It is interesting to compare the efficiency of the drive unit. As a regular viewer of the Jack Rickard's weekly electric vehicle conversion webcasts ( http://evtv.me/ ) much technical information has been revealed. It is generally known that a typical EV conversion requires about 100 watt hours per 1000 pounds car mass per mile. The 1992 BMW 325i being converted in this blog, weighs in at about 4000 pounds. It is intended to use 48 CALB 180 amp hours batteries, each at 3.2 volts, to provide a 27.648 kW pack. ( 48x180x3.2=27,648 watts ). Since the car is about 4000 pounds, about 400 watt hours will be required for each mile driven, thus 27,648/400=69.12 miles of theoretical range. In fact, one can only use about 85% of the pack energy, thus a 58.75 mile range is expected. The current daily commute is about 35 miles each way, so a partial recharge at work will allow the conversion to be a daily commuter. The i3 on the other hand, has a better range due to its greater efficiency, lighter weight, and BMW's use of Lithium ion batteries instead of the Lithium Iron Phosphate batteries that will be used in this conversion.
The Tesla, considered by most observers to be the industry standard for performance, if not for price, has a battery efficiency that is "estimated" by Rickard to be about 70 watt hours per 1000 pounds car mass per mile. The BMW i3 battery pack compares favorably to the Tesla. By calculation, BMW indicates that the i3 is rated at 27.0 kW-hrs per 100 miles. Thus, the pack delivers 270 watt-hrs per 1 mile. Since the car weighs in at 3615 pounds, thus 270/3.615=74.69 watt hours per 1000 pounds per mile.
BMW indicates that they estimate the i3 to have 124 MPGe (miles per gallon equivalent, 137 city and 111 highway) when compared to an "average new vehicle", which is defined as 23 MPG and fuel costs of $11,500 over 5 years. They assume electric costs to be $0.12 per kW-hr and 15,000 miles of driving per year. From this data, they calculate fuel savings of $9,000 during the first 5 years, and with tax credits of up to $7,500 , the car becomes an interesting value proposition for those unable to build their own EV. This car demonstrates what is possible with a 100% electric drive and it may be possible to incorporate some of its elements into an EV conversion. Pictures to follow.
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Picture DSC01783, this picture speaks for itself.
Picture DSC01751 of the front view of the BMW i3.
Picture DSC01788 showing the traditional BMW kidney shaped "grill" without the aerodynamic drag caused by a functioning actual grill. No engine to cool, thus no air flow required.
Picture DSC01753 of the passenger side view of the BMW i3 showing the side profile to reduce wind resistance.
Picture DSC01757 showing oblique view of the BMW i3 drivers side.
Picture DSC01760 showing the passenger side coach style doors that are hinged at the outer edges.
Picture DSC01761 showing closer detail of the passenger side back seat door.
Picture DSC01756 of the rear view of the BMW i3.
Picture DSC01768 with the rear hatchback fully open.
Picture DSC01776 with the back seats folded down for full cargo space.
Picture DSC01764 of the driver side control area.
Picture DSC01769 showing the one button start/stop switch and the three position toggle for D/N/R. The driver "instrument panel" is to the left, and the auxiliary display (navigation, etc.) is to the right.
Picture DSC01754 of the J1772 style charging plug.
Picture DSC01755 of the industry standard J1772 charging socket when the internal illumination is automatically activated. This illuminated port feature would be a good addition to any conversion project.
Several interesting observations should be noted. The test drive, which was enthusiastically offered to us by Angelo, was a unique experience. Although there is a brake pedal, it was really only used at the beginning of the drive when the start/stop was activated, while at stop lights (out of habit) and at the end of the drive when the car was parked. With constant pressure to the acceleration pedal, the car moves smoothly ahead. If pressure is taken off of the throttle, then the car immediately begins to gently brake and the car rapidly comes to a smooth stop. Four of us took the test drive together and our total weight was about 630 pounds. From a full stop, and shall we say, with a little encouragement, this car is really quick and all of us were pushed back into our seats. This is exactly what drivers want to be able to feel, and once the public knows what electric cars are capable of, this car should be really popular. Author's note: To complete the test drive experience, the drive needs to be repeated with only the weight of a single occupant!!
This car is absolutely quiet and it reminded me of the first time I tested the first generation SONY CD player ( http://en.wikipedia.org/wiki/Sony_CDP-101 ) that was offered in 1983 for sale for $1000 at a high fidelity store in downtown Chicago. With head phones on, when I first tested it, it appeared to be broken since there wasn't any background noise traditionally caused by a phonograph needle or a tape head. Incorrectly assuming that the unit's volume setting was set too low, I made the mistake of substantially turning up the volume knob. Let's just say that the subsequent hearing loss was not permanent as I ripped the headphones off as fast as I could once the music began! The quiet of this car should help take music to a new level of automobile enjoyment.
Additional useful information about the BMW i3 can be found here:
http://en.wikipedia.org/wiki/BMW_i3
www.bmwuse.com/bmwi3
http://www.patrickbmw.com/i3
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