The following replies were restored from an online cache:
Re😀ononLSDNiMHcellswearoutmorequickly?
Written by
s0lar on 01-18-2011 04:22 PM GMT
This behaviour can be explained in different ways.
One possibility is that your Panasonic 2600mAh cells are wrongly branded and in fact only 1800mAh. You can test this in a Maha C-9000 for example.
Another possibility is that those Pana's are not as capable of delivering 2A of constant current.
If your torch lights for about an hour, you are drawing 1C, batteries don't really like that.
I think this is the reason your Pana's wear off faster than your Eneloops.
High current performance is more important than capacity.
Check this thread, look for the 2A test results in the graphs.
http://www.candlepowerforums.com/vb/...843#post920843
Re😀ononLSDNiMHcellswearoutmorequickly?
Written by
45/70 on 01-18-2011 08:27 PM GMT
Hi Leif. High capacitycells of over ~2000mAh capacity are not of as durable construction, as lower capacity cells. This appears to be especially true of non LSD cells, but I think applies to LSD cells as well.
In order to build a NiMH cell of much over 2000mAh capacity, some compromises have to be made in the construction of the cell. This generally means that the separator in the cell has to be made thinner, in order to fit more of the active chemical compounds into the cell. As a result these cells,
while initially able to deliver high current loads along with providing
superior capacity, begin to show signs of loss of capacity, inability
to deliver high current (voltage depression) and simply wear out sooner, than cells of lower capacity. This is particularly true when the cells are used consistently in high current load applications. In addition, cells with this type of construction are more fragile, and more easily damaged if the cells, or the device they are installed in, is exposed to shock, such as being dropped etc, as the separator is likely to be damaged.
To get the highest number of cycles from "high capacity" NiMH cells,
it's best to relegate them to use only in low to medium current drain
devices. If the extra capacity is absolutely needed, such as in the
case of a professional photographer, or similar situation, the cells will work, but will simply need to be replaced more often.
Dave
Re😀ononLSDNiMHcellswearoutmorequickly?
Written by
KiwiMark on 01-18-2011 08:32 PM GMT
45/70 said:
Hi Leif. High capacity cells of over ~2000mAh capacity are not of as durable construction, as lower capacity cells.
This sounds very believable to me - my Energiser 2450 This sounds very believable to me - my Energiser 2450 cells
(I think they are actually made by Sanyo) were OK when new but sucked
big time after a couple of years, my Sanyo Eneloops are now more than a couple of years old and are still working great!
Re😀ononLSDNiMHcellswearoutmorequickly?
Written by
45/70 on 01-19-2011 01:48 AM GMT
I should have mentioned that when the separator either simply begins towear out, or becomes damaged, the self discharge rate of the cell increases. Increased self discharge (the inability of a cell to hold charge for very long) is often the first problem that most people notice with high capacity NiMH cells. The other losses in performance are more subtle, occur gradually, and often go unnoticed by the average user.
Dave
Re😀ononLSDNiMHcellswearoutmorequickly?
Written by
s0lar on 01-19-2011 02:37 AM GMT
It is correct that high capacitycells wear, but they should be able to survive at least 500 cycles. Survival meaning still having 80% of original capacity. For a 2500mAh cell
this is 2000mAh. It also depends how they are conditioned, continous
fast charging followed by high current drainage will make it suffer.
You can try to recondition your Pana cells with a MAHA C-9000 and test actual capacity.
Re😀ononLSDNiMHcellswearoutmorequickly?
Written by
InHisName on 01-19-2011 06:44 AM GMT
MyLSD cells are wearing out
differently. They go HIGH. I can test them with break-in and seems
to have almost the same capacity. If I discharge a 800mah AAA cell at 300ma I might get only 2 or 3 hundred. But at 80 ma I might still get nearly 700.
That leaves two ultimate questions that I have not found answers that worked yet.
1. How to stop or slow down the increasing internal impedance of a cell.
2. How to reverse the internal impedance to a lower value.
There seems to be several causes, one may be reverse able, the others
appear to be permanent and NOT reverse able. Can those permanent ones be
delayed by using different usage tactics ?
Mine were discharged 25ma @ 10 hours per night for 3 nights. Then charged 625mah and were done. If I ran it down in 1 cell
light to nothing then charged at 300ma, I'd put in around 800mah. The
radio indicated to change batteries so I did and recharged them.
Approximately 120 cycles with Duraloops Oct '09 to present. 1.57 new
NOW 1.89(almost HIGH) to 2.78 (HIGH) for range of 12 AAAs
Re😀ononLSDNiMHcellswearoutmorequickly?
Written by
s0lar on 01-19-2011 06:48 AM GMT
Using break-in charges and low current discharges could revive them.
They might not be empty after a higher current discharge but show low
voltage. They cannot deliver the current. You could try to deplete them
deeper by discharging one hour after they are showing empty with a lower
current.
Re😀ononLSDNiMHcellswearoutmorequickly?
Written by
45/70 on 01-19-2011 10:22 AM GMT
InHisName said:
There seems to be several causes, one may be
reverse able, the others appear to be permanent and NOT reverse able.
Can those permanent ones be delayed by using different usage tactics ?
Hi In. Hi In. Quickly, from your usage description, I would guess that you are running your cells
in series in the radio. Radios normally have a fairly low current
requirement. This greatly increases the chance of running your cells down to such a low level that one, or more cells become reverse charged at the end of discharge.
Unfortunately, the damage caused by reverse charging cannot be reversed. The best thing to do would be to recharge, or rotate your cells at some point
before the radio indicates that the cells need to be recharged.
Also, it is not recommend to fully discharge any type of NiMH cell on a regular basis in single cell applications. LSD or not, this increases the "wear and tear" of NiMH cells, and will cause premature loss of performance. NiMH cells prefer to
normally
be discharged to a maximum of about 20% remaining capacity, and then
every 20-25 cycles, be discharged to ~1.00 Volt under load, or ~1.20
Volt open ciruit, which equals "fully discharged" for all practical
purposes.
Dave
Re😀ononLSDNiMHcellswearoutmorequickly?
Written by
LeifUK on 01-19-2011 12:43 PM GMT
Thanks for the informative replies. This evening I discharged two freshly recharged Panasonic 2600 mAhcells in a Quark AA2 on turbo, and got exactly 60 minutes on turbo, after which the light dimmed noticeably. When new the 2600mAh cells gave significantly more
runtime, though I cannot find figures. I get the same with Eneloops and
Panasonic Infiniums. So it looks like the high capacity cells
are failing. I also found that the 4 Eneloops I used in the Sunwayman
M40A were in fact 2 Eneloop + 2 Infinium. Not only are
Eneloops/Infiniums significantly cheaper than higher capacity cells,
with low self discharge (doh!) but they ALSO withstand repeated high
current discharge with minimal degradation. I'm glad I only bought 4
2600 mAh cells.
I wonder if the Sanyo XX cells are like Eneloops or the 2600 mAh cells in this respect?
Would anyone like to buy some used Panasonic 2600 mAh cells, 1 careless owner?
Re😀ononLSDNiMHcellswearoutmorequickly?
Written by
45/70 on 01-19-2011 01:50 PM GMT
LeifUK said:
I wonder if the Sanyo XX cells are like Eneloops or the 2600 mAh cells in this respect?
That is part of the reason I suggested that the same may apply to That is part of the reason I suggested that the same may apply to LSD cells. The estimated cycle life of the XX cells is considerably lower than for eneloops (500 vs. 1500? I forget the exact figures).
Dave
Re😀ononLSDNiMHcellswearoutmorequickly?
Written by
LeifUK on 01-19-2011 03:16 PM GMT
45/70 said:
That is part of the reason I suggested that the same may apply to LSD cells. The estimated cycle life of the XX cells is considerably lower than for eneloops (500 vs. 1500? I forget the exact figures).
Dave
Exactly. By the way you got the figures right. It is alright
saying that they will last 500 charges, but really what matters is the
performance drop off curve, for various discharge currents. Exactly. By the way you got the figures right. It is alright
saying that they will last 500 charges, but really what matters is the
performance drop off curve, for various discharge currents.
Re😀ononLSDNiMHcellswearoutmorequickly?
Written by
LeifUK on 02-03-2011 12:31 PM GMT
For what it's worth, I put them through some break in and discharge
cycles on a Powerex C9000 charger, and got 2061, 1997, 1871 and 1833
mAh. Thecells are 2 years old, and have clearly suffered damage which the C9000 cannot rectify. Two of them were used more than the other two hence the asymetric results. Time to give these away to someone who can make use of them.
I tested my old Panasonic Infinium AA cells
and got 1946, 1944, 1943 and 1992 mAh, which is not bad going given the
abuse they have suffered i.e. regular high current discharges. Running
them in a Sunwayman M40A on max on a cold night (close to freezing
point) I got 1 hour 5 minutes which is very good and close to the
results achieved by selfbuilt using Eneloops in good condition.
Re😀ononLSDNiMHcellswearoutmorequickly?
Written by
LeifUK on 02-12-2011 04:15 PM GMT
I've just done a break in on some new Panasonic infiniums and I
got: 1959, 1892, 1872, 1959 i.e. two are worse than the 1 year old ones!
Oddly 2 were uncharged, and 2 had about 75% charge.
Re😀ononLSDNiMHcellswearoutmorequickly?
Written by
mdocod on 02-12-2011 08:10 PM GMT
CPF members, myself included, have been recommendingLSD cells for primary use cells over high capacity cells for years now. The long term benefits of having cells that can be trusted to consistently perform as expected far outweighs the initial higher capacity available with non-LSD big cap cells. LSD cells
from reputable brands have consistantly shown to provide a better user
experience, and this is nearly always the case whether the cells
are charged and used frequently OR infrequently. I would say that the
number of useful cycles that people seem to be able to get out of LSD cells is substantially higher than non LSD cells. This has a lot to do with whether or not the user takes the time to properly exercise their non LSD cells. If you do not want to mess with exercising cells to maintain them, and just have cells that charge up and work as expected when you want them, pick LSD cells.
Eric
Re😀ononLSDNiMHcellswearoutmorequickly?
Written by
Battery Guy on 02-13-2011 01:20 PM GMT
One big difference between "traditional"NiMH and LSD NiMH is the composition of the metal hydride alloy. Traditional NiMH cells use metal hydride alloys that contain manganese. As the metal hydride alloy corrodes with time and use, the manganese leaches out
of the alloy and migrates to the separator, where it forms conductive
deposits that eventually lead to internal short circuits and high self
discharge rates. LSD NiMH cells do not use manganese in the alloy, so they are not susceptible to this failure mode.
Cheers,
BG
