A lot of good info here, but I have some also to offer.
The key problem is "lightly used" - that means the NiCd cells will develop a
memory, unlike more modern ones. A memory of being charged, then
leak-discharged, then trickle charged, etc, etc. The only good way around
avoiding this, is using (as others have said) a discharge cycle (or use to
flat) before recharging, and not leaving them flat.
The age of the cells has NOTHING to do with the expected performance, as
long as you have cycled them properly. I have NiCd cells still working
strongly from the mid nineties.
some chargers are designed to be able to leave the pack in,some are not.
You need to check your manual.
It's been my experience that for longest life,NiCds are best used
often.(use it or lose it)
Once you start storing them for long periods,their life decreases.
NiCds also have a self-discharge rate;just sitting in storage,they
discharge on their own.
If you don't use them much you need to keep
checking the voltage at least once every 1-2
months and make sure the voltage doesn't drop
below 12V. Full charge on a 12V NiCad is about
14V, but that degrades quickly to about 13V and I
check the voltage when charging and stop before it
reaches 14V. Overcharging is the number one cause
of batteries going bad.
Months ? Nicads ? Wet Cell , in a plane ... OK .
Dry types? from da store , for your drill ? naaaaaah .
50% in a 20 days !!
Li-Ion is high rate power , loss can be 1% /month .
priced out of reach , ..... I tossed all my Nimh !
Just too good to be intimadated by price !
But they die if too much amps charge above the 3.65 vdc level .
All batteries will float if the amps are very low .
( BTW Harbor Fright tiny driver $20 , w/ Li-Ion has no greater than
a 1 aH single cell ) .
George E. Cawthon wrote:
I read the responses below that state you should not drain the battery
but when I googled
*NiCad Batteries Drain Completely*
there are articles that state you should drain them.
Here are a few of the articles....
Frankly, I have no idea which is correct (and I did see some articles
to the opposite) but if I'd suggest calling Panasonic tech service.
Draining a NiCd or NiMH cell completely means to remove essentially all
the energy it contains. This requires discharging it to a cell voltage
of about 1.0 volt. Doing this, then recharging, is the way to reverse
"memory" (voltage depression) effects. If the battery has 6 cells or
fewer and they're reasonably well matched, you can usually safely
discharge the battery to 1.0 volt times the number of cells (e.g., 6.0
volts for a 6 cell battery) without risk of reverse charging one of the
cells. If the battery has more cells, this becomes increasingly risky
and the only safe way to do it is to discharge the cells in groups of
4-6. This of course requires getting into the battery pack.
The folks cautioning against trying to discharge down to 0 volts are
absolutely correct. It just about guarantees reverse charging one or
more cells, which will permanently damage those cells. Those cells will
then have even more reduced capacity, so they'll go into reverse charge
even earlier in the battery cycle the next time. There's never any need
to discharge a cell below 1.0 volt. A well designed tool or electronic
device intended for NiCd or NiMH power should quit operating and drawing
battery current when the pack voltage reaches 1.0 volt per cell.
Unfortunately, a lot aren't in this category.
That's the problem with netnews and the Internet
in general. Lot's of incorrect stuff that gets
repeated over and over even by groups that should
Always check major manufacturers for the accurate
information when there is controversial information.
1) Pulse charge and it will return to full energy if it is
still in infancy .
Never deep cycle any battery . Batterys die for being NOT fully
charged . Leave them discharged is to shorten life .
2) NimH and Nicad lose 10% in 1 day , Li-Ion lose 1% .
I gambled on 100 NimH "LenMars" 2.5 aH AA's
from Buy.com .. 25% loss in 1 day , load tested OK ,
i tossed them , not worth my time .
Pulse charge a nicad and it "loses" its memory , return full energy
........ a 4 amp pow supply with a simple Resistor works great .
C cell ( NiCad ,NimH) , as in drills , can take 2-3 amps til
about 1pt36 vdc
(((Linux crap apps ! Konquerer ..Cant see the text , too small , no way
change it so i use pt for decimal point ))))))))
1 ) so pulse with a very low Z pow supply at 1pt48
to 1pt5 vdc
per cell and a Resistor of 0pt25 ohms . Theorectically ,
you must select R ( 0pt25) carefully , use scope to see the
amps , for it will heat up if too much amps above 1pt38 vdc .
2) but since current is so hi and pow supply is
help the current limit anyway , just measure the current above
1pt36 to 1pt37 vdc and adj the supply
Voltage instead of doin the Resistor .
Now the resistor limiter is inside your pow supply and you can
vary period of pulse to "tame" the circuit and keep batteries cool .
Never charge a hot battery ( > 110F ) , they dry up , short life .
Velleman has o'scope ( HPS-40 for $250 ) .
Clever battery chargers use a 2 step current limit , but more clever
is to make the heavy current , resistor controlled .
BTW Li-Ion need a charge rate of less than "c" til 3.6 to 3.65
at 25 Deg C . ( I.E. Sony 920 Notebook has 2.2 aH cells in parallel
so 4.4 times 3 sets in series
+12v in > | |
Ground < | |
-means less than about 4 amps
til 3.6 vdc ...Thus the pow supply will show 4.9 amps to pow notebook
and charge both ( batts/Notebook) same time .
These Li-Ions are worth your while even if you are poor .
They will Kill Nicad/Nimh for they have
1) more energy per cubic inch ...
2) same VERY hi discharge rates .
3) but retain energy beyond a week .
dont fear paralleling , Li-Ions have much less cross talk ( discharge
of lower volt cell by the higher volt cell ) than anything ....
Off Topic Your Z-6 Minolta DigiCam will NOT like alkalines
You must use NimH for the hi power needed . And it dont like
heat , remove batteries to allow heat to escape for 15 minutes
and you can shoot again ... I guess refurbished can mean a
tax dodge , the Camera IS new ! The price drop is combo
of Loss Leader and a pass thru of tax .
Nonsense. NiCDs and NiMH batteries love to be discharged. That's
the only way to store them for long periods. Don't "reverse
charge" cell(s) in a multi-cell battery by discharging it below
about 1V/cell though. They can be left to self discharge without
damage. A single cell battery can be discharged to zero.
OTOH, lead-acid batteries must never be fully discharged and must
be stored with a float charge. Lead-acid batteries are thus better
for things like flashlights, UPSs, safety lighting, and such.
Not any more. NiCds may be 20% per month, usually less. NiMH has
gotten a lot better too, but it was never as bad as 10% per day.
<snipped the rest - too hard to read>
Yes, Gates' secondary battery manual. The chemical reaction stops
with zero terminal voltage. They store quite nicely that way. In
any case, they *will* self discharge and the worse thing possible
for a NiCd or NiMH is to float charge it. THis is exactly the
opposite as is the situation for Lead-acid cells.
Nonsense. They do *not* self discharge totally in a month.
...more like 20% a month. Classically NiMH self-discharges at
about twice the rate of NiCD, but AIUI they've gotten much closer.
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