Preliminary 84V data

[Puppyjump]

I am working with a grad student in doing the upgrade to my ZAP. He is making a master's thesis out of it in regards to Power Technology and EVs. Anyway, today the instrumentation was installed. The Cycle analyst is off in its amps measurement. It is only reading about half of the correct value as determined by a separate shunt and amp meter as reference. I think there is a calibration mode for the cycle analyst so I can fix this, or else the shunt they sent me is only half of the resistance it should be.

As for performance, we ran a test whereby the time from 20 MPH to 35 MPH was measured at 72V and again at 84V. The results are significant. It took 24 seconds on 72V but only 12 seconds on 84V. Thus while not a fast vehicle, the 84V does wonders in maintaining traffic flow.

 

[swbluto]

That seems unusual. That suggests that your acceleration is twice as much, which indicates your motor's thrust is twice as much, which would indicate twice the motor current, which would be unexpected from a ~1/7th increase in voltage.

 

[liveforphysics]

If his 72v run is approaching the back EMF equal voltage point at 35mph, it would make perfect sense.

 

[John in CR]

It's also in line with the subjective results that Steveo posted about his bikes as he's gone up in voltage. Thanks Luke, now I understand why. Now I really need to get on the stick and soup up my 60V controllers. I should really see a drastic performance increase with little risk to my motors using a modest increase in current and 40-50% increase in voltage.

John

 

[swbluto]

If his 72v run is approaching the back EMF equal voltage point at 35mph, it would make perfect sense.

Oh yes, indeed. It just seems funny anybody would gear it so the no-load speed approached a typical speed limit in traffic, for performance reasons on a typical car, unless there was some legal reason but even then...

 

[liveforphysics]

If his 72v run is approaching the back EMF equal voltage point at 35mph, it would make perfect sense.

Oh yes, indeed. It just seems funny anybody would gear it so the no-load speed approached a typical speed limit in traffic, for performance reasons on a typical car, unless there was some legal reason but even then...

Many applications need the gearing dictated by the maximum slope the vehicle can climb.

 

[swbluto]

I wouldn't necessarily think a vehicle climbing 10% at 10 mph to be much more viable than one that couldn't climb 20% at all, so I guess I'm finding out the xebra's stock configuration kind of sucks. Oh well, it must be all that lead, eh?

 

[Puppyjump]

That seems unusual. That suggests that your acceleration is twice as much, which indicates your motor's thrust is twice as much, which would indicate twice the motor current, which would be unexpected from a ~1/7th increase in voltage.

Yes, it certainly seems unusual that adding only 16% more voltage gained such a dramatic increase in performance, but nevertheless, this is what happened. 24 seconds down to 12. I don't know why it made such a difference but it must be related to the way the Curtis controller is programmed?