I meant they're better than lead acid batteries in every way for
off-the-grid applications. Not for things like electric cars or where
weight/volume is a concern.

If I want to build a cabin in the woods (which I intend to do at some
point), nickel iron batteries are the thing to use. Slap on some solar
panels and a wind turbine and you're set for the next 50 years.

On 2013-01-09 8:27 PM, RussellMc wrote:
> 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.
>=20
> 1 Low energy density, certainly volumetric and probably mass.
>=20
> 2 Very high self discharge rate.
>=20
> 3 Low charge efficiency.
>=20
> 4 Wet electrolyte which evaporated and required scheduled maintenance
> and due care.
>=20
> 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.
>=20
> More, no doubt.
>=20
> Is that enough? :-)

Comparing the nickel-iron and lead acid Wikipedia articles side by side
shows that nickel iron is favourable in every way where mass and volume
don't matter.

> 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.
>=20
> 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.

Yeah :(

I will be keeping a close eye on the Stanford stuff. Thanks for the link.

--=20
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