Lithium Ion hold significantly more charge than NiMH?

Discussion in 'Digital Cameras' started by void, Nov 21, 2006.

  1. void

    void Guest

    I was in Best Buy today, looking at the Canon A540 and SD600. The A540
    takes 2 AA batteries, and the SD600 takes one of those rectangular Lithium
    Ion batteries. A couple of Best Buy employees said that the Lithium Ion
    battery holds a lot more charge than NiMH batteries. They said the SD600
    camera would be able to take around 200 shots before the battery ran out,
    while the A540 would only be able to take around 30-40 shots before the
    batteries ran out.

    I am extremely skeptical of what they said. If what they said is true,
    then there is no reason why any camera on the market today would take AA
    batteries instead of the Lithium Ion battery.

    So were they right or wrong?
     
    void, Nov 21, 2006
    #1
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  2. void

    Pete D Guest

    Strictly speaking they are wrong, the NiMh batteries may well be larger in
    capacity but as the stored charge is used the voltage will drop and
    particularly in cameras this can be a problem, LIon batteries on the other
    hand should hold a higher voltage as the stored charge reduces and therefore
    may keep operating even though the stored charge is less.
     
    Pete D, Nov 21, 2006
    #2
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  3. Neither. Each battery has its advantages and disadvantages.

    NiMH AAs can be swapped out easily, and they're inexpensive to buy, but
    store less energy than the Li Ion batteries.

    Li Ion batteries are quite expensive, even if they are designed to be
    swapped out. But they do have a higher energy density.

    My camera is an A540. and it takes NiMH AAs. You can also put Alkaline
    batteries in this camera in a pinch, but they don't last too long. Takes
    non-rechargeable Lithium batteries also.
     
    Pat O'Connell, Nov 21, 2006
    #3
  4. void

    Bill Guest

    They were wrong, but not for the reasons mentioned. The sales geeks
    got their info mixed up.

    Using Alkaline AA cells is a bad idea because they are not high
    current discharge capable like rechargeables, so they tend to work for
    only a few dozen shots before their voltage level drops enough that
    they appear dead to the camera. Allowing Alakaline cells to "rest" for
    a while may help get a few more shots, but they're simply a poor
    choice for high current devices like cameras.

    The Li-Ion and Ni-MH cells can produce higher current levels and the
    camera makes better use of their performance.
    No, strictly speaking they were RIGHT. Lithium-based batteries have a
    higher charge density per weight than any other rechargeable cell.

    The problem is the confusion with AA and rechargeables.
    I'm sorry but you're wrong again.

    Li-Ion discharge voltage also drops, but in a more steady drop (linear
    curve) than Ni-MH or Ni-Cad cells, which tend to dip, then level off,
    then drop off at the end of charge (stepped curve). Li-Ion drops
    steadily and smoothly as the charge level drops - they do not hold
    voltage levels while discharging at all.

    Please research battery technology from reputable sources before
    spreading incorrect information. We already have enough misinformation
    about technology as it is.

    I once had to do research into various battery technologies for a
    work-related contract purchase. If you want specific quotes, try
    places like:

    http://www.hardingenergy.com/

    http://www.electricitystorage.org/
     
    Bill, Nov 21, 2006
    #4
  5. void

    Pete D Guest

    Perhaps you should learn to interpret your infomation sources better. What I
    said still stands up.

    Cheers.

    Pete D
    NiMH Voltage

    The discharge voltage profile of a NiMH battery is considered “flat” (see
    Figure 3.7.2 C/10 Discharge

    Profile @ 25°C) and varies with the rate of discharge and temperature. As a
    fully charged battery is

    discharged the voltage begins at about 1.5 volts followed by a sharp drop to
    around 1.3 volts. The

    voltage remains between 1.3 to 1.2 volts for about 75% of the profile until
    a second sudden drop in

    voltage occurs as the useful capacity of the battery begins to deplete.



    Lithium Ion



    5.4 Rate Capability

    Table 5.4.1: Charge/Discharge Chemical Reactions

    Typical Performance Characteristics of Lithium Ion Batteries



    5.5 Discharge Characteristics

    At a constant current discharge rate, the lithium ion battery maintains a
    relatively flat voltage discharge profile

    with a steep decrease in the profile near the end of discharge. The battery
    should not be discharge to less than

    3.0 volts per battery.
     
    Pete D, Nov 21, 2006
    #5
  6. void

    SMS Guest

    The Best Buy employees are full of it. According to
    "http://www.dcresource.com/reviews/canon/powershot_a540-review/" the
    A540 is good for 360 shots, while the SD600 was rated at 160 shots.
    I wouldn't expect the employees of the big-box electronics retailers to
    know anything about the products they are selling, other than which
    products have the better spiffs.
    Sure there is. If there was a Li-Ion pack the same size as the two AAs
    in the A540, then the A540 would get about 500 shots from a battery. The
    reason the manufacturers use AA batteries is because it saves them the
    expense of providing a rechargeable battery and charger. The AA
    batteries are less energy dense for a given weight and volume, and have
    other performance issues that may or may not be important considerations
    for you, but the main reason they are used in the low-end cameras is
    because they're cheap.
     
    SMS, Nov 21, 2006
    #6
  7. void

    ASAAR Guest

    Typical store drones that have no qualms about spouting
    disinformation. They probably have no idea how many shots the A540
    can take and might even be playing games with customers. The next
    one might be told just the opposite. Canon, like many other camera
    manufacturers is conservative about evaluating battery life, using a
    test based on the CIPA standard test procedure, which among other
    things takes each shot after fully zooming the lens, and every other
    shot uses a full power flash. The manual for the A530/A540 states
    that it's good for 90 shots using alkaline batteries or 360 shots
    using NiMH AA batteries, in both cases with the LCD monitor turned
    on. If the LCD monitor is turned off and the viewfinder is used
    instead, alkalines are good for 600 shots and NiMH batteries are
    good for 1000 shots per charge. These last numbers may not be using
    the CIPA procedure, so perhaps the flash wasn't used for them. But
    in any case, if a salesman tries to compare the SD600 using Li-Ion
    batteries, the A540 should be compared using NiMH rechargeable
    batteries, and whether you use the CIPA test results of 360 shots or
    the less stringent test getting 1000 shots, the SD600 with its
    unspecified 200 shots falls far behind. Dpreview hasn't reviewed
    the SD600, but their review of the SD550, which uses an NB-3L Li-Ion
    battery says "Battery life when using LCD not fantastic" and:
    So it's very likely that the SD600 gets about 1/2 the number of
    shots per charge than the A540 gets, under similar conditions. High
    quality name brand NiMH batteries are much cheaper than Li-Ion
    batteries, and you can get good "smart" chargers that can recharge
    the NiMH AA cells in as little as 15 minutes.

    One other thing to consider. Some people have preferred Li-Ion
    batteries because they could hold a charge far longer than
    traditional NiMH batteries before they need to be recharged, due to
    self-discharge losses. Sanyo and RayOVac have a new type of NiMH
    battery that can go 3 or 4 times longer between charges than Li-Ion.
    Sanyo's are called "Eneloop" batteries, and RayOVac's are called
    "Renewal" batteries (not to be confused with their older, dismal
    "Renewal" alkaline batteries). These new NiMH cells can retain much
    of their initial charge even after sitting on a shelf for up to two
    years, and when charging, any standard NiMH charger can be used.
    Unlike most NiMH batteries that require charging before their first
    use, these new NiMH types state on their packaging that they're
    precharged and can be used immediately.

    Your skept-O-meter is working and well calibrated. :)
     
    ASAAR, Nov 21, 2006
    #7
  8. void

    Bill Guest

    Hardly.

    Read your own words again:
    You said the above, but those are opposites.
    It must be one or the other.

    I know that Ni-MH has a "flat" curve in relation to it's overall
    discharge rate, but it has two large drops in voltage at the beginning
    and end of it's curve - a stepped curve, which is also what I said in
    my last post. Your quoted material merely confirms that.
    You don't specify where you got the info, but it is incorrect:

    http://www.hardingenergy.com/faq.htm

    " The Li-Ion voltage will have a linear decreasing voltage from
    4.2-3.0V."

    While the overall curve is very gradual, it's still a linear and
    steady curve. Ni-MH has a lower voltage drop over the charged and
    discharged states - 0.4v per cell. Li-Ion has a 1.2v drop over it's
    discharge curve.

    I had to research and evaluate this stuff for weeks. But again, you
    can interpret and believe whatever you want.
     
    Bill, Nov 21, 2006
    #8
  9. void

    Pete D Guest

    Actually it is the drops that I was refering to and is the first one that
    many cameras do not like.

    From the URLs that you posted.
     
    Pete D, Nov 21, 2006
    #9
  10. void

    void Guest

    Thanks for the responses everyone!
     
    void, Nov 21, 2006
    #10
  11. void

    ASAAR Guest

    That's nothing. I have some NiMH batteries that take only 4
    minutes to go from flat to a full charge!

    (Unfortunately, that's with my 3 hour charger. If you want to
    know why I didn't dispose of them last year, I'll have to consult
    with my inner packrat.)
     
    ASAAR, Nov 21, 2006
    #11
  12. void

    Mueen Nawaz Guest

    Less energy? Most Li-ion batteries I've looked at (not many,
    admittedly) are rated at less than 2500 mAh. Finding 2700 mAh NiMH
    batteries is quite trivial.

    --
    Intaxication: Euphoria at getting a tax refund, which lasts until you
    realize it was your money to start with.


    /\ /\ /\ /
    / \/ \ u e e n / \/ a w a zanl
     
    Mueen Nawaz, Nov 22, 2006
    #12
  13. void

    ASAAR Guest

    It's impossible to compare Li-Ion with NiMH if you only have the
    mAh rating, since no Li-Ion batteries supply 1.2 volts. But in many
    cases (as you note) the Li-Ion batteries do provide less energy than
    many people would guess. Here's an example.

    The energy that batteries contain is roughly proportional to the
    battery voltage * mAh, and multiplying them provides the capacity in
    Watt Hours. As dpreview notes*¹, Canon's original 7.4 volt BP-511
    battery had an 8 WattHour rating, and the improved BP-511A, used in
    the G6 and 300D, due to its higher 1390 mAh capacity reaches 10.3
    WattHours. In a weird move, Canon supplies their G7, 350D and the
    new 400D with the smaller NB-2LH battery. It's 1.3 oz. lighter but
    at only 720 mAh and 7.4 volts manages only a 5.3 WattHours. That's
    a mighty poor tradeoff, especially for anyone that routinely carries
    one or more spare NB-2LH batteries.

    Compare this with a set of four 2700 mAh AA batteries, as used in
    Canon's smaller A620/A630, which provide 4 * 1.2 * 2700 == 13
    WattHours. This is 26% more energy than Canon's heftier BP-511A
    provides, and 145% more energy than the NB-2LH.

    http://www.dpreview.com/reviews/canong6/page4.asp
     
    ASAAR, Nov 22, 2006
    #13
  14. void

    ASAAR Guest

    Is it really "twice (or more) the weight"? Even if it is, saving
    that extra 1.3 ounces is (as I said) a mighty poor tradeoff for
    getting virtually double the battery life. I'll bet that if Canon
    shaved off another ounce from their Li-Ion battery few would be
    amused. And don't forget, the smaller the battery, the more likely
    it is that the photographer will need to compensate by carrying
    another battery or two, negating the reduced battery size and
    raising the total amount of money sunk into batteries. Saving an
    ounce can make sense for a small P&S, but even lightweight DSLRs
    such as the 350D and 400D will often be used with lenses other than
    the smallest, lightest fixed focal length or kit lenses and other
    "stuff". Canon's decision to cut the battery capacity in half
    brings to mind the familiar "penny wise and pound foolish". <g>
     
    ASAAR, Nov 22, 2006
    #14
  15. But LiIon cells are much higher voltage. Energy is volts times
    amp-hours. A 900 mAh LiIon cell at 3.6 V is the same amount of energy
    as a 2700 mAh NiMH cell at 1.2 V. Another way of looking at it: you
    need 3 1.2 V NiMH cells to equal the energy of one LiIon cell if both
    have the same mAh rating.

    As a general rule, LiIon and NiMH actually store about the same amount
    of energy per unit *volume*. LiIon is much better per unit *mass*,
    since they are so much lighter than NiMH (and alkaline).

    Dave
     
    Dave Martindale, Nov 22, 2006
    #15
  16. void

    Mueen Nawaz Guest

    Thanks for the correction - I did not know they had different voltages.
    My old Olympus took both, and so I assumed they had the same voltage.

    --
    As a child my family's menu consisted of two choices: "Take it, or leave
    it."


    /\ /\ /\ /
    / \/ \ u e e n / \/ a w a zanl
     
    Mueen Nawaz, Nov 23, 2006
    #16
  17. void

    ASAAR Guest

    ??? Are you sure about this? If the Li-Ion cells were connected
    in parallel they wouldn't be providing a voltage in that high 6-8V
    range, but at a lower voltage comparable to what the four NiMH cells
    could provide. Which camera(s) were they? DSLRs?

    One way for cameras to more efficiently use alkaline batteries
    would be to use circuits such as the ones used in Energizer's CHAA
    and CH2AA chargers that use one or two lithium or alkaline AA
    batteries and are used to recharge cell phones in the field.
    Energizer claims "87% typical electronic converter efficiency" and
    says that they can keep providing a 5 volt charging current even
    when the AA cells have dropped to 0.6 volts. The single AA version
    charges at up to a 320ma rate and the two AA version at up to 600ma.
    Circuits such as these would allow cameras to get almost as many
    shots from alkaline cells as from NiMH, where NiMH typically lasts 2
    to 4 times longer than alkaline cells.
     
    ASAAR, Nov 23, 2006
    #17
  18. void

    ASAAR Guest

    Ok, that makes sense. But two parallel pairs is quite different
    than "two cells in parallel". The only Oly battery I've seen is the
    BLM-1 which is rated at 7.2 volts and as far as I can tell is
    constructed using only two cells. You added "or the 6-8V
    from 2 paris of LiIon" at the end of the paragraph, but it
    conflicted with the earlier "two cells in parallel", hence my "???".

    Obviously. In another recent reply I mentioned the similar energy
    version, WattHours == Volts * AmpHours (giving examples using the
    battery mAh ratings). Your reason for mentioning this is ... ???

    Totally wrong. First, an alkaline "battery" contains more than
    one cell. But that's a nit. An alkaline cell does not always
    produce 1.5 volts. Fresh alkaline batteries can, if they're not
    heavily loaded, causing an internal voltage drop due to internal
    resistance. Second, Energizer's data sheets state that the
    efficiency (and I quoted it) is 87%, which is extremely efficient.

    You evidently have no idea what I was talking about. Where did
    you imagine that anything was said about buffering alkalines? Check
    the data sheets on Energizer's web site to see what their CHAA and
    CH2AA charging devices are all about. They're intended to be used
    in conjunction with Li-Ion powered cell phones, and can either
    charge the cell phone's internal power pack or help power the cell
    phone while it is being recharged. If anything can be considered to
    be buffered, it's the cell phone's battery (often a single cell),
    not the AA cells in the external charger which are buffering or
    charging the cell phone. Ultra capacitors weren't mentioned and as
    far as I can tell aren't used in Energizer's charging devices. Are
    they in any way relevant? FWIW, the Energizer chargers are widely
    available in many pharmacy/convenience stores, electronics/camera
    stores, etc. The CH2AA sells for about $20 and includes a pair of
    lithium AA cells. Join me in another several cups of coffee. You
    appear to need a jolt of some caffeine. :)
     
    ASAAR, Nov 23, 2006
    #18
  19. void

    if Guest


    My camera has a 3.7V 1150mA lithium ion cell. It is exactly the same
    overall size as 3xAAA NiMH cells which give 3.6V & 900mA. So the lithium
    ion gives about 25% more power, but costs 3 times as much. In my view the
    litium ion thing is a rip off, and more camera manufacturers should provide
    contacts for AAA as an alternative. Some cameras (eg. Ricoh GR) do give
    this option so it is certainly viable, and a very useful backup.



    --
    _______________________________________________________

    When you make your mark in the world, watch out for guys with erasers.
    -- The Wall Street Journal
    _______________________________________________________
     
    if, Nov 25, 2006
    #19
  20. void

    if Guest

    Someone mentioned lithium ion being lighter than NiMH. Well I just put the
    above batteries on the kitchen scales, not very accurate at this weight
    range but the lithium are indeed a bit lighter, maybe 30g compared to about
    40g for the NiMH. Not really worth bothering about unless your camera takes
    a much bigger battery pack.


    --
    _______________________________________________________

    When you make your mark in the world, watch out for guys with erasers.
    -- The Wall Street Journal
    _______________________________________________________
     
    if, Nov 25, 2006
    #20
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