John Doe wrote in
:

Peter Huebner wrote:

Sadly the NiMH also have a curve of diminishing returns. I
have a 12V Panasonic that came with 2@4Ah NiMH batteries.
Had it for maybe 4 years now. 1 battery no longer takes
more than 5 mins worth of charge, the other still works
but self- discharges within about a week.

As far as I know, NiCad and NiMH both last about 1000
charges, eventually they all die.

I started buying AA NiMH batteries many years ago, about
one year after they came onto the market. I still have them
all, about 18 (plus about 8 AAAs). They are many different
capacities since the capacity keeps improving about 200
milliamp hours every six months. The only concern I'm
familiar with is that multiple cell NiMH devices can
conceivably be damaged if they appear to be discharged
completely but some are still slightly charged. I guess
that's a good reason to fully charge them before
installation. I haven't noticed any degradation here.

Beautiful machine otherwise; I like the very
sleek older 9.6 I have even better. I had the battery pack
for that one rebuilt with NiMH.

Replaced the embedded AA NiCad with NiMH in my electric
toothbrush... much better

Apparently lithium-ion batteries can be recharged twice
as many times as NiCad or NiMH, and do not fade near the
end of their charge.

Drawback with li-ion is the limited lifespan. After nnn
days they die,

That would be very bad news for millions of laptop computer
users.

die, never
mind how you've used them.

As far as I know, their lifespan is very roughly 2000
recharges.

I am looking forward to this technology getting cheaper
and more robust.

I think lithium-ion batteries being safer is a major design
problem also, like with the recent laptop recall.

We now have walkie talkies with Li-ion batteries and I
like them MUCH better than the ones I had before with
NiMH. Lighter, more compact, and they're always in the
charger - 24/7, when not in use.

Model airplane enthusiasts like them (see
rec.models.rc.air), but that's probably high-risk for
fire/explosion.

They are being used in some new cordless drills.







-P.



If you techies want to know how Lithium cells are controlled,
check out this site.

http://www.panasonic.com/industrial/...chem/lithion/i
ndex.html


Battery packs (Li-Ion) now have microchips in them for control
of over current/voltage, in both the charge and discharge
mode.

Makes it hard to get your battery packs rebuilt, because each
manuafacturer has it's own charcteristics for the cells, plus
they can turn off (via the microchip, timed number of
charge/discharge cycles) the control circuits when they think
you've had enough use out of your battery pack.