# All my eneloop XX 2500 mAh batteries dropping like flies



## gooseman (Aug 9, 2015)

In March 2014 I purchased a pack of 8 new eneloop XXs (4HR‐3UWX) from "large online retailer" (before Panasonic rebranding).

I have been using my Maha MH-C9000 to charge them at 1000ma for the past 16 months. I use all 8 batteries and then recharge them, so they are getting even wear.

Within the last week, my C9000 reported 'High' on 4 batteries. I estimate they have been charged only 60-70 times (they should handle 500 charges). The ones that are still "OK" are looking pretty tired in my flashlight fresh off the charger.

I tried C9000's "Refresh Analyze" - and as last resort "Break in", both to no avail (unit says "High" for failed batteries, ~1850-1900mAH for surviving ones).

Is it possible I charged them too quickly @1000mA? Thats less than 0.5C so I thought it would be OK. But the Panasonic BQ-CC17 charges at 300mA.

Thanks


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## Stefano (Aug 9, 2015)

In theory the Eneloop can be charged up to 2C (1C = battery capacity)
Example: The Eneloop white may be loaded up to 2000 mA.
The charger MQR06 (now no more in production) loads on a single AA battery to the speed of 1680 mA - 2 Eneloop AA at a speed of 1100 mA (inserted in "Quick" external slots)
I exclude that your charger has did any damage to your battery charging at 1000 mA


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## Mr Floppy (Aug 9, 2015)

check out power me ups thread about cycle testing of these. You may get your answer to why the cycles are lower than expected.


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## StorminMatt (Aug 9, 2015)

Stefano said:


> In theory the Eneloop can be charged up to 2C (1C = battery capacity)
> Example: The Eneloop white may be loaded up to 2000 mA.



2000mA is 1C for an Eneloop 2000.


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## KeepingItLight (Aug 9, 2015)

Mr Floppy said:


> check out Power Me Up's thread about cycle testing of these. You may get your answer to why the cycles are lower than expected.




*Japanese Vs Chinese Eneloop Cycle Testing Results*

http://www.candlepowerforums.com/vb...nese-Vs-Chinese-Eneloop-Cycle-Testing-Results


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## Mr Floppy (Aug 9, 2015)

Actually, was thinking of this thread 
Eneloop XX Vs Turnigy 2400 Cycle Testing https://www.candlepowerforums.com/threads/391756


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## Stefano (Aug 9, 2015)

StorminMatt said:


> 2000mA is 1C for an Eneloop 2000.



Yes is correct, excuse error


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## MidnightDistortions (Aug 9, 2015)

What was the resting voltage when you regularly charge them? They most likely have high IR but you may want to refresh them with a different charger or try to fully discharge them in one of your lights. Try to get the resting voltage at 1.2 volts or at the very least discharge them to 0.9 volts in your light.


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## Kurt_Woloch (Aug 9, 2015)

Are you completely draining the batteries each time or do you only partly discharge them? 500 cycles is the rating for around 60% depth of discharge at 0.2 C. If you discharge them completely every time the cycle life will probably be much lower... have been tested at around 150 cycles in this case. However, it puzzles me that you still only get half of that.


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## KeepingItLight (Aug 9, 2015)

Mr Floppy said:


> Actually, was thinking of this thread
> Eneloop XX Vs Turnigy 2400 Cycle Testing https://www.candlepowerforums.com/threads/391756




Fascinating read. I bookmarked it. Although I read a lot of it, I did not make it to the end.

What is the bottom line in the analysis made by Power Me Up? Does he say that internal resistance builds up faster in the Eneloop Pros in some circumstances compared to others?


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## Power Me Up (Aug 10, 2015)

In the testing that I've done - that others have already pointed to, I found that the cycle life of the Eneloop XX cells was nowhere near as good as the regular Eneloop cells. The results that I've obtained are only directly applicable to the testing method that I used, but I would be surprised if you could find a usage scenario under which the Eneloop XX cells performed anywhere nearly as well as regular Eneloops when it comes to cycle life.

I don't think that charging them at 1000 mA on the C9000 would likely cause a (significant) reduction in cycle life - the 100 mA top off for 2 hours might cause a little degradation, but I think that if the cells were being deeply discharged, that's much more likely to be the cause of them developing high internal resistance so quickly.


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## WalkIntoTheLight (Aug 10, 2015)

Power Me Up said:


> I think that if the cells were being deeply discharged, that's much more likely to be the cause of them developing high internal resistance so quickly.



What do you consider deeply discharged? IIRC, you do your discharge tests down to 0.9v. I'm assuming you don't consider that a deep discharge? Or do you? Most of my flashlights cut out at around 0.8v or 0.9v per cell, so do you think that is causing damage to standard Eneloops? (I haven't noticed any, but I don't have a thousand cycles on them either.)

I may be misremembering some of your posts, but I thought you busted the conventional thinking that a full discharge was bad?

I know that discharging so low in a multi-cell circuit that you cause reverse-charging is definitely bad. Is that what you mean about deep-discharging causing high IR?


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## TinderBox (UK) (Aug 10, 2015)

Is this not the C9000 being too fussy, and if the OP did not have one, he would have most likely not have had a problem with them, Has he had any reduction in runtime, or noticed any unusual self-discharge issues.

I would give Panasonic or Maha an email and see what they say about the HIGH reading on cells with less than 100 cycles.

John.


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## WalkIntoTheLight (Aug 10, 2015)

TinderBox (UK) said:


> Is this not the C9000 being too fussy, and if the OP did not have one, he would have most likely not have had a problem with them, Has he had any reduction in runtime, or noticed any unusual self-discharge issues.



He did say that on the ones he can still charge, they only have about 1850-1900mAh on them. So, they've lost over 25% capacity. However, we don't know what discharge rate he used for testing. If they're developing high IR, then a fast discharge will definitely show a huge drop in capacity.

Whatever the case, unless his C9000 is malfunctioning, the batteries definitely look like they're slowly failing.


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## ChrisGarrett (Aug 10, 2015)

As I've stated before, I bought 8 Sanyo 2700s in 2/12 and all eight of them have >2.00v IR on my Maha. Four of them are up above 2.60v, so they're about to be retired, since it's getting to be a pain coaxing them into CHARGE. With the one quad, I can insert/charge/remove them a half dozen times and bring the IR down to 2.10v and get them to cycle.

If I have 100 cycles on them in my Marantz RC5000/Pronto remote and wireless RF keyboard, I'd be surprised.

I've always charged them up at 1A.

Now, I just ran a Refresh/Analyze on my 8 Duracell Ion Core 2400 Duraloops and after about 18-20 months of very minor use, they tested in as a group at an average of 2360mAh with an extreme spread of 45mAh, so pretty close.

Those 8, out of their packs averaged 2470mAh with an ES of 70mAh, so a loss of ~4.5%. IRs on the refresh/analyze cycle were ~1.50v, so they're in pretty good shape after ~20 months.

I also bought 12 Duraloop 2000mAh Gen.2 AAs in August of 2013 and 8 of the 12 that I have sound measurements on, averaged 1973mAh with an ES of 43mAh. After ~23 months, those 12 batteries measured an average of 1872mAh with an ES of 55. The 8 that I accurately measured when new, averaged 1877mAh with an ES of 45mAh.

That's an average loss of 4.9% after almost 2 full years of mostly sitting unused. IRs are in the 1.55v range, so they're holding up.

Chris


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## swan (Aug 10, 2015)

I bought 16 x aa eneloops and 4 pack of xx back in 2013, about a year ago i noticed the xx,s would struggle to run my nitecore ea4 in turbo, with the ui switch flashing[50% battery] in protest hot off the charger. The normal eneloops are still like new and wont invoke a ui battery indication flash until 5.2volts.
About a month ago they would only go up to medium level on the ea4 and now finally they wont charge at all.
So for me even though it is only one set of xx,s [12 x charges max] i have sampled, i think i will stay with the normal eneloop 2000mah japanese made cell.
It s funny i guess, i am going to bin them but its kinda hard to admit they are done.


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## MidnightDistortions (Aug 10, 2015)

What are the manufacture dates on these cells? Seems odd the Eneloop XX's are only lasting 2-3 years when Duraloops are guaranteed to last 5 years. Are these the ones from Sanyo or Panasonic?


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## swan (Aug 11, 2015)

MidnightDistortions said:


> What are the manufacture dates on these cells? Seems odd the Eneloop XX's are only lasting 2-3 years when Duraloops are guaranteed to last 5 years. Are these the ones from Sanyo or Panasonic?


My ones are Sanyo HR3UWXA min 2400 mah- date code 12-02A T. My wrappers started to peel along the seem also. As i wrote before, these would of had 12 charges max [prob less] and charged with the same charger as my normal eneloops [prob 30+ recharges] which all look and perform as new. Any one else have XX,s crap out?


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## Power Me Up (Aug 11, 2015)

WalkIntoTheLight said:


> What do you consider deeply discharged? IIRC, you do your discharge tests down to 0.9v. I'm assuming you don't consider that a deep discharge? Or do you? Most of my flashlights cut out at around 0.8v or 0.9v per cell, so do you think that is causing damage to standard Eneloops? (I haven't noticed any, but I don't have a thousand cycles on them either.)
> 
> I may be misremembering some of your posts, but I thought you busted the conventional thinking that a full discharge was bad?
> 
> I know that discharging so low in a multi-cell circuit that you cause reverse-charging is definitely bad. Is that what you mean about deep-discharging causing high IR?



I'd consider going below 0.9V to be a deep discharge. Having said that, in other testing that I've been doing, the results are indicating that even regularly discharging down to only 0.9V does cumulative damage to the cells - even for regular Eneloops. I've got a pair of Eneloops that I've been discharging down to only 1.1V and they've done a lot more cycles than in any other test that I've run:

http://www.ultrasmartcharger.com/phpBB3/viewtopic.php?f=5&t=91

My recommendation these days is that if you want your cells to last, you should charge them early - before they go completely flat - as long as your charger isn't damaging the cells by overcharging them.


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## WalkIntoTheLight (Aug 11, 2015)

Power Me Up said:


> I'd consider going below 0.9V to be a deep discharge. Having said that, in other testing that I've been doing, the results are indicating that even regularly discharging down to only 0.9V does cumulative damage to the cells - even for regular Eneloops. I've got a pair of Eneloops that I've been discharging down to only 1.1V and they've done a lot more cycles than in any other test that I've run:
> 
> http://www.ultrasmartcharger.com/phpBB3/viewtopic.php?f=5&t=91
> 
> My recommendation these days is that if you want your cells to last, you should charge them early - before they go completely flat - as long as your charger isn't damaging the cells by overcharging them.



Thanks, yeah, that does look like 1.1v discharging is far easier on the cells than the 0.9v discharging you did in your other Eneloop test.


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## MidnightDistortions (Aug 11, 2015)

swan said:


> My ones are Sanyo HR3UWXA min 2400 mah- date code 12-02A T. My wrappers started to peel along the seem also. As i wrote before, these would of had 12 charges max [prob less] and charged with the same charger as my normal eneloops [prob 30+ recharges] which all look and perform as new. Any one else have XX,s crap out?



The only thing i can think of is you had them in a device and they kept discharging past 0.9 volts. In my experience any device that runs the batteries totally flat go bad. They don't always reverse charge but the ones that do won't work anymore. The ones that go flat can eat up a lot of cycles. My suggestion is if you do not have a multimeter to get one and do some testing on those other cells in the device you had them in to check the voltage. Best to back track and redo the tests the best way you remember how you had the cells. If you left them in a device unused, the device may still be draining the cells (normally at a slow enough rate not to be a huge concern) such as a flashlight that will continually drain the cells at a slow rate.



Power Me Up said:


> I'd consider going below 0.9V to be a deep discharge. Having said that, in other testing that I've been doing, the results are indicating that even regularly discharging down to only 0.9V does cumulative damage to the cells - even for regular Eneloops. I've got a pair of Eneloops that I've been discharging down to only 1.1V and they've done a lot more cycles than in any other test that I've run:
> 
> http://www.ultrasmartcharger.com/phpBB3/viewtopic.php?f=5&t=91
> 
> My recommendation these days is that if you want your cells to last, you should charge them early - before they go completely flat - as long as your charger isn't damaging the cells by overcharging them.



If your charger is overcharging the cells, i'd get rid of that charger for one that will not overcharge the cells. Eneloop Pro's doesn't specify how long they hold a charge for 3 years or 5 years. I'm curious if there's any testing done on this. I actually consider anything under 1.1 volts deeply discharged. Usually i'll try to recharge the cells at 1.22-1.26 volts and then refresh them every 6-12 months but sometimes i forget to check the voltage and the cells are around 1 volt and need recharging. It seems especially for the pros it's not a good idea to run them all the way down. I also hear of PowerEx 2700mAh cells only lasting a couple of years, but there are people who say they have been using the cells for 6 years and they still work so i'm guessing that the ones who are still using those cells for 6 years must not use them much or recharge them before they get below 1.1 volts.

Also i am curious as to maybe these cells should not be fully charged (when put into storage) that they should only be partially charged (or partially discharged) to avoid the high IR. I know on traditional HSD NiMH cells leaving those in a charged state without use will increase the IR on them. I've run into some cheap cells that have been fully charged a few times and not put in use that have developed high IR, it might be a good idea to leave them with a 40% charge (or maybe less) when put into storage. I think testing this would help some people out that have Eneloop Pro cells. Regular Eneloops i don't think it will make much of a difference but should not be topped off if they are not being used much. This also makes it more apparent that i wanted to use some AAA to AA adapters on low drain devices where AAA cells would be more beneficial in clocks or other low drain devices as they don't hold as much capacity and the cells are a bit cheaper.

As for using high capacity cells, the experiences i had with them degrading, they'll degrade faster if they were completely discharged past 0.9 volts. The only suggestion i can consider if you absolutely need those cells running is to get a charger other than the c9000 which doesn't completely charge the cells unless you let them sit on there for 2 hours or more past the 'done' stage. On top of that on completely depleted cells a slower charge rate imo is better as you will get a more complete charge because Eneloops are usually charged up to 1.55 volts and i don't think the 2 hour top off is enough for the Pros to be considered fully charged. 1000mA on the C9000 for Eneloop Pros might not be a good idea, i would probably choose 500mA, less if cells were discharged under 0.9 volts. I don't have a set of Eneloop Pros (AA) to effectively test this theory out, i could try the Duraloops out to see how much capacity is lost to a possible premature cutoff. The C9000 appears to charge Eneloops and i'll choose the 1A when the cells are around 1.26 volts but as the voltage is lower, i tend to lower the charge rate as well.


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## Power Me Up (Aug 11, 2015)

MidnightDistortions said:


> I actually consider anything under 1.1 volts deeply discharged.



I suspect that you're referring to the unloaded voltage? If the resting voltage is only 1.1V, I'd agree that the cells has been deeply discharged. In the test that I've done where the cells are being discharged down to 1.1V, that voltage is being measured under load which is quite a different thing to measuring the voltage without a load.



> The C9000 appears to charge Eneloops and i'll choose the 1A when the cells are around 1.26 volts but as the voltage is lower, i tend to lower the charge rate as well.



I'm curious as to why you think that it's necessary to lower the charging voltage when cells are more deeply discharged?


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## MidnightDistortions (Aug 11, 2015)

Power Me Up said:


> I'm curious as to why you think that it's necessary to lower the charging voltage when cells are more deeply discharged?



The C9000 only charges up to 1.47 volts, regular Eneloops seem fine while there might be more capacity within 1.47 volts and 1.55 volts then what the 2 hour top off charge can really do. I'm actually going to run a test on my Duraloops to see if the C9000 undercharges those cells.


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## Power Me Up (Aug 12, 2015)

MidnightDistortions said:


> The C9000 only charges up to 1.47 volts, regular Eneloops seem fine while there might be more capacity within 1.47 volts and 1.55 volts then what the 2 hour top off charge can really do. I'm actually going to run a test on my Duraloops to see if the C9000 undercharges those cells.




Sorry - I don't follow you there. I agree that Eneloops aren't normally full at 1.47V but I don't see the relevance of that to the charging rate needing to be different for different depths of discharge?


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## WalkIntoTheLight (Aug 12, 2015)

Power Me Up said:


> I'd consider going below 0.9V to be a deep discharge. Having said that, in other testing that I've been doing, the results are indicating that even regularly discharging down to only 0.9V does cumulative damage to the cells - even for regular Eneloops. I've got a pair of Eneloops that I've been discharging down to only 1.1V and they've done a lot more cycles than in any other test that I've run:
> 
> http://www.ultrasmartcharger.com/phpBB3/viewtopic.php?f=5&t=91
> 
> My recommendation these days is that if you want your cells to last, you should charge them early - before they go completely flat - as long as your charger isn't damaging the cells by overcharging them.



After looking at your graphs again, how do you know that it's the "deep discharge" that is causing shorter cycle life? In your above graph, you're only discharging to 1.1v, but you're also only charging to 1.44v, which is well below a full charge. Is it possible that charging to full is reducing cycle life, and not the discharge down to 0.9v?


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## MidnightDistortions (Aug 12, 2015)

Power Me Up said:


> Sorry - I don't follow you there. I agree that Eneloops aren't normally full at 1.47V but I don't see the relevance of that to the charging rate needing to be different for different depths of discharge?



If the Eneloops on the C9000 reaches full around 90%, the 2 hour top off charge should fully or near fully charge those Eneloops. My theory is that Eneloop Pros would reach the 2 hour top off point at 85% and wouldn't be able to fully charge the cells at the 2 hour top off. The more current that is used to charge a battery the higher the voltage will be. I've noticed voltage will be slightly higher with depleted cells versus those that have only been partially drained. I could be wrong though but normally even with the regular Eneloops, if i fully discharged them i would just charge them at 500mA to ensure they got a full recharge. If i charge them while there's 30% charge left or more the higher i'll put the charge rate.


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## SilverFox (Aug 12, 2015)

Hello MidnightDistortions,

Since capacity is determined through discharge you can verify your ideas by doing a discharge test.

Charge your cells keeping track of the charging current and if you set a timer for 15 minute intervals you can also note the peak voltage reached during the 2 hour top off charge. Then remove the cell from the charger and let them rest for 2 hours, then do your discharge test.

Tom


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## Power Me Up (Aug 12, 2015)

WalkIntoTheLight said:


> After looking at your graphs again, how do you know that it's the "deep discharge" that is causing shorter cycle life? In your above graph, you're only discharging to 1.1v, but you're also only charging to 1.44v, which is well below a full charge. Is it possible that charging to full is reducing cycle life, and not the discharge down to 0.9v?



From that test alone, it's not possible to say which is causing the cells to last longer. I've got 2 more tests running at the moment - one charging with inflection termination and then discharging down to 1.1V and another charging to 1.44V and discharging to 0.9V - I haven't yet published the results, but so far it looks like both are a factor in increasing the cell life.


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## Power Me Up (Aug 12, 2015)

MidnightDistortions said:


> I've noticed voltage will be slightly higher with depleted cells versus those that have only been partially drained.



I've just had a look through some historical charging data for some of my Eneloops and although I can see variations in the charging end voltage, there doesn't appear to be a direct correlation between depth of discharge and final voltage. In quite a few cases, when cells discharged more, the end voltage was lower, but I also found cases where it was higher. 

I suspect that other factors such as the ambient temperature come into play. 

In the end, I would say that depth of discharge may or may not have an effect on the end voltage - if it does, it doesn't appear to be enough that it overcomes all of the other factors to the point where it consistently causes higher end voltages... With enough testing, it might be possible to show that there is a statistical difference, but in the mean time, I wouldn't be too concerned by it...


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## WalkIntoTheLight (Aug 13, 2015)

Power Me Up said:


> From that test alone, it's not possible to say which is causing the cells to last longer. I've got 2 more tests running at the moment - one charging with inflection termination and then discharging down to 1.1V and another charging to 1.44V and discharging to 0.9V - I haven't yet published the results, but so far it looks like both are a factor in increasing the cell life.



Looking forward to your results.


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## inetdog (Aug 13, 2015)

Are you sure that you are not dealing with counterfeit calls?


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## MidnightDistortions (Aug 13, 2015)

Power Me Up said:


> I've just had a look through some historical charging data for some of my Eneloops and although I can see variations in the charging end voltage, there doesn't appear to be a direct correlation between depth of discharge and final voltage. In quite a few cases, when cells discharged more, the end voltage was lower, but I also found cases where it was higher.
> 
> I suspect that other factors such as the ambient temperature come into play.
> 
> In the end, I would say that depth of discharge may or may not have an effect on the end voltage - if it does, it doesn't appear to be enough that it overcomes all of the other factors to the point where it consistently causes higher end voltages... With enough testing, it might be possible to show that there is a statistical difference, but in the mean time, I wouldn't be too concerned by it...



Yeah it looks like you might be right about the voltage thing...

This is the results from the testing i did. 

1st Charged at 1000mA
1.44 v (IR test - 1.51v)
Discharged at 1000mA
2266 / 2272 / 2295 / 2287


2nd Charged at 1000mA
1.45-1.46 v(IR test - 1.42v)
(2307 / 2400 / 2472 / 2423)


Discharged at 1000mA
2333 / 2338 / 2365 / 2354


3rd Charge at 500mA
1.46 (IR test - 1.45v)
2258 / 2348 / 2420 / 2380


Discharged at 1000mA
2376 / 2384 / 2401 / 2385

I'm not sure if that makes much of a difference from charging at 500mA or at 1000mA, however i did let the cells rest for an hour or two. I averaged out the IR test, they were slightly higher the 3rd time but lower than the initial charge which only added about 300mAh into the cells so they were fairly charged. I bought these cells (Duracell Ion Core, 2400mAh) a year ago and so far they are holding up well. I did also want to mention the ambient temp was about 74F with fans going and the cells never got above 105F. 

I think there is some sort of issue if the Eneloop Pros start dying after a couple of years. Heat might be a factor, even though the C9000 does dissipate heat well.


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## kusitb (May 27, 2018)

Hi @KeepingItLight,

Do you happen to have the same test for the Ikea LADDA 2450?

https://www.ikea.com/ca/en/catalog/products/70303876/

TIA,

kusitb


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## marcosg (May 30, 2018)

gooseman said:


> In March 2014 I purchased a pack of 8 new eneloop XXs (4HR‐3UWX) from "large online retailer" (before Panasonic rebranding).
> 
> I have been using my Maha MH-C9000 to charge them at 1000ma for the past 16 months. I use all 8 batteries and then recharge them, so they are getting even wear.
> 
> ...



My Eneloops XX are also doing the same thing. Purchased them about 2 years ago (2 packs of 8) and they probably have about 100 to 120 cycles.
They are the original ones from Japan and I also use the C9000 at the same rate as you.
Only the Lacrosse BC1000 and the Opus BT-2000 will charger them.
The Maha C9000 and the Panasonic chargers won't charge them. I have no problems with my regular Eneloops that I purchased years before.


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## ChrisGarrett (Jun 3, 2018)

marcosg said:


> My Eneloops XX are also doing the same thing. Purchased them about 2 years ago (2 packs of 8) and they probably have about 100 to 120 cycles.
> They are the original ones from Japan and I also use the C9000 at the same rate as you.
> Only the Lacrosse BC1000 and the Opus BT-2000 will charger them.
> The Maha C9000 and the Panasonic chargers won't charge them. I have no problems with my regular Eneloops that I purchased years before.



Not the Eneloop Pros, but the Duracell Ion Core 2450s. Bought 4 back in late '13 and did the break-in on my C9000s. Then I bought two more quads a year or so later. These don't have close to 50 cycles on any quad and have been used in moderation.

The other day, I went break-in the first quad (1-4) and 3 finished, but one didn't. I tried a few things and it wouldn't even take a discharge at 300mA. I put it in the recycle bag, just chalking it up to finally a 'dead' cell. This one wouldn't even read high, it just wouldn't discharge. 

So I'm leaving my GF's place today, where I've kept batteries 5-8 in a SWM D40A and took them home to break-in (I'm going through my AAs before hurricane season scales up and the first one in the C9000s, shuts the BI process down. I tried a few times and same deal. Doesn't even start the process on BI, or even 'charge' and doesn't discharge but for a second before DONE.

I tried another and figured that this quad is like the other one--just bad batteries. I have them charging up on my LaCrosse BC-700 and when they're done (and they're charging fine at 500mA), I'll do a discharge on them and then on my BT-3400 v. 2.2 and see what I see, but it's not looking good. They're at least 3 years old, but not a lot of cycles.

Chris


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## tatasal (Jun 3, 2018)

I don't know with your experiences guys but in my experience with LSD AA cells, only the Eneloop 2000mah has survived and are surviving until now and retaining almost its original capacities...... while my higher capacity, whether the Eneloop Pros or my Powerex Imedion 2450s are all retired, way below the regular Eneloop in cycles.


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## AA Cycler (Jun 4, 2018)

ChrisGarrett said:


> Not the Eneloop Pros, but the Duracell Ion Core 2450s ... C9000s ... LaCrosse BC-700 ... BT-3400 v. 2.2 ...



Charge all of them on BC-700, then read their internal resistance using BT-3400. I bet the ones causing problems will read above 2000 mOhms.

Recycle the cells that read above 1000 mOhm. A good replacement is BPI 2400, they will eventually fail as well, but are cheaper to get.

Cheers,
AA Cycler


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## WalkIntoTheLight (Jun 4, 2018)

I have almost 400 AA and AAA Eneloops, some dating back to 2006. They're all regulars, and the only ones that are showing signs of significant wear are ones that I overheated in a light that gets way too hot. I think this thread is a good reminder to me: stick to the regular Eneloops, not the Pros.

That said, I have many in their original packages that I haven't touched. I think the oldest are around 4 or 5 years. I should get some of these out and test them to make sure they are still good. Perhaps Eneloops require occasional use to stay healthy? I haven't heard that is necessary, but I suppose it's possible.

Many of my Eneloops in current usage only get charged every year or two (they're in low drain things like remotes and clocks). They're still fine, and that doesn't seem too much different than letting them sit in a drawer unused.


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## ChrisGarrett (Jun 4, 2018)

AA Cycler said:


> Charge all of them on BC-700, then read their internal resistance using BT-3400. I bet the ones causing problems will read above 2000 mOhms.
> 
> Recycle the cells that read above 1000 mOhm. A good replacement is BPI 2400, they will eventually fail as well, but are cheaper to get.
> 
> ...



Normally, I'll see the IRs creep up in normal charging, so I'm aware of where things are, even if it's just a faint memory. These actually surprised me, as the first one didn't trigger any high IR alert and didn't shut down the charger. Then this quad (#2) was rejected outright. I did get them to slow charge on the BC-700, then I did a discharge on the Opus BT-3400 and got ~2200mAh out of the four, but I wasn't able to get them to discharge at the 700mA rate on the Opus, rather they hung around the 475mA-525mA level, which is fine.

They're in my RF wireless keyboard right now and I'll just leave them there.

I've used NiMH enough over 2+ decades to know things go south on us, but low I.R.s aren't always the sole indicator.

For me, the moral of the story is: if you're going to use hi-cap HSD-ish batteries, use them and abuse them quickly and then don't jump off of the roof when you have to replace them after a couple/few years. Also, cycles don't seem to be the de facto measure for a battery's health.

Chris


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## Gauss163 (Jun 4, 2018)

Just as for Li-ion, it may be possible to extend life (= cumulative Ah) of high-capacity Eneloops by doing shallower (dis)charges. Indeed, some of AACycler's results (e.g. here and here) seem to imply that shallower cycles can greatly reduce the growth of IR so prolong life. But these tests were for Varta 2100's not Eneloops. It would be interesting to see what gains might be had doing similar for high-capacity Eneloops, i.e. not fully charging them (for that AACyler used 1.48V voltage termination vs 0dv or -dv) and/or using higher discharge termination voltage (e.g. 1.0V vs. 0.9V). I wonder how they would compare to the lower capacity eneloops if used at the same lower capacity, or half-way between the two, e.g. 2200mAh.


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## WalkIntoTheLight (Jun 4, 2018)

With regular Eneloops, I wouldn't worry about trying to maximize cycles. Even if you only get 25% the rated 2100 cycles, that's still way more than most people will ever do.

For the Pros, it sounds like age is killing them more than the number of cycles.


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## Gauss163 (Jun 4, 2018)

WalkIntoTheLight said:


> For the Pros, it sounds like age is killing them more than the number of cycles.



Not necessarily, since they might have also been killed by a much smaller number of _very deep _cycles (or other usage that highly accelerates degradation).


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## Gauss163 (Jun 4, 2018)

WalkIntoTheLight said:


> With regular Eneloops, I wouldn't worry about trying to maximize cycles. Even if you only get 25% the rated 2100 cycles, that's still way more than most people will ever do



2100 cycles appears to be greatly exaggerated marketing hype, since AACycler's tests show between 300-400 cycles to 80% capacity (or 100mΩ) for 2 samples, and 620 for another - see below. So you _should _worry about even for regular Eneloops if you are doing anything that might accelerate degradation.










The Pros degrade 3-4 times more quickly.


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## WalkIntoTheLight (Jun 4, 2018)

Gauss163 said:


> 2100 cycles appears to be greatly exaggerated marketing hype, since AACycler's tests show between 300-400 cycles to 80% capacity (or 100mΩ) for 2 samples, and 620 for another - see below. So you _should _worry about even for regular Eneloops if you are doing anything that might accelerate degradation.



Were those Japanese or Chinese Eneloops?


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## Gauss163 (Jun 4, 2018)

WalkIntoTheLight said:


> Were those Japanese or Chinese Eneloops?



The web pages don't say. There "China" or "Chinese" is only mentioned when comparing the Eneloop lite Japan vs. Chinese versions (the Chinese had 12% more capacity but had 38% of the cycle life of the Japanese). So one would think he'd have explicitly mentioned if the others were Chinese. We'll have to wait for AACycler to confirm (he's in this thread).


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## AA Cycler (Jun 5, 2018)

Gauss163 said:


> The web pages don't say. There "China" or "Chinese" is only mentioned when comparing the Eneloop lite Japan vs. Chinese versions (the Chinese had 12% more capacity but had 38% of the cycle life of the Japanese). So one would think he'd have explicitly mentioned if the others were Chinese. We'll have to wait for AACycler to confirm (he's in this thread).



Hi, couple of notes

* the eneloops and the eneloop pros I tested were made in Japan for EU market. I don't think you can buy Chinese eneloops in Europe
* 420 vs 630 cycles on standard eneloops - I got 420 cycles with -dV termination and 630 cycles with 0dV termination. Going forward I will use only -dV, because this is how people charge their batteries. I will gradually phase out the 0dV results and replace them with -dV results as I re-test the cells. Eventually all my results will be -dV results, just to keep consistency and to avoid confusion...
* 2100 IEC cycles vs 420 AACycler cycles - you can not really compare these two things. I do full cycles (from 100% SoC to 0% SoC) and the IEC standard does partial cycles. My tests show the worst case scenario, the IEC standard shows the best case scenario. In real life you will be somewhere in between

Cheers,
AA Cycler


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## Gauss163 (Jun 5, 2018)

AA Cycler said:


> * the eneloops and the eneloop pros I tested were made in Japan for EU market. I don't think you can buy Chinese eneloops in Europe


Thanks for clarifying that. It would be helpful to add that statement to your web pages.



AA Cycler said:


> * 420 vs 630 cycles on standard eneloops - I got 420 cycles with -dV termination and 630 cycles with 0dV termination. Going forward I will use only -dV, because this is how people charge their batteries. I will gradually phase out the 0dV results and replace them with -dV results as I re-test the cells. Eventually all my results will be -dV results, just to keep consistency and to avoid confusion...


Ah, so that's what the footnote means (it is not clear since the footnote's '*' doesn't reference anything above). Interesting results.



AA Cycler said:


> * 2100 IEC cycles vs 420 AACycler cycles - you can not really compare these two things. I do full cycles (from 100% SoC to 0% SoC) and the IEC standard does partial cycles. My tests show the worst case scenario, the IEC standard shows the best case scenario. In real life you will be somewhere in between


Yes, Panasonic claims "up to 2100 cycles" by "Panasonic internal testing IEC61951-2 (7.5.1.3)", e.g. see p. 25 of the 2017-2018 eneloop catalogue. The referenced IEC endurance test is excerpted on this CPF page. The cycling is done with C/4 charges for 3.17h and C/4 discharges for 2.33h to 1.0V except a couple slow charges (C/10 for 16h) are done to test capacity at every 50th cycle, terminating if a C/5 discharge lasts less than 3hrs, i.e. yields less than 60% of nominal capacity (confirmed by a 2nd such discharge), vs. your stopping at 80% nominal capacity.

So the IEC test will yield much more optimistic results than your cycling tests since IEC uses shallower cycles (60% depth, terminated at 1.0V vs. your 100% terminated at 0.9V) and lower rates (475mAh vs. your 1.0A charge, 0.5A discharge to 0.9V, or was it the old MC3000 setup at 1.5A? Again it would be helpful to say on the web page). Further IEC gains cycles by allowing the cells to degrade further before declaring them "end of life" when the current capacity is 60% (vs. your 80%) of nominal capacity.

In any case, your results will probably better reflect real world cycle life since that does not typically involve shallower cycles such as those used in the IEC testing. This is easier to see with the Pros since they have 4x shorter cycle life (by both IEC & your test) - low enough to be noticeable even to casual users.


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## Kurt_Woloch (Jun 9, 2018)

Sorry for coming a bit late to the party here, but here's some comments from me as well... as written above, the IEC standard always charges the batteries with a fixed amount of charge, which is quite a bit more than what was previously discharged. The C/4 discharges and charges charge the battery with 79% of capacity after taking away 58%, so there's an overcharge of 21% on each cycle. The slow charge which is done prior to the capacity test is C/10 for 16 hours, so it's 160% of capacity, an overcharge of 60%! The thing is, a NiMh battery doesn't need that much of an overcharge in order to be filled up. You can see it on this page by AACycler:

http://aacycler.com/post/nimh-charge-and-energy-efficiency/

As you can see there, up to a point of about 85%, the batteries take up every drop of energy they get (the inefficience actually coming from the voltage difference induced by internal resistance). Only after that the charging energy is being partially converted to heat, but by 115% of capacity, there is not much to be gained by further charging. So a 160% charge goes way beyond that! Compared to that, as also stated on this page, -dV charges the cells with about 106% of what's taken from them, and 0dV charges them with about 104% of the resulting capacity. OK, so the charge currents in these tests were much higher than what the IEC calls for, but I still think the IEC tests are actually harder on the batteries concerning length of charge than AACycler's tests. I think it's mostly the lower end (the end of discharge) where the IEC tests gains its cycles compared with AACycler's tests... but it also could be the speed of charge. But as shown on this page:

http://aacycler.com/post/high-current-vs-low-current/

cutting down the charge rate doesn't result in that many more cycles either.

Just a little bit more to consider...


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## Gauss163 (Jun 9, 2018)

Kurt_Woloch said:


> [...] I think it's mostly the lower end (the end of discharge) where the IEC tests gains its cycles compared with AACycler's tests... but it also could be the speed of charge.



Yes, that's what I surmised above ("So the IEC test will yield much more optimistic results than your cycling tests since IEC uses shallower cycles ... and lower rates"). Also note that AACyler's tests stop when the cell degrades to 80% capacity but IEC goes further (to 60%), so that too exaggerates cycle life.

It would be interesting to know if - like Li-ion - life increases if the (shallower) cycles are _centered _around 50% SOC.

In any case it seems that real-word cycles may be much less than Panasonic's claim of 2100 cycles by IEC test (except in the rare? case that usage is close to IEC tests, i.e. shallow 60% cycles and use them till their capacity degrades to 60% vs. 80% of nominal capacity, etc, as above).


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## Gauss163 (Jun 9, 2018)

Kurt_Woloch said:


> [.. but it also could be the speed of charge. But as shown on this page cutting down the charge rate doesn't result in that many more cycles either.



Keep in mind that those tests were done on the ("worst cycle count") Varta 2100's. Whether or not eneloops behave similarly we can't say for sure till they are tested.


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## WalkIntoTheLight (Jun 9, 2018)

Gauss163 said:


> In any case it seems that real-word cycles may be much less than Panasonic's claim of 2100 cycles by IEC test



In the vast majority of use, cells will see nowhere near 2100 cycles, probably nowhere near even 500. Even if the average lifespan of a (regular) Eneloop is 10 years, 500 cycles would mean charging it every single week. 2100 cycles would mean almost every day!

I only have one pair of Eneloop that I might cycle that much. I have a light for general illumination I use every night. In the winter, I recharge the 2xAA cells every day. In summer, maybe every second day. Frankly, most people would see me as insane, so this is extreme use.

I haven't done a capacity test on them, but so far, I haven't noticed any degradation. They probably have about 500 cycles on them. Granted, they're not full cycles. I top them up to 100%, but they're usually only discharged to about 1.30v or a bit less. The cells are 2nd gen Eneloops from 2012, but have only received high usage in the last year or two.

Anyway, I think, (except for nuts like me) that 2100 cycles is moot. 500 is still plenty. And for some of my cells (in remotes), they will probably only see a dozen cycles in their life. It's the low self discharge and shelf life that matters most.


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## Gauss163 (Jun 9, 2018)

WalkIntoTheLight said:


> In the vast majority of use, cells will see nowhere near 2100 cycles, probably nowhere near even 500. Even if the average lifespan of a (regular) Eneloop is 10 years, 500 cycles would mean charging it every single week. 2100 cycles would mean almost every day!



Daily (partial) charges are the norm in some contexts, e.g. in solar-powered devices such as outdoor lights (e.g. Walmart sells them with Westinghouse 18650s).


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## WalkIntoTheLight (Jun 9, 2018)

Gauss163 said:


> Daily (partial) charges are the norm in some contexts, e.g. in solar-powered devices such as outdoor lights (e.g. Walmart sells them with Westinghouse 18650s).



Ah, yes, I forgot about those uses. I do have solar garden lights, but don't use Eneloops in them. I'm concerned that the constant trickle-charging would prematurely kill the batteries. Maybe the Eneloop Lite is better suited for that purpose?


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## batteryfever111 (Apr 9, 2021)

Today, yet another Eneloop XX cell triggered a blinking warning sign in the charger, and was refused to be charged, and I was looking for some background info on this issue.

Somehow, over the years, all my Eneloop XX and Pro batteries were refused to be charged by the Eneloop chargers form the original ones from the beginning. I only have recent ones functioning.
I don't think I cycled through more than 50 cycles for each of them... 

I bought over the years more than 100 eneloop batteries, since the time they first came out, about half of them of them XX and Pro, AA and AAA mixed. At the beginning Sanyo, then Panasonic, and last year, I bought also a lot of Fujitsu rebranded varieties from Nkon.nl (a rechargeable battery specialist in the Netherlands). They ran in lights for biking, led lights for camping/evening reading, long range flash lights for biking, voice recorders, alarm clock, kitchen scale, hair trimmer, you name it. Usually I used the XX / Pro variety where I wanted the extra bit of capacity, like the long range bike light, voice recorder, or the camping lights.

I think I took average care of them, I used the *Panasonic BQ-CC65* from the moment it became available, before that, *Panasonic BQ-CC17, *and recharged the batteries when my devices showed no more power.

The normal eneloop batteries don't seem to trigger such warning signes.

Maybe I am doing something wrong?

I need to buy some new batteries again, and I just wonder shall I still try to use the Pro variety, or just stick to the standard Eneloops.
In the beginning, I can see the benefit of the Pro having more capacity, but it seems that they just die quickly. It's not even the price, but the hassle to discover the batteries don't charge anymore when I would need them.

I went through the forum posts and articles linked.

Any recent views on this topic would be welcome.


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## ChrisGarrett (Apr 9, 2021)

batteryfever111 said:


> I need to buy some new batteries again, and I just wonder shall I still try to use the Pro variety, or just stick to the standard Eneloops.
> In the beginning, I can see the benefit of the Pro having more capacity, but it seems that they just die quickly. It's not even the price, but the hassle to discover the batteries don't charge anymore when I would need them.
> 
> I went through the forum posts and articles linked.
> ...



Unless you need the extra 20% capacity here and now, or you don't mind replacing the Hi-Caps every 2-3 years, most of us just use the standard capacity Eneloop type batteries.

They just last so much longer, providing more power over life.

Just the nature of the beast.

I'm not buying Hi-Caps any longer.

Chris


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## batteryfever111 (Apr 10, 2021)

ChrisGarrett said:


> Unless you need the extra 20% capacity here and now, or you don't mind replacing the Hi-Caps every 2-3 years, most of us just use the standard capacity Eneloop type batteries.
> 
> They just last so much longer, providing more power over life.
> 
> ...



Thanks for the affirmation. Then I won't buy any Pro batteries anymore...

Slowly, I was coming to the same conlusion, but I was not sure.

The only scenario I can imagine the 20% benefit is when depleting the batteries in one go, and the 20% makes sense, like photography flashes, radio controlled model cars, electric toys and similar.However, all my such devices now function with built-in LiIon batteries.



I collected all my early batteries, and the conclusion is that even my first buy Eneloops work, and even some of the recent Pro batteries have some trouble.


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## NiOOH (Apr 11, 2021)

The cycle life of Eneloop Pros is much shorter than that of regular Eneloops. As said, if you don't need the extra capacity, just stick with the regulars, or buy IKEA LADDA (rebranded Pros) at 1/3 of the price of the Pros and change them more often.


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## zeally (Sep 5, 2022)

Half the top of one of my Eneloop Pro AAs has come off while inside the flashlight


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## knucklegary (Sep 5, 2022)

Did you go swimming with your flashlight in pocket?
Details and Photos will help.


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