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AC Propulsion System Powers the MINI E

AC Propulsion Drive System for MINI E. Click to enlarge.

AC Propulsion is supplying both the electric propulsion and the battery technology for the MINI E electric vehicle introduced at the 2008 Los Angeles Auto Show by BMW Group. (Earlier post.) AC Propulsion has already delivered more than 500 drive systems to the BMW Group factory in Munich for MINI E production.

The MINI E features a 150 kW (204 hp) electric motor powered by a 35 kWh lithium-ion battery pack (approximately 28 kWh usable), with a single-stage helical gearbox transferring power to the front wheels. The electric drive train produces a peak torque of 220 Nm (162 lb-ft), with 0 to 100 kph acceleration in 8.5 seconds. Top speed is electronically limited to 152 kph (95 mph).

MINI E on the road. Click to enlarge.

BMW puts consumption for the MINI E at 190 Wh/mile (120 Wh/km) under the US Federal Test Procedure (FTP), also referred to as UDDS (Urban Dynamometer Driving Schedule). The battery pack will support an approximate range of more than 240 km (150 miles).

The MINI E uses a specially-developed version of AC Propulsion’s proprietary tzero technology to provide high performance, high efficiency, and fast charging. AC Propulsion’s air-cooled copper-rotor induction motor produces maximum torque from zero to 5,000 rpm and spins all the way up to 13,000 rpm. The IGBT inverter drives the motor to produce its peak power of 150 kW. Continuous power is 50 kW.

AC Propulsion also supplies the battery pack for the MINI E. The 35 kWh, 380V pack comprises 48 Li-ion modules, each assembled from 106 small Li-ion cells (5,088 cells in total) using proprietary assembly techniques and battery management technology. Each module sends voltage and temperature information to the management system which controls for optimal battery operation under driving and charging conditions. Battery data are logged to provide information for analysis and evaluation.

The 48 modules are packaged into three battery elements that are compactly arranged inside the MINI E. The 260 kg (573 lb) battery pack extends rearward from the heel plate and replaces the rear seat bench. A temperature-controlled fan ensures a constant operating temperature. A shared high-voltage connection supplies the electric motor with energy from the three battery units.

Miniea Minieb
View of the battery pack from the rear. Click to enlarge. Lower front of the battery pack. Click to enlarge.

AC Propulsion’s patented battery charger is an integral part of the AC Propulsion drive system used in the MINI E. When the wallbox outlet is connected to the charge port on the MINI E, charging proceeds automatically.

The tzero technology includes patented control and construction techniques that allow the power electronics and motor windings to be re-configured as a high-rate Reductive battery charger. By using existing componentry, the Reductive Charger reduces vehicle cost and weight. By allowing safe charging from existing 110V to 240V outlets at rates from 200 W up to 20 kW (with a 240V line), the Reductive Charger reduces infrastructure installation requirements and costs, and a bi-directional power capability allows self contained vehicle battery diagnostics and standby power generation.

Estimated charge times are 23.6 hours at 110V/12A (1.3 kW); 4.4 hours at 240V/32A (7.0 kW); and 2.9 hours at 240V/48A (10.6 kW). The bi-directional charger can serve as a regulated power source with many possible applications including, battery pack self-diagnosis, back-up power, car-to-car charging, and, perhaps most importantly in the future, providing ancillary services to the power grid (vehicle-to-grid, V2G).

AC Propulsion is working with V2G research and development programs throughout the US to supply V2G-capable vehicles, evaluate V2G functionality, and develop the communications and control systems that will necessary to enable electric vehicles to support the power grid.

AC Propulsion was founded in 1992 by Alan Cocconi. It has headquarters, engineering, manufacturing, and test facilities in San Dimas, CA (Los Angeles County), and operates a wholly-owned manufacturing plant in Shanghai PRC. Total employment is over 100 persons and production capacity is more than 2,000 drive systems per year.

AC Propulsion is the owner of 6 issued patents on EV technology, which have been licensed to other companies, including Tesla Motors. Some of this technology was originally developed by AC Propulsion for its tzero electric sports car which achieved 0-60 mph acceleration in 3.6 seconds and 300 mile range while driving 60 mph.



Quick GCC poll:

Is Alan Cocconi the hero of modern EV development?

My vote is yes!


I wish that they had arraned the batteries so that the trunk was one continuous "bed" instead of the two tier thing they have going now.

Other than that, me like! Me want!


I wonder why BMW went with this system instead of the PML Hi-Pa system: http://www.pmlflightlink.com/index.html

They built an electric Mini that beat this one in every category (0 to 100 km/h in 4.5 sec!)... and it still had a back seat! Since this announcement they have removed the electric Mini from their website and are touting a Volvo and a Ford F150.



Perhaps it has to do with reliability, scalability of production, and cost of mass production. I can only guess, but obviously you get what you pay for.


I think it probably had to do with integration. It's a lot easier to take an ICE out and put a single electric motor in the exact same place with nothing more than modified engine mounts than it is to modify the chassis of 500 Minis to accept wheel hub motors.


The reason BMW COULDN'T use the PML Hi-PA system is because it's so far proved to be bogus.

PML claim 600hp and 4000nm of torque from their wheel motors at every opportunity but of the 3 test vehicles shown in videos running them the performace has looked more like 20hp total.

PML are obviuosly still along way, perhaps years, from being production ready for a full sized road car.


Powered off grid only.


150 mile range and where to recharge?

573lbs batteries for only 150 mile range.

Blocks front-rear fold down seat access

The big question is how much lithium batteries can be produced per year and what % of market will that support.

We really need hydraulic Hybrids. Adding all this weight (batteries + cascade of heavier chassis etc.) kills the savings. Could give this idealistic design approach a run for the money.


Wonder what the cost will be.
Can they make it be competative with the
Volt or will it be much more expensive?

150 miles is plenty for my day to day commute.
So I have no issue with the range. I dont plan on
going on vacation with it, only day trips around town.
I cover 100 miles a day so this works for me.


Figure the battery pack is $20-25k, and the Mini itself is $20k (MSRP) and conversion costs would be near $20k. So this vehicle will sell for around $60k - just below a Fisker Karma @ $80k (when avail) and $25k more than Volt.


220 peak torque @ 5000 rpm max speed means 112kW not 150kW!
Strange a similar error ... mumble mumble
is it a fake car?

@ Paul,

Their specs in text above are correct, your mis-calculations are not.
Obviously the power peaks past 5,000 rpm.


The previous post was mine.


OK , if that is so then 162lbs-ft at 204Hp works out at around 6600rpm which happens to be the same as the base speed of the dual FWD motors on the "Impact". Nothing wrong with that in my book.

Impact is the car that Alan Cocconi had a key role in the design while at Aerovironment. When delivered to GM in 1990 it became a single motor FWD under the auspice of the newly acquired Hughes Electronics. And renamed the EV1.

What's interesting here is the single stage which by my calculation- using 95mph = 13000rpm - puts the gear ratio at 9:1.
Tesla OTOH accomplish their new single ratio gearbox of 8.27:1 but with two stages. Unless Tesla have done an independent load test of their gearbox (I doubt it) I would assume a real world effcy of 5% torque loss per stage.
Of course differing tire diameters would throw that 9:1 ratio off somewhat, nevertheless I expect the single stage gearbox will be more efficient.

As long as the ratios lie between 8 and 11 the exact values are not that important. The reason being that a substantial part of the operation above base speed is constant power so once you've gone beyond that point (somewhere around 42mph depending on gear ratio)and are drawing maximum constant power from the battery (or any other power source for that matter) the exact gear ratio loses significance.

The original Impact did 60mph in 8.0secs with 114Hp, whereas the Mini-E is taking 8.5secs with 204Hp ??


I just discovered that the AC Propulsion packs for the Mini contain cells made by by Moli Energy

Henry Gibson

You all may be shocked to find out that the TZERO and its prototypes operated very well on lead batteries. Especially even with the generator trailer to take it cross country. ..HG..


Nice find Kevin, the Molicells are 187 Wh/kg in 18650 format:


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