December 2009 Archives

In my search for info on calculating EV efficiency, came across this interesting article with java calculators: http://www.ecoworld.com/transportation/the-battery-powered-car.html

The articles mention that standard EV car efficiency is around 4.4 kilometers (2.7 miles) per kilowatt-hour.

My little scooter gets around 40 watt-hours per kilometer on SLA (I need to get new figures for the 43.2 volt NiMH packs). Flipping that around, that's 25 km per kWh. That's around 16 miles per kWh.



Here's a great link to why you shouldn't charge your NiMH packs in parallel: http://tlb.org/nimhboom.html

More info will be posted here as to how I'm charging my packs....

I have the Prius NiMH batteries installed and test drove it but the snowstorm of 2009 has put the dampers on harder testing. In any case, here's the new revised bill of materials (BOM) (dated 2009.12):

Base Unit Piaggio Boxer (1971)
- 50 cc 2-stroke internal combustion engine (removed)
Electric Motor HXT 80-100-B 130Kv Brushless Outrunner from HobbyKing
- link to new version of motor
- Tachs: 5600 rpm @ 43.2v nominal (4500 rpm @ 36v; 6000 rpm @ 48v)
- Max amps drawn: 100A @ 43V
- Max watts drawn: ~ 4300 watts
- Speed: 45 kph top speed (at current gearing)
Electronic Speed Controller Castle Creations Phoenix HV-110 (link)
- 110 amps @ 50 volts limit
Throttle Magura 0-5K Potentiometer motorcycle twist grip throttle
Servo Tester (Pot to ESC) Boman Industries Polar-Matic PC-50 (ebay)
Power Monitor Cycle Analyst (link)
Batteries Currently SLA: Prius Gen 2 NiMH
- 6S2P packs (12 in total)
- 43.2 volts nominal @ 13 Ah
- 330 watt-hours (conservative)
- Range: unknown
Power Connectors - Anderson PowerPole 75A on main connections - link
- Anderson PowerPole 30A on sub connections - link
Wiring - 8 gauge stranded copper on main power lines and motor leads
- 12 gauge stranded copper on sub power lines
Lighting - Front lighting using high-power Luxeon LED
- Rear lighting using high-power red LEDs
Low Voltage (12/5VDC) Converters
  1. 12VDC converter using National Semiconductor LM2576HVT-12-ND buck-converter for motor cooling fan, front lighting (via 5vdc) and rear lighting
  2. 12 volt to 5VDC converter using MC34063 Based Switching Regulator for front lighting
  3. Another 12VDC converter using National Semiconductor LM2576HVT-12-ND buck-converter for ESC controller cooling
  4. Quark Pro BEC 3A UBEC for servo tester / RC components
Things I burned out/destroyed
  • E-Sky EK2-0907 Servo Tester
  • Doc Wattson power monitor
  • ELF 100 ESC speed controller
  • Castle Creations Phoenix HV-110
  • Right index finger on burnt out ESC
  • Various burns and scrapes

When I first started building my Boxer-EV, the motor I installed in it was the largest brushless motor available for RC systems:

Model: HXT80-100-B
Wire Turns: 8
Resistance: 32ohm
Idle Current: 2A
ESC Required: 130A
Input Voltage : max. 48V 
Kv : 130 rpm/V 
Weight: 1570g
Shaft: 12mm
Voltage Range: 20-48v
Non Load Current: 2.0A
Maximum Power: 6500W
Equivalent: 60-80cc Gas Engine

I've been very happy with it. With my 48 volt setup, I'm producing enough power that my drive belt started slipping -- so I reduced the gearing a bit to back off the torque. Still, vroom vroom.

ProgressiveRC.com has a great online list of RC brushless motors and you can sort by watts consumed. Looks like there are some great 10,000 watt motors (holy cowabunga!) the only problem being they are around US$2000 and above. My $130 + shipping RC motor is still on the top of the price/performance curve.


It looks like the dealer in Hong Kong I get things from has come out with a new version of the motor. The specs seem the same but they note: "Tight, thick copper windings and 48SH magnets make this motor a real powerhouse. The v2 motor also has screwed end-caps due to the amount of torque this motor produces!"

HXT80-100-A.jpg
HXT80-100B.png
Model: TR80-100-B
Wire Turns: 8
Resistance: 32ohm
Idle Current: 2A
ESC Required: 130A
Input Voltage : max. 48V 
Kv : 130 rpm/V
Weight: 1570g
Shaft: 12mm
Voltage Range: 20-48v
Non Load Current: 2.0A
Maximum Power: 6500W
Equivalent: 60-80cc Gas Engine

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This page is an archive of entries from December 2009 listed from newest to oldest.

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