Progress in the Face of Intimidation!

After the visit to Electric Motorsport, I was both intimidated and inspired. Concrete action helps!

• Identified that a Ninja 250 might be just the bike I am looking for. Light, attractive but not scary, and available - so available that I found one that a co-worker is looking to sell.
• Orded the "Secrets of El Ninja" plans for electric motorcycle conversion. They claim no welding is necessary, but I'm sort of hoping it might be anyway - located a place that rents welding equipment.
  
• I signed up for a weekend motorcycle training class in September.
  
• Found a motorcycle helmet I used for autocrossing!
• I am clearing out garage space - sold my windsurfing kit, and am looking at a bike or two.
• Continue to identify legions of local motorcyclists for assistance, all seem to think the project is very cool. Have been offered a 70's era bike for conversion, but I am going for broke - superbike-like or bust!!
• I keep browsind the web for a Derbi GPR 50, but these babies are rare and pricey.
  

Contacts Made - Project "Tronbike" is Underway

Progress

• I found a potential donor bike, a Honda CBR600F2 with starter issues.
  
• Made contact at Electric Motorsport, they have a GPR in stock but are willing to charge time to help convert.
• Biker Floyd is bored and looking for something to do.
• Uhaul has bike trailers locally, need a tow vehicle. Maybe rent a truck.
  
• Created spreadsheet comparing battery options. LiFePO4 is half the weight at 4X the cost for similar raw power.

Electric Cars vs Electric Everything Else

I got myself all excited again pondering a VW GTI electric vehicle conversion when I spotted a potential donor vehicle on Craiglslist, but then the logistics of dealing with a non-operational car in which I would put $10K into plus batteries and countless time just got me down into the spiral of hopelessness, then anger at the $98K Telsa pricetag, then the logic of the fact I don't drive much and own a freaking Porsche 911 "dreamcar" already-so-shut-up, to looking for a workaround to satisfy my quest for electric validation.

I started shopping electric scooters, mopeds, NEV's and then electric motorcyle conversions. These efforts and products seem to be costing magnitudes less than electric car stuff - I mean $20K AC motor controllers? Come on, get real. Whats been catching my eye are conversions of Japanese superbike-like machines to electric power. This seems manageable suddenly, still cool and styling, just dangerous since I have been fighting to keep my self the hell away from motorcycles - too many dead and injured aquaintances, and the knowledge that *I would love motorcycles*.

So my initial searches got me to this on YouTube (http://www.youtube.com/watch?v=xrFPMLAfs3s&eurl=). A demo of an electric superbike that looks great. I immediately registed the domain name "tronbikes.com".

And this site had a related Make-zine video Electric Motorsport, selling E Bikes, conversions and parts.

Lets Make an ESS Spreadsheet!

I am not liking the capacitance calculation I performed. 1 Farad is a lot of charge requiring a large capacitor - capacitors are not mentioned in the whitepaper.

TO validate the calculations above, I decided to put it into a spreadsheet available for review on Google Spreadsheet. Please let me know where I may have gone wrong in my math!

I am going to share the sheet as a Google spreadsheet (see Resources) and post to the from the Tesla blog.

The Current State of Affairs: Tesla Energy Group ESS, a Starting Point

Tesla Motors is in the process of creating a complete electric performance car. Amen. The core problem of electric vehicle acceptance has been the batteries: poor energy density (compared to gasoline) results in cars with poor range and acceleration.

Called an Energy Storage System(ESS), Tesla motors announced in May 2007 that is is going to resell its ESS technology to Th!nk.

In the Tesla Motors Blog, the CEO author Martin Eberhard was kind enough to direct the reader to a Tesla White Paper describing some details around their ESS. The paper focused on describing safety features around the relatively high energy performance of the pack, but also the general parameters around the pack that could assist others seeking to make their own ESS.

Starting Point: An Analysis

An ESS is made up of many small cells to form a complete battery pack.

This cell is called the 18650 because of its measurements of 18mm diameter by 65mm length (i.e., just a bit larger than a AA battery).

- "The Tesla Roadster Battery System
Tesla Motors, Inc.
August 16, 2006
", Gene Berdichevsky, Kurt Kelty, JB Straubel and Erik Toomre

So I went shopping for bulk priced cells:
4 Panasonic CGR18650 3.7V

4 Panasonic CGR18650 3.7V

Specifications:

- Brand: Panasonic
- Capacity: 1400mAH
- Chemistry: lithium-ion
- Voltage: 3.7V 18650

LightWeight(45 grams per cell)
Comes in a pack of 2

For 75 x 2 cells, $14.67 is the price.

Quick Numbers on Size and Cost

From the paper:

The Tesla Roadster battery pack is comprised of about 6800 of these 18650 cells and the entire pack has a mass of about 450kg.

weight

6800 * 45grams = 306,000 grams = 306 Kg

450kg - 306kg = 144 kg of other stuff in the pack (packaging, electronics)

cost

(6800 / 2) * $14.67 = $49,878

Definitely going to need some bulk pricing.

Deriving Configuration From Pack Specs

From the paper:

The pack operates at a nominal 375 volts, stores about 56 kilowatt hours (kwh) of electric energy and delivers up to 200 kilowatts of electric power.

Total Possible Amps and Volts in Series

6800 * 3.7V = 25160 Volts

The batteries are not arranged in series.

Each cell has 1400mAh.

Watts = Amps * Volts
so
Kilowatt hour = Volts * Amp-Hours = 3.7V * 1400mA hour/1000m = 5.18 watt-hour cell

5.18 watt-hour * 6800 cells = 35224 watt-hours = 35 kwatt hours

This is less than the 56 kwh claimed - is Telsa using higher output cells too?


56 kwh = 6800 cells * X Amp-hours * Y Volts

56,000 wh / 6800 cells = 8.23 wh = 3.7V * X Amp-hour

X Amp Hour = 8.23 wh/3.7V = 2.22 Amp-hour = 2225 mAh

Tesla has cheaper AND better cells. Maybe a different voltage?

Back to shopping, I see better cells, at mAh ratings of 2600, 2200, 2000, 1800, 1650, 1500. I started too cheap.

The 2200 mAh battery.

$9.49 each

Specifications:

   * Nominal Voltage: 3.7V
   * Size: 18650 (Cylindrical)
   * Capacity: 2200 mAh
   * Chemistry: Lithium Ion (Rechargeable Li-Ion)
   * Brand: LG
   * Max Charging current: 2.2A
   * Max Discharging current: 4.3A
   * Included Qty: 1


Dimensions:

   * Length: 65 mm
   * Diameter: 18 mm
   * Weight: 46.5 g (1.64 Oz)

Still can't beat the pricing - 6800 * $9.49 = $64,532, and the weight is up too - 316 Kg.

Check peak load:

200 Kwatts ?= 3.7 V * 4.3A * 6800 = 108.188 Kwatts

about 50% of the claimed.
Even checking the top discharging current of the 2600mAh is only 5 Amps, which results in 126 Kwatts.

Wikipedia pointed me to calculations for Capacitors, the unit is a Farad.

An interesting definition for a Farad Since an ampere is the rate of electrical flow (current) of one coulomb per second, an alternate definition is that a farad is the amount of capacitance that requires one second for a one ampere flow of charge to change the voltage by one volt

F = Amp * Sec / Volts.

The power equation for a Watt is:

Watt = Volts * Amp

SO lets make a formula for Watts given a specific Farad to see if such a capacitor could exist.

Volts * F = Amp * Sec, lets replace Amp = Watt/Volts, so Volts * F = Watt * Sec / Volt, Volt/Watt=Sec/F, SO Watt = Sec * Volt/ F

If we believe the pack can deliver 200 Watts

Watts = 200 Kwatts = Sec * Volt / F.

Large car stereo systems have power capacitors with 40 Farads - see Crutchfield. A max of 16/18 volts is indicated, we have 375 to deal with so maybe its the wrong industrial use.

200,000 Watts= Sec * 16 Volts / 40 F, 8,000,000Watts-F /16 volts=seconds = a lot = 500,000 seconds = 136 hours

Now try with 375 volts:

sec=watts * F / volts, sec=200 watts * 40F / 375 v = 21.3 seconds, which would be plenty to get a Tesla from 0 to 60 and beyond (assuming such a capacitor exists).

Blog Kickoff

Okay, okay, I'll use a real web tool to keep it all digestible.