Interesting... but not recommended...

Children often forget to turn off their battery operated toys. Sometimes they will go
back to play with the same toy again, but often they just move on to the next
adventure.

I always recommend trying to train everyone, including children, in the proper use and
care of rechargeable batteries, but some are more receptive to the information than
others...

I like Eneloop cells. They do everything a rechargeable cell should do and seem to
handle a fair amount of abuse also. My toys, oops, I mean my grandchildren's toys ,
are all powered by Eneloop cells. Most of my cell testing has to do with performance,
but this time I ventured into the "dark side" - abuse testing.

From here on, the story gets a little abusive, so kids and sensitive people should
probably tune out... :devil:








Still with me...?

OK, how many times has it been mentioned that it is not the best practice to over
discharge cells? Yes, lots and lots is a very large number.

Still, I run into people that don't want to use excellent cells in their toys, or their
children's toys because they fear over discharging them, and ruining them.

I grabbed an Eneloop cell that I had purchased some 3 years ago and have been
abusing it by not using it.

I ran a discharge at 500 mA to see if there was anything left in it, and it came in at
1250 mAh on the C9000. Not too bad, about 64% capacity left after 3 years of storage,
and these cells weren't completely charged to start with. I believe they started at
around 75% of full charge.

The next step was to do a Break-In cycle. The cell came in at 1925 mAh.

I then put the cell in a light and drained it. I left it in the light overnight and over
discharged it. I then took a piece of foil and clamped the cell with the positive and
negative terminals in a direct short.

Two days later, I took the cell out of the clamp. The voltage rebounded to 0.1 volts.

Please note that I am working with a single cell and there is no opportunity for reverse
charge. If I can bring myself to do it... I may drag out another cell and repeat this
with a pair of cells.

At any rate the C9000 accepted the cell for charging without problems. I did another
Break-In cycle and the capacity came in at 1939 mAh.

Wow, a slight increase in capacity in spite of being discharged overnight and shorted
out for an additional two days.

I asked my grandchildren how long they would "loose" toys trying to figure out where in
the spectrum of things two or three days fit in. They assured me that most of their toys
would be played with in two or three days, but there may be some that could possibly
get "lost" and go a little longer. Mom nodded in agreement, but thought that a week or
two may be more realistic.

The next step was to once again drain the cell in the light overnight. I then shorted it
out with my clamp and foil set up and left it for 5 days.

When I removed the cell from the clamp, the voltage rebounded to 0.008 volts. Once
again the C9000 had no problems initiating a charge on the cell, however, once again I
ran a Break-In cycle on the cell. This time the capacity came in at 1943 mAh. Wow,
once again a slight increase in capacity.

The point of this exercise is that as long as the cell is not reverse charged, it seems to
handle over discharging with ease. At least with a high quality cell and with the cell
being totally shorted out for 5 days. Even in multicell applications, when Eneloop cells
are being used, they should be well balanced and there should only be a very remote
chance of cell reversal.

At any rate, if you go around and make sure the toys are shut off every 5 days, your
cells should survive.

There is more...

Anticipating that some parents have very busy schedules, and checking the status of
toys every 5 days would just be too much effort, I decided to do another test.

This time I discharged the cell in the light overnight, then shorted it out and clamped it
and this time I left it for 14 days.

When I removed the cell from the clamp the voltage rebounded slowly to 0.002 volts.

The C9000 had no problem recognizing it and I got an IR reading of 1.56. I ran
another Break-In cycle and the capacity came in at 1946 mAh. Another slight increase.

I can't believe that shorting a NiMh cell is good for it, but it looks like it isn't too hard on
it either. Wondering if the low self discharge capability was effected I let the cell sit for
a little over 2 weeks, then ran a 500 mA discharge on it. It came in at 1746 mAh.

Many people save their crap cells to use with toys. The justification is that the cells are
already crap so over discharging won't hurt them too much. I think that care for toys
should be part of the experience of playing with powered toys, and I also think that
crap cells should be recycled. Quality cells work much better in toys, and I think that
children begin to understand that their toys last much longer because of the quality
cells that are being used.

This round of abuse testing seems to indicate that even if the toy is left on and
forgotten for two weeks the cell still has a chance to recover.

In the spirit of full disclosure... I will mention that this round of testing was sponsored
by the influential chairman of "CSOCC."

That would be ME :devil:

Tom
Chairman of the Coalition to Stop Out Crap Cells (CSOCC)

:thumbsup:

Any information on what happens in multi-cell toys?

This is very interesting. I wonder what (if any) difference you would see with other brands of cells. I am particularly interested in the Titanium Brand of LSDs.

Hi Tom,

check "Guideline n. 1" on Ni-CD batteries at NASA:

http://www.nasa.gov/offices/oce/llis/0644.html

This is half-true with traditional Ni-MH, and is invariant for Ni-MH LSD. As long as you don't reverse charge them, LSD batteries should report no damage from "clamped" storage. In traditional Ni-MH (not LSD) the decay of the lattice alloy continues in any case, accelerated from temperature and overcharge.

The little capacity increase you measured is because you exercise the deeper layers of the nickel positive electrode with a 100% discharge.

I fully agree and endorse the findings and implementation of your egregious committee on the ban of "crap" NiMh cells.
My un-based feelings tell me that the "big boys" may want to start selling more down-to-earth, reasonable but lower capacity Ni-MH batteries, and then make a blanket replacement with LSD batteries.
It would be the greenest move of all times in the battery world, which would reduce drastically the number of "crap" rechargeable batteries around. Provided that they can convince people to keep the batteries away from the chargers, after decades they have been saying the opposite.

Regards

Anthony

Why not do the clamp and foil set up whilst fully charged..

Just kidding, great test and information, gotta love those eneloops.

Brian

Hello Egsise,

As soon as I can convince my grandson that he needs to loan me one of his toys for some testing I will try some actual testing with a multi cell toy.

My thought is that the Eneloop cells are very close in capacity, so if they are charged in an independent channel charger, there should be little chance of reverse charging.

How this works out in real life... who knows?

Tom

Hello Crizyal,

I have no idea how other brands will perform, but if your guard against reverse charging during the discharge, they should be similar.

Try some and report back what happens.

Tom

Hello Anthony,

That Guideline is what gave me the courage to try this...

Do you have any idea what "long term" shorting (like months or years) would do to both NiMh and LSD chemistry?

Welcome to the CSOCC group.

Tom

I do not have the analyzing charger as you do and my results would be difficult to document. Might need to invest in yet one more battery charger... My wife can't figure out WTH I am doing with all of those chargers.

Tom,

atomic hydrogen is stored in the "interstices" of the lattice alloy very tightly; this happens because the spatial charge distribution of the hydrogen atom, which is complementary to those of the reticule constituting the alloy.

Storing the Ni-MH battery in a clamped state leaves the alloy "reticule" empty.
There should be no difference in theory, in the sense the alloy shouldn't degrade faster if left empty. Practically, based on the design of the alloy which varies by battery brand, the hydrogen may well concur, on the long term, to keep the stability of the lattice structure.

In traditional Ni-MH batteries (those with cobalt and manganese in the alloy at the negative electrode - and no yttrium in the positive nickel electrode) the degradation of the alloy, especially in those with "high capacity", proceeds so fast that I doubt the lack of hydrogen may count as a significative factor of degradation.

In good LSD batteries, where useful lifetime can be a couple of decades or more, the lack of hydrogen in the alloy may favour a possible collapse of the reticule, by enhancing the effect of impurities in the long term.

In both non-LSD and LSD types, I don't see, at least theoretically, any negative effect on the positive electrode nor on the electrolyte - by clamped storage.

Now talking as flashaholic... I don't see the need to store LSD batteries in a shorted state, and I have already thrown away all non LSD ones. LSD batteries are a major - yet unnoticed - technological breakthrough, which I'm fully enjoying after the past nightmares with rechargeable batteries - of which, clamped storage makes me reminiscent...
...but. For the love of knowledge, and to better understand what happens to batteries left in toys turned on, I will discharge and then short circuit one LSD cell with known parameters, and we will check back here in six months time...

Anthony

Tom, my many thanks for doing this testing - not only useful data but well written also! This gives me great confidence in running single AA lights completely flat (or at least not worrying if I seem to be overusing them).

A while back I left a multi-cell caving headlamp on after a trip and when I found it many days later there was no sign of light at all. I vaguely recall cell voltages in the 0-0.4 V range. But I have no idea which cells they were as there wasn't any noticeable difference in performance. I strongly suspect you're right about them being fine if they have an equal charge to start with.

I have also got rid of all my non-LSD cells ... To be more accurate , I gave them to my Son-in-Law , as the Grandchildren get through a lot of batteries ... I also gave him three chargers as well , as I did have too many.

The other day , I was talking to him about LSD cells and he didn't know much about them ... After a few minutes , he asked me which were the best ... I said that my Eneloops were as good as any others , though I still use the GP Recyko cells and Hybrios ... Anyway , he has now sent off for eight AA Eneloops and has said that he will buy a few more each month plus a few AAAs as well.

I think that eventually most manufacturers will gradually cease production of non-LSD cells and as far as I am concerned it can't be too soon ... I used to top up my batteries every month or so ... Now I do it a couple of times per year ... I might have to consider discharging them fully at least once a year ... Perhaps I will make up a multi-cell discharge box with five ohm resistors ... The AA Eneloops should discharge overnight in 8 or 9 hours ... If I left them on for 12 hours , that should be OK.
.

SilverFox said:

This round of abuse testing seems to indicate that even if the toy is left on and
forgotten for two weeks the cell still has a chance to recover.

Click to expand...

Wow! While I was aware that eneloops are probably the best of the LSD cells, and LSD cells in general are much more resistant to abuse, I had no idea that a cell could hold up to that much abuse, and survive. Amazing results. oo:

I'd be curious to know if this cell has different discharge characteristics after being subjected to this torture test. The fact that the Maha seems to accept it and shows a very reasonable voltage during the impedance check, seems to indicate that the cell remains, more or less normal.

It would be interesting to do a discharge on the Maha to see if the voltage during discharge was "normal", or if the cell is suffering from voltage depression, however all indications point to this likely, not being the case.

What I'm wondering about, is how this cell would perform in a series application with other cells. I have some cells that are not in dedicated groups of 2, or 4 that I use for random applications, such as single cell lights. Occasionally cells from this random group are used in series applications of 3-8 cells. These applications don't rate a dedicated set of cells because of their infrequent use. I just wonder how mistreating some of the members of this group this severely, would affect others in the group in the long run. :thinking: Of course, this group does get analyzed once in a while, and relabeled according to capacity. The voltage under load is frequently ignored however, as they usually seem to be about the same.

Dave

Great thread, SilverFox !

:thumbsup:



Gives me even MORE respect & admiration for Sanyo Eneloops.

lovecpf
_

Superb story, and very useful to know! Many thanks, Tom

Very interesting results.

I'm really impressed with how resilient that Eneloop is.

One thing I am curious about....what will this level of abuse do to the cells LSD capabilities?

I don't plan on brutalizing my Enloops & Duraloops like that but I do happen to have a ROV Hybrid AA cell that was overdischarged a few months ago in a Wii remote.

I charged it up as soon as I found it and set it aside for a self-discharge test. I think I did a R&A on the cell and noted that the capacity had dropped a bit from previous results for that particular cell.

This weekend I'll be discharging it to see if the self-discharge rate has increased as a result of being over discharged.

Even if it is, the results from that test likely can't be applied across the board, due to differences in the components used for the various brands LSD cells.

:thumbsup:

Thank you for the testing and information!

Hello DM51,

Keep in mind that this is still experimental. Before we jump into this with both feet, I think it would be prudent to do more testing.

I was expecting some loss in capacity, and am surprised at the results - so far.

However, if further testing bears this out, we can drop the concern of over discharging and focus on reverse charging. It is also important to remember that Eneloop cells are very robust. Until we have similar data from other brands, I think caution should be exercised.

Tom

Hello Black Rose,

I didn't see any drastic change in the LSD performance over a couple of weeks. Anthony (Ray of Light) is going to short a cell out for 6 months and see what happens. That should shed more light on this.

Tom