BMW 3 series electric conversion

positron

See this story here in Engadget http://www.engadget.com/2012/05/22/electric-motor-werks-hands-on-at-maker-faire-video/

A crowd called 'Electric Motor Werks' in the US, and their conversion costs around $15k - end result is a very normal looking 300 bhp 3 series with 120 mph top speed. Range is either 100 miles or 180 miles depending on the battery pack and at a constant speed of 65 mph. Best part is that it fully recharges in 2.5 hours. Not a bad conversion huh?

biko

Galway -> Cork is 130 miles so that's pretty good mileage.

mickdw

Sounds too good to be true. Surely it not that easy to blow the large car manufacturers out of the water in terms of power and range? Also, at a conversion cost of 15k dollars, you would have to consider that should this exact system be fitted from factory, removing the need for an petrol engine and associated systems, that the cost of the car would only be marginally above the petrol version even without economy of scale, again putting the current major car companies to shame. I dont quite buy it.

b318isp

300bhp is 225kW - a very large motor! I'd guess that alone could be 3/4 of a ton, let alone the batteries. I'd assume that suspension and brake upgrades are included.

positron

Hmm, I don't know, the guy on video said they are planning to sell kits for anyone who want to do this themselves, and they said they are signing up the deal (for selling kits I would imagine) on that show, that day. They go into some detail on the video.

And they have setup Android interface to the car. So you can monitor (and possibly tune, in future) the car on your tablet or phone from inside the home (within the bluetooth range I believe). They are also going to produce kits for BMW 5 series as well.

Sounds really nice tbh! Imagine buying a cheap-ish petrol 3 series and converting it like that - seriously cheap miles!! Depending on how much the battery pack weigh compared to engine etc that are being removed, and how the battery packs are distributed around the car, the handling might just be as sweet as normal BMWs. What's not to like?

positron

b318isp wrote: »

300bhp is 225kW - a very large motor! I'd guess that alone could be 3/4 of a ton, let alone the batteries. I'd assume that suspension and brake upgrades are included.

I don't know my watt from kilos, but didn't he say that car had three battery packs of 10 kW each, over all totally 30 kW? And the engine could do up to 500 bhp, but is limited by the battery pack? They also said conversion cost is going to start from around 15k.

Sesshoumaru

b318isp wrote: »

300bhp is 225kW - a very large motor! I'd guess that alone could be 3/4 of a ton, let alone the batteries. I'd assume that suspension and brake upgrades are included.

I don't see how they could get 160 kilometer range on the base version if they were adding a 750kg electric motor. They don't specify what motor they use in the kit.

http://www.emotorwerks.com/cgi-bin/kits.pl

They do sell motors separately, maybe someone with familiarity of these brand names might be able to tell us how much they weigh?

http://www.emotorwerks.com/emw3/category/component/

positron

From their site:





And the guys behind the site seems to have PhDs in Physics and Particle Physics. May be they are on to something (I am hoping).

beazee

| |
Conversion kit price start at $15-20K (pre grant) for 60m range, 100mph max, 7-8s 0-60m acceleration, reaching $30-35K (pre grant) for 100m range, 140 top speed and 5s acceleration.

Installation should be in the region of 3-5K.

jackbauer

I know the company and the guy behind it. Very smart people and they have been gearing up for this for some time. Designing the power electronics themselves saves a lot of money and grants flexibility. If its the motor i think it is it weighs in around the 70kg mark. Attached a photo of the android display running on my car presently. Just back from work so the battery is nice and warm after blasting up the N11:D

deandean

jackbauer wrote: »

I know the company and the guy behind it. Very smart people and they have been gearing up for this for some time. Designing the power electronics themselves saves a lot of money and grants flexibility. If its the motor i think it is it weighs in around the 70kg mark. Attached a photo of the android display running on my car presently. Just back from work so the battery is nice and warm after blasting up the N11:D

Is this trolling or have you actually got one of these in IRL?

Gumbo

deandean wrote: »

Is this trolling or have you actually got one of these in IRL?

Why would he troll??? :rolleyes:
Have you actually clicked on the clinks in he sig?

jackbauer

I converted my own E36 to electric.As kceire said just visit the link in my sig. That said my car is a grocery getter not a performance build but I do use the EMW android / bluetooth display system as seen in the attached photo, I posted a response just so as people can know that EMW do exist and so does their car and in my dealings with them I found them very reputable.

The main stumbling blocks of a performance build are the batteries , power electronics and motor. Recently motors capable of 500hp+ have become available , the electronics are better and cheaper and the batteries are evolving. I've a sample on test in my workshop right now as I type that fits on the palm of your hand and kicks out power like nothing i've ever seen. Best of all ? the things are $15 each! So yeh , a high performance build is well possible. One of my aims in life right now is to build a performance ev and drive it around Ireland,

b318isp

Ahh, 300 ft-lbs of torque, but no power figures - so, no useful information at all on the motor. I'd like to see torque or power curves given.

I'm also VERY sceptical of any ad stating the words "up to". There is no mention of transmission mods, support structures for the motor or batteries, CE marking/compliance with European legislation, etc., etc.

kirving

No way would that motor weigh 750kg, more like 100kg.

positron

b318isp wrote: »

I'm also VERY sceptical of any ad stating the words "up to". There is no mention of transmission mods, support structures for the motor or batteries, CE marking/compliance with European legislation, etc., etc.

Again, I don't claim to understand any of the above, but if you read thru their site, they have explained a lot of these points.

They did say the conversion was done to both automatic and manual gearbox cars. For manual it stays on 2nd gear and you change it to 4th for motorway use. And they said something about the authorities in the US seems them as just mods - so they will keep treating the car as what it was on paper before conversion + some mods.

Again, if you look at the credentials of the guys behind the project - PhDs in physics etc, multiple awards at national and international level, serious research heads - and while we are trying to comprehend what they are offering, they are charging ahead with their research of 1hr full recharge system.

I am impressed. And I hope it's get cheaper and more popular so that one day novices like me too can afford to convert a half-decent car and get some half-decent use out of it.

PS: Unrelated but have a look at what Jay Leno thinks of the Mission R motorbike - link.

All I can say is, its' happening folks!

b318isp

Kevin Irving wrote: »

No way would that motor weigh 750kg, more like 100kg.

Are you referring to the photo shown or a 225kW electric motor?

Sesshoumaru

b318isp wrote: »

Are you referring to the photo shown or a 225kW electric motor?

Someone who claims to know the guys behind this company and who has done their own BMW EV conversion has already said the motor weighs around 70kg. Maybe they use more than one? Maybe it's just the one motor that outputs that much power. Maybe jackbauer could could elaborate on his 70kg comment?

http://www.evbmw.com/

jackbauer

It actually weighs 101kg. My bad. Was thinking of the standard voltage version.
http://www.evwest.com/catalog/product_info.php?products_id=53

deandean

kceire wrote: »

Why would he troll??? :rolleyes:
Have you actually clicked on the clinks in he sig?

No harm meant, I am only jealous

I'd have one in the morning if I had the money. I love the concept. Brilliant piece of engineering.

b318isp

Interestingly, specs say for the Warp 11:

Rated Torque: 173 Lb Ft @ 72 Volts And 597 Amps (1442 RPM)
Rated Power: 58 HP @ @ 72 Volts And 597 Amps (1442 RPM)
Continuos RPM: 5,000
Max RPM: 8,000

Note the use of the word "rated" rather than "peak". Graphs also do not show power above 1800rpm.

The Warp 8 has ~38bhp, and pulls 500Amps at this point.

Sesshoumaru

b318isp wrote: »

Interestingly, specs say for the Warp 11:

Rated Torque: 173 Lb Ft @ 72 Volts And 597 Amps (1442 RPM)
Rated Power: 58 HP @ @ 72 Volts And 597 Amps (1442 RPM)
Continuos RPM: 5,000
Max RPM: 8,000

Note the use of the word "rated" rather than "peak". Graphs also do not show power above 1800rpm.

The Warp 8 has ~38bhp, and pulls 500Amps at this point.

58 HP @ 72 Volts. I'm not an expert, but my understanding is that they will run this at higher voltage to attain much higher HP.

b318isp

Sesshoumaru wrote: »

58 HP @ 72 Volts. I'm not an expert, but my understanding is that they will run this at higher voltage to attain much higher HP.

Source?

beazee

b318isp wrote: »

Source?

To calculate the horsepower of a motor when current and efficiency,
and voltage are known, apply this formula:

HP = (V * I * Eff)/746

HP = horsepower
V = voltage
I = current (amps)
Eff = efficiency

http://www.elec-toolbox.com/Formulas/Motor/mtrform.htm

in other words:
increase voltage and/or amps, increase efficiency => higher horsepower

b318isp

beazee wrote: »

[code]To calculate the horsepower of a motor when current and efficiency,
and voltage are known, apply this formula:

I'm well aware of the equation, I'm looking for the source of claimed increased voltage and power. You quoted the wrong formula for DC.

You also cannot just increase the voltage on a motor indefinitely.

I also have a problem with the low rpm of the peak power. This would require some form of long gearing to drive at motorway speeds, as well as some form of variability to match the output of the engine.

jackbauer

The figures netgain publish cause more harm than good imho. They test the motors on the dyno at Warfield electric where the max available voltage is 72v. The 11hv is designed to be ran from a pack voltage of over 280v dc. To achieve this it uses interpoles to eliminate armature reaction which is one of the main limiting factors in increasing the voltage to a brushed dc motor. The other thing to keep in mind is that IC engines are rated at peak power whereas motors are rated at the 24/7 power.

To give a practical example the motor I run is rated at 11kw (15hp) at 72v. Pulling out onto a motorway will frequently pump 100kw electric into the motor for the few seconds it takes to get up to speed. My pack voltage is nominally 165v dc. Recently borescoped the commutator and it looks like new. After 20k km.

Gearing can be an issue but its not as bad as one would think. Most ev dc motors have a power band up to about 2500rpm with a medium voltage pack. The hv motors stretch this upto about 3000rpm. My car had a practical speed limit of 110kph up until recently as the diff (3.45) gave 3000rpm , 5th gear , 110kph. After years of looking I eventually found a 2.45 diff from a 318tds and it has made a big difference. 110kph in 5th is now 2200rpm. The motor is much happier and has plenty of pedal left if required.

Regards the necessity to upgrade the drivetrain for a performance build the main weak spot is the clutch. Even a stage 3 racing clutch cant tolerate 0-500hp in 50ms and / or 500hp at 100rpm However the slew rate of the motor controller can be adjusted to alleviate this.

Sesshoumaru

Interesting times when discussing armature reaction and interpoles is part of a car enthusiasts conversation

b318isp

Thanks for the insight Jack, a very interesting project you are working on. A refreshing change to the hyperbole being advertised - the reality is a lot different, but fascinating all the same.