Motors / Engines: August 2008 Archives

On Sunday, I finished making the bearing mount on the right side of the motor spindle. This will help take a lot of strain off the bearings on the motor and prevent it twisting out from the torque. Also, I shimmed the front pulley with the thin metal from an aluminium can -- it was just perfect to close the gap between 12.5 mm and 12.0 mm. As a result, the motor is working much quieter now -- I just love the sound it makes when it accelerates -- gotta post a video.

(And yes, it's made of wood, I'm a woodworker not a metalworker and don't have access to a mill. The 12mm flanged bearing itself is hidden underneath the wood, it has quality roller bearings to support the spindle.).

I got a new V-belt at the local autoparts store to try to make the gearing taller by forcing the rear CVT smaller, but the V-belt was too small. I'll have to split the difference and get a new V-belt later this week.

Instead of depending on my unreliable low-voltage system for fan power (not good that it cuts out at full throttle), I instead wired two of the fans in serial. That means each fan is being driven by 19 volts -- a bit fast but not something they can't handle. One fan is on the ESC controller, the other I mounted in front of the motor. Unfortunately I found out that the mount I used blocked some of the natural airflow, so the motor ended up running hotter with the fan than it did "naked." I'll have to make another mount that diverts more natural and blown air to the motor.

I've ordered more batteries for the scoot, so now I just have to wait.

Some miscellaneous notes that are bouncing around my head.

• The Phoenix HV-110 has a listed max volts of 50 volts, which I thought would mean I could use 40 NiMH cells, with a nominal voltage of 48 Volts. However, you are limited to 36 cells NiCd/NiMH which gives a max nominal voltage of 43.2V. This is a little bit of a bummer since I had planned on doing 5S packs of 9.6V which would have given me 48V. I think this is because although the nominal voltage is 48V in that case, the peak voltage (fresh off the charger) can be in excess of 60V and the FETs most probably aren't rated that high.

• It turns out that I could've bought the 180 kV motor instead of the 130 kV motor. As it stands, I'll either have to get a smaller V-belt or a larger front pulley if I want a max speed of 45 kph (30 mph). No worries.

• I'm wondering what the best way to charge my NiMHs is. They don't sell many 38.4 V chargers, so I may just stick with 2 x 19.2 volt chargers and charge 2 packs at a time. I may want to get even more chargers so I can do the entire megapack at the same time.