hasan wrote:

One thing I've learned about NIMH batteries...they don't sit well. They
do wonderfully if kept trickle charged, but if let to sit, they will
self-discharge in less than two weeks. (at least for digital camera
purposes)I've observed this on three different "sets" of NIMH AA
batteries. All act the same way. Two weeks of sitting and they will only
operate the camera a very short time. Left in the charger and put
directly into service I can shoot well over 75 pictures in a row with no
difficulty.

This was true until a short while ago, but no longer is. A new chemistry
is now being used for some NiMH cells which greatly reduces the
self-discharge rate. Some of the more popular brands are Sanyo's
Eneloop, Rayovac's Hybrid, and Sony's Cycle Energy, but there's a
growing number of others. A bit of web searching will bring a great deal
more information about this. "Low self discharge NiMH" is a good search
string to start with.

So far, the LSD cells have a bit lower capacity than the very highest
capacity conventional cells, with 2000 mAh typical for AA and 800 mAh
for AAA. But they have almost as much capacity after sitting for an
extended time. And the Eneloops, in particular, typically have a
slightly higher voltage under discharge, and hold up very well under
high discharge rates. They're very good cells -- I use them almost
exclusively now.

Roy Lewallen, W7EL

Roy Lewallen wrote:
hasan wrote:

One thing I've learned about NIMH batteries...they don't sit well.
They do wonderfully if kept trickle charged, but if let to sit, they
will self-discharge in less than two weeks. (at least for digital
camera purposes)I've observed this on three different "sets" of NIMH
AA batteries. All act the same way. Two weeks of sitting and they will
only operate the camera a very short time. Left in the charger and put
directly into service I can shoot well over 75 pictures in a row with
no difficulty.

This was true until a short while ago, but no longer is. A new chemistry
is now being used for some NiMH cells which greatly reduces the
self-discharge rate. Some of the more popular brands are Sanyo's
Eneloop, Rayovac's Hybrid, and Sony's Cycle Energy, but there's a
growing number of others. A bit of web searching will bring a great deal
more information about this. "Low self discharge NiMH" is a good search
string to start with.

So far, the LSD cells have a bit lower capacity than the very highest
capacity conventional cells, with 2000 mAh typical for AA and 800 mAh
for AAA. But they have almost as much capacity after sitting for an
extended time. And the Eneloops, in particular, typically have a
slightly higher voltage under discharge, and hold up very well under
high discharge rates. They're very good cells -- I use them almost
exclusively now.

Roy Lewallen, W7EL

Can they (Eneloops) be charged in a conventional NiMH charger, or do
they require a proprietary charger?

hasan wrote:

Can they (Eneloops) be charged in a conventional NiMH charger, or do
they require a proprietary charger?

They can be charged and otherwise treated the same as any other NiMH cells.

Roy Lewallen, W7EL

In article , hasan wrote:

Can they (Eneloops) be charged in a conventional NiMH charger, or do
they require a proprietary charger?

Sanyo's own words:

"Basically eneloop is a modern Ni-MH battery, which can be charged
like any other Ni-MH battery.

Therefore eneloop can be charged also with other, modern chargers,
which are suitable to charge Ni-MH batteries.

However, SANYO cannot accept any liability for the function or safety
of chargers made by other manufacturers.

Also SANYO cannot be held responsible for any damage to eneloop
batteries caused by unsuitable chargers."

On a different Sanyo page (http://www.eneloopusa.com/eneloop.html) they
say that they only provide warranty on the batteries if an Eneloop
or other Sanyo-branded NiMH charger is used. "Quick" chargers (those
charging in under 2 hours) should not be used, as these may reduce the
life of the battery... "2 hours or more" charging rate is recommended
(e.g. 0.5C or so).

A lot of people seem to like the various Maha chargers. One of my
friends here uses a Maha MH-C9000, which is relatively expensive
(currently $60 from Thomas Distributing) but is *extremely* flexible
and adaptable... you can select the charging and discharging rate for
each battery, perform one or more break-in or discharge/recharge
exercise cycles, etc. I have one on order and plan to try it out with
my various NiMH cells.

Seems to me that almost any modern NiMH charger, with a charge rate of
around 500 - 1000 mA per cell, and an effective full-charge cutoff
circuit (thermal and delta-V) would work fine with Eneloops and
similar low-self-discharge NiMH cells.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Dave Platt wrote:

On a different Sanyo page (http://www.eneloopusa.com/eneloop.html) they
say that they only provide warranty on the batteries if an Eneloop
or other Sanyo-branded NiMH charger is used. "Quick" chargers (those
charging in under 2 hours) should not be used, as these may reduce the
life of the battery... "2 hours or more" charging rate is recommended
(e.g. 0.5C or so).


That is very helpful, Dave, especially since I have a very fast charger
that would be very hard on these cells.

I'll get a set and use them on my slower chargers, and also warn people,
no faster than a two-hour charger for the new chemistry cells. (I have a
15 min Energizer charger that does well with Energizer AA and AAA cells,
but have not had a chance to evaluate lifetime. The cells charge nicely,
but 15 seems very hard charging.