> I found this website:
> <
http://www.mpoweruk.com/chargers.htm>
> I don't know if you're going to find the spreadsheet
> you're looking for.
> There are many methods of charging batteries. What
> you may need to do is
> some experimentation.
> You mention that the -dv method slightly overcharges
> cells, creating
> heat. It was my impression that NiMH cells heated up
> as a result of
> becoming fully charged.
> My AA cells get pretty warm in the charger. There
> was an EV (the RAV4?)
> that had to run the A/C when charging, to keep the
> huge NiMH cells at a
> reasonable temp.
> --
> Martin K
>
>
> Philip Pemberton wrote:
>
> >Hi,
> > Has anyone here got a recorded charge profile
> from a NiMH battery? What I'm
> >after is - in effect - a spreadsheet with three
> columns:
> > - Time
> > - Voltage
> > - Current (optional)
> >
> >Does anyone have anything like this kicking around
> their HDD? The battery
> >manufacturers seem to be quite happy to give out
> pretty pictures of their
> >charge profiles, but don't seem to publish actual
> numbers.
> >
> >I want to play around with charge termination
> detection algorithms for my
> >(half-done) NiMH charger, and I don't have any test
> data to feed into my
> >detection algorithms. I figure while I'm waiting
> for the parts for the
> >discharger circuitry to turn up (a DAC, a voltage
> reference and a few
> >op-amps), I might as well get some of the software
> algorithms tested and
> >tweaked for use on a PIC.
> >
> >What's bugging me is that the manufacturers are
> saying one thing (wait for dV
> >to hit -5mV per cell) while all the books and
> websites I've been scanning
> >through are saying different things. One suggested
> "zero voltage delta" (wait
> >for dV to get close to zero) and another suggested
> "inflection point sensing".
> >The latter involved calculating the first or
> second-order derivative of dV/dt
> >and looking for the point where the derivative
> crosses zero. Surely that would
> >produce the same result as zero-delta sensing
> though?
> >
> >The main thing is that -dV is reputed to slightly
> overcharge the cells (which
> >produces heat, which is bad) and 0dV allegedly
> stops that. But if you get the
> >trip point wrong, you end up undercharging the
> cells, which is also bad.
> >
> >As far as preferences go, data for any cell
> manufacturer is fine, but Sanyo
> >(or anyone who rebrands Sanyo cells - Kodak,
> Energizer or Duracell) or another
> >name-brand (Uniross excepted) would be preferred.
> Same for cell count - given
> >the number of cells in a pack, I can get the
> per-cell voltage back pretty easily.
> >
> >Thanks.
> >
> >
>
>
>
> --
> Martin Klingensmith
>
http://wwia.org/
>
http://nnytech.net/