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[Phys-L] Re: Polarity of a 1F (super) capacitor



[from the PowerStor site]

Every supercapacitor either has a
negative stripe or sign denoting polarity. Although
they can be shorted to zero volts, the electrodes
maintain a very small amount of charge. Reverse
polarity is not recommended, however previously
charged supercapacitors have been discharged
to -2.5V with no measurable difference in capacitance
or ESR. Note: the longer they are held charged in one
direction, the more polarized they become. If reversed
charged after prolonged charging in one direction, the
life of the supercapacitor may be shortened



At 07:40 PM 3/24/2005, you wrote:
As far as I know, the polarity doesn't matter. At least for the 1 F c=
apacitor that I bought. As I understand it, these extra-large-capaci=
tance devices don't have polarity. In general, there is such a thing=
as a non-polarized electrolytic. We use the 10 uF size from Radio S=
hack in our RC Circuits lab. - Vickie

________________________________

=46rom: Forum for Physics Educators on behalf of Paul D. Price
Sent: Thu 3/24/2005 7:25 PM
To: PHYS-L@LISTS.NAU.EDU
Subject: Polarity of a 1F (super) capacitor



Friends,

I have recently purchased several 1 F electrolytic (super) capacitors=
for
several labs and demos. However, I am having trouble discerning whic=
h side
is positive for the polarity of the capacitor. I note the the cap ha=
s a
long and short connector, but there is little else (such as an arrow =
etc) to
clearly define the polarity. Before I accidentally reverse the polar=
ity
while charging does anyone with a 1F cap have any insight for me to
guarantee the polarity direction?

Thanks,
Paul
-------------
Paul D. Price
Science Dept. Chair
Trinity Valley School
Ft. Worth, Texas 76132
tvschem@sbcglobal.net


Brian Whatcott Altus OK Eureka!
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