Some voltmeters also read funny in the presence of high frequency noise. An analog meter usually won't lie, but my harbor freight meter can give some creative responses.<br><br><div class="gmail_quote">On Fri, May 15, 2009 at 7:36 PM, Matt <span dir="ltr"><<a href="mailto:mba@hazmat.com">mba@hazmat.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Most likely, the battery pack voltage is drooping under high current (high<br>
load), and the reference voltage for the battery meter is drooping as<br>
well. The measurement is only as accurate as its reference. I would<br>
investigate how you are powering your voltage meter and where it gets its<br>
reference from.<br>
<font color="#888888"><br>
Matt<br>
</font><div><div></div><div class="h5"><br>
On Fri, May 15, 2009 6:20 pm, Chris Robison wrote:<br>
> Some questions:<br>
><br>
> What is the make and model of your scooter? At what points in the system<br>
> are you placing your probes or clips? Can you reproduce the behavior on<br>
> a stand (with the rear wheel raised)?<br>
><br>
> I could imagine motor regeneration causing temporarily higher voltages,<br>
> but if your 64V pack is "sitting" at 110V after shutting down, I'd guess<br>
> you either have a measurement error or a battery pack that won't last<br>
> long.<br>
><br>
> --chris<br>
><br>
><br>
><br>
><br>
><br>
> Aaron Richardson wrote:<br>
>> I put a volt meter on my pack to see how much its sagging under load. I<br>
>> see the resting pack voltage is about 64V (5x12v SLA). When I<br>
>> accelerate the pack sags down to about 55 or so and then climbs as the<br>
>> scooter increases speed. On a freshly charged pack it got to 110V!!<br>
>><br>
>> I dont think Im inducing current into my sense wires because the voltage<br>
>> goes to 64V when I let off the accelerator and coast at high speed. It<br>
>> seems this voltage it right. If I shut the scooter off then this is<br>
>> where the pack sits.<br>
>><br>
>> So, whats causing this voltage and can I trust the sag voltage when the<br>
>> scooter is moving very slowly?<br>
>><br>
>> thanks,<br>
>> Aaron<br>
>><br>
>><br>
>> _______________________________________________<br>
>> AusEV mailing list<br>
>> <a href="mailto:AusEV@austinev.org">AusEV@austinev.org</a><br>
>> <a href="http://www.austinev.org/mailman/listinfo/ausev" target="_blank">http://www.austinev.org/mailman/listinfo/ausev</a><br>
>><br>
><br>
> _______________________________________________<br>
> AusEV mailing list<br>
> <a href="mailto:AusEV@austinev.org">AusEV@austinev.org</a><br>
> <a href="http://www.austinev.org/mailman/listinfo/ausev" target="_blank">http://www.austinev.org/mailman/listinfo/ausev</a><br>
><br>
<br>
_______________________________________________<br>
AusEV mailing list<br>
<a href="mailto:AusEV@austinev.org">AusEV@austinev.org</a><br>
<a href="http://www.austinev.org/mailman/listinfo/ausev" target="_blank">http://www.austinev.org/mailman/listinfo/ausev</a><br>
</div></div></blockquote></div><br>