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  1. #1
    Flashaholic* modamag's Avatar
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    Default Eneloop & Enduro LSD Duration Testing (60 days update)















    === Testing Details ===
    1. Cells repeatedly formed @ 200mA for 16 hr to determine "max" capacity.
    2. Charging method:
    - LaCrosse 200mA pre-charge (allow minimal resting time difference)
    - Triton final-charge with 5mV dT (assure the same end charge condition)
    3. Standard storage at room temperature (Bay Area/CA) 65-80F (18.3-26.7C).
    4. Frozen storage at refrigerated temperature 10F (-12.2C).
    5. Frozen cells are thawed for 8-10 hrs prior to testing.
    6. Discharge rate of 1.0 A
    7. CBAII Details:
    - Software version 1.0.8.1
    - 0.019V offset
    - (-)8mA offset
    - Temperature
    - Powerpole to Battery Test Clamp


    === Interpretation ===
    Vavg - voltage average - higher value result in brighter output in the same "unregulated" light.
    Delta Vavg - how much Vavg change over storage time.
    Vsd - voltage standard deviation - larger value result in more constant output.
    Delta Vsd - how much Vsd change over storage time.
    Current Capacity - how much capacity you'll really get @ 1A discharge.
    Delta CC - how much CC change over storage time.
    Power Capacity - how much power capacity you'll really get @ 1A discharge.
    Delta PC - how much PC change over storage time.
    Runtime - how long you'll get the constant 1A discharge.
    Delta RT - how much RT change over storage time.


    === FAQ ===
    Last edited by modamag; 08-10-2006 at 06:14 PM. Reason: Updated with 60 days data

  2. #2
    Flashaholic* Trashman's Avatar
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    Default Re: Low Self Discharge Duration Testing


  3. #3
    Flashaholic* CroMAGnet's Avatar
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    Default Re: Low Self Discharge Duration Testing

    I like my Titanium 2700 NiMHs but let's see you leave them in a light in the closet for six months! But isn't that what L91's are for?

  4. #4

    Default Re: Low Self Discharge Duration Testing

    Quote Originally Posted by modamag
    Well, all this hupla about low self discharge cell have got me going.
    I was lucky enough to get a small sample from Amondotech (Thanx Wayne) for testing.

    I want to conduct compare them versus your typical 2500 mAh cell of the day to see where the strong and weak points are.

    I will be adding new data set as time goes on. Let's see if these are really low discharge.

    OK, let the graph speaks ...


    Pretty weak start for the Enduro 2100 mAh but let's see if how they fair in two months.
    Look at those Titanium 2700, they're a whopping 5% better than the previous generation.

    * All batteries acquired are brand new in retail package.
    What is the charge method? Quick charging can vary in termination point and introduce error.

    I always use low current, timed charge method. For the purpose of testing, I think it is a great idea to use the testing current used by the IEC, which is 0.1C (270mA for 2.7Ah cell, 250mA for 2.5Ah and so forth) for 16 hours.

  5. #5
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    Default Re: Low Self Discharge Duration Testing

    Quote Originally Posted by Handlobraesing
    What is the charge method? Quick charging can vary in termination point and introduce error.

    I always use low current, timed charge method. For the purpose of testing, I think it is a great idea to use the testing current used by the IEC, which is 0.1C (270mA for 2.7Ah cell, 250mA for 2.5Ah and so forth) for 16 hours.
    Are you going to use low current all the time? How C/D low current cycles do you perform? Better off charging the cells the way you are normally going to charge them! You only need to charge at 1/10C the first cycle anyway.
    Last edited by wptski; 05-23-2006 at 04:57 AM.
    Bill

    I'm a retired mechanic not a electronic/electrical engineer!

  6. #6

    Default Re: Low Self Discharge Duration Testing

    Quote Originally Posted by wptski
    Are you going to use low current all the time? How C/D low current cycles do you perform? Better off charging the cells the way you are normally going to charge them! You only need to charge at 1/10C the first cycle anyway.
    The number of cycles is debatable as the datasheets do not specify number of cycles before full capacity is achieved. For testing purpose, its best to use laboratory conditions that is easily duplicated elsewhere.

    Person A tests brand A 2500mAh using his XYZ smart charger.
    Person B tests brand B 2500mAh using his ABC smart charger.

    Person A produce a report of 2300mAh with 500mA discharage to 0.9V
    Person B produce a report of 2500mAh avg with 500mA discharge to 0.9V

    The problem here is that because charging conditions are different, we don't know which batteries are actually superior. The difference could be a result of the difference in charge algorithm.

    If on the other hand, you use C/x rate for x hours, the charge method is reproduceable anywhere, allowing more accurate assesment of true battery performance under identical test conditions.

  7. #7
    Flashaholic*
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    Default Re: Low Self Discharge Duration Testing

    Quote Originally Posted by Handlobraesing
    The number of cycles is debatable as the datasheets do not specify number of cycles before full capacity is achieved. For testing purpose, its best to use laboratory conditions that is easily duplicated elsewhere.

    Person A tests brand A 2500mAh using his XYZ smart charger.
    Person B tests brand B 2500mAh using his ABC smart charger.

    Person A produce a report of 2300mAh with 500mA discharage to 0.9V
    Person B produce a report of 2500mAh avg with 500mA discharge to 0.9V

    The problem here is that because charging conditions are different, we don't know which batteries are actually superior. The difference could be a result of the difference in charge algorithm.

    If on the other hand, you use C/x rate for x hours, the charge method is reproduceable anywhere, allowing more accurate assesment of true battery performance under identical test conditions.
    The problem with using C/x is that you must discharge the cell(s) fully before using this method of charging but not everyone has the means to do so!
    Bill

    I'm a retired mechanic not a electronic/electrical engineer!

  8. #8
    Flashaholic* modamag's Avatar
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    Default Re: Low Self Discharge Duration Testing

    I'm currently using a 200mA charge rate, 5mV dV then 15mA trickle for a total of 20hrs.

    Typically you want to do low current C/D cycles until the capacity no longer increase to record the maximum cell capacity. This can range anywhere from 3-8 cycles in my experience.

    Guys also keep in mind that there is also cell-cell variation which I can not account for in this test due to limited sample size.

    I would also like to observe the temperature effect on self discharge so 1/2 of the test will be conducted at room temperature ~70 F while the other half is held in refrigerated environment < 30F.

    The main purpose of this study is self discharge among different cells with variation of storage temperature.


    Scimmia: Keep in mind that I'm doing 1A discharge to reflect more closely of how we use the cells not 0.1C (or was it 0.2C) discharge, what the manufacturer usually use for capacity gauge.

    This is only the begining of the test to see the "low self discharge" and where/when it's more appropriate to use LSD vs high capacity NiMh regardless of $$$.

  9. #9

    Default Re: Low Self Discharge Duration Testing

    I'm not sure I see the point of this graph. You're comparing a 2100mAh rated battery against 2500-2700mAh rated batteries? Is anyone suprised they didn't last as long? The Enduro registered about 7% less than it's rated capacity on your test, while the Energizer was about 6.7% less, the Ti-2600 was about 13.8% less, and the Ti-2700 was about 8.4% less. I'd say things don't look very good for the Ti-2600, everything else is as expected.

    What I really want to see is a test of the low self discharge feature.

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