A total of 4 4pack duracell aaa ion core 850mah were purchased a few years back. Thought would go the poor man's eneloop route. 2 packs went to use, 2 into freezer. The 2 packs (8 aaa's) used were powering a sansa slotmusic mp3 player on a regular basis throughout the years. The 8 batteries were rotated with the said player and I would say I had to recharge all 8 every 2 weeks or so. Usage pattern: full charge discharge cycles. Again I didn't keep track of time but it feels like I got at least 2 years out of them. All 8 died simultaneously. At first I was using the panasonic bq-cc17 charger. After only a few cycles the charger didn't want to charge the batteries (most likely internal resistance check problem). That was a surprise, so I had to resort to what else I had, the energizer chvc2 charger. The chvc2 is a dumb charger and charges aaa's at the rate of 90ma, so the timer was used to charge for 11-12 hours. The batteries were never hot to the touch while charging and it felt like I was still getting the same number of hours with my mp3 player. Eventually the batteries weakened to the point where they didn't turn the player on any more. I ran some discharge tests with my hobby charger from full to .1v with the current of 100ma. The batteries still retain 600+mah of capacity. However when the discharging starts, the voltage drops significantly under 1v right away. As the discharging progresses the voltage rises a little (not over 1v) and goes steadly from there. Based on this observation, I've tried a fully charged battery in a flashlight for under a minute. The flashlight would light up and stay lit, no problem there. Then I would take that battery out of the light and insert into the player. The player would turn on and start working normal. Yeah, that's neat but I won't be doing that just to listen to my player again, the batts are obviously dead. This is my first long run experience with the nimh and I'm not sure what it says about the quality of these batts. I still have 2 more packs which were in the freezer. They have the serial numbers but I don't know how to convert those to the manufacture date. All I can find on the packaging is the year 2014 next to the copyright symbol. Also the packaging says made in Japan, guaranteed to last 5 years and recharge up to 400x. What do you guys think?
duracell aaa ion core 850mah (duraloop) didn't last long or did they
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LittleBill
Newly Enlightened
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i think you should stop using a dumb charger.
Do you think it was constantly overcharging them and that eventually killed them? 1 other thing to add is i was carrying the batteries in a cheap chinese plastic holder which was not a secure fit and the batteries were always rattling inside it
With such a simple article, it makes no sense to philosophize about the exact year of manufacture.
Just use it and try to treat it as gently as possible. That saves the most money.
For rechargeable batteries that already have an increased internal resistance, I also go sometimes a little deeper (0.8 - 0.9 V).
600mAh after the capacity measurement shows, that the cell is already largely consumed.
You can still use it, but the aging symptoms will progress rapidly.
In general, NiMH batteries are far less robust than the NiCds were.
If you want a comparison for the quality, just get a set of the white Eneloops and use them alternately to the pack from the fridge.
Just use it and try to treat it as gently as possible. That saves the most money.
If rechargeable batteries become empty again and again during continuous use, it is not necessary to carry out a discharge charging cycle.
0.1V discharge voltage at 100mA is far too low. This will damage the batteries. The recommended discharge end voltage for NiMh is 1.0V.
For rechargeable batteries that already have an increased internal resistance, I also go sometimes a little deeper (0.8 - 0.9 V).
600mAh after the capacity measurement shows, that the cell is already largely consumed.
You can still use it, but the aging symptoms will progress rapidly.
In general, NiMH batteries are far less robust than the NiCds were.
If you want a comparison for the quality, just get a set of the white Eneloops and use them alternately to the pack from the fridge.
WalkIntoTheLight
Flashlight Enthusiast
If the BQCC-17 charger was rejecting your cells after only a few cycles, that indicates they developed high internal resistance. That should not happen with good cells after just a few cycles. Eneloops give over a hundred cycles before that happens, the regulars about 300 full cycles. You can look up AA Cyclers tests for that.
If this is typical of Duraloops, they're crap.
If this is typical of Duraloops, they're crap.
Thanks so much to all who replied. Yea, just trying to learn from own mistakes before opening the next pack of nimh's for this. Trying to do the right thing for the planet and all. What i meant to say is, yes, although the batteries were becoming empty again and again, the discharge operation was carried out exclusively for showing the current capacity. I was not doing such discharges regularly and at this point anyway the batteries are only good for flashlight, remote control, very low drain use. .1v may be a little low, however presently the batteries are in such a condition, where they give off 600+mah under the 100ma load at only .6-.7v steadily. The voltage drops immediately under 1v (and under .8v too) after the load is applied to a fully charged battery. At this point it was more of experimenting than preserving the remaining life. I agree, the bqcc-17 story shows the cells were crap to begin with. But i got the most out of them anyway. Maybe i shouldn't have used a dumb charger for this afterwards. Have read about how trickle charging nimh's at .1c reverses polarity and how nimh's allowed .05c trickle charge at most. My dumb charger was most likely overcharging the 850mah cells with 90ma every time for couple hours, especially given the reduced capacity state. I think for this i will go the non-lsd route and a simple slow peak detect charger with no internal resistance check
WalkIntoTheLight
Flashlight Enthusiast
Once NiMH cells develop high internal resistance, your best bet is to use a slow dumb-charger. Yes, you'll probably over-charge them, but so what? They're crap cells anyway.
I have some old NiMH cells I use in low-discharge LED lights. Some I built myself with 5mm LEDs and resistors. They only use 20mA. Even old crap cells can power that easily. I have to use a dumb charger to recharge them, which is fine.
Eventually, they wear down to the point they can't hold a charge at all. But there's plenty of life between "crap" and "dead", as long as you don't need high discharge.
I have some old NiMH cells I use in low-discharge LED lights. Some I built myself with 5mm LEDs and resistors. They only use 20mA. Even old crap cells can power that easily. I have to use a dumb charger to recharge them, which is fine.
Eventually, they wear down to the point they can't hold a charge at all. But there's plenty of life between "crap" and "dead", as long as you don't need high discharge.
After all, the cells are made in Japan, i'm still inclined to think i mistreated them. The thing is the cells were subject to frequent shock and vibration. I used and carried them mostly on my weekly bicycle rides. The bike is fully rigid (no shocks). The batteries were carried in a cheap holder in which they rattle just from walking around with it. All batteries have distinct wear marks on their wrappers where they were touching the holder. I tried googling the effects of vibration on nimh cells but didn't find much info. I mean non-lsd cells are more robust in some aspects, isn't that true?
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WalkIntoTheLight
Flashlight Enthusiast
All of the testing I've seen on Eneloops has been about charging and discharging methods. Things like trickle-charging, number of charges, cycle depth, etc. I haven't seen anything on physical vibration testing. I suppose it's possible they can age prematurely from that, but I haven't seen any evidence of it one way or the other.
I know from my own anecdotal experience (which I know isn't scientific), that Eneloops survive quite well from frequent drops. I'm clumsy when replacing cells.
My guess is that the jelly-roll structure inside the cell isn't too susceptible to occasional bumps, but that's not the same thing as constant vibration.
Shock/vibration can kill them, as can over discharging - NiMHs are dead when they hit 1.2V and they should be recharged as soon as possible to prevent damage. You don't need to fully drain NiMHs, you can charge them at any time. Dumb chargers will also kill them but this usually takes some time (though it sounds like your cells were done in by the time your eneloop smart charger rejected them). Eneloops stand up well to abuse but they are not indestructible.
WalkIntoTheLight, you're spot on, constant vibration is exactly what the cells were exposed to. I've now cut a piece of foam for the holder to rid some out. I still have conflicting thoughts as of whether discharging a single cell with 100ma to .1v is a bad idea. I've read number of threads where ppl generally say it's bad, but then others say that .1v is ok for a single cell, just not ok for a pack. I understand why it's generally bad for a pack. But is it really bad for a single cell if you're not going to leave it neglected in this state? Or is it because 100ma is still high a current for a small cell? I mean like it's been mentioned in this thread, small lights discharge with 20ma which means even deeper discharge state for a cell, does it not?
Thanks for your input. In the given application, namely mp3 player, the player is mostly responsible for discharging the batteries. It's not some china noname brand player, so i pretty much trust their (sansa/sandisk) power management. Again, the batteries were discharged to .1v in a hobby charger only a handful times. I've also taken a battery out of the player, which the player deemed empty and into the hobby charger, ran the discharge test to .1v just to see how well the player empties the batteries. The charger would still squeeze out some 30+mah, so i think the player was not deep discharging those cells regularly
WalkIntoTheLight
Flashlight Enthusiast
It's not good, but it's not going to kill a cell if you just do it a few times. I frequently over-discharge Eneloops, and I don't notice any damage. I've even reverse-charged a couple of cells down to -0.6v (IIRC), due to an over-discharge in a 4-cell device. I had to recover it by forcing current into it with a dumb charger for awhile (obviously a smart charger thought it was inserted upside-down). After that, it charged fine, and capacity measurements are consistent with all the other cells of that age.
You've got hundreds of cycles in Eneloops. Over-discharging may kill off a few cycles... who cares?
Ok, so i now have purchased some cheapest nimh aaa's i could find (performax solar lighting 800mah made in china). Out the box all cells came with approximately same resting voltage, no surprises there. I took 1 cell to check the remaining charge by running a discharge test. Base on the suggestions from this thread i decided to no longer run down any cells down to .1v, so out the box, at 100ma i actually had to run down the chinese cell to .9v to make it give off the most remaing juice. The cell gave off ~500mah which makes me think the cells are lsd (the packaging didn't spec on that). Lsd cells do make sense in solar lights. I then tried charging the cell in the bq-cc17: the charger refuses to charge a brand new cell ! My observations so far suggest that these are some special nimh cells somehow designed to run at a lower voltage for solar lights? The intended application suggestion also makes me think that the cells are possibly more robust to overdischarges. This is important because i now think that my player actually does overdischarge cells. The theory is that it is designed to fully drain regular alkalines. To support this theory i ran down a brand new performax cell to .8v at 100ma and tried it in the player. The player would run on it for additional ~30mins before telling me it's empty. Conclusion: the duraloops may have been overdischarged regularly
WalkIntoTheLight
Flashlight Enthusiast
Actually, LSD is rather pointless in solar lights. The lights are charged every day, so LSD certainly isn't needed. The cells you bought may be LSD, or they may just be fairly new. Even non-LSD cells will last a few months without charging.
That said, it would be odd for them to pre-charge non-LSD cells, so they may be LSD.
I'm starting to suspect your BQ-CC17 may not be operating properly. It shouldn't be that sensitive.
Nothing to do with voltage. NiMH all have pretty-much the same voltage characteristics.
Yes, for sure solar light batteries should be tolerant of over-discharging.
Okay, that might explain some of why they died early.
Next, I suggest getting a new smart-charger. Yours seems like it's not working right. I have three BQ-CC17 chargers, and they all work fantastic, even with non-Eneloops. It's only really old cells with high internal resistance that they reject.
WalkIntoTheLight, see, my friend, there's definitely something funky about these brand new performax cells. I remember when i ran a discharge test on a back then (fairly) good duraloop, my hobby charger would show ~1.2v for the most discharge process. With this cell, out the box it gave off the ~500mah within the 1v down to .9v range. Not 1.2v as is typical with nimh. Not even 1.1v. When i hit the start button, the voltage would immediately drop to 1v, as if it was a high internal resistance cell. Yet the packaging says (c) 2019, and these are brand new! Given they were the cheapest, they may be crap out the box. But my player loves them so far. But now i'm running a discharge test on the fully (i think) charged performax cell, and i'm presently showing 1.14v at 100ma with 230mah already taken out of it. It's still under 1.2v but much better than the 1v i saw before. Could it be due to the mythical charge forming process i've heard about before? Also the question i have is, how long do i have before i really really need to charge an overdischarged cell? I understand the answer would be asap but i guess i want to know whether i have hours, days or weeks before the real damage kicks in
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WalkIntoTheLight
Flashlight Enthusiast
They're meant for solar lights, so yeah, they're obviously meant to be used only in low-drain applications. Your discharge test is putting a high load on them, and it's causing voltage sag. That's why you're seeing lower operating voltage from them.
I suppose it's possible that even when new, those things already have very high internal resistance. Because they're only meant to low-drain solar lights, the high IR doesn't matter much. Unfortunately, maybe your charger is okay, but sees the high IR and rejects them. Strange, but I guess if these are super-cheap cells, they could be crap even when new.
Your player is low-drain, so these cells are probably okay with it. I wouldn't use them in a flashlight, though.
I suppose it's possible that even when new, those things already have very high internal resistance. Because they're only meant to low-drain solar lights, the high IR doesn't matter much. Unfortunately, maybe your charger is okay, but sees the high IR and rejects them. Strange, but I guess if these are super-cheap cells, they could be crap even when new.
Your player is low-drain, so these cells are probably okay with it. I wouldn't use them in a flashlight, though.
WalkIntoTheLight, exactly my thoughts. Just found an ancient panasonic aa cell which would charge fine in the same bq-cc17, so the charger isn't likely the problem. I'm now very confident that it's mostly the constant overdischarging by the player that's responsible for the duraloops to fail early. I guess i'll be sticking with the cheap solar rechargeables from now on and find a better use for those brand new duraloops i still have. The chinese cells won't likely last the 2+ years that duraloops did but the possible overdischarge tolerance makes me curious. Time will tell
Since my last post, i have an update for the curious. I am able to use the old duraloops in my player again. I experimented reducing the time to charge those crap cells with my dumb charger, so now they power my player again and deliver a decent number of play hours. Basically i found out the hard way that overcharging a nimh cell reverses its polarity. Reversed polarity means lower operating voltage to begin with. The lower operating voltage in my case was low enough to not power my low drain player. I found out that charging the cells in my case for 8 hours instead of 11 fixes the reversed polarity issue. The lesson is, when using a dumb charger it's important to take the reduced capacity into the account. Also, I've been measuring the resting voltage after a cell has been discharged by the player, the voltage was never below 1.2v, meaning the player was not overdischarging those cells regularly. Since overdischarging was not likely, it leaves constant vibration and overcharging as the primary causes for the duraloop early failure
WalkIntoTheLight
Flashlight Enthusiast
Overcharging a NiMH cell (or any kind of chemistry) does not reverse its polarity. That only happens during discharge, when you have more than one cell in series, and the cells are not properly matched to capacity.
Charging less time, if you don't need the extra time for a full charge, is a good thing to do. However, it won't result in higher overall capacity for that specific charge cycle. It will help with the health of the battery in the future, but charging 11 hours (if only 8 is needed), is still going to result in a 100% full battery. It's just going to do some long-term damage, which might show up in a few dozen cycles if you keeping doing that.
Something else is causing your result. Maybe your charger is messed up, and draining your cells after 8 hours.
Charging less time, if you don't need the extra time for a full charge, is a good thing to do. However, it won't result in higher overall capacity for that specific charge cycle. It will help with the health of the battery in the future, but charging 11 hours (if only 8 is needed), is still going to result in a 100% full battery. It's just going to do some long-term damage, which might show up in a few dozen cycles if you keeping doing that.
Something else is causing your result. Maybe your charger is messed up, and draining your cells after 8 hours.
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