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Smart Fortwo EV..... High power version!!

442K views 357 replies 70 participants last post by  brian_ 
#1 · (Edited)
Hi all

Many of you have view my motorcycle project http://www.diyelectriccar.com/forums/showthread.php/suzuki-drz-sm-2005-electric-48239.html

But it was only a test for introduce the mecanical guy in mine to electric power...
So now it's time to the real project: An electric car fun to drive!

My first idea, last year, was to convert my old mercedes 190 for have a high power RWD fun to drive car (just a step under the Cro Driver BMW...:rolleyes:). But I performed some calcul and the cost have no sense for the performance I need.
So because my budget is a bit limited I decide to reduce all the need in part like less powerfull controller and motor, less quantity of battery and that give:

-Donor car: BUY! Smart fortwo 2005 (real 730 Kg Go-Kart) It have a lot of room under the floor!
-Battery: Headway 10Ah, 48S-8P for 154V and 1000A at 12.5C
-BMS: Mini BMS centralized (3x 16S)
-Controller: BUY! Kelly KDHD 156V 1000A
-Motor: 11" modified forklift motor for good torque
-Gear box: Direct drive with 3.5:1 to 4:1 ratio



And now I have few question for you....

-I find a crown 11" forklift motor (W11AB02). I think it is a bit small! The frame is only 7-7/8" long and it's rate 9.6 Kw at 48v. The battery are rate for 115 Kw, the controller is rate for 180 Kw, so do you think this motor will be capable enough Kw to match with battery and controller? Or I need something much close to a Warp 11?

-I think don't use the original transmission because it's probably not enought strong to pass all the torque and I need a LSD differencial. I'm probably capable to build a fix ratio transfer case with integrated limited slip but I will need 4 kilovac contactor to go in reverse. In the other way I'm probaly capable to integrated some FWD LSD transmission (Honda, Volks, or....) without clutch and set to a fix ratio to have a mecanical reverse. What will be the better choise?

-What kind of charger I can match with mini-bms on 120v outlet (1800w) can give the shorter time of charge (1800w x 0.9 effiency = 1620w / 173v (48x3.6v) = 9A...... 64Ah / 9A = 7.1h of charge...... oh! fucking long)

-What do you think about the project? Good voltage? to low? Other BMS suggestion? Motor? Other concern?


Thanks

Final product: http://www.evalbum.com/4155
December 2015. Many pictures are not shown anymore, so I've create an album here: https://imageshack.com/a/uyz4/1























 
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7
#2 ·
Looks like a fun project.:)
The motor is similar in size to my 11" for my trike but mine is 80v 12.6kW.

When I bought a mig welder from a closing down factory unit recently, the seller was a disabled trike builder. He showed me a differential unit he says is use in rally cars. LSD, quick change ratios and a reversing lever so that the diffs can be used in either rotation.

Now, annoyingly, I can't remember the manufacturer details but a quick search on disabled trikes brought up this:
http://www.trikeshop.co.uk/disabled_adaptions.htm
At the bottom of the page is a reversing gear adaptor that might be useful for you to put between the motor and transmission.
There will, no doubt be other types available but maybe searching around disability adaptations might be a good start.
 
#3 ·
At the bottom of the page is a reversing gear adaptor that might be useful for you to put between the motor and transmission.
Add another component between motor and gearbox isn't the best way to get a simple and efficient design. Also, 11" motor can probably give to much torque for this kind of equipement.

Well there is not a lot of reply....

At this moment I have buy the 730Kg Smart Fortwo, the 1000A controller and the 1000A capable Headway battries, so now the most important thing to know is if the 11" Crown motor is capable to puch this set-up to 60 Mph under 6 or 7 second!!!

How much torque is capable this motor at 1000A and for how many RPM it can sustain this torque?
 
#4 ·
For what its worth, you can use MiniBMS with any charger, so charger selection is not related to BMS, but based on what available mains circuits you will have for charging, so you don't blow their fuses.

Also, you mix 1000Amp figures in motor side and battery side calculations, but you will never actually pull 1000Amp on the battery side, especially with Kelly controllers, which are well known for their fictional ratings. You didn't mention your planned EV range, which depends on C rate you pull from the pack. More C rates means less time to drive on one charge.

I am not a motor expert, but I know the main challenges of direct drive is limited RPM/power band of DC motor and heat buildup at low RPMs. Its quite difficult to find a single sweet spot in gearing down which allows for enough power at low speed yet be within motor's RPM limit at top speed. Direct drive certainly means much less electrical efficiency, hence more motor/controller heat to deal with.

At high C rates, you may even have to deal with battery cooling, especially the cells inside the pack, where heat is not easily removed. If ignored, middle cells might fail sooner than others if they get hot on regular basis.

I have seen several attempted direct drive conversions and I can't recall one where it didn't suffer from this decision. Either poor acceleration or poor range, or poor top speed, or overheating of power components.
 
#5 ·
Thanks for the answer.

you will never actually pull 1000Amp on the battery side, especially with Kelly controllers.
It's the "new" type of controller from Kelly. Supposed to be more powerfull than the old model....
Maybe it's a bad choise, but now I need to test it! Wish me luck!!


You didn't mention your planned EV range
I expect to drive between 40 and 50 miles in normal condition.



I know the main challenges of direct drive is limited RPM/power band of DC motor and heat buildup at low RPMs. Its quite difficult to find a single sweet spot in gearing down which allows for enough power at low speed yet be within motor's RPM limit at top speed.
I try to resolve this problem with the equation: Lightweight car + Overbuild motor and controller + 90 mph top speed = good compromise.

My direct drive motorcycle had great acceleration (0-50 Mph around 5 sec.) but the problem was the limited top speed of 68 Mph. I think this problem will be resolve with the relatively high voltage (154v) for the Smart compared to the 84v of my motorcycle.

I have calculed the weight of the Smart (with me onboard) is 3.8 time more than the weight of my motorcycle. So to have similar acceleration I need roughly 3.8 times the torque of the 6.7" D&D es-15-6 motor and that give 305 lbs-pi. The short 11" Crown motor can give this torque?


At high C rates, you may even have to deal with battery cooling, especially the cells inside the pack, where heat is not easily removed. If ignored, middle cells might fail sooner than others if they get hot on regular basis
I know! I need to design a good managed battery pack. I work on this right now!
 
#7 ·
Hi Yabert

I have been thinking about the reverse gear issue - for a lightweight 2 seater

(1) -No reverse just push it back
(2) - Use the reversing contactor I got from an old forklift - should never be actuated under load
(3) - use two double Alderson connectors to reverse the field coils
unplug the green ones plug in the red ones!
(4) - Lotus 7 type cars with motorbike engines use a starter motor to drive the car backwards
 
#28 ·
I have been thinking about the reverse gear issue - for a lightweight 2 seater

(1) -No reverse just push it back
(2) - Use the reversing contactor I got from an old forklift - should never be actuated under load
(3) - use two double Alderson connectors to reverse the field coils
unplug the green ones plug in the red ones!
(4) - Lotus 7 type cars with motorbike engines use a starter motor to drive the car backwards
I have another idea to put on the table about reversing motor rotation in a direct drive application.....

What do you think about add another small controller to the motor?
I have a 156v 1000A controller to go forward and I think about a cheap (100$) 12v 200A controller to go in reverse!

This configuration have the the important advantage than no power is lost in the reversing contactor. Why lose 100% of the time 0.5% of your power in the contactor (even more in stop and go in the city traffic when motor often see 1000A) when you only need this contactor to go in reverse 0.5% of time during a ride?

I only need a good auxiliary battery coupled with the DC-DC. 200A is less than an engine starter need during some sec.
Or, if that exist, I need a small 156v 200A controller!
In fact, I'm not persuaded I need 200A to go in reverse at 5 mph during 5-10 sec.

What do you think about this solution to go in reverse?
 
#8 ·
Hi Yabert

It looks like we're in a similar position: both planning to convert lightweight cars using motors we know very little about, and wanting to achieve decent performance from a single-ratio transmission. I can't provide the information you really need, which is a torque curve and maximum speed for your motor, though I did find this: http://img214.imageshack.us/i/pdfeb7.jpg/

Your suggested gear ratio of 3.5-4.0 sounds about right to me. What motor rpm would this require to get you to 90 mph?

I've found it useful just plugging different values into this calculator: http://www.diyelectriccar.com/forum...-charts-ev-performance-spreadsheet-41565.html (Thanks to maxvtol!)

Working with a maximum motor torque of 150 ft lbs I found that the optimum gear ratio for decent acceleration and a top speed of 80 mph is around 4.5:1. (For a 1500 lb vehicle with rpm limit of 6000 for my 7" motors).

I know a lot of people dislike the idea of fixed gear drive, and I agree that it's a big compromise. For example I also found when playing with the calculator that by using a three-speed transmission with optimised ratios I could get my 0-60 time down from just over 8 seconds to around 5 seconds and increase top speed to 90 mph, though this didn't include shift times. Even so, the advantages of using a single ratio are sufficient to make me think it worthwhile, especially in a lightweight vehicle with very limited space. One of the things I really like about my bike, which is also fixed gear, is just the simplicity of it and the way the power winds on so smoothly. It doesn't feel incredibly fast, but sails away from the lights leaving most other traffic behind. It's surprising how much time is lost with gear changes.

I'm also trying to decide how to get reverse. Costs are about the same for a good set of reversing contactors or a starter motor for reverse drive, but the reversing contactors are lighter and easier to install.

Your plans look good to me, and now you've got the controller there's no point in worrying about voltage any more. That's one less decision to make!
 
#12 ·
What motor rpm would this require to get you to 90 mph?
My wheel have a diameter of 22.58" so at 90mph with 3.7:1 ratio that give 4955 motor rpm.

Thanks a lot for the link for the performance calculator.
But I see one strange thing when I played with the prameter of this calculator. Why at 125v (48s sag to 2.6v) the Warp 9 give his max torque from 0 to 3750 rpm and the Warp 11 can give his max torque only from 0 to 2750 rpm. When I played with gear ratio that give me the same 1/4 miles time. Strange?!!? Why a smaller motor will has a wider power band?

One conclution I can see from this calculator was it's a big advantage of try to go higher in voltage to have a wider power band. In my case go to 54s 7P vs 48s 8P would be a great advantage. What do you think?



duncan said:
No reverse just push it back
Hahahaha!! I like your idea, but I think the idea to use a old reversing forklift contactor will be the better one.


dimitri said:
I would recommend to design your battery pack such that you can add more cells in parallel to existing 48 groups later on, if/when you realize you need more capacity to get your range, so you can get from 48S8P to say 10P or 12P without having to redo a lot of work.
I don't have the space and the money to put more cells in paralel. If My calcul is right I will need around 80A to drive at 50mph and that give me a range of 40 miles at 80% DOD. So if my range will be less than 40 miles I can't do anything and I will do with. Less range maybe, but it's less money for an electric car and that is the most important thing.



Well, in conlusion, because the Crown motor is around 80% of the lengh of a Wrap 11 or similar motor I think I need a bigger motor to perform a realy fast 0-60 mph. The torque capacity of this short Crown motor is probably more comparable to a Warp 9 and it isn't what I need.
 
#10 ·
Hi Yabert
On the direct drive v gearbox
You may be in the same situation I was in -
I intended to use an old Ford gearbox - I even bought one!
Then I did some calculations and decided that with a 750Kg vehicle I would be able to break traction in top gear
top gear was 1:1 and top speed 80 mph
(at 5,000 rpm - I hope my forklift motor doesn't blow up)
Without a gearbox the motor fits in what would have been the transmission tunnel - leaving the "engine bay" for batteries

If you can break traction then a gear box is unnecessary!

Calcs

Motor torque x axle (diff) ratio = wheel torque
Wheel torque / tire radius = Force at tire contact patch

Vehicle weight on the driven end x tire coefficient of friction (0.8 for "inexpensive" road tires (did I mention I am a Scotsman)) = Max force the tires can use
 
#11 ·
That looks like an interesting equation there Duncan.

Just wondering where you got it from, and the units you are using, because I can't seem to get it to work with numbers I've been running, and I'd be quite interested in it.

Just to illustrate, I have an 02-05 Ford Fiesta currently. Weight is about 1045kg. Max Torque from the 1.25 is 110Nm. Wheel radius is 0.292m.
Motor Torque (Nm)Gear RatioWheel Torque (Nm)Wheel Force (N)
11015.286616825760
1108.24119073106
1105.46566012058
1104.05654461527
1103.24523571223

Given your equation:
"Vehicle weight on the driven end x tire coefficient of friction (0.8 for "inexpensive" road tires = Max force the tires can use"

and an estimate of 60% weight on the driven wheels (627kg)

627 * 0.8 = 501.6N

Much lower than the force available in any gear. And Force divided by mass gives acceleration, so that would be 0.48 m/s^2, or a 0-62 of about a minute. Pretty sure my car isn't that slow... So I think it must be a different units thing, please let me know what you're equation is using.


What I've been using to judge the maximum usable torque is:

Torque = distance (radius of wheels) x mass (kg) x acceleration (m/s^2)

Then looking at other road cars to see what a reasonable max acceleration is. The maximum seems to be about 0.5g for FWD, and 1g for RWD.

Using that equation on my Fiesta gives about 1497Nm (about 5 times the force of the previous equation). First gear makes more sense with that result.


And for Yabert:

On the Smart, 0.287 radius wheels, 750kg, RWD, gives 2112Nm maximum. I'm not sure the smart is really set up to handle that much though, so just think of it as an absolute maximum.

In order to achieve 0-50 in 5.2 seconds (0-60 in 6.3) with direct drive, you'd need about 1200Nm of Wheel Torque, or 300Nm of Motor Torque with a 4:1 ratio. That is about 56kW of power.

If 90mph is the max speed, and 4:1 is the ratio, then 60mph is 3440rpm; so you need a motor that can develop 300Nm or more Torque from 0-3440rpm. That's 0-60 in 6.3s ish.

If you did get the torque of a warp 11 at 1000 Amps (434Nm, according to evsource), you'd get better than Tesla Roadster level acceleration.


I don't know much about motors, so hope for one of the more knowledgeable guys to come along, but this is my best guess with what you have.

The 9.6kW at 48v is 200A continuous, similar to the warp motors. The commutator section looks quite big, so should overload quite well, and will probably take the 1000Amps if they Kelly really supplies it, for a short time. I don't know how much torque per amp you will get though, if there is a torque rating on the motor, please let us know.

5000-6000rpm for that size motor would seem like a reasonable limit. If the motor has an rpm rating, it would help to know that too.

My concern would be that at 150v it might be spinning too fast, or if it is spinning at a good speed, would not be producing the torque that you need.
 
#13 ·
Hi Lloydn

and an estimate of 60% weight on the driven wheels (627kg)

627 * 0.8 = 501.6N


You changed units from Kg to Newtons - 1 kg exerts 9.81 Newtons downwards due to gravity (I normally use 10 as a conversion)

This becomes

and an estimate of 60% weight on the driven wheels (627kg)

627 * 0.8 = 5016 N

Which means that you should be able to spin the tires in first gear but probably not in second!

My "car" (partly built)

Vehicle weight - 650Kg / 50/50 weight distribution 325 Kg on back wheels
325 x 10 x 0.8 = 2600N

or 325 x 2.2 x 0.8 = 572 lbs force

Tires are 1 ft in radius therefore 572 ftlbs torque

Final drive 4.1 : 1

prop-shaft torque required is 572 / 4.1 = 140 ft lbs

I have a 48volt 10Kw Hitachi forklift motor - 11inches diameter 14 inches long weighing 102 Kg

I think (guess) that it will be comparable to a Warp11
The Warp11 graph goes to 140 ftlbs at about 450 amps

So I decided not to go for a gearbox!

I have ordered an OpenRevolt controller kit - 500 amps

I don't know what max revs - 5000rpm is about 80 mph - should be good enough - if I blow it up I will have to find another one!!
 
#14 ·
Hi all

What do you think about dual motor. Something like one 8" motor coupled to each rear wheel by 4:1 ratio.
I have 350$ budget for a helical LSD, but with two motor, I don't need LSD. I only need to coupled each motor in parallel (500A, 154v each) and they give me similar torque to each tire. This set-up will probably weight a bit less than big 11" motor+ helical LSD, but I'm not sure about power capacity.

Comment?
 
#17 ·
What do you think about dual motor /snip/ I only need to coupled each motor in parallel (500A, 154v each) and they give me similar torque to each tire.
Dual motors sound good. I've also been considering running two motors in parallel but recently saw this comment from CroDriver that left me a little uncertain: (http://www.diyelectriccar.com/forums/showthread.php?p=208510&highlight=parallel#post208510): "the problem is that there is no way to make both motors perfectly same, the wires are not the same and the connections are not the same. There will always be a different resistance from the controller to the motor. That will kill one motor if you're close to the limit of both motors. That happened to me. I fried one motor while the other one was like new."

I guess the only way to find out is to try for myself, but I will definitely be making cables exactly the same length and installing a pair of ammeters on the dash to monitor both motors carefully.
 
#15 ·
Thanks Duncan, I see I mixed up weight and mass. That gives a more reasonable number.

It's surprisingly hard to find good numbers for static coefficient of friction on the internet. I've seen anything from 0.7 top 1.0 for normal cars on dry tarmac, and 0.3 to 0.8 for wet.

I think it's quite important to include weight transfer if you are using the equation you are, as most of the recorded acceleration times, especially of RWD cars, are not possible with the equation as it stands. For Yabert's Smart, it would mean 0-60 in less than 7s is impossible.

Regarding battery setup, I just had a look at the Kelly website, and the max operating voltage is 180v. A 48s pack is the maximum you can really run for that, charging each cell to 3.75v. If you put any more in series, then the Kelly would not work with the fully charged voltage. 48s8p is a good set up though.

If your motor is 80% of the size of a warp 11, and if you get 80% of the torque, then you should get better than your required acceleration (less that 6s 0-60 if you're lucky). The big two ifs are if the motor is like a warp11 with 80% torque, and can the smart put the torque down? Only way to find out is to test it really.

Range wise, I think you'll make your 40 miles quite happily at 50mph, though I don't have a calulator worked out for a real driving cycle. That's just calulcated from rolling and air resistance, and 80% of the charge of the battery.

You might want to consider a seperate fan for cooling the motor, for low speeds, and it can't hurt when driving it harder too.

If you can fit the two motors and gearing, that might be a viable option too. It might be hard to get two reasonably well matched motors.
 
#16 ·
Hi Yabert

Which diff are you looking at - I just scored a complete front and rear setup including an LSD for a Subaru for $200

Subaru LSD's seem very common here - they are made by Fijutsi Heavy industry and I think are used in Nissan's as well

If you get a cheap LSD - a single motor would be easiest - (my motor cost $100 - did I say I am a Scotsman?)

Hi Lloyd
Weight transfer (fore-aft)
Force at tire contact x height of center of mass = wheelbase x wt transfer

So a dragster can have a high C of G,
I like cornering so I am going for a low C of G

For my car which is quite long with a very low C of G it gave very little weight transfer - I think it was 10%

It's surprisingly hard to find good numbers for static coefficient of friction on the internet. I've seen anything from 0.7 top 1.0 for normal cars on dry tarmac, and 0.3 to 0.8 for wet.

Thats what I found which is why I went for 0.8 - for cheap tires (did I say I am a Scotsman?)

I don't think less than 7 seconds to 60mph and cheap tires go together!!
 
#19 ·
I have the controller right now! 180v max. I will charge each cells at 3.65v, but it drop to around 3.34v after I stop charger.

At 1000A connected the motor in series this give around 65 volts to each motor. It's probably not enought to sustain the max torque at least to 60 mph.
 
#21 ·
I got the cells!

Total of 338 cells buy direct from Headway. It's like they have a new style of positive terminal!
I tested around 10% of the cells and all are between 3 and 3.5 mΩ.

The price is around 17$ each including shipping and taxes.

I need to add 46 cells from my motorcycle pack to complete my 48s 8p pack.

So 1000A / 8 = 125A
125A x 0.0035 mΩ = 0.4375
3.2 - 0.4375 = 2.76 v

And (2.76 x 48) x 1000 = 132.48 KW peak...... not bad in a Smart Fortwo!










 
#120 ·
I got the cells!

So 1000A / 8 = 125A
125A x 0.0035 mΩ = 0.4375
3.2 - 0.4375 = 2.76 v

And (2.76 x 48) x 1000 = 132.48 KW peak...... not bad in a Smart Fortwo!
Hi Yabert

I was wondering how close you got to this in your completed pack? Are you able to determine your voltage sag under a certain load while driving?

This would be helpful to me, I'm looking at getting the same cells and wondering on voltage sag on a completed pack.

I'm also interested in the resistance of a completed pack using the 16ah cells. If I find out I'll let you know.

Thanks
 
#23 ·
Hi
My 38120S 10Ah are coded JI03 and JI04. The first box contain a warning paper about too long screw they push on rupture disc.


And after many weeks of search and design about limited slip drive train I finaly concluded that will be realy complex and costly to build a custom direct drive lsd drive train. It's easy in a motorcycle or a go-kart, but it's another way in a car.
So now, the best way I find is use a Sentra SE-R Spec-V transmission. They come stock with a helical lsd (Torsen) and have 6 speeds.
I think use the 4e and 5e gears to have a 4.378 and 3.345 ratio. I can get one at scrap yard for 300$.
After some calculs, that give me the same 0-60 mph time than direct drive set-up cause by the 0.5s shifting delay. So a faster 0-45 mph, same 0-60 mph and a faster 0-75 mph and 1/4 miles.

I'm a bit disapointed to don't go direct drive, but I know it will be probably a bit more efficient and a lot less complex. So it's not bad.... I think!
 
#24 ·
The small 800cc CDI diesel motor is out of the frame. It haven't a lot of place for a big 11" motor and a Nissan transmission.....
The ICE is put at 45° in the rear of the Smart and pass over the drive shafts. So, replace it for a big 11" cylinder will be not easy!!




















 
#26 ·
I'll say. This will be interesting to watch! How are you going to keep the front end on the ground when you floor it?
I will don't have race tire on, so no problem.... the car will be a doughnut machine.:D
 
#27 ·
Hi

What do you think about this insulating varnish to insulate a bit more an old GE forklift motor?
It is pretty cheap at less than 10$ for an Aerorols. 2900 volts per 0.001".


PERFORMANCE

TEMPERATURE CLASS:
Class F (155°C / 310°F)
DRY HEAT RESISTANCE:
Constant: 310°F
Intermittently: 400°F
DILECTRIC STRENGTH:
(ASTM D 115-07)
Red: 2,600 VPM
Green: 2,890 VPM
Clear: 2,300 VPM


ONE WEEK HARDNESS:

(ASTM D 3363 SHORE A 24hr / 1 Week): 6B

FLEXIBILITY:
(ASTM D 522) Pass
CHEMICAL RESISTANCE:
Aliphatic hydrocarbon solvents: Moderate
Alkalis: Severe
Aromatic hydrocarbon solvents: Severe
Chlorinated solvents: Moderate
Salt water: Severe
Glycol ethers, alcohols: Severe
Inorganic acids: Severe
Organic acids: Severe

Oils: Severe


DRYING SCHEDULE

DRYING TIME AEROSOL @ 70°F @ 50% R.H.:
To Touch: 1 Minunte
To handle: 5 Minutes (Tack Free)
Full cure: 7 Days

DRYING TIME BULK @ 70°F @ 50% R.H. 1mil wft:
To Touch: 10 Minutes
To handle: 1 Hour (Tack Free)
Full cure: 7 Days

Curing can be accelerated by baking for 1 hr @ 300 degrees F
RECOAT: Anytime


 
#29 ·
Sounds like a good alternative to me, in fact I might just do the same myself. It means a small weight penalty, and a little more complexity, but like you say it eliminates voltage drop across the reversing contactors. With a car that is as short as your Smart (and my Mini) it's not as if we'll need to reverse very often :) You might want to avoid parking facing down a steep hill though, just in case someone parks right in front of you...

Were you thinking of using the same throttle potentiometer for both controllers?
 
#32 ·
How do you connect a second controller to a series motor and get reverse? You still have to reverse the field respective to the armature.

Eeeeeh!! scheize!!...:rolleyes:

I haven't thinked enough before write my question.
The problem is the A2-S2 connection. I can put a small contactor (200A) between S1-S2, but I can't disconnect A2-S2 without a big contactor (1000A).
And 4 kilovac EV200 contactor cost 500$......

I can't believe it's that costly and complex to go in reverse!



 
#36 ·
I was thinking of a small geared motor with a sprocket to engage the chain on my trike to get reverse. I figured in the same way that motorbike converted trikes do it. Might even get away with no controller, just a big switch, though a small 12v bike controller would do.

The other option I thought about would be a big double pole change over switch.
I'm sure you could make one with a rotary barrel, like they did on old electric milk floats, and it wouldn't need to switch a live current so no arcing to worry about.
 
#35 ·
Hello,

This is a great project and something like that I want to build. My dream car would look something like this;

- Smart 451
- Soliton Jr. controller
- Kostov new 9" 220V motor
- 69s5p Headway 40160s 16Ah, which is approximately 18kWh and 175kg

Yabert, I wonder if you measured the space for batteries, what are the dimensions of space. I plan to put the battery in this place.




My battery configuration





the entire battery pack would be about 600 x 800mm and 200mm high with battery box

 
#39 ·
Hello,

This is a great project and something like that I want to build. My dream car would look something like this;

- Smart 451
- Soliton Jr. controller
- Kostov new 9" 220V motor
- 69s5p Headway 40160s 16Ah, which is approximately 18kWh and 175kg

Yabert, I wonder if you measured the space for batteries, what are the dimensions of space. I plan to put the battery in this place.


Really nice picture!!...:D

I will put all the battery at the same place. The Smart engineers will also put the battery box at this place.
The green area on your picture mesure aproximately 500mm x 1030mm x 200mm.

So you can't put 18Kwh of energy with todays battery technologies. I will put 48S 8P of headway 10Ah 38120S for 12.3Kwh and it's realy tight!

But your set up will be awesome with Smart/Soliton Jr/Kostov 220v and probably a bit less Kwh. If you don't need great performance you maybe can find less powerfull battery with a bit more wh per liter (more kwh for same space but less Kw).



 
#37 ·
It occured to me, as I was in the shower just now, that I have a shed load of 200A-300A 440Vac switchgear.
I should be able to find parts to make a usable reversing switch on the basis that it only needs to carry the dc current but not switch it. It will only ever operate when the current is zero so no arcing problem. It can also have a built in throttle pot cut off to kill the controller before it breaks the contacts.

That maybe your solution to an affordable reversing switch too.
 
#38 ·
Cool project. Why can't you fit a FWD transmission in it? Does the smart have an existing trans? A Geo Metro 5-speed is quite small and light,
you might even think of using an Automatic version so the manual shift linkage isn't an issue to get into reverse.

Why such a big deal to avoid using reversing contactors?
They are used commonly with DC motors.
 
#40 ·
Cool project. Why can't you fit a FWD transmission in it?
Too big. The Nissan sentra Spec V transmission is really too big!

Does the smart have an existing trans? A Geo Metro 5-speed is quite small and light
They can not transfers 250-300 lbs-pi of torque produce by the motor.

Why such a big deal to avoid using reversing contactors?
They are used commonly with DC motors
Yes, but not at 1000A
 
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