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'Battery Expert' from in N. Illinois

Discussion in 'Introduce Yourself' started by batteryguru, Aug 1, 2012.

  1. batteryguru

    batteryguru Loaded Pockets

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    New to the forums, but not to the concept of EDC. I've been into flashlights for awhile now, knives since I wasn't old enough to buy them on my own, and guns for the last decade or so. I work on the side as an instructor and salesman for a small start-up firearms dealer, but full time I manage a Batteries Plus that I've worked at for the last four years. I would be more than happy to field any questions regarding batteries (or anything else I might be able to answer). I found the forum by looking for backpack reviews and instantly got sucked in.

    I'm sure this will be a productive stay.
    -Anthony
     
  2. xtrajack

    xtrajack Loaded Pockets

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    Welcome to the forum, watch your wallet.

    Do you have any knowledge about LiFePo4 batteries? I will be in the market soon for a 10Amp/hr LiFePo4 battery.
     
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  3. powerring
    • In Omnia Paratus

    powerring Loaded Pockets

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    Welcome Anthony! EDCForums is one of those sites you stumble upon during a Google search but becomes a place you'll visit again and again. There are lots of knowledgeable and friendly folks here. :)
     
  4. EveryDayBeer
    • In Omnia Paratus

    EveryDayBeer Loaded Pockets

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    Greetings and welcome to EDCF!

    Very likely productive, but you might have to work some overtime soon. Heed the warning of xtrajack!
     
  5. batteryguru

    batteryguru Loaded Pockets

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    Lithium Iron Phosphate. What do you want to know? They're an intrinsically safe alternative to traditional lithium ion (lithium cobalt), but at the cost of energy density. They also suffer from a higher self discharge rate. They can, however, be charged many more times than lithium cobalt. What is the application?
     
  6. xtrajack

    xtrajack Loaded Pockets

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    It is being used with my Ezee front hub motor on my bicycle in my avatar. The place that I originally got it from is no longer in business.

    I have had it since 2009, it is still working but the trip to work and home seems to be taking more out of the battery than it used to.
     
    Last edited by xtrajack, Aug 1, 2012
  7. batteryguru

    batteryguru Loaded Pockets

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    If I had to guess, it's probably comprised of a bunch of 18650s in a big series-parallel mess; they're like the lego bricks of lithium-ion packs. I also wonder how true to the 10Ah rating you were actually getting. 10Ah is a big pack. What is the voltage?
     
  8. batteryguru

    batteryguru Loaded Pockets

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    Thanks for the welcomes, btw
     
  9. xtrajack

    xtrajack Loaded Pockets

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    It is a 36volt pack, although according to my Cycleanlyst, when the battery comes off the charger, it reads between 42.2~42.7 volts.
     
  10. batteryguru

    batteryguru Loaded Pockets

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    The full charge voltage is always higher than the nominal voltage of a given battery. For example, a common nickel metal hydride AA is rated at 1.2v nominally, but is nearer to 1.4v fully charged and after the surface charge dissipates a bit.

    36v doesn't make a ton of sense for that chemistry. At 3.2v nominally per cell, you would have either a 35.2v or 38.4v pack. Have you disassembled the pack by any chance? It's starting to sound to me like a sealed lead acid assembly, which are pretty common in that application. They are notoriously mislabeled.
     
  11. xtrajack

    xtrajack Loaded Pockets

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    I have not disassembled it, I am fair certain that it isn't lead acid. It isn't as big as a loaf of bread, although it weighs more than a loaf of bread. It says it is a 12 cell, 36volt 10 Amp hour 30A (3C) max. discharge rate. It was made in june '09 and I had to have a cell replaced in dec '09--- apparently poking a hole in the cell isn't a good idea. (It was an accident)
     
  12. batteryguru

    batteryguru Loaded Pockets

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    If you had a cell replaced, it can not be SLA. Those must be some big cells to get 10Ah out of them, definitely not 18650s if there are only 12 cells (which makes it a 38.4v pack, actually). As I said, they're notoriously mislabeled.

    What is it specifically that you wanted to know?
     
  13. xtrajack

    xtrajack Loaded Pockets

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    Where can I get a decent quality replacement?
     
  14. enki_ck

    enki_ck Loaded Pockets

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    Welcome to the forum, it seems you'll fit right in. :)
     
  15. KAMM
    • In Omnia Paratus

    KAMM Loaded Pockets

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  16. reppans

    reppans Loaded Pockets

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    Too cool... a battery expert! Welcome!

    Hope you don't mind me asking, but I had some questions on maximizing the life of Li-ions, primarily on today's iDevices which are now all coming with non-removeable batts. I've done pretty extensive research on CPF and settled on these 2 sources to help with my best charging practices.

    http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

    and:

    [​IMG]

    From Here:
    http://www.cerdec.army.mil/directorates/docs/cpi/Cycled_Aged_LiIon_Cells.pdf

    My take from the two sources above is that, after high heat, the next greatest wear factor for Li-ions is high voltage (charging to 4.2V and maintaining at higher charge levels), and it's worse than deep discharges, or even discharging to 0%. In fact, the graph leads you to believe that the lower the state of charge you can live with, the longer the battery will last.

    So I'm charging my iPad, for example, on a light timer so that it terminates at about 80% just before I wake up and start using it again. I'll then use it whatever % during the day to usually 40% but sometimes 20 or 10%, and then repeat. I'm not going to bother plugging in during the middle of the day, unless I'm going to run out of juice during the day, and so have selected to terminate at 80% although even lower seems beneficial.

    Does all this sound consistent to what you know?
     
  17. JonSidneyB
    • Administrator

    JonSidneyB Uber Prepared
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    Overcharging is bad. The anode becomes plated with lithium. You will get many more charging cycles by not stressing the batteries. This is actually changing the chemistry of the battery.

    In some designs and chemistries what happens is carbon trixoxide becomes carbon tetroxide becoming unstable. The anode plating can form dendrils.
     
    Last edited by JonSidneyB, Aug 1, 2012
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  18. batteryguru

    batteryguru Loaded Pockets

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    Jack, the only place off the top of my head to get a cell like that would be from a place called all-battery.com. That is basically the retail site for Tenergy, a brand you may have heard of. I checked, they do have 10Ah LiFePo4 cells. Finding the assembled pack may be difficult to say the least, but the good news is that it sounds like it is serviceable.

    Kamm, what is that you want to know? I generally classify Lithium Manganese type batteries into A, B, and C grades. Duracell, Panasonic, Rayovac, Energizer, and a couple others are in A territory. Most of the flashlight manufacturer's are B in terms of run time. C is stuff you don't want to mess with. I like Panasonic stuff a lot, and they make Rayovac's for them as well as Duracell if I'm not mistaken. B grade is safe, but they last only about 80% as long on average as an A grade.

    Reppans, the "happy area" for traditional Lithium-Ion (we'll throw Lithium Polymer [Li-Po] in there as well because their charge and discharge characteristics are identical) is between 40-80%. You can get more charge cycles out of a given battery by keeping it within those parameters, but you should fully discharge and fully charge it every 40 cycles or so to reset the end of charge and end of discharge flags in the battery's "digital memory". Now, in terms of construction, you can build a battery to either give you longer service life or longer life between charges. The iStuff batteries are typically geared towards longer service life, and they do a decent job of that, where as HTC and Samsung products for example typically swing in the other direction. Minimizing use while on a charger is another tip, as the excess heat generated is bad news for the battery. It will also prolong the life of the charge port, which is probably the number one non-impact related smartphone failure.
     
  19. batteryguru

    batteryguru Loaded Pockets

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    Jon, you are right about not overcharging, although the EOC (end of charge) value will vary depending on the device. Everything sold in the US will have redundant protection against actual overcharge, as Lithium Ion is highly intolerant to overcharge and can easily cause "rapid disassembly". Things like hybrid vehicles have their EOC set relatively low to prolong service life, while things like digital cameras will have their EOC set for maximum run time.
     
  20. JonSidneyB
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    JonSidneyB Uber Prepared
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    You have to remember many people are getting them from out of country. I was the person that got the RCR-123's created and lost my shirt on them.
     
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