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Discussion Starter #1 (Edited)
Hi All,

Opening a new build thread here. After converting a Fiat Spider convertible (haha, such a wordplay), EVs are a way to go for me. Fiat thread: http://www.diyelectriccar.com/forums/showthread.php/noob-starting-1977-fiat-124-spider-51822.html

So we are taking one of my other cars (2001 330Ci) and making it high-octane electric. In doing so, we will plan to develop bolt-on designs that can be easily replicated on other E46 bodies.

Target parameters:

0-60 below 5 sec. It just HAS to be faster than stock (which is not super-easy to do with a 330...), EDIT: EVcup qualifier is <5 sec 0-60
125 mph top speed. EDIT: EVcup qualifier is >200km/hr top speed
100 mile city range

Configuration options we decided on so far
Battery: 90 CALB 100Ah cells for a 288V nominal 800A peak pack
Controller: 1000A DC (most likely Soliton1 but if I can get 1400A WarpDrive in less than 4 weeks, I'd try it)
Motor: Kostov 11" 250V SFM, with space left for dual 11" setup later.
Charger: our own design (open-source, http://www.diyelectriccar.com/forums/showthread.php/10kw-60a-diy-charger-open-source-59210.html) - 10kW, 60A
Drivetrain: not a direct drive (see below)
Coupler/transmission plate: from ElectricCarInternational. Can't beat the price and no design fee. Plus good discounts on subsequent orders of same design.

Open Questions:
1. Mechanical drivetrain setup. I definitely want to have a transmission. The question is: do I keep stock manual 5 speed or swap it for one of the automatic sets like http://www.grassrootsev.com/tranadapt.htm. Benefits are: even higher drive-ability and ability to use idling to belt-drive accessories
2. Accessories. How to best set up heating, AC, power steering, vacuum, etc. In a Fiat, I have ignored all of these - after all, it's a small convertible so braking is fine without assist, heating is a joke anyway with top open, no power steering / AC. In a beemer, all 4 of these will have to work. Now, if you do that in a 'traditional EV DIY' way, that's 4 electric motors and subsystems you have to mount somewhere, etc. Why not keep all the original pumps and pulleys and just mount then on the backplate of the motor and drive all from idle of the main motor (if using automatic tranny) or one small high-voltage DC motor?
3. EV management system choice (or build) - I want a big color screen displaying everything I want about the vehicle at all times. It has to look like a production electric car, without any ammeters on the dash, etc. At this point, the thinking is to build our own system based on Arduino for data gathering and Android tablet for display. If anyone knows any other systems available on the market today, please let me know.

Comments / suggestions?

Let the fun begin! (again...;-)

Valery.
 

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Hey! be careful.

You don't have enough battery power because your voltage is too low!

800 x 0.0009 = 0.72 - 3.2 = 2.5v x 90 = 225v.
800A x 225v = 180Kw from cells and roughly 200 hp at motor shaft....... so, not enought!

You probably need at least 250 hp....
 

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Discussion Starter #3
Hey! be careful.

You don't have enough battery power because your voltage is too low!

800 x 0.0009 = 0.72 - 3.2 = 2.5v x 90 = 225v.
800A x 225v = 180Kw from cells and roughly 200 hp at motor shaft....... so, not enought!

You probably need at least 250 hp....
Thanks Yabert! I was thinking of going to 100 cells which would take care of that. But then again,
1. pure hp rating matters more for top speed than acceleration
2. My latest shipment of CALB cells lists 0.3-0.5 mOhm IR (each cell is tested separately). So the sag should be lower (at least on new cells).

V
 

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Excellent news! Calb 100Ah at 0.5 mhom... seem awesome!

pure hp rating matters more for top speed than acceleration
It's barely true, because a different gear ratio can give the advantage. An high torque isn't enought alone, you need to keep this high torque to high RPM to have a powerful car.
It's why higher voltage is important.

Especialy because having a good torque at high speed can give you the important advantage of having a single Kostov motor to acheive your goal performance instead having two engines that provide more torque, but lower rpm and roughly same power.
96 or 100 cells seem really good to acheive your goal... 270v x 800A = 216 Kw.

After all, If Crodriver managed to generate 500hp from its Warp 11 HV, I do not see why a Kostov 11 250v could not produce 250-300 hp at lower amps.

Good luck..., your car will be awesome. I can not wait to see him finish.
 

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sounds like a fun build, for the power level you are looking for you might want to look into higher power density cells to shed some weight unless you need it all for the range you are looking for. Headway/A123 etc.

I really like your display ideas, nothing like taking a step towards a Tesla model S and away from an obvious garage creation.

I kind of like the idea of a higher end automatic, I know the transmission in my G35 shifts faster than a stick, and it doesn't have the typical automatic lag. The only thing I'd complain about is it's always in the wrong gear, but with the wider power band of an electric it would be much easier to keep it in the right gear.

Using the idle feature in the Soliton1 has been very helpful while setting up my belt driven A/C even though the car is a manual.
 

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Discussion Starter #8
80 100AH CALB cells are in! Another copy of our 10kW charger is built and tested on the pack - ready to go!

ICE coming out this weekend (I hope). Will post pics soon.
 

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Discussion Starter #9
you'll probably beat the build time on the ranger, Let me know how the kostov works out.
Kostov was great on my Fiat. Plenty of power. Couple of notes though:
1. You need a high-voltage pack for it. Seems like a very obvious need but for some reason did not get through to me initially so I was running a 250V motor with a 192V pack and it didn't work very well. 256V nominal is getting there.
2. Pros say that you can't overload Kostovs for as long as NetGains (lower thermal mass) but that is likely to be relevant only for racing.

I still can't get over the fact that you can get dual Kostovs for less than 2 motors bought separately!! ;-) Direct drive with dual 11" in series on a 340V pack and 1000A controller, anyone? 1800lbs (0.5G) push at the wheels from 0 to 70-80mph? mmm... ;-)

V
 

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Kostov was great on my Fiat. Plenty of power. Couple of notes though:
1. You need a high-voltage pack for it. Seems like a very obvious need but for some reason did not get through to me initially so I was running a 250V motor with a 192V pack and it didn't work very well. 256V nominal is getting there.
2. Pros say that you can't overload Kostovs for as long as NetGains (lower thermal mass) but that is likely to be relevant only for racing.

I still can't get over the fact that you can get dual Kostovs for less than 2 motors bought separately!! ;-) Direct drive with dual 11" in series on a 340V pack and 1000A controller, anyone? 1800lbs (0.5G) push at the wheels from 0 to 70-80mph? mmm... ;-)

V
yes please!

I want to do a similar conversion as you maybe into a newer E92 or a porsche 911... very excited for your results, good luck!
 

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Hey! be careful.

You don't have enough battery power because your voltage is too low!

800 x 0.0009 = 0.72 - 3.2 = 2.5v x 90 = 225v.
800A x 225v = 180Kw from cells and roughly 200 hp at motor shaft....... so, not enought!

You probably need at least 250 hp....
The conversion from kw to hp seems low in your calculation....

180kw / 0.745 = 242hp
 

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Discussion Starter #12
The conversion from kw to hp seems low in your calculation....

180kw / 0.745 = 242hp
I think Y meant mechanical hp - after taking into account ~80% motor & drivetrain efficiency...
 

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Discussion Starter #13
Hi Guys,

still musing over the details of this conversion.

Narrowing down the DC motor choice to Warp11HV mated with 340V CALB pack. It just have to have a big DC motor to provide the power we need.

However, we are going to do some long-range demo drives in this car and every bit of efficiency counts so I was thinking of adding something like an AC50 system to the big DC motor. AC50 would then soak up braking / downhill and provide most of the 'baseline' load on freeway etc. Being AC and therefore more efficient, it should further add to the economy.

What do you guys think? Has anyone done it before? Any links / pointers?

Thanks,
Valery.
 

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Several of the 914 ev guys use ACXX motors, you could do a search at http://groups.google.com/group/914ev .
Hi Guys,

still musing over the details of this conversion.

Narrowing down the DC motor choice to Warp11HV mated with 340V CALB pack. It just have to have a big DC motor to provide the power we need.

However, we are going to do some long-range demo drives in this car and every bit of efficiency counts so I was thinking of adding something like an AC50 system to the big DC motor. AC50 would then soak up braking / downhill and provide most of the 'baseline' load on freeway etc. Being AC and therefore more efficient, it should further add to the economy.

What do you guys think? Has anyone done it before? Any links / pointers?

Thanks,
Valery.
 

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Discussion Starter #15

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Do you only compare the coplete efficiency of the AC50 vs WarpHV????

DC = 99% controller efficiency x 87-88% motor = 87% efficient than seem good to me....

What about AC50?.... 94% x 92% = 87%???????

My final advice: Put a bit more cells. They costing less and they weighting less than an AC50 systems!!
 

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Discussion Starter #17
My final advice: Put a bit more cells. They costing less and they weighting less than an AC50 systems!!
good point. 150lbs of cells are ~20 miles of range, after all...
 

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Discussion Starter #19
http://www.evconsultinginc.com/articles/hybridizing_dc_system.html

The article above points out that the average car only needs 5kw to cruise @ 40mph (city speeds). So a 100 mile distance @ 40mph requires 12.5kwh
Hi Bowser,

this would be awesome. However, I think these guys either missing some power loss contributions or talking about purely mechanical power or using really streamlined / lightweight car example or all of the above. I've used formulas from the book 'Build your own electric car' before and am coming out at 27hp required for a 3500lb BMW to move at 60mph (as opposed to 15hp that these guys quote). My calculation gives me ~330 Wh/mile which is in the right ballpark for 60 mph.

This gets me the range of just shy of 100 miles at 60 mph. At 40 mph, it's 140 miles or 40% higher.

V
 

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Discussion Starter #20
ok guys! FINALLY some good stuff to look at ;-)

$1K in the friendly shop gives you an EV-ready beemer! Engine, radiator, gas tank and exhaust systems are out

design work is starting today. Everything in CAD to be replicable for our E46 kits.

V
 

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