diyelectriccar.com/forums/showthread.php?t=72681


Hi Major
I just realized what has been bothering me about this picture

He is getting in on the wrong side!
Probably because somebody fitted the wheel on the wrong side!


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## Lipo Louis (Oct 29, 2012)

Thanks Duncan, 

http://www.autosnout.com/0-60-Calculator.php

500kg is 1100 LBS and 140 kw is about 188 hp

According to some calculators you reach 60 mph in about 3.5 sec

But under 600A of load the efficiency is no more then 75 % of the total setup ??

So a more KW is always better since you can reduce it.

So the whole idea should be possible ?


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## major (Apr 4, 2008)

Lipo Louis said:


> Thanks Duncan,
> 
> http://www.autosnout.com/0-60-Calculator.php
> 
> ...


The vehicle I showed in the photo is called the SuperLite Roadster (SLR). It sports a Warp9 and Zilla 1k so should easily do the 140 kW. It uses a 6-speed transmission. But runs 24 40Ah Pb-Acid and weighed in at 2400 lbs. It does have 6.6 kW of charger on-board and a passenger seat, but not a lot of extras.

Obviously you can find a high power small Lithium battery and knock a big chunk of mass off a chassis like this. But 1100 lbs? And don't forget to throw in the driver for your calcs 

BTW, last month, we didn't dyno this car. But I saw several others on the dyno running Warp9s with 1000 A controllers hitting around 170 hp at the wheels.


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## Lipo Louis (Oct 29, 2012)

Based on my google search a finished MEV rocket with 1.6 Litre engine weights 530 KG

http://www.kitcarcollection.com/used-cars/mevrocketdemo.php


Replacing the ICE motor for a warp 11 and 100kg of batteries and a controller etc will keep the same weight I was hoping.

170 WHP for a warp 9 and 1000A controller ? I really wonder how much power input it will take.

Can we say 170 kw input will be around 170 hp output ? or is this too optimistic ?


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## major (Apr 4, 2008)

Lipo Louis said:


> Based on my google search a finished MEV rocket with 1.6 Litre engine weights 530 KG
> 
> http://www.kitcarcollection.com/used-cars/mevrocketdemo.php
> 
> ...


I think that's about right. 1000 A limit of that controller. 170 V recommended top voltage for the Warp9. We were just seeing the dyno output so I can't be sure of V & I at that point. 75% efficient from battery to wheel is good number to use. Might actually do a little better


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## Yabert (Feb 7, 2010)

Lipo Louis said:


> Can we say 170 kw input will be around 170 hp output ? or is this too optimistic ?


It's roughly true...
Let say, 170v and 1000A from battery = 170Kw x 0.98 (controller efficiency) = 166.6 Kw x 0.76 (motor efficiency at 1000A) = 126.6 Kw / 746 = 170 hp


Hey... don't use a Warp 11!
Warp 9, Warp 11HV or Kostov Alpha, but not a Warp 11. His weight is too high compare to his power capability.


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## Lipo Louis (Oct 29, 2012)

http://www.evsource.com/tls_warp11.php

Warp 11 or Warp 11HV only 5 kg difference in weight ?


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## marc02228 (Jan 15, 2011)

You could consider the Kostov 11 Alpha, too.
You're from the Netherlands, right? So you don't have to pay the import tax.
The Motor is much lighter than the Warp 11 /Warp 11 HV and will probably have enough power for your application.


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## tylerwatts (Feb 9, 2012)

Kostov11 Alpha will handle the 1000A for the short bursts you want, has in my opinion better cooling with the axial fan and is CONSIDERABLY lighter than the Warps. Plus no import tax or high shipping as it comes across land from not far away!


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## EV West (Jan 12, 2012)

Lipo Louis said:


> http://www.evsource.com/tls_warp11.php
> 
> Warp 11 or Warp 11HV only 5 kg difference in weight ?


The 11HV is actually a 9 on the inside, in the case of an 11 (with inter-poles)

You'd probably be happier with twin 9's. (better heat dissipation, and faster spin up than the 11)

Your project sounds like something we'd really be interested in helping with. 

We were looking at a Factory Five 818 that they are releasing in Jan.


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## Yabert (Feb 7, 2010)

Lipo Louis said:


> Warp 11 or Warp 11HV only 5 kg difference in weight ?


Based on 1000A controller, Warp 11 peak power is 170-192 Kw (170-192v x 1000A) and Warp 11HV is 288 Kw (288v x 1000A) or even more...
Take a look at Kostov motor. I think they can be really good for high power application during short time.


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## Lipo Louis (Oct 29, 2012)

Thanks I will look into that.
Maybe I want in the future another car with more weighth, let's day 1000 kg. Would this Kostov 11 Alpha still be as good as a Warp 11 HV ?

I just noticed there is an option for a roof too for a MEV Sonic 7


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## Bowser330 (Jun 15, 2008)

major said:


> The vehicle I showed in the photo is called the SuperLite Roadster (SLR). It sports a Warp9 and Zilla 1k so should easily do the 140 kW. It uses a 6-speed transmission. But runs 24 40Ah Pb-Acid and weighed in at 2400 lbs. It does have 6.6 kW of charger on-board and a passenger seat, but not a lot of extras.
> 
> Obviously you can find a high power small Lithium battery and knock a big chunk of mass off a chassis like this. But 1100 lbs? And don't forget to throw in the driver for your calcs
> 
> BTW, last month, we didn't dyno this car. But I saw several others on the dyno running Warp9s with 1000 A controllers hitting around 170 hp at the wheels.


Any more details or data from the dyno session?

What setups were dynoed?, besides warp9 with 1000A controller (Soliton?)

Any 11" motors? Any Kostovs? and Zilla controllers?


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## MalcolmB (Jun 10, 2008)

Hi Louis,
You seem to be leaning towards an enclosed car, but have you looked at the Mevabusa, also from MEV: http://exomotive.com/mevabusa/

Only 380 kg with Hyabusa engine.

Stuart Mills, who designs the MEV cars, has also built an electric version of one his earlier cars (MEV R2), so he's familiar with its special requirements. He's very helpful and keen to develop his cars, so it might be worth giving him a call and discussing your ideas.


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## major (Apr 4, 2008)

Bowser330 said:


> Any more details or data from the dyno session?
> 
> What setups were dynoed?, besides warp9 with 1000A controller (Soliton?)
> 
> Any 11" motors? Any Kostovs? and Zilla controllers?


It was at EVCCON this year. Jack had a portable chassis dynamometer set up for any attendee to use out at the airport where the races were held. I saw a couple of runs. I don't know if anybody published a report or not. Tesseract's Porsche had the highest power at 356 HP (dual W9/dual S1) and Vex's Tesla Roadster Sport hit 271 HP.


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## MN Driver (Sep 29, 2009)

That's the one thing that disappointed me about EVCCON is that all the information wasn't taken down. We have a drag racing thread that leaves out cars and many runs and the autocross details are nowhere. The only dyno runs that people were really paying attention to were after the drag racing and autocross stuff was packed up for the day, those we had a few Youtube videos of. Not sure if we had any dyno runs of Kostov motors but I do know at least 1 car with a Kostov motor was there. 

I definitely know what is going on my pre-show 'What do you want to see this year' entry when I sign up for next year, for this information to be taken down and posted just like we had with the drag race details posted for the 1st EVCCON. Really hoping there is an EVCCON next year because I should have my car ready to go out there. I'm developing plans to actually drive it from MN and it will be a serious challenge the midwest has very little J1772 infrastructure and I don't know if I can trust these 50 amp service RV campgrounds to not gouge the [email protected]# out of me for parking and charging for 2 hours in an RV space.


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## Lipo Louis (Oct 29, 2012)

For the batteries I would like to use the A123 20ah pouch cells 90s2p from victpower or other chinees seller.

I thinkmost people ride with a BMS ? I could just monitor each cell level but I can imagine that the regulations in Holland will not allow this and need some sort of BMS.

I havent's found a 1000A 90S BMS, how does this work for most EV builders ?


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## marc02228 (Jan 15, 2011)

Lipo Louis said:


> For the batteries I would like to use the A123 20ah pouch cells 90s2p from victpower or other chinees seller.
> 
> I thinkmost people ride with a BMS ? I could just monitor each cell level but I can imagine that the regulations in Holland will not allow this and need some sort of BMS.
> 
> I havent's found a 1000A 90S BMS, how does this work for most EV builders ?


I'm gonna use the EMUS BMS from elektromotus in my MX-5 (Miata) conversion with 96S3P A123's, Soliton 1 and Kostov Alpha.
I compared many BMS and finally decided for this.

I've got 130 of the A123 cells from victpower left, if you are interested in. But I'd sell only 100 of them in case I kill some.
I am from Germany.


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## Lipo Louis (Oct 29, 2012)

Emus BMS never heard of it, just checked their website and that looks really great !! Any idea of the price ?

96s A123 is just the max voltage right for the Soliton 1 right ?

Marc, did you get the full tab cels from victpower ? and about what city do you live in Germany ?

Where can I find you build on the internet ? Ev album ?


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## marc02228 (Jan 15, 2011)

Lipo Louis said:


> Emus BMS never heard of it, just checked their website and that looks really great !! Any idea of the price ?
> 
> 96s A123 is just the max voltage right for the Soliton 1 right ?
> 
> ...


I think it's the best to send them a mail with the components you need. You should get an answer pretty soon.

Exactly, I wouldn't use more than 96S with the Soliton.

The cells I got from Victpower have full tabs.

I am studying in Cologne right now but do the conversion at home.. pretty close to Bremen.

This is the thread to my conversion...


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## Lipo Louis (Oct 29, 2012)

Thanks ! What a Nice ride are you building. Bremen is 2 hours away from where i live.
I love the a123 pcb boards, Did someone made that for you ?


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## marc02228 (Jan 15, 2011)

Lipo Louis said:


> Thanks ! What a Nice ride are you building. Bremen is 2 hours away from where i live.
> I love the a123 pcb boards, Did someone made that for you ?


I designed them and Multi circuit boards did the manufacturing


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## Lipo Louis (Oct 29, 2012)

Very helpful, I think the EMUS BMS in combination with a tablet can be very nice. I don't know about the German regulation, but I think we need many other things to car of to get a full car registration to get in legally on the road, did you run into trouble yet ?


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## Lipo Louis (Oct 29, 2012)

What do you people think is better for a 500 kg car with a Kostov 11 Alpha motor ? About 180 KW.
With tranmission or direct drive ?

The goal is to reach 0-100 km/h as fast as possible, top speed 140 km/h.

A direct drive will have less losses and therefore less Watthour/ KM

But I'm afraid it will accelerate slower at higher speeds ?
And maybe less efficient when accelerating from zero ?


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## MalcolmB (Jun 10, 2008)

Unless you have a gearbox that is very well set up and you are able to change gear very quickly I reckon the time saved on gear changes would more than make up for any reduction in acceleration for a direct drive system.


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## Yabert (Feb 7, 2010)

For ultra fast 0-100 km/h, direct drive give you good advantage. Don't lost 0,5 to 1 sec to shift one or two speed is nice.
Reverse remaining a small problem.

With a proper battery pack, a proper controller, a proper gearing and a limited weight, I think the Alpha will do a good job.

Finaly, don't bother with lower efficiency a low rpm... who care, that is probably less than 1% of the discharge time.


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## Lipo Louis (Oct 29, 2012)

And what would be realistic range ? Is it possible to reach 140 km/h with direct drive and still accelerate as fast as possible to 100 km/h ?

And for a quarter mile dragrace, Direct drive still possible ?


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## major (Apr 4, 2008)

Lipo Louis said:


> And for a quarter mile dragrace, Direct drive still possible ?


Hi Lipo,

Do you know what NEDRA stands for? Look it up. John Metric is current president of that association. He runs a pretty mean 1/4. http://www.diyelectriccar.com/forums/showthread.php?t=69476&highlight=plasma 

Pretty much, up to this year, all the fast electric drag racers ran direct drive, no shift. Recently several have started using an overdrive called GearVendors (GV).



Lipo Louis said:


> Is it possible to reach 140 km/h with direct drive and still accelerate as fast as possible to 100 km/h ?


Sure, set your peak power point to 100 km/h.



Lipo Louis said:


> The goal is to reach 0-100 km/h as fast as possible, top speed 140 km/h.
> 
> But I'm afraid it will accelerate slower at higher speeds ?


With a direct drive and geared to stay in current limit up to exit speed will set that top speed at the maximum power point and give you a constant torque from zero to exit speed, so of course, acceleration decreases as speed increases. Shifting gears can increase wheel torque and acceleration at lower vehicle speeds but not near top speed.



> And maybe less efficient when accelerating from zero?


At launch or zero RPM, you're zero percent efficient no matter what the gear ratio. So it can't be any less efficient than that. Efficiency will increase as motor speed increases and that will happen faster with lower gears. However, efficiency is a small concern due to the fact that it is such a small time at those low speeds the lost energy is quite small and not a factor in the battery range and just a small factor in the power laid down. Also consider losses in the transmission and clutches during shifts when comparing efficiencies as well as the energy required accelerating the mass and rotational inertia of a transmission.



Lipo Louis said:


> And what would be realistic range ?


It depends on your battery and what type of driving you're doing. I think these guys with purpose built drag EVs might expect 5 to 10 mile range city driving. Guessing maybe 4 or 5 passes on the strip, but most charge in between runs.

Regards,

major


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## Lipo Louis (Oct 29, 2012)

Thanks for the information I will look into it.

What I meant with range was, what range between 0 and topspeed would be realistic for a direct drive. I thought due to a max voltage of about 340v the motor reaches it topspeed, so be as fast as possible from 0-100kmh is possible but will have consequences for higher speeds since you are not able to shift up.
I can not use a too high gearing I guess, that will effect the acceleration from the standing start.


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## marc02228 (Jan 15, 2011)

Lipo Louis said:


> Very helpful, I think the EMUS BMS in combination with a tablet can be very nice. I don't know about the German regulation, but I think we need many other things to car of to get a full car registration to get in legally on the road, did you run into trouble yet ?


Yes, It's not too easy, but one can do it with a little bit of effort


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## Bowser330 (Jun 15, 2008)

Lipo Louis said:


> Thanks for the information I will look into it.
> 
> What I meant with range was, what range between 0 and topspeed would be realistic for a direct drive. I thought due to a max voltage of about 340v the motor reaches it topspeed, so be as fast as possible from 0-100kmh is possible but will have consequences for higher speeds since you are not able to shift up.
> I can not use a too high gearing I guess, that will effect the acceleration from the standing start.


That "range" of speeds can determined by the redline of your motor using a simple online calculator like this one....http://www.apexgarage.com/tech/gear_ratios.shtml

If you input your tire diameter, lets assume 25", input your proposed gear ratio, set the gear(s) to 1.0 and the final drive to your direct drive ratio, lets assume 5.0, then set the redline of your motor, lets assume its 5500rpm for a Warp series DC motor.....the result = 82mph top speed. You can exceed it but you may destroy your motor.

Your lightweight kit car may be okay with a single 11" motor with 1000A...the Warp11 with 1000A =~ 330ftlbs

Generally, I would suggest people use dual motors and high current controllers for direct drive, because with the higher starting torque you can lower the gear ratio and increase your top end speed.


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## Lipo Louis (Oct 29, 2012)

Thanks, that was very helpful.

Since the car total weight is about 500 Kg I assume a direct drive with a single Kostov 11 Alpha should be ok ?

A 130 km/h topspeed is a bit to low i'm afraid.

http://en.wikipedia.org/wiki/Wrightspeed_X1

I hope to get about these performance of the Wrightspeed X1.
But it say's a gear ratio of 8.25:1 with a direct drive, and a top speed of 167 km/h. So he has a motor that runs 11500 RPM ?


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## Lipo Louis (Oct 29, 2012)

Another thing what I am wondering about, the MEV Sonic 7 kit car is based on a Ford focus technology, they install the motor and transmission of a front wheel drive ford focus and place it in the back of the car.

How would it be possible to install only one 11" motor as a direct drive to the rear wheels. Since the drive shafts go into the gearbox and I don't want a gearbox with Direct drive.

I am not a car mechanic but I would like to learn as much as possible so I can convert it myself.


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## Ziggythewiz (May 16, 2010)

Even with direct drive you usually have a gearbox with a fixed gear ratio to give you torque multiplication, also still need the differential.


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## Lipo Louis (Oct 29, 2012)

If the gearbox has about 5-10% losses then maybe I go not for a direct drive, if that is easier to install, maybe test a bit and find the right gear ratio and if necessary build it later to a direct drive. If the 4th gear is about 1:1 I can find out if it is good enough to make a it a direct drive.

What are the options to make a reverse drive for a direct drive motor ? Install a reverse contactor ?


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## Yabert (Feb 7, 2010)

Hey Louis, do you talk about instaled the motor in front or in rear? I mean, where is the differential in your calcul?

Most FWD transmission have a 4e gear ratio around 1/1, but you need to add the differencial ratio (often 3/1 to 4/1) who is inside the transmission.
Used a FWD transmission is the easiest way to build a light car with rear motor because direct drive or not, you will need a kind of transfer case (often 3/1 to 4/1 ratio) and a differencial. Short, you build a transmision (one speed) or used an existing one (5-6 speed).

To go in reverse with direct drive and using a serie DC motor, you can use contactors rated for high current ($$$) or a second small motor just to go in reverse.


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## Lipo Louis (Oct 29, 2012)

The kit car has a ford focus fwd motor and transmission in the rear.
So I think I keep the transmission and install a Kostov 11 alpha, I didn't thought about the gear ratio of the differential.


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## Duncan (Dec 8, 2008)

The other way to do this is to use a rear wheel drive independent suspension differential
Mazda, Subaru, Mondeo, BMW

Then you can either drive it with a short drive-shaft - the way I am

http://www.diyelectriccar.com/forum...-dubious-device-44370p2.html?highlight=duncan

Or you can mount the motor on top of the diff and use a chain drive 

The drive-shaft option keeps the C of G lower - but the chain drive gives greater flexibility - selecting the ration for the circuit you are on


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## Lipo Louis (Oct 29, 2012)

Thanks, I think to make things easier I'll go for a the original gearbox since that installed anyway.

Now I need a mounting plate for a Kostov 11" Alpha to a 1.8 L Ford Focus 2001 gearbox. I have seen conversions that keep everything original and keep the heavy flywheel, wouldn't it be better to deinstall or make a really light flywheel for the Electric motor ? especially for dragracing I think we don't want a heavy or flywheel at all right ?

And is possible to buy a stock mounting plate for this conversion ? Or do we have to design our own ?


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## Lipo Louis (Oct 29, 2012)

I got inspiration on building an EV like this because of my 6kw Ebike. This is so much fun without any errors, I ride with a 72v 85A setup brushless Hub motor.

I do see HUB motors or In wheel motors on the internet but no serious fast riding cars, so in the near future a good working brushless in wheel motor is probably no option ? Also the brushless controllers of about 200 KW peak will be too expensive, more than 10k ?

On this forum I also read something about 100 Kw brushless motors, but no one with real life experience. I just find it is a step backwards to work with brushes, I want to ride with 1000A peak,( at 250v ) I almost can't imagine that those small brushes on a Kostov 11 can handle 1000A.

Can someone convince me that a Kostov 11 motor really can handle 1000A without a lot of trouble ? Replacing the brushes after a few 1000 KM it is no problem for me. Brushless has so many benefits that it is a bit disappointing to invest so many money in something with brushes, but if it works good than why not ? 

Do I need special brushes btw or any other upgrades can I just use a stock Kostov 11 Alpha ?


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## Jesse67 (May 12, 2009)

If you want to be able to shift quickly with your gearbox then you'll need to keep the clutch but you can use a light weight flywheel. If you plan on leaving it in one gear most of the time or just using one gear for slower speeds and one for higher speeds and you don't mind a bit of a delay shifting you can directly connect the motor to the input shaft and not use the clutch or the flywheel. You just rely on the syncros to shift. 

I have an AC50 (brushless 3 phase AC) in the mini truck with direct drive, 6.83:1 gear ratio, 22" diameter tires. The truck weighs about 700kg and is geared so the top speed is only about 85km/hr at 6000rpm. It has ~0.5G of acceleration up to ~40km/hr when the torque drops off because of the low system voltage and it feels peppy but is by no means fast after that point. You need a full 1G up to 100km/hr if you want 3 sec 0-100km and at the moment the only reasonably priced way to do that is with a big series DC motor and a high amp controller, or lighter weight. 

I've driven a 410kg vehicle with an AC 31 (slightly smaller than the AC50), direct drive and the max system voltage that controller (same one as my AC50) can handle, ~130v and it feels very fast! Probably 6 seconds or so to 100. His gearing is such that top speed is about 170km/hr but the torque doesn't drop off till after 100km/hr due to the higher system voltage. So it accelerates at 100km/hr the same as it does right off the line! A 500kg car with slightly lower gearing to get say a 150km top speed could be just as quick and there is an updated 650A controller now but that's about it for reasonably priced brushless setups and that's only about 80kw max.
http://www.nappepin.com/LithiumHawk.htm

If you want crazy fast your idea so far with a kostov 11 and a soliton 1000A controller should work great and will be insanely quick in a car that light! 

Have fun!


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## Lipo Louis (Oct 29, 2012)

Thank you for the inspirational words 

So an affordable brushless system up to 200KW isn't really going to happen the next couple of months ? 

Than I'll stick to the plan and go for the Solition 1 with kostov 11.

About the gearing. Well I have no experience so I can not tell what I want.

Maybe just keep the gearing do a lot of testing and than decide what to do next.

I wonder if the differential will survive this Electric 200 KW power, the motor and transmission is from a 118 HP ford focus. So probably not, and to experience the best possible acceleration I probably also need a LSD ?

Are there any solutions to make a stronger differential with LSD or buy a Ford focus St 170hp gearbox ? Probably hard to find.

Any idea's ?


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## Jesse67 (May 12, 2009)

Hmm, yes if you're using a focus gearbox it may not handle that kind of power, even in a light car, but the makers of the kit car likely have more experience in what kind of transmission can handle that much power or how much power it can handle. I imagine they've made some pretty quick gas powered ones, I would talk to them. Otherwise I bet a 9" kostov motor and a soliton jr would still make a 500kg car very quick and the weight and cost would also be less and I don't think you would have to worry about blowing up your transmission. As your first ev it might be wise to start with something a little less crazy anyways.


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## nat_ster (Oct 19, 2012)

If the front wheel drive trans out of a ford Focus is too week, then just use one out of a Honda. Tuners push unreal power through them all day long. Almost unbreakable. Later B series engines have limited slip diffs also.

There were some that were also 4x4. Front wheel drive till you press the button on top of the 5 speed shifter, then the back tires engage.

Nat


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## Yabert (Feb 7, 2010)

Limited slip transmission is essential for high performance.
You can see here some stock car coming with lsd transmission. http://en.wikipedia.org/wiki/Torsen

I often regret than the Sentra SE-R Spec-V transmisson I found for only 400$ can't be instaled in my Smart.


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## John (Sep 11, 2007)

0-100km/h in 2-3 seconds will be quite challenging from a physics point of view. 100km/h is 27.778 m/s. The coefficient of friction of rubber on dry tar sealed road is about 1.4 (not sure what sticky drag tires would push this to though). If you were driving all the wheels in contact with the road you could in theory accelerate at 1.4g. Gravity is equivalent to 9.81m/s/s. So 27.778/(1.4*9.81)=2.022 seconds. More reasonable 1g acceleration would give you 2.83 seconds. If you positioned the Center of Gravity of the car so that the front end of the car almost completely unloads during acceleration it might still be close to that with just rear wheel drive. Its just not great for car control having the front end almost off the ground. The coefficient of friction will drop once slipping starts to happen so balancing the torque at the wheels just bellow slipping is also important for maximum acceleration. For a constant acceleration you will want a constant torque at the driving wheels. Constant acceleration equals maximum acceleration when it is limited by the coefficient of friction (a constant). Electric motors are very good for this because when the motor is in the amperage limited phase (constant current) they output pretty much a constant torque.


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## Duncan (Dec 8, 2008)

Hi john

coefficient of friction
I don't think you can achieve 1.4 in a rolling situation, - not without special drag tires that would not be usable on the road

The maximum tire grip is usually in a slip situation - for good road tires 0.8 is the number I keep hitting on 

This makes control easier - it is a lot easier to control for 10% slip than to control just below a slip condition

Incidentally this is very noticeable if you have driven on a track, people normally drive on the roads with very little slip - like driving on rails
When you are on a race track you can see that you are not "driving on rails" but sliding as you corner - the maximum grip is achieved with the right amount of slip

In the real world the coefficient of friction is definitely NOT a constant!


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## John (Sep 11, 2007)

Duncan said:


> coefficient of friction
> I don't think you can achieve 1.4 in a rolling situation, - not without special drag tires that would not be usable on the road
> 
> The maximum tire grip is usually in a slip situation - for good road tires 0.8 is the number I keep hitting on
> ...


Hi Duncan,

When talking about rubber one does have to be a bit flexible in the application of laws. When talking about slip angles and 10% slip you aren't necessarily talking about the rubber sliding on the surface it is gripping. The distortion and stretching of the rubber in the contact patch could account for slip angles and speed miss match without any actual sliding occurring. In most situations the static coefficient of friction is higher than the sliding coefficient of friction. Quoting a coefficient of 1.4 may have been misleading though I recall an Alpha sprint (one of the first cars fitted with ABS) achieving a stop of 1.3g. At 0.8 the maximum possible acceleration to 100 km/h would be about 3.54 seconds if driving all wheels in contact with the road. The Wrightspeed X1 claims 0-60 in 2.9 seconds in a RWD car. This must have been seriously pushing the limits of adhesion of some very sticky tires.
It seems that velocity both sliding and rolling reduces the coefficient of friction.


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## Lipo Louis (Oct 29, 2012)

People. thanks for thinking with me. I have no idea about the G numbers and calculations. I was just thinking 200-250 hp on 500kg should get me real quick to the hunderd 

From there on I think I need to experiment with tires, wouldn't snowtires be a good choice ? The car is lighter so the rubber can be more soft.

500kg is going to be 600kg  MEV Sonic7 with Kostov 11, Solition1 and 84s3p A123 is going to add 250 KG and stock motor with parts will be about 175 kg ?


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## John (Sep 11, 2007)

Lipo Louis said:


> I have no idea about the G numbers and calculations. I was just thinking 200-250 hp on 500kg should get me real quick to the hunderd


 
I didn't mean to confuse the straight forward ambition with maths. I just wanted to point out that a 2-3 second car is starting to push the limits of tires. If I wanted to build something that fast it would have to be AWD. That way I wouldn't be building a drag car but something that could still handle.


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## Lipo Louis (Oct 29, 2012)

I prefer AWD also, but for a lightweigth car with about 600 kg I didn't see possibilities.


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## John (Sep 11, 2007)

A Kostov K11 Alpha produces 193 Nm of torque at 500A. A Honda prelude transmision ratio is 1.956 in second gear times a final drive ratio of 4.266 giving a total ratio of 8.3443. Say static loaded radius of your tires are 0.29m. 193*8.3443/0.29=5553N of force. Divide by 9.81 N/kg = 566kgf, enough for 1g acceleration if your car weighs 566kg. Flip side of this is motor RPM at 500A is 4850 RPM at 230V or 80.833 rev/s. Circumference of tire is pi*D. C=3.241527*0.58=1.822m/rev of tire. Max speed = 1.822*80.833/8.3443=17.65 m/s. 17.65*3.6 = 63.5 km/h. You could assume that the Kostov torque scales fairly linearly with amps to give around 400Nm at 1000A. This would mean that you could get acceptable acceleration in 4th gear. 4th gear is 1.034 ratio for a total ratio of 4.411. This would give about 620kgf acceleration assuming the transmision could handle 400Nm (origional engine peaked at 211Nm). Considering the RPM declines with increasing amps You would still only be able to accelerate at this rate to about 95km/h. You could improve this by increasing voltage. Say your pack could handle a C5 draw rate for spike loads. You would need 200Ah and this at 230+V would need a 46+kWh pack! You would need to push your pack to a C10 draw rate to get down to 100Ah (still a 23kWh battery pack). I'm not sure what A123's can handle.


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## Jesse67 (May 12, 2009)

Don't worry about the numbers, a car that light and with that much power will be savagely fast. Unless you're actually going to competitively drag race what you're looking for is a fun driving experience right? The point is to actually build it and make it drive, if you do it right it will be fast but considering all the variables you won't really know how fast it is until you build it. Did you find a rolling chassis yet? 

You'll want some sticky performance tires, not snow tires. My snow tires have terrible dry pavement traction but that's not the point is it, they're for snow!


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## Lipo Louis (Oct 29, 2012)

Thanks people,

I like the numbers ! but as for the battery I have the following in mind:

84s3p A123 = 277v 60ah = 16.5kwh

Under 1000A load about 15C discharge about 230V

So that is about 230 KW for 150 kg of batteries

I already have one pack of 28s3p and make a model of carton and bring it with me to a MEV Sonic 7 that is for sale nearby, to see if I can fit 3 of these 28s3p packs inside the Kit car.

Later I maybe can add another 7s3p pack to add some extra voltage and AH and therefore also another 20Kw of power.

So maybe it is better to fit a Honda gearbox that is build for more power and install this, otherwise I have to make a second mounting plate for the ford AND the honda.


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## John (Sep 11, 2007)

Just be mindfull of the direction of rotation of Honda gearboxes. I think some Honda motors rotate backwards relative to other makes.


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## Lipo Louis (Oct 29, 2012)

I bougth the MEV Sonic kit car and expect it to have it soon at my workshop 

In mean time I have been reading a lot at this great forum and my conclusion is that I have to keep the idea that I had, Kostov "11 Alpha with Solition 1 controller.

I prefer to install a brushless motor kit, like the AC 50 if 100 hp peak would be enough, but this car has to be extremely fast from 0-100 km/h and for a 200-250 KW AC brushless system we have to pay about 25.000 usd IF we can buy it.
Unless there is something I didn't know than please tell me.

At a 600 KG car I probably won't use 200 KW very often, but it is fun to know that is just under the right foot 

Anyway, to start with, I won't go for a direct drive. I want to try the original Ford Focus gearbox. My question is, what would be a good solution to get this Kostov motor mounted to the the gearbox ?

I probably can find a local machine shop that can make the coupler and mounting plate ? Never checked. But I also have seen websites like this :
http://www.electriccarpartscompany.com/Adapter-Plates_c_31.html

Any suggestions ?

Also, can a Kostov 11" motor just " hang" on the transmission ? I think an extra cradle would be more solid, but I have seen a lot of EV converting pics where the motor was just mounted to the transmission with any support from a frame.


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## Bowser330 (Jun 15, 2008)

I think it goes without saying that you should have some sort of additional motor mount/support for the $2,500 motor, no?

Personally I would try to incorporate motor mounts to help with the vibration/stress, the way I see it, these forklift motors are normally used in forklifts that run primarily on smooth warehouse cement floors. So are they engineered to withstand the vibration of our cracked, crumbling, pot hole ridden, speed bumped, roads? I don't know.


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## Ziggythewiz (May 16, 2010)

Lipo Louis said:


> Also, can a Kostov 11" motor just " hang" on the transmission ? I think an extra cradle would be more solid, but I have seen a lot of EV converting pics where the motor was just mounted to the transmission with any support from a frame.


An important part of the question is the transmission used. A good many conversions are old VWs where the entire engine was mounted off the transmission, so obviously a 1-200 lbs motor is fine *for them* without additional support.


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## Lipo Louis (Oct 29, 2012)

People, I want to decide what motor is should buy.
The kostov 11 alpha or just the kostov 11 250v.
Any suggestions?


The alpha is a few kg ligther,has a fan and can handle some more current for a longer period, atleast that is what I am thinking, but for my 600 kg car I need real power for short moments and I live in a country with low temps and no hills.

So are there any benefits why I should go for the alpha ?


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## Jesse67 (May 12, 2009)

Are there any downsides? Efficiency? Peak power? Cost? I would think any 11" motor will have more than enough mass to handle anything you can dish out to such a light car.


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## Lipo Louis (Oct 29, 2012)

I want to accelerate as fast as possible, would the alpha be any better for it?
The price is 300 euro more expensive, at the total conversion costs of about 15.000 euro, it is not really a big difference, so as I'm typing this I think the alpha is the way to go


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## Bowser330 (Jun 15, 2008)

Lipo Louis said:


> People, I want to decide what motor is should buy.
> The kostov 11 alpha or just the kostov 11 250v.
> Any suggestions?
> 
> ...


I would go with Alpha, more rpm for very little difference in torque..

*Alpha Graph*
http://kostov-motors.com/files/productattachments/046de95abf0344b1e46ff48da45b73e3_S250F03%20%282%29.pdf

210V (230V)
500A (500A)
85% eff (85%)
89kw @ 4500rpm (98kw @ 4950rpm)
195nm torque (195nm)

*K11 Graph (Series Field Mode, 248V/210A)*
http://kostov-motors.com/files/prod...5d3fca2c5160d76be63770_perfK250-S192F01.1.pdf

230V
500A
80% eff
92kw @ 4200rpm
210nm torque


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## dtbaker (Jan 5, 2008)

Lipo Louis said:


> People, I want to decide what motor is should buy.
> The kostov 11 alpha or just the kostov 11 250v.
> Any suggestions?
> 
> ...



alpha sounds better....

personally I think you'd get just as good performance with a warp9.... with far lighter weight, higher rpm.... you're going to be traction limited even with the Warp9. You'll need HUGE sticky tires, or 4wd, to prevent burnout and wheel hop shooting for sub-5 second 0-60.


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## dtbaker (Jan 5, 2008)

Lipo Louis said:


> Anyway, to start with, I won't go for a direct drive. I want to try the original Ford Focus gearbox.


I don't think that's going to hold up long.... you should plan on something built to handle 250+ ft# of torque and common heavy duty clutch mods available.... something from a mustang perhaps.


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## Bowser330 (Jun 15, 2008)

dtbaker said:


> alpha sounds better....
> 
> personally I think you'd get just as good performance with a warp9.... with far lighter weight, higher rpm.... you're going to be traction limited even with the Warp9. You'll need HUGE sticky tires, or 4wd, to prevent burnout and wheel hop shooting for sub-5 second 0-60.


The real advantage to the Warp9 is the ability to withstand higher amperage...1000A easy...compared to the Kostovs which I have read do not withstand 1000A as easy.

Because of this J.Rickard was able to get 156hp from the Warp9 Soliton1(1000A) combo...

http://1.bp.blogspot.com/-WV0zVFAY3pg/TaQ1OA5SK_I/AAAAAAAACIk/p8nlABpZW00/s1600/redux4thgear-2.jpg

I am not sure the Warp9 would give him higher rpm than a K11 Alpha, due to the Warp9 voltage being more limited (170V) by potential arcing, right?

Due to the high amperage the cells sagged down from 180V to 147V which hurts the peak power rpm, 156hp @3200rpm, even with 170V at the motor (no sag) thats only 15% better voltage so only 15% better rpm, 3680rpm... 

The Warp9 weighs 143lbs and the K11Alpha 165lbs, not too much lighter either.


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## Lipo Louis (Oct 29, 2012)

Thanks for thinking with me, I was searching a long time for these curves, I never found them, are there more to find ? And are those real dyno numbers?

Due to the alpha's wider size I was hoping to get more torque, I hope the tires are the limiting factor, I prefer to buy equipment with overkill, I always can set lower amps at the controller, or lift the throttle

Another question, at my ebike bicycle, I have installed a 3 way speed switch where speed 3 is 6kw, and when I hand the ebike over to my wife I set it to speed 1 for a limit of 1,5kw with a 30kmh speed limit. Is something like this also possible with a soliton 1 ? So the car won't be to aggressive for my wife


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## Bowser330 (Jun 15, 2008)

Lipo Louis said:


> Thanks for thinking with me, I was searching a long time for these curves, I never found them, are there more to find ? And are those real dyno numbers?
> 
> Due to the alpha's wider size I was hoping to get more torque, I hope the tires are the limiting factor, I prefer to buy equipment with overkill, I always can set lower amps at the controller, or lift the throttle
> 
> Another question, at my ebike bicycle, I have installed a 3 way speed switch where speed 3 is 6kw, and when I hand the ebike over to my wife I set it to speed 1 for a limit of 1,5kw with a 30kmh speed limit. Is something like this also possible with a soliton 1 ? So the car won't be to aggressive for my wife


I do believe it is possible to configure the soliton is such a way so as to have different modes of operation based on throttle limit, so you would have the throttle limit up to 100% for yourself where as your wife would have a throttle limit up to 50%...so she could only demand 50% of the amps/torque.


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## Lipo Louis (Oct 29, 2012)

It would be handy to have some switch for this instead of programming the controller, or is this what you mean? If not maybe add a resistor inline with the throttle? And enable or disable this with a switch? Can also be handy in rainy conditions, set the controller or throttle at 35% and even at full throttle you can ride more safe.


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## marc02228 (Jan 15, 2011)

Lipo Louis said:


> It would be handy to have some switch for this instead of programming the controller, or is this what you mean? If not maybe add a resistor inline with the throttle? And enable or disable this with a switch? Can also be handy in rainy conditions, set the controller or throttle at 35% and even at full throttle you can ride more safe.


You can put a switch between +12V and the Soliton (e.g. IN1) and declare it as throttle limit in the soliton setup. This is also written in the Soliton manual.
I use it in my Miata in combination with a key switch. I set it to 43% which helps me to drive conservatively. 

I didn't read the whole thread, but in your car I would remove the transmission, use a good and stable diff, so that you run out of rpm at about 140km/h.

I am still thinking, if I should remove the clutch in my miata, because I already killed it. It's still working, but it slips at much less torque.


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## nat_ster (Oct 19, 2012)

dtbaker said:


> I don't think that's going to hold up long.... you should plan on something built to handle 250+ ft# of torque and common heavy duty clutch mods available.... something from a mustang perhaps.



Your thinking is on the right track, but a little off. Stay away from anything that was from a heavy v8. Also stay away from sub standard parts from Ford. 

Pound for pound, Honda transmissions are a far stronger than anything Ford ever used. Ford was also horrible for having uncommon, non interchangeable parts. Honda's parts are vary common, and interchangeable.

Nat


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## Lipo Louis (Oct 29, 2012)

What part is the weakest part of a manual gearbox? I'm planning to go for the stock ford focus gearbox since it is already installed inside the car. I ordered the Kostov 11 alpha and wonder how long the gearbox will survive and what part will break first, I probably need a limited slip differential too, and if I install a high quality LSD would that mean that my gearbox can handle more power? I believe the differential is the weakest part, or am I wrong about this.


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## Bowser330 (Jun 15, 2008)

Lipo Louis said:


> What part is the weakest part of a manual gearbox? I'm planning to go for the stock ford focus gearbox since it is already installed inside the car. I ordered the Kostov 11 alpha and wonder how long the gearbox will survive and what part will break first, I probably need a limited slip differential too, and if I install a high quality LSD would that mean that my gearbox can handle more power? I believe the differential is the weakest part, or am I wrong about this.


Good call on the K11 Alpha, make sure you supply it with plenty of voltage so you can keep the necessary amps low and therefore keep the motor running cooler. The high voltage will give you high peak power rpm so it will more simulate an ICE than a low voltage system.

I would reach out to ford focus performance tuners, I am sure they have clutch upgrades and other upgrades for the manual transmission.You can also try to increase motor torque step by step until you feel comfortable the transmission isn't being too stressed.

Depending on what controller you get, you can limit the throttle sensitivity for torque delivery to prevent form breaking anything with the instant torque of the e-motor.


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## Duncan (Dec 8, 2008)

Re - Gearboxes

This is not as much of a problem as you are thinking,
The limits on a gearbox are set by the amount of torque that can be put on the ground

You are going to use sticky tires - increased load
But less weight - reduced load

And you are going to be kinder to the gearbox than an IC - no dumped clutches


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## Lipo Louis (Oct 29, 2012)

Ok thanks !

I mean time I have the car and with 120 HP it is sooo much fun and sooo fast 
I have been riding with my tuned 350 HP BMW 535d but this so much better, the exact weigth of my kit car is now 595 KG.

I have the following idea, please think with me again on this one:

I will look up what gearbox exactly is now at my kitcar, I'll buy a second gearbox of the exact same type, then I will install a LSD and a stronger clutch to this gearbox and let someone made an adapter plate and coupler for the Kostov 11 Alpha. So when everthing will fit together I can easily swap the ice for the kostov. Why ? Well then I can ride every day untill the above is ready to use instead of having the car standing still for a few months during summertime

I go for 84s3p A123 Cells.

I don't know all ajustmentments of the Solition, is it possible to set peak power at a higher rpm ? So you can simulate a ICE ? The car now has lot's of grip because it is low torque and high power at high rpm, with a strong Kostov the torque and power will be present at lower rpm and therefor maybe too much from the start. I had a Kelly controller that I god set to low torque mode and at this setting it was just like an ICE motor.


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## Yabert (Feb 7, 2010)

Lipo Louis said:


> I don't know all ajustmentments of the Solition, is it possible to set peak power at a higher rpm ? So you can simulate a ICE ?


No.

The Soliton is an awesome controller, but despite it can control the peak power and the motor current ramp rate (controlled torque at start), it can't displace the peak power. If you reduce peak torque at start, peak power will be reduce.

But by chance the Soliton have an increadible feature, it allow to your right foot to determine the moment you need peak power...
So, don't bother with the too high torque, it isn't a real problem inside a car builded to have fun!

Pic of your car?


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## John (Sep 11, 2007)

I think the torque the motor produces is proportional to the amperage. So the first part of the torque curve is amperage limited and since the amperage is constant the torque is mostly constant for this part of the curve. The controller chops the voltage in this part of the curve to keep the amperage below limits. As the motor rpm increases it starts to generate more and more back EMF. At some RPM this back EMF is sufficient to keep the amperage below the limit so the curve enters the voltage limited (constant voltage) part of the curve and as the amperage drops off so does the torque. You could move the point where torque starts to drop off by either reducing maximum amps or increasing voltage. Or if you could somehow alter the back EMF characteristics of the motor which isn’t really possible in a Series motor. I think this might be what field weakening does in SepEx motors. Limiting amps would simply reduce peak torque and hence it would run into voltage limited curve at higher RPM. Increasing the voltage would keep it in the amperage limited phase longer. 

Trying to emulate the peaky ICE torque characteristics would I think be counterproductive. The electric motors flat torque curve is better suited to performance. Feeding constant torque to your driving wheel would produce a constant shear force on the tire contact patch. If this force could be balanced to be just below the limits of adhesion of the tires, for the conditions at the time, maximum acceleration could be achieved without having to constantly adjust the accelerator position to hunt for the desired torque. This is also why a single ratio is desirable for a performance electric vehicle. It also removes the delays in acceleration introduced by changing gears.


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## Lipo Louis (Oct 29, 2012)

Rainy and cold outside but can't stop riding, just amazing !


As for the peak torque from the start, yes it is good and I think it is even better to get the car fast from 0-100 km/h, but at the moment the 120 hp at 6000 rpm is very forgiving at the corners, also on a wet road. The power will build up and there is plenty of time to notice that I'm going to slide sideways, so you lift the throttle and you are ok.

I can imagine that when you have so much instant torque and power at the rear wheels it can be tricky when accelerating from a corner. But we will find out after the conversion.


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## Yabert (Feb 7, 2010)

Nice little car (exept the color... sorry, personal preference!)
I think you have all in hands to build an incredible performant electric car. Build it correctly at first try and don't hesitate to asking advices from experiment members here.

Where do you think put the battery? Each side of the cockpit? In the rear, just over the motor and transmision?


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## Lipo Louis (Oct 29, 2012)

The red parts are going to be deep blue, red is also not my color.
At the rear 1 x 28s3p a123 behind the seat 1x 28s3p and in front 4x 7s3p battery.

Not 100% sure yet, I have to see the 7s3p modules.


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## nat_ster (Oct 19, 2012)

I saw pics....

Now I can't wait for more. 

Nat


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## MN Driver (Sep 29, 2009)

Lipo Louis said:


> ...I go for 84s3p A123 Cells.
> 
> I don't know all ajustmentments of the Solition, is it possible to set peak power at a higher rpm ? So you can simulate a ICE ? The car now has lot's of grip because it is low torque and high power at high rpm, with a strong Kostov the torque and power will be present at lower rpm and therefor maybe too much from the start. I had a Kelly controller that I god set to low torque mode and at this setting it was just like an ICE motor.


Peak power at a higher RPM? More voltage.

You can't do that with the non-interpoled WarP 9 motor for example and end up arcing the comm at the high 100's of voltage. If you feed the Kostov or another motor with interpoles with a higher voltage you are raising that peak power RPM and therefore increasing the peak power while you supply the high amperage for torque. 84 in series? I'd use more. I'd aim for the mid 90's in series if you can fit them, you can always limit voltage at the controller but with 84 you will be limited as your voltage sags when you need it the most. I'm planning for 100 CALB CA 60Ah in my conversion although I may need to step back a few cells or lower my charge voltage slightly if my controller gets upset, 96 is supposedly the magic number of LiFePO4 cells for the Soliton.


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## Lipo Louis (Oct 29, 2012)

I can go for 91 cells in serie as well, I always can add more cells, but I can test with 84 cells.

Yesterday I picked up my Solition 1, kostov 11 Alpha, Elcon 2.5 Kw charger.

Nat_ster here advised me to use a gearbox from a Honda Prelude because it stronger than a ford gearbox. John tells me that some Honda gearboxes have a different rotation, I just can the motor spin the other way around right ? Or is it better to spin the motor in only one direction ?

Another thing, I will need an LSD for traction, now some Honda Prelude's Intergra type R and Civic type R do have a stock 60% LSD so maybe a honda gearbox is a good idea. Mounting a LSD into a Ford focus gearbox will also be very expensive.

Now I just need to know what gear box exactly I need for this.


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## Lipo Louis (Oct 29, 2012)

I made up my mind, and go for a Honda Integra type R S80 gearbox.
I already have the gearbox, inside is a 80% Drexler LSD, if this is to agressive, I can swap it for a stock 60% LSD.

I can spin the motor the other way around so the different rotation is no problem.

Next step is to find someone that can make a mounting plate and coupler.


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## naturals (Jan 9, 2011)

Hey Louis,
Any news on this? I've been a member of DIYEC for a while but actually found this thread via the MEV forums. I've very interested in a Sonic 7 myself (I saw a few at a show today and was really impressed) so I'm following this thread with interest!


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## Lipo Louis (Oct 29, 2012)

I have bougth a Honda Intergra type R gearbox ( Honda S80 ) with a 80 % Drexler LSD. I can use this gearbox to try it, I think the 80% LSD is way to much and can swap it later for a stock Honda 60% LSD.

I brougth the gearbox and the Kostov 11 Alpha to a company that is now making the adapter plate and coupler.

I have a 28s 3p a123 pack and am waiting a long time for Victpower to send the rest of 9 x 7s3p packs

Calb 60 ah would have been a good option, but can not deliver 1000A without enormous voltage drop, also that would have been 220kg of batteries and the a123 is much ligther. So I hope I will receive the 7s3p packs after all.


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## Lipo Louis (Oct 29, 2012)

At the moment I still did not receive my 9x 7s3p A123 packs from Victpower, she can not get these packs anymore and offered me selfmade packs but I only want original OEM stock A123 packs that has been for a Fisker Karma or so. So I'm getting a refund. ( waiting )

So now I need other batteries, I have a 28s3p a123 OEM pack, but I don't think I can use this in combination with other cells.

At the moment the best solution would be Winston 40Ah or 60Ah cells, it is much heavier than the A123 cells but i'm afraid there is no better solution. The good thing is, is that it easier to install and replace a bad cell.

http://www.ev-power.eu/Winston-40Ah-200Ah/WB-LYP40AHA-LiFeYPO4-3-2V-40Ah.html

It says 800A max discharge, and for the 60Ah cell 1200A max discharge, I wonder what voltage sag they have at this 20c discharge.


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## marc02228 (Jan 15, 2011)

Take a look at the CALB CA 60Ah cells. I like these cells, from the data, I saw in the internet, but didn't test them, myself.

Alternatively, I've got 120 A123 cells left from my miata project. I could sell you 60 cells and the PCB's to build two 10s3p modules out of them.
They are located in Bremen/Germany.
Pictures are in my blog --> Signature

RWaudio mixed the Calb CA and the A123's in his Porsche 944, if I remember right.

P.s.: I would be very careful with victpower, I bought my cells from them, too. But they seem to sell nothing but rubbish cells since a couple of weeks... Maybe they get some good cells again, but I'd be careful


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## Lipo Louis (Oct 29, 2012)

Marc,

Yes, maybe it is possible to use this A123 pack in series with some Calb kinda cells, I wonder how the balancing would go. Maybe if you get just 50ah out of both 60ah cells it will be ok.

About your cells, maybe that is a solution too, but I'm afraid of errors, puffy, leaking cells if it is not an OEM pack.That is why I ordered the OEM 28s3p and 7s3p pack. But I will think about it.

You can miss 60 pcs ? I need many more to get a good 90s 3p.

Victpower told me they will refund me tomorrow.............


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## rwaudio (May 22, 2008)

I'm using a mixed pack of A123 and Calb CA60FI in my car right now. I have 74 of the CALB 60's and 18S4P of the A123's. Everything is bottom balanced and the charger terminates at around 60Ah leaving the A123's just over 3/4 full. So far the set up works very well with no issues yet. The car is running great, voltage sags to 255v (2.77v per cell avg, more sag on the CALB's less on the A123's) after 3-4 seconds at 500A, which is a lot worse than just A123's but when that's the only option you do what you gotta do. I've just upped the battery current on the controller to 720 battery amps but I'm not sure what the pack sags to yet.


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## galeson (Oct 25, 2009)

I have 150 A123 assembled into 3P10S packs I am not going to use. I'm in San Francisco so getting them to you may be a big problem.


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## Bowser330 (Jun 15, 2008)

rwaudio said:


> The car is running great, voltage sags to 255v (2.77v per cell avg, more sag on the CALB's less on the A123's) after 3-4 seconds at 500A, which is a lot worse than just A123's but when that's the only option you do what you gotta do. I've just upped the battery current on the controller to 720 battery amps but I'm not sure what the pack sags to yet.


720A draw from CA60 cells (12C) would be nice to know. I am a little surprised the CA60 cells are sagging to 2.7V with only 8C discharge, i thought when JackR. tested them they sagged to 2.7 @ 12C....


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## rwaudio (May 22, 2008)

Bowser330 said:


> 720A draw from CA60 cells (12C) would be nice to know. I am a little surprised the CA60 cells are sagging to 2.7V with only 8C discharge, i thought when JackR. tested them they sagged to 2.7 @ 12C....


Jacks test is a single cell on the bench with the voltage measured at the terminals...... throw 74 of those, some A123's copper connecting bars, a bunch of 2/0 cable into the mix and you have a system voltage drop as outlined above.

If I measured the voltage of one cell at the terminals during that load it would be higher (likely matching Jacks results), but that isn't the actual voltage at the controller so it's meaningless. 

Data is always good, so if I get the chance I'll measure the voltage of a cell under load at it's terminals and the "system" voltage under the same load which would help estimate actual battery voltage from the performance of a single cell on the bench.


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## Lipo Louis (Oct 29, 2012)

So a drop to about 2.7v at 8c or 12c, but at what time ? Will the voltage drop immediately to 2.7v and stay there ? I wonder what happen the first 3 seconds, maybe it will drop less ?

What about these :
http://www.ev-power.eu/Winston-40Ah-200Ah/WB-LYP60AHA-LiFeYPO4-3-2V-60Ah.html

They are about the same price as the Calb 60Ah but they "claim" a much higher C rating, 1200A ! And also are 2.3 KG and Calb 60Ah is 2.5 KG.

I wonder if they really can deliver 1200A without dropping to 1.5V


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## nucleus (May 18, 2012)

*Re Winston Batteries*



Lipo Louis said:


> So a drop to about 2.7v at 8c or 12c, but at what time ? Will the voltage drop immediately to 2.7v and stay there ? I wonder what happen the first 3 seconds, maybe it will drop less ?
> 
> What about these :
> http://www.ev-power.eu/Winston-40Ah-200Ah/WB-LYP60AHA-LiFeYPO4-3-2V-60Ah.html
> ...


No one has been able to buy Winston batteries for years.


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## Lipo Louis (Oct 29, 2012)

http://www.ev-power.eu/Winston-40Ah-200Ah/WB-LYP60AHA-LiFeYPO4-3-2V-60Ah.html

It says : 6 on stock.

Are cells so hard to get ?


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## rwaudio (May 22, 2008)

Lipo Louis said:


> http://www.ev-power.eu/Winston-40Ah-200Ah/WB-LYP60AHA-LiFeYPO4-3-2V-60Ah.html
> 
> It says : 6 on stock.
> 
> Are cells so hard to get ?


Those cells have very bad sag, I've used some of the 100Ah cells and although they are great batteries. Once the C rate starts to go up the voltage goes DOWN. I would say they are similar or possibly a bit worse than the CALB SE's for voltage sag, the CALB CA's are much better, not as good as A123, but the best prismatic I've seen.

From the previous comment it's hard to see exactly when I hit 500 battery amps, these are observations of gauges not a log file or anything. On hard acceleration it takes a couple seconds to hit 500A then I draw 500A for 2-3 seconds and I'm speeding. The previous observation was the voltage as I was about to let off the throttle, so it was about 5 seconds of load on the cells, increasing to 500A the first couple seconds and maintaining that for a few more seconds. It might also be noteworthy that the ambient temp was about 15C but the pack might have been a bit warmer than that. A warmer pack would also sag less.

I'll try and get a log file with my 720A settings which would likely be of more use than some observations of gauges. Others have commented the CA's aren't good cells for racing, they just heat up too much. If you are doing short bursts, or longer duration (EV West uses CA's in the desert buggy) they might work, my application is just a fun street car, and it does that VERY well.


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## Lipo Louis (Oct 29, 2012)

_Yes the next delivery is to happen in August.

The 60Ah cells are capable of providing up to 1200A in very short bursts. It should work fine with your project_

Above is respons from Evpower.

Ok so the Calb should be better although they claim only have the C rate of Winston 

I want to accelerate from 0-100 km/h with a 650 kg car in asap and hope to reach it in about 3 seconds, from then on the cells can cool down. So I only need very short burst with a lot of time in between.

I have the EMUS BMS with small balancing boards, for these prismatic Calb 60ah I better can use the normal balancing boards for higher balancing power, but if that will work together I don't know.

I would like to see the 720a LOG FILE


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## marc02228 (Jan 15, 2011)

rwaudio said:


> I'll try and get a log file with my 720A settings which would likely be of more use than some observations of gauges. Others have commented the CA's aren't good cells for racing, they just heat up too much. If you are doing short bursts, or longer duration (EV West uses CA's in the desert buggy) they might work, my application is just a fun street car, and it does that VERY well.


I'll take a log file from my A123 packs, as well. Should be interesting to see, how the calm/A123 hybrid pack behaves to the A123 Pack. Would be great to get some data from a Calb only pack, too.

Bought a little 15 Euro Router which is powered by an internal battery to get my data to the PC...


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## marc02228 (Jan 15, 2011)

Just did a quick test. Unfortunately the soliton log only shows the motor current.

I cut 20ms to much away at the beginning of the chart, so it starts at 314V.

Actual voltage at the start was 316V and at the max sag point 277V. Current was 900A most of the time.

But the chart actually explains itself...

Soliton settings:
max motorvoltage: 250V
max. motorcurrent: 900A
Slew Rate: 1000A/s
max RPM: 5400 (have to get rid of the noise)


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## Lipo Louis (Oct 29, 2012)

Nice. So it is hard to tell how about the IR of the pack. I did some test with the a123 pack and have 1 mOhm of internal resistance for 3p20ah pouch. 3,32v drop to 3,12v at 300a

316v to 277v drop is 39v sag / 900a would be 44 mOhm. But that's probably not correct.


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## marc02228 (Jan 15, 2011)

Lipo Louis said:


> Nice. So it is hard to tell how about the IR of the pack. I did some test with the a123 pack and have 1 mOhm of internal resistance for 3p20ah pouch. 3,32v drop to 3,12v at 300a
> 
> 316v to 277v drop is 39v sag / 900a would be 44 mOhm. But that's probably not correct.


How long did you apply the 300 A?
If you tested an 1S3P pack, you have to multiply it by 96 to get to the resistance for a 96S pack. 

The 39 V sag was for my 96S3P pack at the controller. All contact resistances, etc. are in there.
I am quite confident, that my pack is actually pretty good assembled and thought out. But it would be nice to have some data to compare.

At the test it was almost fully charged and temperature was about 15°C, if I remember right. I can't imagine, that you get a much better value out of the A123's.


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## Tesseract (Sep 27, 2008)

marc02228 said:


> Just did a quick test. Unfortunately the soliton log only shows the motor current....


Ahem... From p24-25 of the Soliton owner's manual:



> Using the data from Illustration 16 as an example, battery voltage times duty cycle gives you motor voltage (e.g. - 144V * 0.345 = 49.7V)
> while motor current times duty cycle gives you battery current (e.g. - 480A * 0.345 = 166A). Appendix B has a brief overview on how PWM
> motor controllers work that explains these relationships in more detail.


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## Siwastaja (Aug 1, 2012)

*Re: Re Winston Batteries*



nucleus said:


> No one has been able to buy Winston batteries for years.


Apparently the sellers that sell these everyday claim otherwise.


OTOH, false claims that "Winston has stopped selling" and "no one has been able to buy Winston" or "Winston cells are low-quality" have been going on since the Sinopoly/Winston split, usually by members with relatively low postcount. I have stated this many times, but I really think the moderators should check this up, check the IP addresses and ask for the source of the information. It seems to me that it is well possible that Sinopoly is making up these claims. I have seen one confirmed case where one forum member distributed Sinopoly's (Winston's direct competitor) claims of Winston cell quality directly without first-hand experience.

OTOH, people who did buy these "unavailable" cells that are for sale everywhere, report good performance, similar to other Chinese prismatics in the same price range, but somewhat higher internal resistance than a bit more expensive cells.


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## Lipo Louis (Oct 29, 2012)

I tested my 300A load for only a few seconds, shortcut with a long 10Awg wire.
And get 1 mOhm IR at 1s3p. Never could test 96s, but would that be 96 mOhm IR ? 

Today I tested a single Calb 130 AH cell

http://www.ev-power.eu/en/By-Brand-...Ah.html?listtype=search&searchparam=SE130AHA 

A few meter 10Awg wire short cut at single cell for a few seconds.

3.33V to 2.80V at 170 A =3 mOhm of IR

And that for a 130Ah cell.

A 60Ah would than have 6 mOhm of IR ? Or isn't this correct ?

Than it would never be possible to run 1000A even for a few seconds.

Or am I missing something ?


EDIT, the above is wrong

I tested again and now better. 

Nominal Voltage 3.33V
Under load 3.15V
At 333A

Voltage drop 0.18V / 333A x 1000 = 0.54 mOhm for a 130Ah cell. Would that mean that a 60Ah cells is about 1 mOhm ?

Now I'm lost in numbers.

What if I had 96 x 60ah CALB cells at 1 mOhm, they would drop with double from the above at 0,36v at 333A, so from 3.33v to 2.97v x 96 = 285V

At 1000A that would be from 3.33 v to ?


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## marc02228 (Jan 15, 2011)

Lipo Louis said:


> I tested my 300A load for only a few seconds, shortcut with a long 10Awg wire.
> And get 1 mOhm IR at 1s3p. Never could test 96s, but would that be 96 mOhm IR ?
> 
> Today I tested a single Calb 130 AH cell
> ...


Sounds correct... and quite bad for the Calb cell^^
So that was a blue Calb cell? The grey ones should be a bit better, but that's just hearsay. Someone told me, that EVTV tested the grey calbs. Maybe you'll find something, there.

Yes, for 96s, the internal resistance would be 96mΩ, then.

Did you already see these modules?
http://evolveelectrics.com/Enerdel_MP310-049_Moxie.html

What about Lithium Polymer, Turnigy for example? Jozzer uses these cells to power his Miata. Seems, like he has only about 3% sag at 1000A... 
http://endless-sphere.com/forums/viewtopic.php?f=34&t=38171

In Germany it's not possible to get a car approved which uses these cells. I don't know, if the dutch RDW (?) likes them...


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## Lipo Louis (Oct 29, 2012)

Sorry, I edited my post the same time your replied. Check it again please. 

I didn't check the Enerdel cells. I will look into that.


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## marc02228 (Jan 15, 2011)

Lipo Louis said:


> Sorry, I edited my post the same time your replied. Check it again please.
> 
> I didn't check the Enerdel cells. I will look into that.


OK, if you expect the 60 Ah cell to have an internal resistance of 1 mΩ (it should be in that range), pack voltage sag at 1000A will be 96 V.

96 * 1 mΩ * 1000 A = 96V


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## marc02228 (Jan 15, 2011)

Tesseract said:


> Ahem... From p24-25 of the Soliton owner's manual:


Ok, your right. That makes sense... 

Packcurrent was 826A
Voltage drop stays at 39V

So the resistance of the 96S3P pack, measured at the Soliton terminals, is about 47mΩ.


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## Lipo Louis (Oct 29, 2012)

I have bought a complete battery pack of a 2012 Opel Ampera/ Chevy Volt 
288 pcs of 15Ah LG Chem cells.

96S3P 360V 45kwh 16 kwh

Today I'm going to take this big pack apart and see how to connect balance wires and main leads to this animal battery 

If for some reason the internet will go down around europe than something went wrong at my shop


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## Lipo Louis (Oct 29, 2012)

381V for the whole pack and could not reach a single cell yet, there is a BMS and many other parts on top of it. Too bad I can not use this OEM BMS. Also there are hoses for cooling and warming up the pack. 

Very curious what to expect.

It are several modules, I can skip the smallest modules so I will not exceed the 345V for the Soliton 1 Controller.

I now also can get the controller, motor, charger and everything that is at an Opel Ampera, it is a Opel Ampera that has been in the water for a part and the insurance company got rid of it. I wonder if it then is maybe possible to use the OEM BMS.


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## Lipo Louis (Oct 29, 2012)

I can reach the cells very easily, and did a quick test.

3.99V to 3.66V at 400A for a few seconds. = 0.85 mOhm IR at 3P15ah so 45AH

My A123 was 1.0 mOHm at 60Ah cells, so it's about the same.


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## tylerwatts (Feb 9, 2012)

Wow very interesting Louis. That is quite a find. What chemistry are the cells? What drive train is in an ampera? Are they hybrid or electric? Could be a good donor and if you use the cry system that May should be useable also. Nice! Any pics of the cells?


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## Lipo Louis (Oct 29, 2012)

Same car as Chevrolet Volt, brushless AC stuff. The car has been in water, no idea if motor and controller are OK. Also no idea if a DIY guy can get it to run. Maybe it needs the car to function.

Cells are 96s3p LG Chem. Very good access with very long tabs.balance wires and everything very good to use.


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## tylerwatts (Feb 9, 2012)

Well the motor will be fine, as will wiring. You may lose controller and May. I'd suspect the controller is sealed so water should not have had any effect. 

Do you HAVE the whole car, or access to buy parts from it? If you have it you could dry it out and try the system out to see what works. 

How about some pics then of the cells? And of the motor if you can please. I will try the web also but it usually lacks details.


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## Lipo Louis (Oct 29, 2012)

Here are some pictures, the whole pack is made out of 9 modules but in 4 big blocks. Also every block or module seems to be easy to replace.

In fact, I think it is even possible to remove a single 3p cell and replace it.

Because the tabs are so long and wide, it is easy to bold/clamp something to it.

Each module has it's own balance connector and mating connector, so it can be handy to install your own BMS.

The Soliton can handle 350v so I probably use 85 cells in serie and charge it to 4,10v per cell for 348V

I than have 11s3p for spare cells.


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## tylerwatts (Feb 9, 2012)

Raise look really nice Louis! Excellent that you can use the whole modules. Are you thinking of going DC still? Why not use the Volt AC motor? Is it single speed? I don't recall. You could use the motor with your own trans and something like a Scott Drive controller.


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## marc02228 (Jan 15, 2011)

Lipo Louis said:


> I have bought a complete battery pack of a 2012 Opel Ampera/ Chevy Volt
> 288 pcs of 15Ah LG Chem cells.
> 
> 96S3P 360V 45kwh 16 kwh
> ...


Woow, congrats. That seems to be a really great battery. What's the weight of the whole thing?

Where did you see, that the insurance company wanted to sell it?
Did you buy the whole car?


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## Lipo Louis (Oct 29, 2012)

Well, I just saw the advertising from a demolition company and was not interessted since I made up my mind to go for CALB, in combination with my a123 pack. These GM 16kwh is lion and would need to find a way to connect the cells. But after all this is the best pack I have ever seen, I still can use the bottom and mounting plates, each of the 9 module is bolded, I can use the balancing wires from the original BMS with contra connector. I also found 5 expensive Panasonic Relay contactors 200 usd each, I can use them !

Also some small pumps for liquid cooling/warming is inside.

The whole pack including mounting and all parts is 197 kg, each cell is 383 gr.
That is 110 kg for 16 kwh

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110011197_2011010830.pdf

Page 5 and 9


The strange part is these small wires, that is inside.
I was thinking of using 120mm2 of wire, but these OEM wires are only 10mm wide ( not square ) as you can see here.










I did measure a Opel Ampera at full throttle and it is draining 350A at acceleration.


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## tylerwatts (Feb 9, 2012)

Hey Louis. Been reading up on your Volt drive train. It is impressive. I would recommend using it for your car. It would be good to run the generator motor as a boost supply and also for regen then you could run either electric motor in a more efficient mode. That might be too complicated.
If you could run the trans from the or controller and trick it to power the generator in boost mode or something maybe that would be good. 
I'm speculating cause I don't know what is possible with your setup. To be honest a 3s 0-60 is ambitious and you probably need a more power dense drive train.


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## Lipo Louis (Oct 29, 2012)

I already have a Solition 1 and a Kostov 11.
About the 0-100 km/h About 300KW input power =300 HP at 650 KG with 80% LSD, I hope around 3 sec should be possible.

2 days ago I took a ride to the company that had all kinds of parts from Opel Ampera/ Chevy Volt. Maybe there was something interesting for me. But I saw the controller unit, at least I think it was and nothing useful to me, I also saw the AC motor, but it is inside a metal box, more like a gearbox. It needs all kinds of wires, probably will only run with the complete electric train, So many connectors. Also another metalbox that needs connectors from the BMS etc. Don't know what it was. You probably even need there LCD screen. Also the car has been inside the water for a part and was not running anymore so that makes it even harder to let it run. I think you can get these parts for real cheap since the company don't know what to do with it.

The only thing I bought extra was this :
http://www.es-store.co.uk/ev-cables/EV-C-16A-M3-TYPE-1-2-8M.html

And the female or male side that is attached inside the car, maybe it is possible to charge with a original EV power source. ? But probably won't use it.


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## John (Sep 11, 2007)

0-100km/h in 3 seconds would require an average acceleration of 0.944g. Power at speed = force (in Newtons) x distance (meters)/ time (seconds) which in this instance P = 650kg x 9.81(N/kg) x 0.944g x 2.778 m/s = 167207 W or 167kW. This would be at the wheels and also doesn't account for the rotational acceleration of rotating parts. 300hp would be around 225kW. Say the coefficient of friction of your tyres is a generous 1.3, 0.944/1.3 = 0.726, so you would need more than 73% of the vehicles weight over the driving wheels to generate the necessary friction to achieve your acceleration requirement. This could include weight transfer during acceleration.


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## tylerwatts (Feb 9, 2012)

Sounds feasible then John. I think the key, Louis is weight distribution and getting that traction. Jozzer will confirm that motor controller combo will get you there. And those cells you have are great. So the car is the missing link now. I look forward to its progress.


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## Lipo Louis (Oct 29, 2012)

Thanks guys, my wishful thinking is just based on other cars with these specs like fast Ariel atoms, and other lightweights with about the same specs


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## tylerwatts (Feb 9, 2012)

So what car are you wanting to base your build on? Which kit car? An Ariel type car? There are plenty options in that regard.


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## Lipo Louis (Oct 29, 2012)

http://www.autojunk.nl/2013/03/mev-sonic-7

I already have the car,and ride very often with it, it has now 120 kg at 595kg and is pretty fast.
My mounting plate and coupler is almost finished. The car will look something like this when it is finished.

http://www.roadtrackrace.co.uk/rtr_sonic7.html


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## John (Sep 11, 2007)

We shouldn't discount rotational acceleration of the vehicles rotating parts as it won’t be trivial in terms of power consumption. I didn't hazard a guess in the previous calculation as there are too many unknowns. If I were to say that the armature of the motor weight was 20kg and that it had a radius of 125mm or 0.125m and treat it as a solid cylinder its Polar Moment of Inertia would be 20 x 0.125^2 / 2 = 0.15625 (kg.m^2). If I was to suppose that the angular velocity of the motor was 6000 rpm or 628 radians per second (rad/s) at 100km/h, Power = 0.15625 x 628^2 / 3(seconds) = 20540W or 20.5kW just to accelerate the armature of the motor. Then there are the rotating elements of the rest of the drive train and the wheels and brake rotors etc. The wheels would probably have a higher Polar Moment of Inertia but a much lower angular velocity. You can see how weight is the enemy even in the rotating parts of the car.


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## Tomdb (Jan 28, 2013)

In past projects i have used this site as a guide to determining the effect of the rotating parts.

http://stephenmason.com/cars/rotationalinertia.html

Its a guide to help you replace the energy required to accelerate rotating objects with a "mass". This keeps the math plain and simple.

You will find that wheels with tires and brakes are a large factor because you have a light car. I would suggest looking for the lighest option for these.


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## tylerwatts (Feb 9, 2012)

Agreed! Rotational mass is a killer and when working for a light weight vehicle rotational mass will make far more difference than 100+ kgs of batteries! I've experimented on multiple vehicles. Simple set of light wheels made more improvement than 40% power increase on 120bhp diesel! 
A direct drive with light rotational mass will kill in 500kg car! Plus less weight anywhere will mean more battery weight and performance or drive time. 

That is my simple experience, not done math to verify.


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## Karter2 (Nov 17, 2011)

tylerwatts said:


> Simple set of light wheels made more improvement than 40% power increase on 120bhp diesel! ..
> ...., not done math to verify.


 Yes, that would be some interesting maths calculation !


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## tylerwatts (Feb 9, 2012)

To clarify Karter, that was seat of the pants improvement. Overall power may have been better but 'pick up' and response was great! This is what the calls are not done, a power curve is hard to calculate and I have not had the car dyno'd like that. It would be interesting to see what a dyno days with the different sets of wheels. Would cost too much in the UK for my curiosity though... so I conceive overall that it may sound like nonsense but in reality the difference felt greater in everyday driving with the lighter wheels than more overall power.


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## Karter2 (Nov 17, 2011)

Tyler, ..Im sure it does make a measurable difference, but lets be realistic as to what the actual results are.
There have been documented tests of the benefits of lighter wheels showing very limited improvements.
Many of us have at some time in our lives done this up grade personally and know that the biggest change is aesthetic !
Theoretically, to get the most benefit from reduction of wheel inertia ( and weight), you should be fitting much smaller diameter wheels since that would reduce bothe the wheel weight , tyre weight, and effective radius of both those weights.
However, that never seems to be done in practice, even in drag racing where they strive for every fraction of a kg and second of ET. ??


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## John (Sep 11, 2007)

Doing a quick calculation based on 9kg 16" Miata wheels, with 7.5kg 205/40R16 tires, and a 6kg brake rotor, power consumed accelerating 4 of these at 0.944g at 100km/h is about 13.5kW. 

Total power consumed accelerating rotating components is probably in the vicinity of 40-45kW at 100km/h and 0.944g (0-100km/h in 3 seconds) or around 210kW total power requirement. Note that the power required to achieve this acceleration increases linearly with speed i.e. 0kW at 0km/h, 210kW at 100km/h, 420kW at 200km/h etc. 

Aero drag increases with the square of speed so if it consumes 20kW at 100km/h this will jump to 80kW at 200 to 180kW at 300. This will also eat into power available for acceleration as speed increases, not so much at slow speeds.


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## Karter2 (Nov 17, 2011)

John said:


> Doing a quick calculation based on 9kg 16" Miata wheels, with 7.5kg 205/40R16 tires, and a 6kg brake rotor, power consumed accelerating 4 of these at 0.944g at 100km/h is about 13.5kW.


 So, ..if you changed to some lightweight ( 5kg ?) wheel rims you could reduce the wheel assy' weight by about 18%...
..which at most could reduce the power consumed by about 2.4kW ? ?
Not much of a return on a $1000 investment..


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## John (Sep 11, 2007)

Those Miata rims are already quite light. Going from steel rims to something like that would drop a bit of weight. Surprisingly the tire has about 3 times the inertia of the rim. Going from say a steel belt to a performance tire reinforced with aramid fibers would make a big difference I would imagine.


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## Tomdb (Jan 28, 2013)

your calculations are correct, yet i wanted to clarify the calculation for others

the power required to accelerate the components is way less.

By using the equivalent mass calculation I posted, i get 12 kg eqv for wheel 14,5 kg for tire and 7 kg for disc. That would be 36 kg roughly per corner, total of 135 kg for the total car (note i have rounded the numbers in my post).

Then using the basic formula of Force=Mass x Acceleration 

135 x 1g= 1350 Newton

Then Power = Force x Speed

1350 x (100/3.6) = 37500 watts. so 37 Kw. 

To be noted how ever, at 0 km/h its 0 kw and at 100 its 37 kw.

This means your acceleration will be harder in the beginning and decrease with the increase in speed, this is no problem just as long as you get your target average.

When you opt for lighter tires and wheels, these are only things to do when you want to get those last tenths of a second off.


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