Russel,
why so big deal?
The NiMH are so cheap now that it doesn't care if life time is 1 or
0.5 it was specified.
4x2100mAh NiMh can be as low as euro 4 ($6.6), austrian price (not australian)

Vasile

On 9/21/08, Apptech <apptech@paradise.net.nz> wrote:
> Bob said:
>
> > We went thru a whole deal on this NiMH battery charge system.
>
> > The most important factor is battery temperature.
> > As the NiMH cell tops off, battery temp rises
> > to 45C or so. For the most part, charge level can
> > be determined simply by the temperature.
>
> > As a general rule, charging without monitoring temperature
> > is a good way to have a fire.
>
> > As the cell is approaching full charge, the cell voltage rises to
> > 1.50V per cell. Cut it off there, if you can. The knee is softer on
> > NiMH and more difficult to read.
>
> > ... and DON'T trickle-charge NiMH cells, they don't like it.
> > Charge at a rate of C/5 for good cell life.
>
> > Good documentation is hard to find. But Tynergy Batteries
>
> Maybe Tenergy ???
>
> >  has V-I charts that are accurate.
>
> All good stuff where you have essentially unlimited charging energy
> available and "normal" temperatures apply.
>
> Just to add perspective: In my main applications energy source is limited
> energy solar and ambient temperature may be as high or even above Bob's  end
> point temperature. (The latter is not good for battery life!).
>
> NimH long term low rate charge end point voltages are lower than under
> typical conditions. Maximum end point voltage / cell would typically be
> never above 1.45V/cell and may even be less so a 1.5V end point would never
> be reached..
>
> My available charge rates vary with application but are in the C/4 - C/8
> range at full rate and can be anything below that when the enerrgy source
> decides to hide behind clouds or increasing amounts of the atmosphere.
>
>
>            Russell.
>
>
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