> They're obsolete?
>
> Seems like their service life and durability is unmatched by any other
> battery technology.

Undergoing a renaissance.
But, the original ones had major shortcomings.
Some of these will be being addressed BUT it would pay to check
carefully re all specifications as some of the shortcomings are major
ones in some contexts.

1 Low energy density, certainly volumetric and probably mass.

2 Very high self discharge rate.

3 Low charge efficiency.

4 Wet electrolyte which evaporated and required scheduled maintenance
and due care.

5 Oil was added above electrolyte to slow evaporation rate , but if
cell was then tilted oil could go where it did not belong and poison
electrodes.

More, no doubt.

Is that enough? :-)

The first 3 are potentially tolerable in daily cycle solar use if you
get good cost per cycle and very long life in exchange.
4 & 5 are OK in large fixed installations but are less tolerable in
developing country and small home use roles - but probably addressed
in some modern versions.

Note as per an earlier post of mine that there are several recent or
current manufacturers (including in USA and China) and that Stanford
University* has developed a version that does 2 minute  charge and 30
second discharge cycles (or the other way around - see prior post).
That's nominally 30C and 120C rates! Even at low energy densities that
MAY be useful in a hybrid vehicle for eg energy regeneration during
urban cycle driving. High energy transfer rates during braking are not
handled well by many battery technologies.


 Russell McMahon


* http://news.stanford.edu/news/2012/june/ultrafast-edison-battery-062612.h=
tml



>
> On 2013-01-03 4:13 PM, Michael Klein wrote:
> > Hello,
> >
> > Nickel Iron is an obsolete rechargeable battery technology... many
> > better
> > available alternatives out there..
> >
> > check out *http://en.wikipedia.org/wiki/Nickel%E2%80%93iron_battery
>
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