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Discussion Starter #1
Hello,

I'm from the middle of Europe, from Germany and I'm glad to have found this forum. Full-time I was self-employed for almost 10 years and built recumbents. Meanwhile I work as a "normal" mechanical engineer in the industry.

Now I want to realize a long-cherished dream and build my own electric car. The last few years I only built combustion engines. I'm more fun for that because I do not drive 5000km a year.

Base: Polo 2F built in 1991
Buget: about 15000 €
Target: under 6seconds from 0 to 100km / h, over 250km range

Currently I own two VW Polo 86C with 89hp ("Genesis" Edition with 1.3l DIY Engine runs with MegaSquirt) and 150hp (1.4l Turbo). The car with 150hp was rebuilt from scratch. All sealants, insulation and paint were removed (over 45kg!), All rust removed and repainted.

The attachments such as doors and bonnet are replaced by GRP (own CFRP parts are currently too expensive for me, because I have to build a separate mold for each part). This reduces the weight by another 50kg. In addition, the sides and rear windows are replaced by plastic. The entire interior is removed, the dashboard of the previous model used (lighter), as well as a 6kg CFK / Aramid bucket seat installed. Everything is removed which is not absolutely necessary and light aluminum rims of the VW Lupo 3l used. So I reach about 450kg without engine.

Currently I am looking for a battery pack that is light, provides a high voltage and is not too big. Here in the forum is just one offered, I hope the purchase works. Then I would have laid the foundation stone. 350V 30kWh of a Kia Soul. The installed cells are likely to be LQ 1729-A2 from LG. Do not look so good on the durability, but the next few years will do a lot anyway with the batteries. In addition, I drive really little car. According to the data sheet, however, one cell can deliver 450W. That would be 90kW for the battery pack. I hope I can tickle out more. Otherwise, I can also obstruct a lighter engine.

The engine is a Tesla "small drive" with the EVBMW controller. This I get cheap from nearby (3000 ¬ + board).

What I'm still looking for:
- good charger (9kW?)
-BMS (Orion2?)
-small DC / DC Converter (need only 500W max at 12V)

Here are a few pictures of polos, engines and my most used vehicle: my Velombil
 

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Welcome! :)

A Polo a nice size to convert, since it is relatively small and light. That will make it difficult to fit in a substantial battery pack (such as the Kia Soul pack that you have chosen), but you'll need that large battery to meet your performance goals.

I look forward to the build thread when you get started on your project. It will be interesting to see how you fit a Tesla drive unit in that car.
 

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Discussion Starter #3 (Edited)
Hello,


30kWh is not too big battery. A normal Tesla has more than three times as much on board. 250km range should also be achieved :)
And since I threw out all the interior, I have enough space for batteries :p
PS. anyone know how i got a speed-signal out of the Tesla-Engine?
 

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30kWh is not too big battery. A normal Tesla has more than three times as much on board.
While 30 kWh is a suitable capacity for this vehicle, it is a big battery for the size of the car. Yes, a Tesla Model S has a much larger battery, but it is also a much larger car...
VW Polo Mk IIF:
  • Wheelbase = 2,335 mm (91.9 in)
  • Length = 3,655 mm (143.9 in) to 4,030 mm (158.7 in)
  • Width = 1,570 mm (61.8 in) to 1,590 mm (62.6 in)
  • curb weight = 736–804 kg (1,623–1,773 lb)
Tesla Model S:
  • Wheelbase = 2,960 mm (117 in)
  • Length = 4,980 mm (195.9 in)
  • Width = 1,964 mm (77.3 in)
  • curb weight = 2,108 kg (4,647 lb) (85 kWh 2WD model)

The Model S battery fills the whole length between the axles and width between the rockers of that big car.

The Kia Soul EV has a different floor than the regular Soul, to fit the battery under the seats... and the Soul is larger than a Polo:
  • Wheelbase = 2,550 mm (100.4 in)
  • Length = 4,105 mm (161.6 in) to 4,120 mm (162.2 in)
  • Width = 1,786 mm (70.3 in)

And since I threw out all the interior, I have enough space for batteries
I assume that you are going to use the rear seat space, and perhaps cut out the floor in that area to combine the fuel tank space with the seat space to provide room for the battery... that's what would make sense to me.
 

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Target: under 6seconds from 0 to 100km / h, over 250km range
...
350V 30kWh of a Kia Soul... According to the data sheet, however, one cell can deliver 450W. That would be 90kW for the battery pack. I hope I can tickle out more.
The Soul EV battery can definitely handle 90 kW: that's the Soul EV's stock motor power. It can probably handle more, briefly, at the expense of shorter life.

6 seconds 0-100 km/h is half the time of a stock Polo, and substantially faster than a 90 kW Soul EV. Although the converted Polo will be lighter than a Soul EV, the difference might not be enough to make that acceleration time on 90 kW; it might be good to plan on needing more power than that.

The Soul EV goes 150 km (93 miles) on that 30 kWh; that's 200 Wh/km (320 Wh/mile). Again, the Polo will be lighter, and it has less frontal area so it will likely have less drag, but an extra 100 km (120 Wh/km or 193 Wh/mile) seems to me like a big range improvement to expect. Would you be satisfied with a 200 km range?
 

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Discussion Starter #6
Depending on which battery it will be, I will accommodate them differently. Your idea is one of them :)

The "YAEC" Excel helps with these decisions. Have you just discovered here in the forum. Without wheel slip, a setup with a maximum of 90kW would come in 4.9sec to 100km / h. The car weighs less than 750kg with driver and electrical conversion. Thus, less than half the power must be applied for the same acceleration. The effective frontal area of ​​0.53m² (cw0.30 after some improvements, A = 1.78m²) is also quite good.

I have also recalculated how much torque I get on the road at all. At the weight and then lower center of gravity are the max. 800nm. Thus, under 100Nm from the engine (since 1: 9,34 gearing) to have permanently spinning tires. The intended setup means: spinning wheels up to 90km / h.

A Hyper9 really seems the more usefull choice, especially since I then have no problems with the mechanical speedometer.
But I have to remember that makes the gearbox in the long term.

PS. Could i get squeeze more out of the Hyper9?
 

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Hi Jack

I'm not doing much better than 4.9 seconds to 100kph - I did 7.9 to 150 kph

My car is 800 kg - rear wheel drive with 55% on the rear wheels and a Limited Slip Diff and sticky tyres - but I have about 400 Kw

I just don't see 90 kW giving you anywhere near 4.9 seconds to 100 kph
 

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Discussion Starter #8
Hi,


And i know that 5sek is unrealistic, but only because wheelspin.

A timed run with my 89hp and heavy Polo "Genesis" (840kg) reach 4,3m/s² max. and 8.9sec.


https://network.perfexpert-app.com/results/ki8KBic2GV


25% lighter and 50% more Power (with continous torque) should be enough to get the 6s. from my 1.4l Turbo. This was driven with slicks. With normal tires 7-8sec are realistic.


Does anyone have tips regarding the converters and loaders?
 

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Just realised the 90kW is from the battery

Don't worry!! you can draw a LOT more than that for a short period - and you will only need it for seconds

I am drawing 400 kW from 12 kWh of Chevy Volt batteries

You will be able to feed your Tesla motor with full power! -

You WILL spin the tyres
 

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Discussion Starter #11
Ok, thats good news. Whats with the heating of the battery? The teslapacks are watercooled, most of the others Not.
and should i take the hyper9, more efficent and easy to build in, or tesla, pure Power.
 

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Ok, thats good news. Whats with the heating of the battery? The teslapacks are watercooled, most of the others Not.
and should i take the hyper9, more efficent and easy to build in, or tesla, pure Power.
Tesla!
The hyper9 is expensive and wimpy!
 

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Discussion Starter #13
And whats with a emrax 268? Anyone used one? With a small differential from passat or different bmw this setup wight less then half of the tesla with much better efficenty. Price is only a little more.
 

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The teslapacks are watercooled, most of the others Not.
In fact, many EV and plug-in hybrid packs are liquid cooled
  • Tesla (Model S/X and Model 3): coolant tubes snake between rows of cylindrical cells
  • Chevrolet Volt: coolant passes through plates between pouch cells
  • Chevrolet Bolt, Chrysler Pacifica, various German models: aluminum fins from one edge of each pouch pressed against "cold plate" base with coolant circulating in it

The Leaf battery is (or was, for a while) very commonly used in EV conversion projects, and is a relatively rare example of a modern EV pack without active cooling.
 

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... should i take the hyper9, more efficent and easy to build in, or tesla, pure Power.
I'm not sure that the HyPer9 is any more efficient than a Tesla motor. Why are you expecting that... because the Tesla would be used well away from its ideal operating point of load and speed?
 

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Discussion Starter #18 (Edited)
The battery of the Kia Soul is also "only" air-cooled.
How much do the batteries heat up at all? I have no experience there.

The Hyper9 has a better efficiency in use has two reasons (Tesla Model 3 use a reluctance motor;)):
-Synchronius reluctance permanent magnet motor (almost no losses in the rotor! What also means that you could cool the engine pretty well)
-5Gang manual transmission -> always in the right power range
better especially in low speed and power range

To the Forklift engine:
-more than double the weight for the same performance
Controller costs a lot

A question to the forum:
What speaks against z.b. a Hyper9 (not HV) with other controller at e.g. to operate at 180V?
And does anyone have experience with the Emrax engines?
@Duncan : You ever tested the Hyper9?

Greeting,
Patrick


PS. anyone send me a PM, but i cant open it?!
 

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Hyper9 $4,150 - PEAK power 88 Kw

My $200 Forklift motor with a $1000 controller - peak power 400 Kw

DC series motors are simple crude and easy to work with

There are three options these days

DC (forklift) - cheap cheerful and powerful

Re-purposed OEM (Tesla/Leaf) - much more sophisticated - cost a bit more

Then there are the "Motors for EV's" like the Hyper9

MORE expensive than OEM motors and less powerful

Saying that you are talking about a Tesla motor for $8000 - my innate Scottishness would not permit me to buy that

In your shoes I would be looking for a crash damaged Leaf for about $4000

You get the lot! batteries/charger DC-DC motor Inverter - everything
 

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Discussion Starter #20 (Edited)
We dont have much e-cars here in Germany (eg. 5000 Nissan Leaf. In the USA are over 110000 of them) Find a "crashed one for 4000€" is nearly impossible...
And a 200kg Forkliftmotor ist way too heavy.


So the small tesla Engine is the best option i had at this time, right? (but its about 5000€ more expensive then the Hyper9...)
 
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