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  1. #1
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    Problem with light

    So here I am, happy to finish up the first light.... proud of my little metal box.... but it doesn't work right now.

    I bench tested the light with a power supply I have at my work bench. The light is bright and beautiful. Order my batteries and a charger.... charge the batteries (Tenergy 18650 2600mah; protected), put them into my battery holder (DX 4s1p holder), plug in my light... hit the switch... WTF?!?!?

    The light is barely on. My iPhone flash light is brighter than this. I tested the batteries before I put them into the holder and they were all at 4.18-4.2V. I pull them after a few on-off cycles and one battery is already down to 3.8v (the first time I tested it, it read 0.96 but waited a minute or so and it tested higher). I think this means the one cell is damaged some how (kind of how a car battery is bad if it dips below 9.6 or so volts on start up). I printed the RMA and will return the batteries.

    Am I crazy? What else could have done the battery in like that? 10% voltage drop with less than 60 seconds of dim lighting seems excessive. Looking for input in general. The build went really well, but this is disappointing.
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  2. #2
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    Have you tried firing it back up on the power supply on the test bench at work? Would prove out that the drive is OK.

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  3. #3
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    If you're using that DX holder with original wires, then you have a bottleneck for current to the light. Those wires are really thin and contacts are crap, so you have huge resistance.

  4. #4
    Light freak
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    I am curious, why the 4s pack for one LED?


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  5. #5
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    I think he ment 1S4P

  6. #6
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    I questioned those little thin wires, but used them anyway. I am going to order a new set of batteries since these won't charge now, but I will rewrite the battery box.

    And nope, I mean 4s1p because that was the easy battery box to pick up for my first build... the DX holder is in series not parallel. This first build was modeled after the easy XML build in this forum... just a different container for the light.

    I planned in ordering some digikey holders to wire in 2s2p but wanted to prove I wasn't clueless in building a light before ordering more stuff.
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  7. #7
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    Oh and I will retest with my power supply but I would think less power (amps and volts) from the battery would hurt it. I will double check when I resolver the holder.
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  8. #8
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    Which driver are you using? And where did you order the Tenergy batteries from?
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  9. #9
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    Probably not the cause of your problem, but.....

    Thinking the drive is this one or one similar - T6 3-Mode Regulated LED Driver Circuit Board for DIY Flashlight (2500~3000mA 4.5~18V) - Free Shipping - DealExtreme

    Even though the input voltage range is 4.5-18V's, it is better practice to closer match the battery voltage to the forward voltage of the LED's when using a buck driver.



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  10. #10
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    Quote Originally Posted by scar View Post
    Thinking the drive is this one or one similar - T6 3-Mode Regulated LED Driver Circuit Board for DIY Flashlight (2500~3000mA 4.5~18V) - Free Shipping - DealExtreme

    Even though the input voltage range is 4.5-18V's, it is better practice to closer match the battery voltage to the forward voltage of the LED's when using a buck driver.
    ****
    Scar has it exact. This was suppose to be a cheap "proof of concept" type build for me. Not something badass. I have a B3Flex waiting for another build, but I want to prove to myself I could do this first.

    Since the driver needs higher than 4.5, I would like to be in a 2s2p configuration. I sourced the Tenergy batts from Amazon (sold by Battery Superstore, fulfilled by Amazon) because I didn't want to drop the coin on Panasonics (see above about this being more of a trial run) and knew to stay far away from *Fire batts. Tenergy presented a price point that was decent yet should provide decent batts.

    I can't see the voltage being the problem (at least not the only problem). The bench supply is a 15v/10a supply.

    I am stuck at work (like a lot of folks) and will play some when I get back to my house.
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  11. #11
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    Battery holder. Just in general. It does NOT make good contact with these batteries (non-button top). I messed with it for a long time today trying different things. Going to order some digikey holders instead now.
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  12. #12
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    Digikey will deffo get you reliable battery holders fast. If the price/shipping doesn't suit, fasttech just started carrying 18650 holders that don't look like the junk DX has. (Please note, I haven't handled/used the FT ones; I'm just judging by photos.)
    $1.71 2*18650 Serial/Parallel Battery Holder Case w/Lead Wires - serial / parallel configurable at FastTech - Worldwide Free Shipping
    (They have a few different ones; I linked this one b/c I liked the way the leads were attached. The digikey/mpd ones always seemed a bit messy.)
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  13. #13
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    Quote Originally Posted by Knight511 View Post
    I tested the batteries before I put them into the holder and they were all at 4.18-4.2V. I pull them after a few on-off cycles and one battery is already down to 3.8v (the first time I tested it, it read 0.96 but waited a minute or so and it tested higher). I think this means the one cell is damaged some how (kind of how a car battery is bad if it dips below 9.6 or so volts on start up).
    Just for what it's worth...
    Resistive contacts and thin wire should not have contributed to any excessive battery drain or caused the light to not function correctly. Even a piddly little 28 gauge wire should be able to carry the current to the light without too much trouble, especially if it's short. For a 28 gauge wire, you're looking at 0.005 Ohms per inch, so let's say 0.07 Ohms for a foot of wire. If you're trying to drive the emitter at 9 watts, the you also have to pull 9 watts plus about 15% (driver loss) from the batteries, say 10.5 watts. The batteries will have some internal forward drop under load, so lets assume that while running at 10.5 watts, the voltage across the fully charged batteries will be around 15.6V. This would require roughly 0.67 Amps out of the batteries.

    Now lets assume that you had some REALLY ridiculously bad connections in the battery box and you had a whole OHM of resistive loss in the path to the light. At 0.67 amps, you're only dropping another 0.67V down from the starting battery voltage. The end result is that your battery holder and connections would start getting warm, but the light should have run perfectly normally.

    Since these were "protected" cells, you should have never been able to pull one down to 0.96V via normal discharge. If you measured 0.96V, then, like you say, something is wrong and the battery has likely been damaged. I'm not sure what would happen if you had one of the three cells "reversed" and inadvertently crammed a lot of current through it in the wrong direction. The fact that it "recovered" quickly is definitely suspicious.

    Just thinking out loud... good luck trouble shooting

  14. #14
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    FWIW, I believe the 0.96v rating was in a situation where the protection had been tripped (for what reason, I am not quite sure at this point). By the time I submitted the RMA, the cell tested back at 3.9v. Now that is still a problem to dump that kind of voltage in such a short amount of time. The cells are still on their way back with a new set inbound already.

    The problem wasn't the wiring at all, in the end. the problem was POOR POOR POOR battery contacts in those crappy holders. You should see the holders as the stand now... I freaking butchered them yesterday trying to make horse crap work. I did finally get the light to fire correctly using 2 cells (the fact that I had 2 cells wired correctly in a 4 cell holder tells part of the story). For the record, the wires were also TERRIBLE. Poorly soldered connections and wires about as thick as one of my cat's whiskers. For what I paid for them, no big loss. I still like the DX drivers because they are cheap and do their job... the battery holders are just rubbish though.

    And again, this forum has been awesome. All the help, all the build threads and the great SIMPLE directions to get someone started... you folks are great.
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  15. #15
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    Quote Originally Posted by borrower View Post
    Digikey will deffo get you reliable battery holders fast. If the price/shipping doesn't suit, fasttech just started carrying 18650 holders that don't look like the junk DX has. (Please note, I haven't handled/used the FT ones; I'm just judging by photos.)
    $1.71 2*18650 Serial/Parallel Battery Holder Case w/Lead Wires - serial / parallel configurable at FastTech - Worldwide Free Shipping
    (They have a few different ones; I linked this one b/c I liked the way the leads were attached. The digikey/mpd ones always seemed a bit messy.)
    Why don't you put this on the sticky DIY parts supplier thread? They look good, even if the wires are a touch flimsy.

  16. #16
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    Quote Originally Posted by Ofroad'bent View Post
    Why don't you put this on the sticky DIY parts supplier thread? They look good, even if the wires are a touch flimsy.
    I've got an FT order soon; I'll throw a couple on and report back. I'd a bit reluctant to put them in the sticky until I've actually touched them.
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  17. #17
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    This is why I've started having my packs welded up and quit dealing with holders all together.

  18. #18
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    "It ain't pretty."



    "Extended" the positive terminals and converted the 4s1p to a 2s1p. I can just swap batteries if I run these down. This isn't final, but I wanted to run the light this Friday ad I won't get a new box before then. The replacement will be a 2s2p for this light....
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  19. #19
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    And I taped everything up after the pic to not have any "loose ends" that could short out.
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  20. #20
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    Just wanted to note that my earlier mention of fasttech battery holders probably wasn't helpful... someone on BLF accidentally started arc welding with one: 4x18650 holder/arc welder - WARNING FIRE HAZARD | BudgetLightForum.com
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  21. #21
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    I actually bought some of those holders and spotted that trouble before trying anything with them. It will be easily fixed with some small pliers to bend the tab back.

    I just thought it would tear my battery cover up, I didn't think about it being a true hazard. I will mess with them some before ditching on them... worst case, I will just use some rivets to extend the posts on the DX holders.
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  22. #22
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    Remove the battery negative end first from the holder and you can't short it.

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