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Thread: Eneloop XX Vs Turnigy 2400 Cycle Testing

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    Default Eneloop XX Vs Turnigy 2400 Cycle Testing

    Out of curiosity, I decided to run a cycle life test to compare the high capacity Eneloop XX to the Turnigy 2400. In Australia at least, the Eneloop XX cells are quite expensive - about 30% more than regular Eneloops and they rarely go on special. Regular Eneloops are often on special at less for an 8 pack than the Eneloop XX cells cost for a 4 pack! The Turnigy 2400 cells on the other hand are quite cheap. Ignoring shipping costs, they're cheaper than regular Eneloops even when the Eneloops are on special.

    To begin my testing, I took a single Eneloop XX cell and a single Turnigy 2400 cell and placed them both in the same charger. For this test, I decided to run both charging and discharging at only 1 amp - as the cells are only rated for 500 cycles each, I decided that it was worth running the test at a lower rate.



    To my surprise, despite being more expensive, the Eneloop XX cell lasted for a significantly lower number of cycles than the Turnigy cell. I then decided to run another test with a pair of Eneloop XX cells to make sure that there wasn't something unusually wrong with the first cell that I tested:



    One cell performed very similarly to the first test, but the other lasted for a significantly larger number of cycles. The pattern of capacity decline is pretty much the same, just over a longer number of cycles. It's hard to say what the cause of this difference is - it could be that there is some variation between cells, but I wouldn't expect this considering that normal Eneloops are very consistent, and I would have expected that consistency to carry over into the Eneloop XX line as well.

    As a follow up, I decided to run yet another test to compare a Eneloop XX with a Turnigy 2400 cell:



    In this latest test, I ran both charges and discharges at 2 amps. In this case, the Eneloop XX survived for more cycles than 2 of the 3 previously tested - despite being run at twice the current. The Turnigy cell managed to last for more cycles, but at no point did it manage to beat the Eneloop XX in capacity.

    Overall, I'd say that this is a disappointing result for the Eneloop XX. Unless the absolute maximum capacity is required, I would generally recommend the Turnigy 2400 cells ahead of the Eneloop XX cells - particularly considering the large price difference!
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    Flashaholic Tobias Bossert's Avatar
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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Do you know what causes the abrupt end of life for NiMH cells?
    I always thought that there will be a continous decline of capacity, not an abrupt end.
    What is the behaviour of the cells when they switch to zero capacity: short cirquit or high ohmic?
    Were there any temperature problems during testing?

  3. #3

    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    I have a lot of the Turnigy 2200 cells. I have never compared them with my Eneloops, but they seem to do just as well.

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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Interesting, any chance you could do this test with regular eneloops as well?
    Warm white.

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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Quote Originally Posted by LessDark View Post
    Interesting, any chance you could do this test with regular eneloops as well?
    Like this one?
    http://www.ultrasmartcharger.com/php...c.php?f=5&t=69
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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Quote Originally Posted by Tobias Bossert View Post
    Do you know what causes the abrupt end of life for NiMH cells?
    I always thought that there will be a continous decline of capacity, not an abrupt end.
    What is the behaviour of the cells when they switch to zero capacity: short cirquit or high ohmic?
    Were there any temperature problems during testing?
    There weren't any temperature problems during this testing - the tests were done a few months ago over winter (in Australia) - it has taken me a while to get around to posting the results.

    The cells aren't completely dead when they hit zero on this test. What happens is that as the cells age, their internal resistance increases - it eventually gets to the point where as soon the discharge starts, the voltage drops below the 0.9V cutoff. Prior to that, the voltage drops significantly, but as the cell warms up, the internal resistance drops and the voltage recovers. A normal discharge has the voltage starting high and constantly decreasing. With high current discharges on cells with high internal resistance, the voltage curve ends up looking like an upside down U:

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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Very interesting results. I am surprised at the results.

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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    A couple of ideas here:

    - Could the differences you're seeing in the same battery be due to differences in the two slots of your charger? If the voltage sensor is off in one, you could be overcharging in one slot and not the other which would dramatically reduce cycle life.

    - Maybe the inflection point termination is not working well on the XX cells and causing an overcharge.

    - The fact that the 2amp charge resulted in better cycle life performance than 2 of the 1amp charge rate cells, points to some evidence the termination might be working better at 2 amps, and/or that charge rate also helps the termination end more reliably with less overcharge.

    - Due to eneloop voltage profile during charge being quite different from other nimh cells, the charging mechanism could be overcharging XX and correctly charging your turnigy cells leading to these results.


    Those are just some ideas on what might be going on here. Maybe do a log of charge and discharge in the ultrasmartcharger of both slots, trying both types of batteries, including voltage, current, and temp data and we can spot if anything is amiss. The data is pretty random for very consistent cells which points to not a cell problem but a setup problem in my opinion.

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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Thanks for the tests!
    Very interesting.
    its almost as bad as swearing against eneloops
    just kidding.

    I`m quite surprised. Its also very strange to see they just die with even so much juice in them....... I would imagine they would go much worse before totally giving up..
    It could definitely be the rest time between the cycles?
    How many of those charger/discharge setups do you have?
    would be interesting to see, how long they last if they have longer rest time between each cycle. Just like in a real life situation.

    can you post pictures of both the XX cells and Tunirgy cells? Are the XX 1st gen?

    At least till now, the Std. eneloop seem to be the better option..

  10. #10

    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Quote Originally Posted by bcwang View Post
    A couple of ideas here:
    ...
    I could also add the case the XX eneloops used to be fake.

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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Quote Originally Posted by bcwang View Post
    A couple of ideas here:

    - Could the differences you're seeing in the same battery be due to differences in the two slots of your charger? If the voltage sensor is off in one, you could be overcharging in one slot and not the other which would dramatically reduce cycle life.
    There is a single external 18 bit ADC used for both channels. The ADC has an internal 2.048V reference that is used for all channels. IMHO, a faulty voltage reference would be the most likely cause of incorrect voltage readings, but that would affect all channels the same. There are other possible causes for ADC errors of course, but they shouldn't actually matter too much as long as the error is consistent.

    Absolute voltage is critical when charging Lithium Ion cells, but isn't as important when charging NiMH cells because NiMH termination is done based on changes in the voltage rather than the absolute voltage. (let me know if this isn't clear and I need to do a better job of explaining it)

    The first 2 tests were done in the same charger. The cell that performed worse was in slot 1 in one test and in slot 2 in the other test, so that pretty much rules out any difference between the channels. I did move the charger to a different location though, so maybe there was some external environmental condition which affected one channel more than the other (i.e. if there was air moving from one side to the other, you would expect that the side on the receiving side would run a bit cooler than the other)

    - Maybe the inflection point termination is not working well on the XX cells and causing an overcharge.
    The inflection point ALWAYS occurs before a -dV signal occurs (by definition) If inflection termination causes overcharging, then -dV termination (which always incurs overcharging) is always going to be worse! Having a quick look at the charging data from the first test, I can't see any cases where the cells appear to have been overcharged.

    Inflection detection is very reliable - I haven't had a single missed termination in all of the testing/charging that I've done with the UltraSmartCharger - and that includes some cells that were in really bad condition.

    This is the first charge for the Eneloop in the first test:


    This is the last charge for the Eneloop, again in the first test:


    The last charge heats up more at the end, but still terminates OK. I suspect that the increased heat generation is due to lowered charge efficiency caused by damage to the separator increasing the internal resistance.

    - The fact that the 2amp charge resulted in better cycle life performance than 2 of the 1amp charge rate cells, points to some evidence the termination might be working better at 2 amps, and/or that charge rate also helps the termination end more reliably with less overcharge.
    Inflection termination should work reliably at pretty much any current (unlike -dV detection) I haven't done any testing at ultra low charge rates, but I could do that if anyone is interested?

    The lower discharge current allows for a more complete discharge. I'm wondering how much damage is actually being done at the end of the discharge as opposed to the end of the charge. I'm thinking about running some tests to see if that if it's possible to work out if deep discharging does more damage than slight overcharging...

    - Due to eneloop voltage profile during charge being quite different from other nimh cells, the charging mechanism could be overcharging XX and correctly charging your turnigy cells leading to these results.
    I can't say that I've noticed any significant difference in the voltage profile when charging Eneloops. Do you have any information that you can point to which shows that there is a difference?

    Those are just some ideas on what might be going on here. Maybe do a log of charge and discharge in the ultrasmartcharger of both slots, trying both types of batteries, including voltage, current, and temp data and we can spot if anything is amiss. The data is pretty random for very consistent cells which points to not a cell problem but a setup problem in my opinion.
    As I mentioned above, I'd be inclined to think that an external environmental issue might have been a factor - that seems more likely than inconsistent Eneloops...
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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Quote Originally Posted by ChibiM View Post
    I`m quite surprised. Its also very strange to see they just die with even so much juice in them....... I would imagine they would go much worse before totally giving up..
    It seems that increased internal resistance is the cause of these failures and in this case it has happened before much capacity has been lost.

    The cells are still usable with good capacity for low current devices.

    It could definitely be the rest time between the cycles?
    Shorter rests does mean that the cells don't have as much time to cool down, so yes, I would expect that to have some impact on the results. Checking the data, it's quite clear that the cell temperature haven't had a chance to fully stabilize after each charge/discharge. Ironically, in the short term, the higher cell temperatures will generally mean that the cells will give better performance during the discharge, but in the long term, I wouldn't expect it to be good for their longevity.

    How many of those charger/discharge setups do you have?
    I've currently got 3 chargers running testing 24/7. I've got a 4th charger that I'm planning to put into cycle testing service fairly soon.

    would be interesting to see, how long they last if they have longer rest time between each cycle. Just like in a real life situation.
    Might be worth running another test to see what the difference is - I agree. It will mean that the test will take longer of course!

    can you post pictures of both the XX cells and Tunirgy cells? Are the XX 1st gen?
    Not just at the moment, but I'll try to do it later... I'll have to check which generation they are. Checking the date codes, it looks like 2 of them were made in 2012 and the other 2 were made in 2014...

    At least till now, the Std. eneloop seem to be the better option..
    As long as there isn't a pressing need for the increased capacity (and swapping cells isn't an easy option) then, yes - I definitely agree!
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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Quote Originally Posted by apagogeas View Post
    I could also add the case the XX eneloops used to be fake.
    That did cross my mind.

    Fakes generally have way less capacity that they're rated for, so I think that makes it unlikely that they're fakes.

    I also purchased them from Dick Smith Electronics - probably the biggest retailer of Eneloops in Australia. Although fakes can creep in, I wouldn't think that to be too likely since they should be being sourced from the official distribution channels.

    I also tested cells from 2 cells each from 2 different packs with different date codes to ensure that I didn't have cells from a faulty batch.
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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Well, a greatly reduced number of useful cycles has always been a drawback of Eneloop Pros (or XX). Despite this fact, I have still chosen to use nothing but Eneloop Pros in all my applications (except for a some early, non-LSD, Panasonic NiMH cells which I am still using until they finally "die off" completely and can be recycled).

    Another commonly mentioned drawback is the higher cost of Eneloop Pros. Neither the higher cost, nor the low number of cycles has ever concerned me, however. (In my opinion, the question of whether or not you should be concerned about these two issues depends on how often you intend to recharge your cells, and how many years you hope to keep using them.)

    I live in Japan where Turnigy 2400 cells are not a practical option. Turnigy is hardly sold here at all, and almost all "hits" I could find on the internet pertained to "Turnigy" branded multi-cell packs in both Li-Ion and NiMH chemistries for Remote Control hobbyists.

    The only Turnigy AA cell I could find was a 2200 mAh version which were available for purchase at 210 Yen each from one single R/C Hobby Shop. That price is in comparison to 199 Yen for a Standard Eneloop, and 249 Yen for Eneloop Pros. (At the moment, the Yen Dollar exchange rate is fairly close to 100, so you can think in terms of US$2.49 per Eneloop Pro cell.)

    While Panasonic literature written in Japanese claims "approximately" 500 cycles (based on the JIS C8708 standard) for the Eneloop Pro cells, it also includes the caveat "depends on your device and device usage -- actual performance may vary." I think it is a well known issue here in Japan that 500 cycles is a rather optimistic claim.

    The following is a graph titled "Eneloop Pro Cycle Endurance based on JIS C8708 standard testing methods" that I found on the internet and have partially translated into English:



    As you can see, 250 Cycles, or perhaps 300 Cycles (depending on your performance needs) is the most that you can expect. At 350 Cycles the Eneloop Pro has deteriorated very significantly.

    The following is a portion of the raw data associated with the above cycle tests:



    The JIS C8708 testing involves charging the cell at 0.25C for 3 hours and 10 minutes, then discharging the cell at 0.25C until the cell reaches 1.0 Volts. In order the pass the test, the cell must take longer than 2 hours and 20 minutes to reach 1.0 Volts. Every 50 cycles, the cell is charged at 0.1C for 16 hours, rested for 4 hours, then discharged at 0.20C until it reaches 1.0 Volts.

    As the above printout shows, the 376th cycle was the last cycle to "pass" this test. (It took exactly 2 hrs. 20 mins. to reach 1.0V) The cell failed on the 377th cycle because it reached 1.0V in only 2 hrs. 19 mins. The rest of the handwritten notes on this printout refer to the fact that at 400 cycles and 450 cycles, this cell "instantly" registered less than 1.0V (it took "zero time").

    As I mentioned at the beginning of this post, I (personally) am not particularly troubled by these results. I am willing to accept 200 or 250 cycles as the practical life of my current Eneloop Pros. (That doesn't mean that they cannot still be useful in many low drain applications, even after they have begun to deteriorate significantly.) Since I rarely recharge more than once per week, in my case, 200 or 250 cycles translates into 4 or 5 years. (It is hard for me to predict that far into the future, but I suspect I will be willing to re-invest in whatever the "latest and greatest battery technology" is at that time.)

    Without getting into great detail, if you assume 200 or 250 cycles, you will quickly find that the initial higher cost of the Eneloop Pros is trivialized over time. What should not (in my opinion) be trivialized is the nearly 29% increase in capacity. The current Japanese language Panasonic Eneloop website claims "min. 1,900 mAh" for Standard, and "min. 2,450 mAh" for Eneloop Pros.

    Furthermore, the Eneloop Pro has 22% more capacity than the Standard even after 1 whole year, despite its lower 85% capacity retention rate (90% for Standard). To me, these capacity increases are significant. I have recently read where some on this forum have posted that you will see only a very slight increase in capacity, but I wonder how factual that is.

    I do not have any Standards to compare with my Pros, so I cannot say from any firsthand experience, but I do know that Sanyo claimed a 31% runtime increase in an LED flashlight driven at 300 mA. And, to my mind, 31% longer runtime for your flashlight, available every day, whenever you may need it, is pretty significant. (But, I am sure that this depends on your application.)

    In summary, I use Eneloops Pros in every device, whether they are needed or not, because that is where I am keeping my "emergency stash" of backup flashlight cells. If my power goes out for any real length of time, I can rob cells from countless "nonessential devices" and use those cells to power more important things like flashlights. I figure that, so long as I make sure and recharge everything (even "nonessential devices") at least once a year, I will always have the "maximum" emergency capacity (always greater than the same number of Standard cells).

    Therefore, quite a few of my Eneloop Pros may only get recharged once a year (= 250 to 300 year cell life?) Others will get recharged about once a week (= 4 to 5 years), but only a very few will get recharged much more often than that. I try to keep my cells in matched sets, and occasionally make note of their measured capacity in an Excel spreadsheet that I keep. I am interested to find out for myself when (if ever) I will notice a significant drop-off in capacity.

    Some may argue that I shouldn't have spent the money on (made the investment in) Eneloop Pros. But, as previously noted, the cost difference between Standards and Pros is trivial when amortized over time and even "only" 200 cycles. And, in the meantime, I have never purchased another Alkaline cell, I am able to enjoy the highest possible capacity (longest possible runtimes) on a day-to-day basis, and I also have the greatest amount of capacity available for emergency use (should I ever need them). Whats not to like? (Besides initial cost...)

    Think about it, though... How many of us are spending hundreds of dollars on flashlights? Why not invest some of that money into the cells that power those flashlights? Eneloop Pros are not all that expensive when compared to the cost of a quality flashlight.

    (Lets say a good 6 x AA flashlight costs around $100 or so, and the difference between Pros and Standards is $0.50 each. That means 6 Pro cells + 6 spare Pro cells are only going to cost you $6.00 more over Standard Eneloops! You may pay a greater premium for Pros in your market, but I still don't see it as very likely that using Pros is ever going to increase the cost of your flashlight by more than 20%, and even that huge premium seems worth it to me, assuming you are going to experience an appropriate increase in runtime in your application.)

    I agree, however, that those who are recharging several times a day, or even once a day, might be better off with Standard... although in my mind even that is still "debatable."
    Last edited by Rosoku Chikara; 10-26-2014 at 10:38 AM.
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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Very interesting tests! Thanks!

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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Thanks for the great post Rosoku!

    I should have reiterated that my recommendation against the Eneloop XX cells is largely based on their significantly higher cost (at least in Australia)

    If I could get Eneloop XX/Pro for only 25% more than the regular Eneloops, I'd do the same as you and standardise on them despite the lower number of cycles that they're capable of. Even for devices that require regular recharging, it might still make sense to use Eneloop XX/Pro cells despite a slight price increase just for improved convenience. Their higher capacity slightly offsets their lower number of cycles as well.

    Unfortunately, though, in Australia at least, we have to deal with not just a 25% increase in price but a minimum of 40% more. When the regular Eneloops are on special (which is quire often), the price difference works out to 180% more! Even when the XX/Pro cells are on special they're generally still double the cost of the regular Eneloops on special!

    For a handful of cells, the price difference isn't that big a deal, but when you've got over 700 rechargeables in service, the (Australian) price difference makes a huge difference unfortunately!

    BTW, I have an Eneloop XX in my EDC torch...
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    Flashaholic* Rosoku Chikara's Avatar
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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Quote Originally Posted by Power Me Up View Post
    ...For a handful of cells, the price difference isn't that big a deal, but when you've got over 700 rechargeables in service...<snip>
    Wow, that really is a whole lot of rechargable cells!

    Sorry to hear that Eneloop Pros are so much more expensive in your market. I noticed that Eneloop Pros (in particular) are being sold on eBay.com.au from Japan, but the prices being charged for them are indeed very high.

    In the case of Japan, it seems that the price of Standard Eneloops has gone down. Not too long ago, it was occasionally possible to purchase Pros for less than Standards. (I guess this was because, in general, Pros are not as popular and don't tend to "sell through" quickly enough for some online retailers.) But today, Standards seem to always be cheaper than Pros by a minimum of about 25%.

    In any case, I still tend to believe that the difference in cost is overblown, when you take into account that you are likely going to eventually use your cells for at least 200 cycles. Even if you pay twice as much for Pros, that difference amounts to fractions of a cent per cycle... (Of course, Standards probably can achieve well over 1,000 cycles, so their per cycle cost gets ridiculously low, but to me that is beside the point.)

    However, as you noted, the difference initial investment cost looms pretty large when you must purchase 700 cells! (I guess you are kept pretty busy recharging all those cells?)
    Last edited by Rosoku Chikara; 10-26-2014 at 06:00 PM.
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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Quote Originally Posted by Rosoku Chikara View Post
    However, as you noted, the difference initial investment cost looms pretty large when you must purchase 700 cells! (I guess you are kept pretty busy recharging all those cells?)
    It's not that bad. There are a lot in kids toys that don't get used a lot, so they just get recharged when they go flat. I've also got quite a few unopened in packs (bought at ridiculously low prices) so it's probably a bit over the top on my part to complain about the cost of that many Eneloop XX/Pros when I don't actually need that many in the first place...
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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Quote Originally Posted by Power Me Up View Post
    I also purchased them from Dick Smith Electronics - probably the biggest retailer of Eneloops in Australia. Although fakes can creep in, I wouldn't think that to be too likely since they should be being sourced from the official distribution channels.
    I was thinking you had fakes too but if they are from Dickies then they are genuine. At $27 for four, that is some expense to pay for this experiment.

    Now the questions is if Jaycar's XX's are the same or better ... (seriously, don't go out and buy them just for this test)

    I guess we don't really buy XX's just for the cycles but the ability to handle high loads but this does put a little perspective on it. Still buying the XX AAA's though

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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Quote Originally Posted by Mr Floppy View Post
    I was thinking you had fakes too but if they are from Dickies then they are genuine. At $27 for four, that is some expense to pay for this experiment.
    Just going from memory, I think I managed to get at least one of the packs for about $20 on special...

    Now the questions is if Jaycar's XX's are the same or better ... (seriously, don't go out and buy them just for this test)
    Wasn't planning to. Maybe I should ask Panasonic if they are interested in donating a couple of packs for testing purposes...

    I guess we don't really buy XX's just for the cycles but the ability to handle high loads but this does put a little perspective on it. Still buying the XX AAA's though
    Capacity wise, the XX AAA cells are of even less value than the regular Eneloops - 900 mAh min vs 750 mAh min is only a 20% capacity increase compared to 2450/1900 = 29% increase. DSE at least doesn't give a discount on the AAA cells compared to the AA cells even though there are less material costs. (Lower demand for AAA would offset some of these savings of course)

    Of course, with the capacity of AAA cells being so low, any increase in capacity could be considered worthwhile in a lot of cases...
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  21. #21

    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Quote Originally Posted by Power Me Up View Post
    Wasn't planning to. Maybe I should ask Panasonic if they are interested in donating a couple of packs for testing purposes...
    Maybe Fujitsu will, I've noticed Fujitsu's 2500mAh range available in Australia now, HR-3UTHB model. Lots of the blurb talks about made in japan, original etc.

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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Quote Originally Posted by Mr Floppy View Post
    Maybe Fujitsu will, I've noticed Fujitsu's 2500mAh range available in Australia now, HR-3UTHB model. Lots of the blurb talks about made in japan, original etc.
    I strongly suspect that they are the same cell as the Eneloop XX...
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  23. #23
    Flashaholic* Rosoku Chikara's Avatar
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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Quote Originally Posted by Power Me Up View Post
    I strongly suspect that they are the same cell as the Eneloop XX...
    I believe that you are absolutely correct. It is my understanding that they are manufactured in the same plant, and even on the same line at the FDK facility in Takasaki City, Japan.

    When Panasonic acquired the Eneloop brand from Sanyo, FDK acquired the Eneloop manufacturing plant and manufacturing technology from Sanyo. (I know this sounds really odd, but Panasonic could not acquire the actual manufacturing plant due to antitrust issues that would have prevented the Sanyo/Panasonic merger from moving forward.)

    Unfortunately, the FDK cells are not low cost. They usually cost more than Eneloops. (However, they are indeed the "original," whereas the new Eneloop cells that are made in China, may or may not be up to the standards set by the original Eneloop. Since Panasonic now owns the Eneloop brand, whatever Panasonic wishes to call an "Eneloop" is a "real" Eneloop. But, we may have to wait and see just how good the new Chinese Eneloop cells are.)
    Last edited by Rosoku Chikara; 10-26-2014 at 11:27 PM.
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  24. #24
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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Quote Originally Posted by Power Me Up View Post
    The cells aren't completely dead when they hit zero on this test. What happens is that as the cells age, their internal resistance increases - it eventually gets to the point where as soon the discharge starts, the voltage drops below the 0.9V cutoff. Prior to that, the voltage drops significantly, but as the cell warms up, the internal resistance drops and the voltage recovers. A normal discharge has the voltage starting high and constantly decreasing. With high current discharges on cells with high internal resistance, the voltage curve ends up looking like an upside down U
    Good explanation of why your tests show the capacity suddenly dropping to zero when using 1A discharge. At 0.1A discharge, they may still have plenty of life left.

    I notice that they still seem to take a 1A charge okay, even when they can no longer do a 1A discharge. And they only heat up slightly more. Is that expected behaviour? I have some very old (non LSD) NiMH cells, and they can do a slow-discharge fine. However, they must also be charged slowly, or they quickly terminate their charge early. They would quickly overheat if I forced a 1A charge into them.

    So it seems odd that the XX Eneloops are able to take a 1A charge, even when internal resistance has wrecked them.

  25. #25
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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Quote Originally Posted by WalkIntoTheLight View Post
    Good explanation of why your tests show the capacity suddenly dropping to zero when using 1A discharge.
    Thanks!

    At 0.1A discharge, they may still have plenty of life left.
    Undoubtedly! Even at a 500 mA discharge, they still had substantial capacity remaining even after they failed a 1 amp discharge.

    I notice that they still seem to take a 1A charge okay, even when they can no longer do a 1A discharge. And they only heat up slightly more. Is that expected behaviour?
    Yes, I'm not surprised by that. Higher IR just means that the charging voltage will be substantially higher than for a cell with low IR. Initially, the cells heat up more, but as they warm up, the IR drops and charging becomes more efficient than at the start.

    I have some very old (non LSD) NiMH cells, and they can do a slow-discharge fine. However, they must also be charged slowly, or they quickly terminate their charge early. They would quickly overheat if I forced a 1A charge into them.
    It depends on how high the IR is - If it's high enough, then yes, you can't charge them at high rates. I had some old cells that I did some testing on and they had IR values over 1 ohm - they definitely wouldn't charge at 1A, but they couldn't even do a discharge at 0.5 A

    With the UltraSmartCharger, I've programmed it to initially reject cells that have an IR over 300 milliohms (so that you can't accidentally recharge alkalines, etc) you can still override this to charge high IR cells - with the default settings, the charge current will be automatically reduced if the IR is over 400 milliohms. As the cells warm up and their IR drops, the charger will automatically increase the charging current to suit.
    Firmware Developer for the UltraSmartCharger: Open Source Charger/Analyzer for NiMH/NiCad/NiZn batteries.
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  26. #26

    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Fair comments about genuine or not XX batteries and indeed it looks like a surprise to have another brand exceed XX in cycle life. However, a couple of extra points here: what is the average capacity of Turnigy vs XX? So do we really compare the same thing here? I know XX state minimum 2400 but in practice it is more than 2500, at least those I have here, so if Turnigy is let's say average 2450mAh and XX registers 2530mAh or so, we have almost 100mAh extra which can be a huge difference in actual life. After all, 2530(XX)-1980mAh(standard eneloop)= 550mAh is enough to significantly drop the cycle life from 2100 down to 500 only! If just 550mAh are enough to cause this, it could make sense to expect lower cycle life when we compare a 2530mAh battery vs an 2450 one and in reality, if XX produced the same average to Turnigy the real XX cycle would be superior. I just find hard to believe, an equal capacity battery of another brand performs better to eneloop technology when eneloop is the only battery that claims the highest cycle life on standard eneloops and the same technology is used on XX, so at least part of that performance is expected to also show on XX. So, maybe the difference is due to Turnigy actually producing a lower overall capacity?
    Anyway, good to know there is a good alternative nevertheless. It is not impossible for Turnigy to actually have produced a superior battery but if they did, I would expect they'd also produce a 1900mAh minimum capacity battery that surpasses standard eneloops too in total cycle life using that superior technology. I'm not aware of such a battery yet.

  27. #27
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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Yes, the Eneloop XX has more capacity than the Turnigy 2400 - you can see the difference in the graphs in my first post.

    You're quite possibly right that the increase in capacity is relevant - getting higher capacity requires compromises in other areas, so it's quite possible that Sanyo had to make more compromises to get that little bit extra capacity.

    BTW, for anyone looking for the Turnigy cells, I purchased mine from HobbyKing:
    http://hobbyking.com/hobbyking/store...y_to_use_.html

    There is now a Turnigy 2550 mAh cell, so it might be interesting to test it at some stage:
    http://hobbyking.com/hobbyking/store...4pc_pack_.html

    Looks like the price on the 2400 mAh cells has dropped significantly at their international warehouse - I'm guessing that they're clearing out stock now that the 2550 mAh cells are available!
    Firmware Developer for the UltraSmartCharger: Open Source Charger/Analyzer for NiMH/NiCad/NiZn batteries.
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  28. #28
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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Quote Originally Posted by ChibiM View Post
    can you post pictures of both the XX cells and Tunirgy cells? Are the XX 1st gen?
    Sorry I didn't get around to taking the photo until now:



    Full size version:
    http://www.ultrasmartcharger.com/Ene...2400 Photo.jpg

    Looks like the model code on the Eneloops are HR-3UWXB which would make them 2nd gen.

    Edit: Date codes on 2 of the Eneloops are: 12-10 HM. The other 2 are: 13-08 EE
    Last edited by Power Me Up; 10-28-2014 at 04:39 PM.
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  29. #29
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    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Quote Originally Posted by Rosoku Chikara View Post
    The JIS C8708 testing involves charging the cell at 0.25C for 3 hours and 10 minutes, then discharging the cell at 0.25C until the cell reaches 1.0 Volts. In order the pass the test, the cell must take longer than 2 hours and 20 minutes to reach 1.0 Volts. Every 50 cycles, the cell is charged at 0.1C for 16 hours, rested for 4 hours, then discharged at 0.20C until it reaches 1.0 Volts.
    Do you have access to the actual JIS C8708 testing standard? If so, can you confirm what rest periods are included in the test. From your text and the image that you posted, it appears that there isn't any rest after charging or discharging, except after the 16 hour 0.1C charge.

    I'm thinking about running another test following that standard as closely as I can. The main difference would be that I won't be keeping to standard lab temperature - unless Panasonic or someone else wants to pay for the electricity bill to run my (Panasonic no less) air conditioner 24/7 for the duration of the test. Would take around 3 months or so for the Eneloop XX cells - maybe around a whole year(!) for standard Eneloops!
    Firmware Developer for the UltraSmartCharger: Open Source Charger/Analyzer for NiMH/NiCad/NiZn batteries.
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  30. #30

    Default Re: Eneloop XX Vs Turnigy 2400 Cycle Testing

    Quote Originally Posted by Power Me Up View Post
    I'm thinking about running another test following that standard as closely as I can. The main difference would be that I won't be keeping to standard lab temperature - unless Panasonic or someone else wants to pay for the electricity bill to run my (Panasonic no less) air conditioner 24/7 for the duration of the test. Would take around 3 months or so for the Eneloop XX cells - maybe around a whole year(!) for standard Eneloops!
    What temperature would that have be? I have full access to a rack in our computer room, the room is set to be 18 degrees C but normally it is around 26 in the racks.

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