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  1. #1
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    L33.2MC - 7.4V vs 9.6V

    What are the advantages/disadvantages of running the L33.2MC at 7.4V vs 9.6V?????

    This will help me get the appropriate battery pack for my needs. Thanks in advance!

  2. #2
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    what is 9.6V? which kind of battery?

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    NiCad / NiMh

  4. #4
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    The 7.4V battery pack I saw was LiMnNi from batteryspace.com. It is composed of 4x26650 cells. It has 4000mAh capacity and weights about 400 grams.

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    4x 26650 cells would be 8Ah capacity. My 2s/1p 26650 is 4Ah.

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    Your right! How are yours working? Are you satisfied with size/weight vs capacity/performance? I am really thinking about going in this direction vs the more standard 18650

  7. #7
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    Check out my 7.4v shootout...I'm quite pleased with these IMR's. Granted, I didn't use AW cells for my 18650 test piggys...but it still wouldn't matter enough to change my mind on the 2x Long-C's. I love 'em.

  8. #8
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    Quote Originally Posted by fujio001
    What are the advantages/disadvantages of running the L33.2MC at 7.4V vs 9.6V?????

    This will help me get the appropriate battery pack for my needs. Thanks in advance!
    Hopefully Quazzle can chime in again regarding the efficiency of his drivers at different voltages.
    Drivers typically run more efficient when the input voltage is closest to the output voltage. i.e. when the battery voltage is closer to the forward voltage of the LEDs you're driving. This is probably the difference between 90% and 97%, so IMO it's minimal.

    The bigger question is what type of battery chemistry and configuration you want to use. Lithium ion cells output ~3.7V per cell, NiMh and NiCd are ~1.2V per cell. So 2 series Li-ion cells get you to 7.4V and 8 series NiMh get you to 9.6V.

    You'll see a huge bias toward Li-ion cells in this forum because of their high energy density and lighter weight. But NiMh are less expensive and easier to manage regarding charging and discharging.

  9. #9
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    assuming that a fully charged NiMH cell may be 1.4V (not loaded), 8S LiMH battery may fry L332 as the output voltage (11.2V) lays far beyond the allowable maximum limit - 9.5V. 6S-7S is better. Yes, the higher the input voltage, the higher power conversion efficiency of the driver.

  10. #10
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    It sounds like regardless of the battery, something around 7.4V is the safest choice if you are planning on using the L33.2MC. Does everyone else agree?

  11. #11
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    Quote Originally Posted by jmitchell13
    Hopefully Quazzle can chime in again regarding the efficiency of his drivers at different voltages.
    Drivers typically run more efficient when the input voltage is closest to the output voltage. i.e. when the battery voltage is closer to the forward voltage of the LEDs you're driving. This is probably the difference between 90% and 97%, so IMO it's minimal.

    The bigger question is what type of battery chemistry and configuration you want to use. Lithium ion cells output ~3.7V per cell, NiMh and NiCd are ~1.2V per cell. So 2 series Li-ion cells get you to 7.4V and 8 series NiMh get you to 9.6V.

    You'll see a huge bias toward Li-ion cells in this forum because of their high energy density and lighter weight. But NiMh are less expensive and easier to manage regarding charging and discharging.
    About your last statement...while true not really a major factor. A single NiMh cell might cost less than a single 18650 but it will take *more NiMh cells to reach the voltage you need to power your led light ( *unless you only need one cell such as in a mini-torch ).

    Standard NiMh's ( not low self-discharge ) type cells tend to lose so much capacity after a year ( in my experience ) that you have to buy new ones. You really have to baby standard NiMh's. Unless you use a trickle charger a charged stored cell will lose a lot of the charge even after a short number of days. For me standard NiMh's were more trouble than they were worth. I can't tell you how many times I went on rides where my NiMh batteries crapped out on me. That never happens to me when I use Li-ion cells unless I just plain forget to charge the batteries.

    The low self-discharge NiMh cells ( Eneloop or Duracell version ) on the other hand work much better and last longer. They are only 2000mAh cells but that is the trade off if you want cells that are longer lasting and hold their charge when stored ( without trickle charging ) So far I have no complaints about my eneloop or Duracell low self-discharge cells and I've owned them for about two years. Four eneloops will run my Dinotte 200L exactly two hours on high. Standard cells a little longer ( if they are new ) but like I said before, after a year they have lost so much capacity that I end up throwing them away.

    Li-ion on the other hand, I've not had any of those problems. Prices range anywhere from $3 to $13 a cell ( depending on whether they are protected or not and what Brand / where you chose to buy ). A typical average quality Trustfire 2600mAh protected cell is about $4 a cell if buying from D/X. Li-ion cells lose capacity too but nothing like standard NiMh. They are very low self-discharge and hold nearly a full charge for over a month when stored. I still have cells that I bought more than two years ago that are still running well with usable run times. At some point I suppose I will throw them away but that hasn't happened yet.

    In a nut shell, the 18650 Li-ion cell is light-weight, low cost and long lasting. That's why almost everyone uses them. As long as you don't store them in an ultra-hot environment and charge them in a good charger you will own them for at least a couple years. Getting a bad cell ( one that flares or craps out ) is very rare. Li-ion technology is safe, if it wasn't the lap top and cell phone companies wouldn't use them. Anyway, FWIW...hard to beat the all-around usefulness/cost of the 18650 cell. This is why so many DIY'ers / bike light users are going with the 18650 cell holders...It helps keep the cost of buying higher cost*batteries ( * multi-cell sealed units ) down to a minimum.

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