Cycling new Ni-Mh batteries...

Hello again group,

I just got some new 2200mAh Ni-Mh rechargables primarily for use in my
digital camera. I know that such batteries must be cycled ~3-5 times
before they reach their peak performance. I would like to go ahead
and do that ASAP so I don't have to deal with reduced-capacity
batteries when I next go out to take photos. I just need some
recommendations for quick, safe, and easy ways to discharge my
batteries(other than putting them in my camera and taking photos of
nothing until they run out, which is obviously a ridiculous idea) so
that I can put them through the necessary initial cycles. I've read
in previous threads that flashlights and similar "low drain" devices
are not good ideas because they may overdrain the batteries(below 1.0
V) and reduce their lifespan(I have no expertise in batteries, so I
have no idea whether or not this is a legitimate concern, I'm just
stating what I've read). I also read that most portable electronic
"high-drain" devices will shut off before the batteries' voltage drops
low enough that overdraining would be a concern. So with all this in
mind, would it be reasonable to pop my rechargables into a portable TV
or similar device, turn it on, leave it for long enough for the TV to
die, and then go recharge them again? Or have I been lead horribly
astray? If so, please set me straight and give me some suggestions
for relatively quick, safe, and easy ways to do the necessary 3-5
cycles.


Thanks very much in advance,

Brian

 

Use a torch (flashlight) to drain the batteries.

However, I measured approximately the mAh rating on my new 2100mAh batteries
after their first full charge and they were there or thereabouts, so I wouldn't
worry too much about reduced capacity.

 

I use NiMh battery packs on my hand held radios. I've never bothered
to cycle them. OTOH, I run my Lithium rechargeables through at least
two conditioning cycles at the start. I much prefer the Lithiums to
the NiMh *except* in cold weather.

I've gotten very good life out of the NiMh batteries. Out of 16
Lithiums I've had one fail.

I've lost count of how many NiCads I've had fail, but it's been
basically every one I've ever purchased. Hence the hand helds now use
the NiMh.

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)

 

Brian

Am using a little torch working with a single AA cell. Overdischarge (going
below 1.0V) is _not_ a risk if you do it with single cells. With groups of
cells connected in series however this is bad because the weakest cell risks
to be reversed (voltage going below 0V). A periodic deep discharge is even
recommended to keep your cells in good shape. See: http://www.buchmann.ca/
Especially when your cells are used in a device that switches off before the
cells are fully discharged - most digicams do so - a periodic (every couple
of months) deep discharge is a good thing to do.

Markus

 

Personally I don't think it is a real issue. The difference is not all
that much and I doubt if it is worth the difference. Just use them.

The only time it is normally important is if you are conducting capacity
test.

 

I am also finding the ratings don't mean much. My non rated Quest perform
better than my Digital 1800 or Rinpoche 1800 mah units. I've heard the Quest
are 1300 mah but can't find any claimed rating.
Dave Cohen

 

I just got some new 2200mAh Ni-Mh rechargables primarily for use in my

I don't understand why you are so concerned about getting peak
performance from the start. Even with the first charge, the 2200 will
give you outstanding performance. Besides, after awhile their
performance will begin to decline anyways as they don't last forever.

But if you insist, 'low drain' or not, no rechargeable battery likes
very deep discharges (the problem is mostly if left that way for a
long period of time), but removing the batteries for charging before
the light completely goes out from the flashlight will do the trick
just fine. A quicker way would be to use them in a motorized device
such as a CD or tape player.

 

Do *not* do this, unless you are using the flashlight for something and
stop when you notice the light output dim noticeably.

If you put the batteries in a flashlight, turn it on, and walk away,
you'll end up reverse-charging at least one of the cells. There's
always a weakest cell, and when it reaches zero volts the other 3 are
still producing power. So current continues flowing, and this current
starts to charge the weak cell in reverse. It's a good way to destroy
the cell.

It's only safe to discharge NiMH or NiCd batteries this way if you have
a *one cell* flashlight. Otherwise, you need some sort of low-voltage
cutoff. Most electronic devices have this, but flashlights (and
resistors) do not.

Dave

 

(Dave Martindale) wrote in @mughi.cs.ubc.ca:

He can get a few one cell flash lights. Maybe hard to find but they do
exist.

Tim

--

"The strongest human instinct is to impart information,
and the second strongest is to resist it."

Kenneth Graham

 

True. I did say that one-cell flashlights were an exception to the
rule.

Dave

 

(Dave Martindale) wrote in @mughi.cs.ubc.ca:

Sorry, I missed that in your last post. Guess my brain had a stack
overload.

Tim

 

My Maha C-204F charger has a built-in conditioning cycle that
pre-conditions new NiMH AA sets quite nicely. If I get a new set and
have the time, I usually pre-condition it as you describe. Otherwise,
I just use it in the camera, taking care to bring along extra backup
sets. I've seen some very short runtimes in brand new unconditioned
AAs. Don't use a flashlight unless you're willing to babysit it very
closely, as other replies have indicated.
--
Jeremy McCreary
Denver, CO
www.cliffshade.com/dpfwiw/
-------------------------------------------

| Hello again group,
|
| I just got some new 2200mAh Ni-Mh rechargables primarily for use in
my
| digital camera. I know that such batteries must be cycled ~3-5
times
| before they reach their peak performance. I would like to go ahead
| and do that ASAP so I don't have to deal with reduced-capacity
| batteries when I next go out to take photos. I just need some
| recommendations for quick, safe, and easy ways to discharge my
| batteries(other than putting them in my camera and taking photos of
| nothing until they run out, which is obviously a ridiculous idea) so
| that I can put them through the necessary initial cycles. I've read
| in previous threads that flashlights and similar "low drain" devices
| are not good ideas because they may overdrain the batteries(below
1.0
| V) and reduce their lifespan(I have no expertise in batteries, so I
| have no idea whether or not this is a legitimate concern, I'm just
| stating what I've read). I also read that most portable electronic
| "high-drain" devices will shut off before the batteries' voltage
drops
| low enough that overdraining would be a concern. So with all this
in
| mind, would it be reasonable to pop my rechargables into a portable
TV
| or similar device, turn it on, leave it for long enough for the TV
to
| die, and then go recharge them again? Or have I been lead horribly
| astray? If so, please set me straight and give me some suggestions
| for relatively quick, safe, and easy ways to do the necessary 3-5
| cycles.
|
|
| Thanks very much in advance,
|
| Brian

 

someone I know bought some 'party favor' flashlights at one of those paper
stores (I think)
single AA battery. plastic is not thin, fragile. $1 each. I've used one to
drain old nicads, but hardly have use for the nicads

(I hardly have use for any battery other than 9v alkaline for smoke alarms).