PV cells are DIODES. There is no need for an additional one to 'isolate' it
from the battery.

On Mon, May 7, 2012 at 5:23 PM, doug metzler <doug.metzler@gmail.com> wrote=
:

> Based on the google research I did before I built the circuit it was
> consensus that it's probably not good for the panels to have power
> pushed back into them at night so I went ahead and added the schottky
> diode.
>
> I don't think, within reason, that the voltage matters much, it's just
> a matter of pushing electrons back into the battery.  I'm sure the
> batteries never got fully charged, but that didn't matter too much (in
> fact was probably safer) for my application.
>
> My panels were 3" * 4" and the design called for them to drive 5 LEDs
> from dusk to midnight, and they did that just fine.  I used a boost
> converter LED driver to drive the LEDs and had a simple little PNP
> transistor circuit to determine whether it was dark or not.  Used 2@AA
> NiMH.
>
> Caveat I live in Seattle, not Arizona :-)
>
> I can send you the schematic if you want to take a look at it.
>
> Thanks,
>
> DougM
>
> On Mon, May 7, 2012 at 12:19 PM, Ruben J=F6nsson <ruben@rjjournal.net>
> wrote:
> >
> >> I built a similar circuit that had a diode between the solar panel and
> >> the batteries so they wouldn't try to feed power back to the panel and
> >> it worked great.
> >>
> >
> > Would that be a problem? Is this bad for the panels?
> >
> > The original unit did not have any diodes in series with the battery.
> >
> >> I don't know if that's strictly necessary, though, but it makes sense
> >> intuitively.
> >
> > Yes but a diode voltage drop is pretty much in this circuit. Even for a
> > schottky diode.
> >
> >>
> >> DougM
> >>
> >
> > /Ruben
> >
> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D
> > Ruben J=F6nsson
> > AB Liros Electronic
> > Box 9124, 200 39 Malm=F6, Sweden
> > TEL INT +46 40142078
> > FAX INT +46 40947388
> > ruben@pp.sbbs.se
> > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D
> >
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