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Thread: All my eneloop XX 2500 mAh batteries dropping like flies

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    Unhappy All my eneloop XX 2500 mAh batteries dropping like flies

    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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    Flashaholic* Stefano's Avatar
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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    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

  3. #3

    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    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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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    Quote Originally Posted by Stefano View Post
    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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    Flashaholic* KeepingItLight's Avatar
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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    Quote Originally Posted by Mr Floppy View Post
    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/...esting-Results
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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    Actually, was thinking of this thread
    Eneloop XX Vs Turnigy 2400 Cycle Testing http://www.candlepowerforums.com/vb/...d.php?t=391756

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    Flashaholic* Stefano's Avatar
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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    Quote Originally Posted by StorminMatt View Post
    2000mA is 1C for an Eneloop 2000.
    Yes is correct, excuse error

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    Flashaholic* MidnightDistortions's Avatar
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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    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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  9. #9

    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    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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    Flashaholic* KeepingItLight's Avatar
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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    Quote Originally Posted by Mr Floppy View Post
    Actually, was thinking of this thread
    Eneloop XX Vs Turnigy 2400 Cycle Testing http://www.candlepowerforums.com/vb/...d.php?t=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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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    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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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    Quote Originally Posted by Power Me Up View Post
    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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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    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.

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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    Quote Originally Posted by TinderBox (UK) View Post
    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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    *Flashaholic* ChrisGarrett's Avatar
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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    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.

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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    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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    Flashaholic* MidnightDistortions's Avatar
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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    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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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    Quote Originally Posted by MidnightDistortions View Post
    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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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    Quote Originally Posted by WalkIntoTheLight View Post
    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/php...c.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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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    Quote Originally Posted by Power Me Up View Post
    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/php...c.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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    Flashaholic* MidnightDistortions's Avatar
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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    Quote Originally Posted by swan View Post
    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.

    Quote Originally Posted by Power Me Up View Post
    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/php...c.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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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    Quote Originally Posted by MidnightDistortions View Post
    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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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    Quote Originally Posted by Power Me Up View Post
    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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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    Quote Originally Posted by MidnightDistortions View Post
    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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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    Quote Originally Posted by Power Me Up View Post
    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/php...c.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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    Flashaholic* MidnightDistortions's Avatar
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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    Quote Originally Posted by Power Me Up View Post
    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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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    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.

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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    Quote Originally Posted by WalkIntoTheLight View Post
    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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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    Quote Originally Posted by MidnightDistortions View Post
    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...
    Firmware Developer for the UltraSmartCharger: Open Source Charger/Analyzer for NiMH/NiCad/NiZn batteries.
    http://www.ultrasmartcharger.com

  30. #30
    Flashaholic*
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    Default Re: All my eneloop XX 2500 mAh batteries dropping like flies

    Quote Originally Posted by Power Me Up View Post
    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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