Barrett wrote:
Dave, the batteries are called Supreme Power 2600mA standard charge
14-16 HRS x 260mA, quick charge 4-6 HRS x 550mA. REG USA Made in China.

I am waiting for a friend to bring by his old NiCad charger and I will
give it ago. I will let you know how I got on.

For future reference would you have an idea on how long I should charge
the batteries for using the MFJ?

I don't know who or how the charger circuit has been modified. I could
ask W&S what sort of circuit has been used.



"Dave Platt" wrote in message
...
I borrowed some 1800mA and these are charging fine in the MFJ-259,
so it
looks like the
problem is with the batteries. I have never experienced this with
these type
of batteries before only NiCad's.

What brand and type are the batteries that don't work?

It's possible that you simply received a bunch of batteries that are
completely defective (open) or are counterfeit dummies. Seems a bit
implausible.

Another possibilty is that the 2600 mAh cells are actually OK, but
were delivered to you in a completely-run-down state. That seems
plausible... the manufacturer may not have precharged them, or they
may have self-discharged in storage after manufacture. The older type
of NiMH cells do have a relatively high self-discharge rate, and can
go flat after as little as three or four months of storage.

If the batteries read 0 volts, then it's possible that a smart-charger
might fail to detect their presence and start charging... I believe
that some of the newer NiMH-aware charge-control ICs depend on the
detection of _some_ voltage from the cell to detect the cell and start
the charge.

Try sticking a few of the cells into an old-style "dumb and slow" NiCd
battery charger for a few hours. These are usually fixed-current
chargers (100 mA or so) with no battery-detect or charge-cutoff
circuits, so they're not a good choice for general use with NiMH
cells. They _will_ feed some charge into the cells if the cells
aren't entirely open, and should bring the cells up to 1.0 volts or
better fairly quickly. After 2-3 hours, take the cells out of the
dumb charger, check the open-circuit voltage, and put them in your
smart-charger, and see if they are accepted and begin charging. If
so, they may be OK. If not, they're probably defective or bogus and
you may want to return them to the seller for a refund.

Since an MFJ analyzer is the sort of device that tends to sit around
unused for weeks at a time, I think that high-capacity high-self-
discharge NiMH cells (e.g. most 2500 or above) are a poor choice.
Unless you recharge for an hour or so once a week, you'll probably find
them weak or dead when you want use the analyzer.

High-capacity NiCd cells are the traditional choice for this sort of
application (and are what I use in my own MFJ). Another possibility
is the newer low-self-discharge NiMH cells, such as the Imedions,
Eneloops, Hybrios, and Hybrids. These are typically 2000-2100 mAh,
and will hold the majority of their charge for a year or more. If
your MFJ has been modified to charge NiMH properly (e.g. with a good
temperature or zero-delta-V cutoff circuit) they might be a good choice.

--
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!

I've had the same set of NIMH 2100 maH Energizer cells in my 259B for
over 3 years. I have had them on the internal charger 24x7, except when
in use. I have had no trouble with the batteries overcharging with the
internal charger in the 259B. (obviously, or I would have cooked them a
long time ago).

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.

In article , hasan wrote:

I've had the same set of NIMH 2100 maH Energizer cells in my 259B for
over 3 years. I have had them on the internal charger 24x7, except when
in use. I have had no trouble with the batteries overcharging with the
internal charger in the 259B. (obviously, or I would have cooked them a
long time ago).

Good to know, thanks! Possibly the trickle charge is of a low enough
rate that the cells do not overcharge much and overheat. Heat is the
enemy of service life.

According to the battery-manufacturer literature I've read, NiMH cells
tend to have poor "charge acceptance" when trickle-charged at very low
rates. If you try to charge them at a rate of, say, .01C (20 mA, for
a 2000 mAh cell), almost none of this energy actually recharges the
cell - essentially all of it turns into heat.

One manufacturer's writeup I've read says that if it's necessary to
trickle-charge the cells to combat self-discharge, it's best done
through a periodic pulse-charging technique. Pulses of current in the
range of .05C through 1C, lasting for .1 to 60 seconds, are suggested,
with the time between pulses set so that the average rate of charge
delivered is around .02C per day. This is enough to combat
self-discharge, without overcharging.

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.

High self-discharge rates are indeed an issue with the older NiMH
formulas (which account for most of the higher-capacity cells on the
market).

There seems to be a very real tradeoff between capacity and
self-discharge rate... it's a result of the different metal-hydride
alloy formulas used.

The new-generation "ultra-low self discharge" batteries are quite a
bit better in this regard. The Sanyo Eneloops and similar types are
billed as losing no more than around 10% of their total charge after a
month of storage, and still retaining as much as 60% after a year.
The price you pay for the longer holding time, is a reduced maximum
capacity (typically 2000-2100 mAh for an AA, as opposed to 2500-2700
for the ultra-high-capacity type).

Many reports indicate that new NiMH cells, and older ones which have
been sitting around unused for some time will exhibit reduced
capacity, until they've been fully charged and discharged once or
twice.

--
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!

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.