NiMH Chargers that I May Have Missed

Discussion in 'Digital Photography' started by SMS, Jul 2, 2007.

  1. SMS

    SMS Guest

    I'm updating my charger web site (http://nordicgroup.us/chargers) and
    was hoping that if anyone knows of any chargers I've missed that meet
    the following criteria, that they will let me know:

    Criteria for Inclusion
    ----------------------
    -Unbundled price of $60 or less
    -Minimum of 600mA current per AA cell in fast charge mode
    -Individual charging circuits for each cell (as opposed to requiring
    charging in pairs)
    -AC and DC power input possible, preferably with car cord included.


    I'm especially interested in any other models that have a built in AC
    power adapter (flip out plug) but that still have a jack for a car cord,
    and that still meat the other criteria. These types of chargers seem to
    be rare.

    I'm also interested in models that can be plugged into a USB port that
    still meet the other criteria.

    So far the only charger I've found that has a flip-out AC plug, USB
    capability, as well as the other criteria, is the Tenergy T60008, but
    this charger has a relatively low charge current (good for battery
    longevity, but it takes a long time to charge). Hopefully there are some
    others as well.

    Steve
    http://nordicgroup.us/chargers
    http://batterydata.com
     
    SMS, Jul 2, 2007
    #1
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  2. SMS

    Dave Cohen Guest

    You missed the one I use from Green Batteries
    http://www.greenbatteries.com/nibachwilcdd.html

    It says 1.6A for AA's, which I would guess is for 4 cells so it might
    miss your 600 ma number, but I'm not sure why you would want to make
    that restriction. This one is cheap (why I got it), monitors each cell
    with lcd charge state indicators and does AAA's as well as NiCd. Comes
    with AC and 12v auto cord. Works fine and they have excellent service.
    Dave Cohen
     
    Dave Cohen, Jul 2, 2007
    #2
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  3. SMS

    SMS Guest

    Less than 600 mA and the charging is really slow. However too high a
    current is undesirable as well, as the fast charging causes
    significantly reduced battery life due to the heat generated by the fast
    charging.

    The Maha MH-C9000 is ideal, allowing fast charging when absolutely
    necessary, but allowing lower current charging when the fast charging
    isn't needed.

    If the Green Batteries charger is charging high capacity batteries in
    two hours then the 1.6A refers to the current through each battery, and
    the charge rate is too high.

    I've taken out all the chargers that don't allow charging at 1000mA or
    less, it's just too damaging to the batteries. I know that many people
    will say that NiMH batteries are now cheap enough that it just doesn't
    matter if the life is reduced by high current charging, and there is
    some truth to that, but most people don't need to be doing high current
    charging all the time.
     
    SMS, Jul 2, 2007
    #3
  4. The MH-C9000 suggests charging at 0.5C to 1.0C, which means for a typical
    2500mAh battery, the battery can be charged at 1.3A to 2.5A. Since the
    MH-C9000 only goes to 2.0A per cell, I guess all out is fine for a battery of
    such capacity. To get the longest life on your battery, the low end is best,
    so the lowest you want to charge based on the recommendations for this charger
    is 1.3A! Why you might ask? Well, apparently the delta temperature and delta
    voltage tests can sometimes fail if outside of this range resulting in a
    battery that is over charged.
    If you note above, it isn't true about 1000mA or less being the only "safe"
    range for a battery. In fact, it is worth noting that according to the
    MH-C9000 manual, it is not recommended to charge batteries of capacity greater
    than 2000mAh at less than 1.0A. An exception of course being the IEC forming
    charge.
     
    Thomas T. Veldhouse, Jul 3, 2007
    #4
  5. SMS

    SMS Guest

    Thomas T. Veldhouse wrote:

    When I read the MH-C9000 manual it stated:

    "Choosing the right charging & discharging rate

    Charging at a rate below 0.33C and above 1.0C is not recommended.

    Charging too slow may prevent the charger from terminating
    correctly.

    Charging too fast may damage the battery.

    Typically speaking, slower charging rate will yield better battery
    performance but requires longer time. Faster charging rate may not
    charge as fully and battery temperature can be higher."

    0.33C on a 2700 mAH battery would be 900 mA.

    I wonder if the 0.5C was a change they made because they discovered a
    problem with the way the MH-C9000 detects temperature and voltage, or if
    the on-line manual is newer and they fixed the problem so now 0.33C is
    acceptable. The on-line manual says "Copyrighted ® 1998-2007 Maha Energy
    Corp." What are the dates on your manual that says 0.5C?

    "http://www.mahaenergy.com/download/mhc9000.pdf"

    If the MH-C900 has a problem in detecting end-of-charge with 1000mAH
    charging current then it's a design flaw.
     
    SMS, Jul 3, 2007
    #5
  6. Perhaps you have an older or newer version of the manual, as mine says 0.5C to
    1.0C.
    Could be ... or could be something else. Perhaps to understand the issue and
    to keep your website accurate [?] you should email them and find out.
     
    Thomas T. Veldhouse, Jul 3, 2007
    #6
  7. SMS

    SMS Guest

    Thomas T. Veldhouse wrote:

    What's the copyright date on your manual?

    I checked the PDF date tag on the on-line manual, and its date is
    December 11, 2006.

    I'd assume that Maha keeps the latest manual on-line, but that may be
    too much of an assumption.

    I e-mailed the author of the MH-C9000 manual, William Chueh, with this
    question. If the e-mail doesn't bounce (the address I found was from
    1998), maybe he'll answer.
     
    SMS, Jul 3, 2007
    #7
  8. SMS

    Guest Guest

    I've got a drawer-full of chargers that don't work.
    but
    I'm very happy with my KODAK K6000
    NiMh/Ni-Cad charger.

    It charges AA or AA batterys.
    Does it in an hour.
    Turns itself off when it's done.
    and, most importantly... it actually works !

    <rj>
     
    Guest, Jul 3, 2007
    #8
  9. SMS

    JohnR66 Guest

    I have a Quest Q2 charger. It has a channel for each cell and two color LED
    on each channel indicating charging state. Audible signals indicate end of
    cycle. It goes into a trickle charge mode after normal charge cycle. I don't
    know the current, but it must be in the neighborhood of 600ma. It is 12
    volts, but has external wall transformer. It charges AA and AAAs.
    John
     
    JohnR66, Jul 3, 2007
    #9
  10. SMS

    SMS Guest

    NiMH chargers seem to definitely be something that don't last forever. I
    had two Panasonic chargers go bad. One melted, one had one channel go
    bad. Maybe it's the heat that destroys chargers.

    The Maha MH-C401FS has a "lifetime warranty." Usually such warranties
    are worthless, but in this case it seems to be something that could be
    worthwhile.
     
    SMS, Jul 3, 2007
    #10
  11. SMS

    SMS Guest

    According to "http://www.steves-digicams.com/2001_reviews/quest_q2.html"
    it's only 430mA. That's really low, though for overnight charging it's
    okay.
     
    SMS, Jul 4, 2007
    #11
  12. SMS

    Wayne Guest


    The newly revised Maha C-9000 (says 0G0GB01 on the label - a few months ago)
    manual has been revised to now say to charge at 0.5 to 1.0 C, in order to
    detect delta V cutoff more reliabily. Actually, I'm not certain it is still
    delta V, but the early two versions (0FAB01 or 0FAB02) didnt always do all
    that well on shutoff termination at lower currents. Both the charger and
    the recommendation were changed for this problem. I believe Maha will
    replace older versions.
     
    Wayne, Jul 4, 2007
    #12
  13. SMS

    SMS Guest

    So they couldn't meet the specs, so they changed the specs. I guess it's
    not a terribly big deal, 0.5C is 1350 mA for 2700 mAH batteries, a
    little high in terms of maximizing battery life, but not as bad as 2000 mA.
     
    SMS, Jul 4, 2007
    #13
  14. I just checked and I didn't see a date anywhere, other than a copyright for
    2007. It does most definitely list 0.5C to 1.0C though. I just tried a
    charge at 0.4C without incident so, perhaps the online PDF is correct and the
    manual I have is incorrect.
    Please, let us know the response.
     
    Thomas T. Veldhouse, Jul 5, 2007
    #14
  15. Can you support that claim [that it is a little high for maximizing battery
    life]?
     
    Thomas T. Veldhouse, Jul 5, 2007
    #15
  16. SMS

    Wayne Guest

    No, they revised the chargers termination procedure, which is now version
    0G0B01 on the rear label (my typo before). Maha has been replacing older
    units 0FAB01 or 0FAB02. Apparently NiMh cells don't have much of a delta V
    peak at low currents, which risks overcharging if missed. It can still be
    set as low as 200 mah, and they left the default charge rate at 1000 mah,
    unless changed, but the printed recommendation now is 0.5C to 1.0C. Another
    related change is that it used to charge up to about 20000 mah unless
    terminated, and now it shuts off after 4000 mah.

    The definitive place the Maha C-9000 charger is discussed is at
    http://www.candlepowerforums.com/vb/showthread.php?t=140144

    However that long thread starts off very old (Nov 2006), about the initial
    units. The 0G0B01 update was maybe about March 2007. WillChueh of Maha was a
    participant in that thread, and on that forum in general.

    The Maha C-9000 is a fantastic charger.
     
    Wayne, Jul 5, 2007
    #16
  17. That doesn't make a lot of sense. If the limit is set to 4000 mAh before
    termination, then there will be no way to charge high capacity batteries
    should they become available [i.e. greater than 3000mAh]. Granted, the
    likelihood of significant capacity growth with this particular chemisty is
    rapidly diminishing, but never-the-less.
    I like it ... but the 4000mAh limit disturbs me a bit.
     
    Thomas T. Veldhouse, Jul 5, 2007
    #17
  18. SMS

    Wayne Guest


    The most you would ever have to do is to restart the charge (remove and
    reinsert the battery), for a second 4000mah. Like if you rigged some adapter
    to charge D cells. But it has never been any issue here, my largest
    batteries are 2700mah AA.
     
    Wayne, Jul 5, 2007
    #18
  19. Of course, that is ludicrous. Especially if you program several cycles or do
    a refresh analyze. There are already 2900mAh batteries available and such a
    battery is already brushing up against the 4000mAh charging capacity limit.

    Afterall ... this is how it was sold to me by Thomas Distributing!

    "Question: Does the MH-C9000 battery charger have any limit on rechargeable
    battery capacity ?

    Answer: Answered by: William Chueh of Maha Energy : The micro controller can
    support higher capacity batteries without any problem (however the capacity
    calculation limit is 20,000mAh)."
     
    Thomas T. Veldhouse, Jul 5, 2007
    #19
  20. SMS

    Wayne Guest


    I think you may be worrying about imagined problems instead of actual
    problems. It does not seem to be any problem for AA cells, and of course, it
    does not support larger cells. For example, the competitive Lacrosse BC-900
    only allows 3000 mah. The Maha costs more, but runs circles around it in
    several ways, doesnt seem to burn up for one. :)


    20,000 mah was true then about the first two revisions, 0FAB01 or 0FAB02.
    But the updated 0G0B01 version has been sold after March, and it cuts off at
    4000 mah now. There were a few NiMh termination problems in the first two (at
    lower charge rates), and Maha is replacing those with the newer one. The delta
    V termination parameters were changed, and also this 4000 mah safety
    termination was added. I see it as a good thing.

    The manual also says 1 hour delay between discharge and recharge in the
    Recycle mode, which was true then, but the 0G0B01 is two hours now. The
    manual was only revised about the 0.5 to 1.0 C recommended charge rate.
     
    Wayne, Jul 5, 2007
    #20
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