Karen Nakamura: July 2009 Archives

My little Piaggio-EV is back up and running. I made the following mods:

  • My replacement HV-110 is now installed in an external plexiglass box with (much) better airflow and forced as well as passive air cooling. The forced cooling is on full all the time rather than the temperature variable fan that I used to have.
  • Extra caps (470 uF x 6) soldered in parallel with input leads
  • (Slightly) beefier wiring used -- 8 gauge rather than 12 ga
  • 75 amp Andersen PowerPoles used instead of 30A
  • Wiring shortened a bit
  • Thermometer probe directly on caps to monitor heat

So far, it seemed ok. After my ride to work this morning, the caps heated up a bit -- from 17°C ambient at the beginning to 37°C ambient at the end of the 5 kilometer ride. I'm working on getting even more cooling in there.

6 amps used. 30 watts/kilometer average energy expenditure.

My project has expanded to use standard size servos (link back to my micro servo comparison). Here's a little table that I'm using to compare various options.

TowerPro MG930Digital36.2x15.2x28.7 mm26g0.14sec/60°3.6 kg/cm0.11 sec/60°Metal$16
Hitec HS-225BB Analog32.4x16.8x30.8mm27g0.14 sec/60°3.9kg/cm0.11 sec/60°Nylon$20
Hitec HS-225MG 31gMetal$30
Hitec HS-5245MG Digital32.0x17.0x31.0mm32g0.15 sec/60°4.4kg/cm0.12 sec/60°Metal$48
MKS DS9660Digital35.0x18.0x28.0mm35g0.13 sec/60°3.7 kg/cm0.10 sec/60°Metal$57
Futaba S9650Digital36.0x15.0x29.0mm26g0.14 sec/60°3.6kg/cm0.11 sec/60°Nylon$65

The conversion for torque from kg/cm to oz/in is to multiply by 14.7. So a servo with a torque of 1.0 kg/cm has an imperial torque of 14.7 oz/in.

iMax B6AC charger

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I just bought a used iMax B6AC charger (LiPo/Li-Ion/NiMH) to complement my previous Turnigy Accucel-8 charger. I had trouble finding the user manual but finally located it. I'm posting a copy here just in case anyone wants it: And here's a little comparison table that I drew up comparing the iMax with the Turnigy units:
iMax B6ACAccucel-6 Accucel-8
Max Power50 watts50 W150 W
Max Current5.0A5.0A7.0A
Max LiPo Cells668
Max NiCD/NiMH Cells151527
Max Pb20v20v36v
Power Input100-240 VAC
11-18 VDC
10-18 VDC10-18 VDC

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This page is a archive of recent entries written by Karen Nakamura in July 2009.

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