> 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.

For certain well controlled ranges of "slap" :-)

You'd need to look at the spec sheets for modern versions to see to
what extent the old shortcomings were still present.

Self discharge rate needs to be low enough to not waste an
unacceptable amount of energy over the desired storage period.

Charge today, 'use tonight' is liable to be OK
If you are snowed in and want to eke out a full charge over 2 / 4 / 8
/ 16 days you need to be sure that self discharge will not eat your
breakfast.
Few storms last for more than 16 days wholly sunlessly. Choose your
desired backup period.

Ye Olde versions needed water added occasionally.  Could be automated.
May have been overcome.

Charge efficiency needs to be checked.
LiIon, LiFePO4 is very high - 99%+ current efficiency. Lead acid can
be > 90% with care.
LiFe =3D ?

While of life (LiFe? :-) ) cost needs checking.
With discounted cash flow, distant events have minimal effect on net
present value. More than about15 years out (depending on discount
rate) and it matters not. Factor in cost of lugging in new batteries
when comparing.

It MAY be that LiFePO4 works out better. You can get 10 year
warranties when deep cycling daily !!! for some versions.



 Russell
--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.