ArmyTek        
Page 1 of 2 12 LastLast
Results 1 to 30 of 37

Thread: Are NiMH Batteries Dying Out?

  1. #1

    Default Are NiMH Batteries Dying Out?

    Hi there,



    NiMH Batteries are pretty useful, but I feel like they tend to die out, which is a real shame in my opinion. The primary use of these cells are small electronic devices and flashlights. But these days more and more devices are sold with integrated Li-ion batteries for obvious reasons:



    - They are cheaper to manufacture
    - Li-ions are easier to charge
    - The energy density is higher (NiMH: 140–300 Wh/L vs. Li-ion: 250–676 Wh/L according to Wikipedia)
    - Low quality Li-ion batteries are likely able to withstand more cycles than their NiMH counterpart
    - When the Battery is dead, many people will buy a new product instead of just replacing the battery
    ...

    1. Do you think Li-ion batteries are going to replace NiMH ones entirely in the future?

    2. I'm also wondering why NiMH batts were never used in energy storage systems (at least to my knowledge). Ni-Cd batteries were (and probably are) quite common in this kind of application.
    High quality cells like eneloop don't suffer from high self-discharge rates. It's true that NiMH batts lower their charge efficiency when SoC is above 90% (according to AA Cycler http://aacycler.com/post/nimh-charge...gy-efficiency/) but a constant voltage charging algorithm that charges to about 90% SoC would eliminate this inefficiency and extend the battery's cycle life, as he has also shown (http://aacycler.com/post/charge-algorithm-comparison/).
    So I don't see a reason why NiMh batteries aren't suitable for big energy storage applications. Cost maybe?

    3. Does anyone know if Panasonic is going to continue researching NiMH-technology? Or are there other companies that do so?

    Thank you very much for taking the time. And please correct me if I'm wrong with some points

  2. #2

    Default Re: Are NiMH Batteries Dying Out?

    it seems that way, little by little they are phased out.
    i only have 2 lights that still use nimh, in 1 light i use aa in fivemega holder, another light has cells built in, in all new builds i use li ions.

  3. #3
    Flashaholic* ChrisGarrett's Avatar
    Join Date
    Feb 2012
    Location
    Miami, Florida
    Posts
    4,670

    Default Re: Are NiMH Batteries Dying Out?

    I don't think that the AA/AAA form factor, or NiMH batteries are going anywhere too soon.

    They're ubiquitous and zillions of items use the AA/AAA NiMH offerings.

    Flashlights fans are so small a blip on the overall consumer metric, that's we're statistically insignificant.

    Just go into any Costco, BJ, Sam's Club, Lowes, Target, Walmart, Best Buy, Home Depot or the drug store of your choice and look at how many alkaline and even NiMH AA/AAA batteries that they actually have on hand, on any given day.

    Zillions I tell you, zillions.

    Chris
    Convoy: S2, S2+, M1, M2, Fenix: P1D, PD32, HL30, ET: D25C Ti, SF: 6P, ZL: SC-600, Klarus: P2A, Jetbeam: BA-20, Icon: Rogue 1, L3: L10, Xeno: E03, ShiningBeam: I-Mini, Olight: i3s, SWM: D40A, M11R, V11R, Maglite: 6Ds, MMs, Solitaires, LaCrosse BC-700, Maha C-9000, XTAR VP2, MP1S, XP1, MC1+, WP2 II, NiteCore i4, v2.

  4. #4

    Default Re: Are NiMH Batteries Dying Out?

    I still find them useful in the AA format, but mostly for power hungry devices I use in my own home, like video game controllers. Honestly, when it comes to AA flashlights I'd rather run them on disposable, because it's more convenient to chuck a dead cell than carry it around with you. Obviously that doesn't apply to less common batteries. But if the chemistry changed for rechargeable AAs I don't think my feelings about them would change.

  5. #5
    Flashaholic*
    Join Date
    Oct 2012
    Location
    Norcal
    Posts
    2,190

    Default Re: Are NiMH Batteries Dying Out?

    Quote Originally Posted by BattBoi View Post
    2. I'm also wondering why NiMH batts were never used in energy storage systems (at least to my knowledge). Ni-Cd batteries were (and probably are) quite common in this kind of application.
    Nicad probably became used for this purpose because, at the time, it was the only viable alternative to lead acid in situations where lead acid was not feasible (such as if weight and/or if death by sulfation due to partial charges were factors). Nowadays, Li-ion is considered a better lead acid replacement, and LiFePO4 in particular excels in this area.

  6. #6

    Default Re: Are NiMH Batteries Dying Out?

    situation reminds me when nimh came out and were supposed to replace nicd, yet in some applications, (like power tools) nicd were used right untill they were replaced with li ion.

    i'm in construction\building maintenance businesses for over 15 years, i never seen a good quality drill that used nimh, a cheap toys that looked like drills, yes, but not a good quality one.

  7. #7

    Default Re: Are NiMH Batteries Dying Out?

    Nimh batteries aren't dying out at all but more and more electronic devices have gone to proprietary lithium batteries mainly due to size/shape considerations. There are more and more lithium based flashlights and lanterns but in the local stores they still are a minority. The problem with nimh is light manufacturers often tend to be tied in with battery sales and try to not design lights that cant use alkaline batteries we see the higher output ones going to larger alkalines (C & D cells) instead of telling you to use nimh. There is also the lousy selection of chargers for nimh in stores (almost no single channel versions) which often has even better nimh batteries being tortured and failing faster in use because of it.
    Then you have the last 10 years digital cameras going from AA to lithium to being replaced by phones for most people (that use lithium ion batteries).
    There still is a viable market as long as we have battery makers profiting greatly off alkaline batteries and even lithium primary batteries (L91/92) there will be the option for using nimh.

    Personally I've been using 18650 based stuff more for one simple reason in that LED lighting favors the chemistry and also power banks too because it takes 3-4 nimh or boost circuitry to equal lithium ion and nimh cells in series have a chance of being overdischarged damaging 1 or more of the cells in use plus having to juggle and track a lot more batteries that can differ in capacity vs just one lithium ion cell.
    I think the only two things that can spell the demise of nimh is dirt cheap lithium primary batteries (Energizer's patent expires) or a new battery technology that is even more powerful and safe (and cheaper) than lithium ion.
    Fenix Split rings 1400+ sent, SWIVELS now available also!
    Psalm 112:4 Light shines in the darkness for the godly. They are generous, compassionate, and righteous.

  8. #8

    Default Re: Are NiMH Batteries Dying Out?

    Well, I cannot see all device manufacturers moving to Li-ion batteries, by far. Even the integrated batteries of some devices such as Roomba robotic vacuums or Oral-B toothbrushes are still NiMh, not Li-Ion.

    And then there's the fact you can use certain popular types of NiMh batteries as a replacement for disposable batteries, and I don't think we'll run out of devices designed for disposable AA and AAA batteries for a long time. Some of the device makers even acknowledge the existence of NiMh batteries although they ship their devices with disposables:
    - Yamaha has switched at least some of their consumer keyboards from D to AA cells and included a mode for NiMh batteries.
    - A $6 electric toothbrush I bought comes with 2 AAA alkalines, but the packaging specifically states that you can use NiMh batteries.
    - Shure has switched their wireless microphones from 9V to 2 AA batteries and, other than before, now considers NiMh batteries a viable alternative for powering them.
    And there are many more devices still being sold that at least partially are designed for using disposable batteries, but happily take NiMh batteries as well if you charge them externally, such as RC forklifts, wall clocks, cheap LED flashlights, portable cassette digitizers/players, soap dispensers, remotes of robotic vacuums and probably many, many toys.

    So as long as there are disposable batteries, and I think they will be here for decades to come, there will also be NiMh batteries you can replace them with, while you can't do that with Li-Ion batteries because they have a different voltage.

    I think NiMh batteries were never used in energy storage systems because they used to have a lower cycle life. Now they have been superseded by Li-Ions which can be built with a higher cycle life and still cheaper than NiMh's. Yes, Li-Ion batteries used to be more expensive as well, but they have come down in price thanks to electric cars where their smaller weight is important, so they are now the better solution for energy storage as well.

  9. #9

    Default Re: Are NiMH Batteries Dying Out?

    I still see tons of people grabbing 48 packs of AA's at Costco when I'm there. Clearly, there is no shortage of products that use AA's.

    Which makes sense - the manufacturer doesn't need to spend money including a rechargeable battery and charging circuit in cheap devices, and the consumer can change the batteries out as needed.

  10. #10

    Default Re: Are NiMH Batteries Dying Out?

    yes i noticed that too, just few week ago bought an electric sweeper, it uses nimh AA. (old one, same model used sub C cells, and had more power, the new one is weak) but i think it has more to do with cost, and relatively simple charging circuit. existing manufacturing process, and safety, (cheap nimh has almost no chance to explode, cheap li ion otoh, not so uncommon) in time i have no doubt those will use li ion.

    actually nimh rated for more cycles than li ion, 1000 vs 300-500, but it is on paper, in real world to get that many cycles, cells had to be exercised regularly, they are not best to use as long term storage, or back up. sure lsd would help, but iirc lsd nimh came too late to change anything on large scale. they came out already outdated

  11. #11

    Default Re: Are NiMH Batteries Dying Out?

    I thought of this thread when I saw the battery rack in my local supermarket yesterday... surprisingly, most of the slots were empty, and there were just a few choices of AA cells left:
    - 12-packs of Duracell Alkalines
    - Vartha Lithium
    - NiMh rechargeables by Varta and Duracell

    Here it rather seemed to me that Alkalines were dying out rather than NiMh because there were actually more choices of NiMh batteries than Alkalines. ;-)

  12. #12
    Flashaholic* Thetasigma's Avatar
    Join Date
    Nov 2015
    Location
    Michigan, USA
    Posts
    602

    Default Re: Are NiMH Batteries Dying Out?

    This is another reason I went back to Xbox, i can use my NiMH Eneloops in it, the PS4 has a POS Lithium battery pack that can't hold a charge and all packed into a POS controller.

  13. #13

    Default Re: Are NiMH Batteries Dying Out?

    Ridiculous. No, NiMH is here to stay as long as Alkaline is. If anything, Li-ion's grave has been dug. Li-ion cell failures and fires has brought down airlines. The industry is scrambling to find a safer and more stable high-energy density replacement than Li. Get them while you can, Li-ion secondaries days are numbered in the consumer market.

  14. #14

    Default Re: Are NiMH Batteries Dying Out?

    AA batteries are still over 80% of the world market

  15. #15
    Unenlightened
    Join Date
    Mar 2017
    Posts
    1

    Default Re: Are NiMH Batteries Dying Out?

    As far as I know, all Toyota hybrids, other than the (quite rare) plug-in hybrid versions, use NiMH batteries.

    The battery in my 2005 Prius is still working fine, so it seems this battery chemistry is robust.

  16. #16

    Default Re: Are NiMH Batteries Dying Out?

    As long as Xbox controllers take AA batteries there will always be plenty of demand for AA batteries, The Wii is still in use in many homes and that requires a ton of AA batteries, almost every kids toy takes AA or AAA batteries and some toys like Playmation take A LOT of batteries like 6 x AA per toy so that is also a huge demand.

    All Xbox battery packs I have seen are crap and most people complain about these dying after a few months and some of these chargers cost $25-40 each, so they are spending $40 twice a year to replace their console chargers while investing in a decent charger and some rechargeables is money well spent compared to the alternatives.

  17. #17

    Default Re: Are NiMH Batteries Dying Out?

    ^^ I have two friends that bought some variation of xbox rechargeable pack. One set was so bad it would work for only a few hours after a year and the other guys is holding charge for a day of playing tops. My loops last at least 3 if not 4 longer for equivalent in game time between charges and will be doing so for at least 5 to 10 times longer than their packs lasted. All for about $10 less. The guy with the really crappy batteries has now switched to loops. He loves em. He now gets days of battery life instead of hours and he's on more than me. The other guy is too hard headed and just says I already paid for these and they are gonna work right, even when they clearly don't and he complains about it regularly. Oh well. They works handily for me. I still use plenty of nimh powered lights and nimhs in other places. They aren't going anywhere any time soon for me.
    Last edited by Repsol600rr; 03-22-2017 at 11:41 PM.

  18. #18

    Default Re: Are NiMH Batteries Dying Out?

    Quote Originally Posted by chillinn View Post
    Ridiculous. No, NiMH is here to stay as long as Alkaline is. If anything, Li-ion's grave has been dug. Li-ion cell failures and fires has brought down airlines. The industry is scrambling to find a safer and more stable high-energy density replacement than Li. Get them while you can, Li-ion secondaries days are numbered in the consumer market.
    And even reputable manufactures like Samsung. Even them couldn't keep their cells safe with the note 7's. When it comes to Li-ion/polymer; there is no room for errors, geeze. As it stands now though, it's like a tug of war of nimh/alkaleaks and lithium primaries vs Li-ion/poly because due to the fact that when it comes to powering/charging devices. Li-ion's wins, especially in power banks. Good luck trying to charge your device of a AA power bank. It will 1 melt (due to the high amperage draw exceeding the 1A rating) or 2, Those cells will be dead less than an hour and only able to charge your device up to probably 25% depending what you are charging. Speaking of toothbrushes. I recently bought one that takes 2 AA's but before that. I saw one with a built in rechargeable battery that all you have to do is dock the tooth brush and it is charging. Granted that this is a more expensive toothbrush system (100 bucks or so). I went for the 2 AA because it was cheap. But you get the point though. How long before everything will soon have a rechargeable battery built in. What would be the point for AA/AAA format then?

  19. #19

    Default Re: Are NiMH Batteries Dying Out?

    Quote Originally Posted by MarioJP View Post
    And even reputable manufactures like Samsung. Even them couldn't keep their cells safe with the note 7's. When it comes to Li-ion/polymer; there is no room for errors, geeze. As it stands now though, it's like a tug of war of nimh/alkaleaks and lithium primaries vs Li-ion/poly because due to the fact that when it comes to powering/charging devices. Li-ion's wins, especially in power banks. Good luck trying to charge your device of a AA power bank. It will 1 melt (due to the high amperage draw exceeding the 1A rating) or 2, Those cells will be dead less than an hour and only able to charge your device up to probably 25% depending what you are charging. Speaking of toothbrushes. I recently bought one that takes 2 AA's but before that. I saw one with a built in rechargeable battery that all you have to do is dock the tooth brush and it is charging. Granted that this is a more expensive toothbrush system (100 bucks or so). I went for the 2 AA because it was cheap. But you get the point though. How long before everything will soon have a rechargeable battery built in. What would be the point for AA/AAA format then?
    I think it will take either a new rechargeable format/chemistry that is cheaper and safer than current lithium rechargeables and/or government intervention to force alkaline (heavy duty too) battery chemistries to be unacceptable. I don't see battery companies not lobbying heavily to keep alkalines on the market big time so AA is here to stay for now.
    You can't buy something and fuel it cheap with rechargeable any type of cells vs disposable batteries. People don't usually want to buy a $5-$10 light and pay $5-$10 for batteries plus perhaps another $20 for a charger when alkalines will do.
    Fenix Split rings 1400+ sent, SWIVELS now available also!
    Psalm 112:4 Light shines in the darkness for the godly. They are generous, compassionate, and righteous.

  20. #20

    Default Re: Are NiMH Batteries Dying Out?

    As for toothbrushes, my first electric one was a 6 EUR kiddie brush that ran on 2 AAA's (Alkalines included, but rechargeables useable according to the packaging). I bought it intentionally because I didn't have good faith in devices with built-in rechargeables. Unfortunately, the switch broke after about 3 and a half months and rendered the device useless, apart from the fact that there's no replaceable brush heads for it. They replaced it for free but said maybe it came from me using rechargeables in it instead of Alkalines. Well, the replacement brush did the exact same thing, but I didn't bother returning it again. I then bought a Oral-B Vitality toothbrush for 25 EUR which has a built-in rechargeable battery which charges on docking it, as yours does. This one now has lasted me since over 5 years and shows no signs of stopping yet... I only had to replace the brush heads a few times, but these also last for at least a year as long as you buy the original ones.

    I don't think there will ever come a time where everything will have a rechargeable battery built in, unless some common battery-powered items like wall clocks or alarm clocks are completely being phased out. There are still devices which commonly run for a year or longer on one battery or set of batteries, so that it wouldn't make sense to provide a rechargeable from the get-go. Even most "normal" flashlight owners use their flashlights only sparingly so that the batteries last for a long time... so long that flashlights are even given as applications for zinc-carbon batteries over alkalines (sometimes). Though I can see the charger thing being not so bad as you imagine... maybe there will be items that do have a rechargeable battery built in, but don't come with a charger... to recharge them, you would have to connect them to an USB socket, as you do with your phone, which becomes more and more common.

    And I think before the AA/AAA format of batteries dies, there will be probably other, less common battery sizes dying out, like C, D, 9V, AAAA or N. But even that isn't happening right now, although it does get hard to find rechargeables in those sizes already.

    Quote Originally Posted by MarioJP View Post
    Speaking of toothbrushes. I recently bought one that takes 2 AA's but before that. I saw one with a built in rechargeable battery that all you have to do is dock the tooth brush and it is charging. Granted that this is a more expensive toothbrush system (100 bucks or so). I went for the 2 AA because it was cheap. But you get the point though. How long before everything will soon have a rechargeable battery built in. What would be the point for AA/AAA format then?

  21. #21

    Default Re: Are NiMH Batteries Dying Out?

    Next time anyone goes to Home Depot or Toys are Us or any big box retailer take a good look at the bulk packs of AA's for sale. Approx. 80% of the worlds market is the AA format. Probably sell more that 10,000 for every 18650 sold.

  22. #22
    Flashaholic
    Join Date
    Jun 2014
    Location
    Pune(India)
    Posts
    179

    Default Re: Are NiMH Batteries Dying Out?

    AA/AAA cells are here to stay, there are million devices other than torches that use those cells and they are available in everywhere in the world. I really dont think Ni-MH is dying rather its here to stay whether we like them or hate them.

  23. #23
    A&Q Moderator
    Woods Walker's Avatar
    Join Date
    Jun 2008
    Location
    New England woods.
    Posts
    4,262

    Default Re: Are NiMH Batteries Dying Out?

    Sometimes as people progress in this gear hobby they move on to lithium ion. Soon there is a feeling the rest of the world is following but I don't think so. I think LSD NiMH like Eneloops are just fantastic on so many levels. Lithium primaries in CR123/AA/AAA are great in the cold and for other applications. AA/AAA alkalines are all over the earth. Lithium ion is also good but believe AA/AAA NiMH will be here for a long long time. Another thing to consider is some lights using AA NiMH can give lithium ion lights a run for their money. The difference in overall energy between some NiMH and 14500 batteries in terms of watt hours can be negligible. Then again who knows?
    The TK20. Yes it still rocks.

  24. #24

    Default Re: Are NiMH Batteries Dying Out?

    Quote Originally Posted by Chaitanya View Post
    AA/AAA cells are here to stay, there are million devices other than torches that use those cells and they are available in everywhere in the world. I really dont think Ni-MH is dying rather its here to stay whether we like them or hate them.

    All one has to do is go to the scientific publications and you will see just how many research papers are currently being published each year on NiMH research. Literally hundreds every year. We forget that we are consumers playing with flashlights. There is a whole other world out there. We are but a tiny, tiny, tiny fraction of the battery market. How many TV remotes (per household) do you think are out there are compared to flashlights?

  25. #25

    Default Re: Are NiMH Batteries Dying Out?

    Quote Originally Posted by chillinn View Post
    Ridiculous. No, NiMH is here to stay as long as Alkaline is. If anything, Li-ion's grave has been dug. Li-ion cell failures and fires has brought down airlines. The industry is scrambling to find a safer and more stable high-energy density replacement than Li. Get them while you can, Li-ion secondaries days are numbered in the consumer market.
    I hope you're right. I prefer primaries over li ion because I dread charging them. The trouble is most flashlights are being designed for li ion now. They may take primaries but often at dangerously high current. I don't like charging NIMH either. They get hot. I don't like that. Yes I have several NIMH chargers including a Nitecore but the batteries get hot in all of them. I prefer throw away batteries.

  26. #26
    Flashaholic
    Join Date
    Sep 2011
    Location
    Somewhere in Hastings florida.
    Posts
    278

    Default Re: Are NiMH Batteries Dying Out?

    Yeah, I really don't think NiMH is dying. Like others have said, items are still being made that use AA-AAA cells. Such as my Xbox controllers, the cheap li-ion rechargeable pack that I got with it for the controller is only 1400 mAh, while my eneloops are 2000. I've never had a NiMH overheat on a good charger.
    Plus using NiMH for almost 10 years now, all the money I've saved on not buying throw away alkaleaks.

  27. #27

    Default Re: Are NiMH Batteries Dying Out?

    Quote Originally Posted by recDNA View Post
    I hope you're right. I prefer primaries over li ion because I dread charging them. The trouble is most flashlights are being designed for li ion now. They may take primaries but often at dangerously high current. I don't like charging NIMH either. They get hot. I don't like that. Yes I have several NIMH chargers including a Nitecore but the batteries get hot in all of them. I prefer throw away batteries.
    In a while I will explain in more detail why they get got during charging. It has to has to do with overcharging and the generation of oxygen gas in the cell at the end of the charging cycle. The oxygen is recombined by the electrode giving off heat (exothermic reaction). This is a special feature designed into the battery to help prevent swelling and venting of the cell. If the battery is getting hot towards the end of the charge it means you have a bad or cheap charger which is not terminating in time. You are overcharging and the recombination of Oxygen cannot keep up and you are effectively ruining the cell. NiMH is a great technology. Unfortunately because they don't explode and cause fires people abuse them and are unwilling to learn how to charge them properly. Cheap chargers are just that CHEAP!!!!. Although they have a lower energy density than Li-ion they have a higher specific, are much safer and have a cycle life of approximately 10X more (unless you are using a $20 charger). Manufacturers do not have to make good NIMH chargers since the recharging cycle, in principle, is not dangerous and 99% of the consumers will never be aware that they are gradually ruining their batteries with every recharging cycle. No consumer grade test equipment will detect a %2 decrease in charge but even 10 cycles later you have already lost a significant amount of capacity (for good if you were overcharging). With proper charging NiHM actually increases in capacity during the first 200 charges. So if you are loosing capacity before that, guess what?
    Last edited by Lumencrazy; 03-25-2017 at 12:37 PM.

  28. #28

    Default Re: Are NiMH Batteries Dying Out?

    Quote Originally Posted by chillinn View Post
    Li-ion secondaries days are numbered in the consumer market.
    I don't think so... pretty much all of the mobile phones, smartphones, tablets and laptops you can buy now come with Li-Ion secondaries and people are used to using them. Surely mishaps happen like the Note 7 or the flaming hoverboards, but they still are the vast minority against probably millions of other devices sold each day which succesfully employ Li-Ions.

  29. #29

    Default Re: Are NiMH Batteries Dying Out?

    Quote Originally Posted by recDNA View Post
    I hope you're right. I prefer primaries over li ion because I dread charging them. The trouble is most flashlights are being designed for li ion now. They may take primaries but often at dangerously high current. I don't like charging NIMH either. They get hot. I don't like that. Yes I have several NIMH chargers including a Nitecore but the batteries get hot in all of them. I prefer throw away batteries.
    Most flashlights? Depends on where you look. If you're an ordinary consumer who doesn't do much with flashlights, you can still see lots of them in supermarkets and department stores powered by alkalines. Surely they've become more modern as well... they are now LED lights which probably pump out the same lumens from AAA or AA alkalines which were formerly produced by incandescent bulbs using C or D cells, but they don't use dangerous currents at all.

    As has been said, the reason the NiMh get hot is that there's a standard charging procedure (-dV) where they actually get overcharged, and this is because unlike with Li-Ion you can get away doing this to NiMh's without risking a fire or explosion, so that the charger manufacturers didn't do more than necessary in order to keep costs down. This approach might be necessary in multi-cell packs to keep the cells balances, but if you charge the cells separately, one could charge them using a similar algorithm as for Li-Ion cells, and then they wouldn't get hot. I think HKJ once even tested a charger which takes both chemistries and does charge the NiMh's using the same approach as for Li-Ions, which is also much easier on the batteries.

  30. #30

    Default Re: Are NiMH Batteries Dying Out?

    Quote Originally Posted by Kurt_Woloch View Post
    Most flashlights? Depends on where you look. If you're an ordinary consumer who doesn't do much with flashlights, you can still see lots of them in supermarkets and department stores powered by alkalines. Surely they've become more modern as well... they are now LED lights which probably pump out the same lumens from AAA or AA alkalines which were formerly produced by incandescent bulbs using C or D cells, but they don't use dangerous currents at all.

    As has been said, the reason the NiMh get hot is that there's a standard charging procedure (-dV) where they actually get overcharged, and this is because unlike with Li-Ion you can get away doing this to NiMh's without risking a fire or explosion, so that the charger manufacturers didn't do more than necessary in order to keep costs down. This approach might be necessary in multi-cell packs to keep the cells balances, but if you charge the cells separately, one could charge them using a similar algorithm as for Li-Ion cells, and then they wouldn't get hot. I think HKJ once even tested a charger which takes both chemistries and does charge the NiMh's using the same approach as for Li-Ions, which is also much easier on the batteries.
    There is an oxygen recombination chemistry that is absolutely fundamental to NiMH technology, and just voltage change is not fast enough to be accurate. One needs to go to the technical literature where this is explained in detail. You can use all kinds of algorithms that seem to work (by our inability to measure accurately) but there is also the correct way. For this I can recommend "Lindens Handbook Of Batteries 4th edition." There is an entire section on NIMH chemistry. Electrode and separator design and every chemical reaction that occurs during the charging process. Bring along some organic and inorganic chemistry books for reference.
    Last edited by Lumencrazy; 03-25-2017 at 01:13 PM.

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •