[ausev] Ive discovered my scooter is over unity!!!

[Aaron Richardson]

The scooter is a Z-20a.  I am looking from the negative battery pack
terminal to the positive pack terminal.  The wires are somewhat long in
length, ~6 ft.  The meter is a $3 special from Harbor freight.  I
suspect back EMF is the cause for excess voltage reading.

I did not test on the stand, but will try to do that tonight.  Im sure
Ill get the same reading.  I do have some fans to cool the batteries
that are connected directly to the pack at the same place as the meter.
When I turn these fans on the excess voltage reading disappears.

Aaron



On Fri, 2009-05-15 at 18:20 -0500, Chris Robison wrote:
> Some questions:
> 
> What is the make and model of your scooter? At what points in the system 
> are you placing your probes or clips? Can you reproduce the behavior on 
> a stand (with the rear wheel raised)?
> 
> I could imagine motor regeneration causing temporarily higher voltages, 
> but if your 64V pack is "sitting" at 110V after shutting down, I'd guess 
> you either have a measurement error or a battery pack that won't last long.
> 
>   --chris
> 
> 
> 
> 
> 
> Aaron Richardson wrote:
> > I put a volt meter on my pack to see how much its sagging under load.  I
> > see the resting pack voltage is about 64V (5x12v SLA).  When I
> > accelerate the pack sags down to about 55 or so and then climbs as the
> > scooter increases speed.  On a freshly charged pack it got to 110V!!
> >
> > I dont think Im inducing current into my sense wires because the voltage
> > goes to 64V when I let off the accelerator and coast at high speed.  It
> > seems this voltage it right.  If I shut the scooter off then this is
> > where the pack sits.
> >
> > So, whats causing this voltage and can I trust the sag voltage when the
> > scooter is moving very slowly?
> >
> > thanks,
> > Aaron
> >
> >
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>