Sunday, July 19, 2009

2009 Mini Cooper Clubman

We have started our 2009 Mini Cooper Clubman conversion, actually some weeks back. I'm remiss in posting, and indeed the process will be MUCH slower than the Porsche Speedster.

We are trying to document each step of the conversion process. There are some 450 participants in the lease process from BMW for the Mini-E. At the end of a year, they are going to have to give them back. My intent is to do a BETTER conversion than BMW did, on a better car (The Clubman version instead of the S) and have it completed before the end of that period. But it moves very slow because of the overhead of documenting every bolt removal on video, and of course we are having to learn to shoot video and edit it, along the way.

The result is that this is going to be the longest EV conversion project in history. And the videos promise to be the longest, most boring videos in the world. I would love to compress it to 50 seconds and compete with "Charlie Bit My Finger" but the nature of the beast dictates probably 20 hours of video after editing.

This is gruesome. But potentially useful. If you want to do a Mini Cooper, it will pretty much show you all the necessaries. But be forewarned, I have expensive tastes, and like quality equipment. You'll have to make some changes to economize. We spent $32,000 on a brand new Clubman. And it's looking like about $35,000 just in parts for the conversion.

For a drivetrain, we have selected the MES-DEA 200-250 motor with a MES-DEA TIMS600 controller (http://www.metricmind.com) This is nominally a 30kW AC induction motor with a 400 amp 3-phase inverter/controller. We intend to operate with a 320v nominal 360 volt max battery pack made up of 100 Blue Sky 100 Ah cells.

This works out to about 128 kW of power. The motor actually delivers precisely 177 ft lbs of torque at 300 amps which is EXACTLY the torque delivered by the Peugot ICE engine that came in the car - at 1600 rpm. I think this is a SUPERB match to this vehicle, and gives us the ability to do regenerative braking.

This may seem an odd choice. BMW used the AC Propulsion 200kW drive train. We talked to them, extensively, and decided to pass. FIRST, their specs are just wishful thinking. They do 200kW about as well as I do with a AAA battery in my mouth. Second, their system is very much tied into their battery modules. The battery modules consist of 5088 individual cells assembled into modules. It is a design recipe for a fire. And the controller/charger doesn't deal with them particularly artfully when charging.

There wouldn't be much point in doing a video about converting a vehicle using components you can't buy yourself anyway. But after looking at the specs and talking with AC propulsion, we don't think its the best choice anyway. I DO like the idea of having a charger and inverter and DC/DC converter all in one box. But not this box.

The Blue Sky's are not quite as light and easily packaged, but we have a little more room in the car than the S model, and we think they'll be much more durable and less likely to cause problems.

We will again use the Brusa charger. To do higher voltages we'll use the NLG-513. Unfortunately, with a pack size of 36 kWh, this would take about 9.5 hours to fully charge and that's off of 240vac. The Mini-E lessees that were unable to get a 240 vac charge station approved have been seeing 120 vac charge times of TWO DAYs. Unfortunately, the laws of the universe prevail.

So we are going to be forced to install TWO of the Brusa chargers at about $3400 EACH. That's right - $6800 just for chargers for this vehicle. But it should bring us back down to a 5 hour charge process, quite programmable, and quite good for dealing with these LiFePo4 batteries.

We DO have an option. For $4400 you can get a Manzanita 75 amp charger. They have just released this new model, and if you can get your garage wired for a 75 amp 240 vac circuit (we can, we do our own wiring) which will probably be difficult to get a licensed electrician to do. But it has the potential to charge this car in less than 2 hours and for a third less cost than the Brusa.

It does NOT have the programmability of the Brusa. And it is far too large physically to have in the car unless you really want to give up your cargo space. But it would be less expensive. And it should be a monster. We've ordered one for the garage as a general purpose "quick" charger for all the vehicles. I would see hooking up the Manzanita for an hour, and then doing the finish charge on the Brusas during the day.

At night, I will simply use the Brusas. We'll use both for the bulk charge stage one and just one for the finish charge stages that require less current and more care.

3 comments:

  1. Jack,
    Love the blog and your comments on the ThunderSky mail list.
    Can you delve into your reasoning for going AC on the Mini? Top speed or just something different?
    I look forward to the videos.
    --Z

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  2. Something different. Top speed really isn't a problem. We get 85 out of the Speedster and that's about as fast as I want to go.

    It is quite difficult to get DC series wound motors to do regenerative braking. It CAN be done, but it's pretty icky and never does work very well. AC induction motors pretty much do it by default.

    We wanted to do regenerative braking. But I have some ideas about how to do it a bit more artfully than the Tesla or Mini-E. We are going to tie it to the brake light switch, and at least initially leave the brakes unassisted - no vacuum pump. Then we're going to provide a control in the cockpit for adjusting the amount of regen.

    My thinking is that I can adjust the regen to closely approximate the power assist. When you first press on the brakes, it will go into regen to slow you down. If you really need to brake, you'll have to mash em.

    Ultimately this might have to be tied in with a bit of vacuum as well, as it will in all likelyhood there will be a gap between optimum regen performance and the unassisted brakes. If I do, I will probably further complicate it with a very tunable vacuum pressure switch to adjust the level of power assist. I'm convinced this can be made more natural than it is, and get some regen. I think most designers are going for maximum recoverable energy.

    AC induction motors have no brushes. There are instances of such motors in continuous operation for over 100 years without a rebuild.

    They are just hardier because they have even less parts that a DC series wound motor.

    The price you pay is for complexity in the controller - it is now essentially a 3 phase inverter with pulse width modulation. That gets pretty gruesome, and expensive.

    But you could certainly do the Mini project with a Netgain, and less expensively. I would probably use their 11 inch, and in fact, I happen to know they are within a couple of months of a high voltage 11 inch that will do 288 straight up and 336 volts with advance timing. OH, and it is going to have interpoles so you COULD conceivably do REGEN especially WITH their new controller. As they have a Youtube video of their controller installation, it can't be too much of a secret. Check my favorites on YouTube for this very new video.

    The other problem with what I'm doing is spares. IF there WERE a problem with my controller or motor, the manufacturer is in Switzerland and not very responsive. Victor at Metric Mind is our source for these and he's been pretty good with the support, but it still makes me a little goosey. If you use a Netgain, they're made at the Warfield Motor plant in Illiniois. And now that Netgain is going to do a controller as well, even I would be more comfortable with that kind of parts availability.

    Jack

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  3. The mini cars are very comfortable for me specially when i need to park in a small place, they can go fast when there are traffic jump that is why I love the mini cars, they are really beautiful Actually i think to approach costa rica investment opportunities and a mini car there would help me a lot.

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