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Thread: Yet another EL 3AA-to-D battery holder rebuild

  1. #1
    Flashaholic* milkyspit's Avatar
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    Default Yet another EL 3AA-to-D battery holder rebuild

    Okay, we've all been through the drill around here. So apologies for that.

    [img]/ubbthreads/images/graemlins/dedhorse.gif[/img]

    With that out of the way, I'll say that I was up late soldering one night, and had a good mod in mind for my Blaster Jr. But I wasn't happy with the current flow coming from 3AA NiMH cells, and suspected that excessive resistance in the now-infamous EL 3-to-D holder was the culprit. (Yes, I know there's a new version coming out real soon now, but I got impatient.)

    The thing I didn't like about the other mods I'd seen was that they seemed really involved, or required cutting the holder in half, or just went over my head as far as how to do the mod. So I improvised. [img]/ubbthreads/images/graemlins/wink.gif[/img]

    First, all good mod projects involve a little scavenging, right? So I snagged some nifty springs out of a Radio Shavk 8AA holder. I could have used a less expensive holder, but this one was all I had at the time, so out came the cutters, heh heh. [img]/ubbthreads/images/graemlins/crazy.gif[/img]

    (Trashed Radio Shack 8AA holder in background, with newly fashioned dual spring in the foreground, like a phoenix rising from the ashes.)


    I put two of the individual springs together to replace the connected pair in the bottom of the stock 3-to-D holder. To connect them, I tucked a short length of desoldering braid between coil turns on each, pointed the stiff wire extentions toward each other (they're underneath the braid), then applied a considerable amount of solder. The desoldering braid, of course, took the solder like a sponge, then when all had cooled to room temperature, the result was a very stiff, very sure connection with essentially no resistance.

    (Closeup of springs connected by desoldering braid.)


    Next, I removed the internals of the 3-to-D holder without damaging the physical holder itself. In general the bits inside came out easily once a couple solder welds were snapped off using a pair of needlenose pliers. I also removed the metal contacts on the outside by gently drilling through the rivet; once finished, the contacts simply fell off.

    After attaching another piece of desoldering braid to a htird scavenged spring (not shown), I ran it out the hole left by the now-vacant rivet, and soldered the other end to a scavenged negative endcap from a heavy duty D cell. I was pretty generous on the solder to make sure it stayed put, heh heh. [img]/ubbthreads/images/graemlins/ooo.gif[/img]

    (Bottom of 3-to-D holder with braid and D cell endcap, ready for permanent attachment.)


    With the above work finished, the bottom of the 3-to-D holder had effectively been rebuilt. Now only the lid remained. Taking the simple approach, I soldered a short strip of braid across the existing metal bridge to ensure good contact, and tinned the portions that would make actual connection with the cells. As for the third, individual contact, I ran some desoldering braid through the existing rivet hole, folded and tinned (heavily) the end left inside to contact the cell.

    (Closeup of modded 3-to-D lid.)


    The other end of desoldering braid, the one extending out the rivet hole on the lid, was soldered to a positive endcap scavenged from a heavy duty D cell, then the endcap was permanently attached to the lid of the 3-to-D holder.

    (Finished! Upright view.)


    The rebuilt holder worked well! It had the desired improvement as far as achieving very low resistance throughout. The new endcaps did make the holder marginally taller, but in most lights the spring will flex the extra millimeter or so to allow a good fit anyway. I will say that inside things got tighter as well, but the holder still closed, barely.

    Bottom line: SUCCESS! [img]/ubbthreads/images/graemlins/grinser2.gif[/img] I like the minimally intrusive nature of this mod, meaning the physical holder itself wasn't cut or mutilated. It also just "feels" right with those actual D cell endcaps in place. However, the mod took a fair amount of work, so whenever Elektrolumens has those revised holders, I think I'll be a buyer, assuming they work as advertised. [img]/ubbthreads/images/graemlins/grin.gif[/img]

  2. #2

    Default Re: Yet another EL 3AA-to-D battery holder rebuild

    Nice work Scott. Interesting take on the problem and an inventive solution.

    Wilkey

  3. #3
    Flashaholic
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    Default Re: Yet another EL 3AA-to-D battery holder rebuild

    Can't go wrong with solder braid.. Love that stuff. Cool mod! Scavenging is always a good thing. The currentcoins are using SMD parts from dead hard drives.. [img]/ubbthreads/images/graemlins/grin.gif[/img]

    I remember fighting with my old boss about resistance. "Milliohms don't matter!" "I've only got 12V to start with and 1000A starting current. You bet it matters!!"

    By the way, one of those terminally cute bench P/S showed up yesterday. I'm working on a current metering mod to give it a safe 200ma full scale mode. Will post howto if it works. Nice for those low current mods.. Cute unit, decent quality, and a $30 free DMM from Circuit Specialists. $40 gets the rs232 DMM with PC software as well. Gotta try that soon.

    Yours, drs the crazed..

  4. #4
    Flashaholic* milkyspit's Avatar
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    Default Re: Yet another EL 3AA-to-D battery holder rebuild

    Thanks guys. [img]/ubbthreads/images/graemlins/grin.gif[/img]

    Drs, resistance indeed DOES matter. Somehow I always seem to be on the edge, trying to squeeze that last bit of efficiency out of the cells, where they're almost at the level I want. Maybe that's somehow my battery destiny, if there's such a thing. [img]/ubbthreads/images/graemlins/icon15.gif[/img]

    Find a way to drop resistance by a few tenths of an ohm, and we're often back in business! [img]/ubbthreads/images/graemlins/crazy.gif[/img]

    BTW (and off topic), I've been stress testing some Milky Candles around the house lately. I've been running 123 cells until they drop to 0.01A flash amps and well under 2V unloaded. Then there's the 8AA holder I use to drain the last dregs of juice from already spent AA cells, vampire style, until some of the cells actually go negative. In other words, they REVERSE their polarity! I assume that's pretty dead, muahahahahaaaaaa... [img]/ubbthreads/images/graemlins/mad.gif[/img] [img]/ubbthreads/images/graemlins/naughty.gif[/img]

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    Flashaholic* EvilLithiumMan's Avatar
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    Default Re: Yet another EL 3AA-to-D battery holder rebuild

    Wow - a great approach to the 'current' situation! I really like the implementation of the D cell's end caps. Great job [img]/ubbthreads/images/graemlins/cool.gif[/img] .

    By the way - version 2 of the 3-to-D adapters are now for sale. The initial order screen shows the V1, but if you click on the 'info' link or view the actual order, you'll see the V2 listed.

    Back to those D cell end caps. How do you disect a used D cell? Do you need to neutralize your tools with baking soda afterwards? I would think it is a messy process.

    (And don't forget to update us on that BL-JR mod!)

  6. #6
    Flashaholic* milkyspit's Avatar
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    Default Re: Yet another EL 3AA-to-D battery holder rebuild

    EvilLithiumMan, did you receive the new holders yet? That link to the writeup of the new ones has been there for a while, but I was under the impression that they weren't in stock yet, and the old ones were still shipping. Guess we'll see! Anyway, please let us know which ones you receive.

    Hmm... maybe I should have asked if you ordered any? [img]/ubbthreads/images/graemlins/icon15.gif[/img]

  7. #7
    Flashaholic* EvilLithiumMan's Avatar
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    Default Re: Yet another EL 3AA-to-D battery holder rebuild

    I ordered them yesterday. The page where you 'add to shopping basket' shows version 1. But if you click the 'Click here for more info' link, it will show and say the V2's. Also my completed order form stated V2.

  8. #8
    Flashaholic* LitFuse's Avatar
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    Default Re: Yet another EL 3AA-to-D battery holder rebuild

    Hmmm.... I hope that's what you get ELM. I just can't imagine that that these would go "in-stock" without any fanfare at all from Wayne J. Not even a peep.....

    Maybe it's possible that he is accepting orders because they are "this close" to arriving? Do you know if you're order has actually shipped Evil one?

    Peter


  9. #9
    Flashaholic* EvilLithiumMan's Avatar
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    Default Re: Yet another EL 3AA-to-D battery holder rebuild

    I ordered them on Thursday, not Friday and I stated earlier. The finalized order form clearly stated 'Version 2'. It usually takes Wayne a few days to ship. I would expect to have them by the end of the week. I will post here when they arrive.

  10. #10
    Flashaholic* EvilLithiumMan's Avatar
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    Default Re: Yet another EL 3AA-to-D battery holder rebuild

    [ QUOTE ]
    LitFuse said:
    Hmmm.... I hope that's what you get ELM. I just can't imagine that that these would go "in-stock" without any fanfare at all from Wayne J. Not even a peep.....

    Maybe it's possible that he is accepting orders because they are "this close" to arriving? Do you know if you're order has actually shipped Evil one?

    Peter



    [/ QUOTE ]

    Got my order today. Was worried when I got the e-mail confirmation - it made no mention of the version number. I'd swear the final on-line order screen stated 'V2', but I didn't take a screen shot of it so I have no proof. Anyway, you guys were right; it's still version 1 that is shipping.

    And those version 1's aren't getting any better with age: [img]/ubbthreads/images/graemlins/smile.gif[/img]

  11. #11
    Flashaholic* milkyspit's Avatar
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    Default Re: Yet another EL 3AA-to-D battery holder rebuild

    ELM, when life gives you lemons, make lemonade. [img]/ubbthreads/images/graemlins/smile.gif[/img]

    Now you have an excuse to do the mod! [img]/ubbthreads/images/graemlins/naughty.gif[/img]

    A little desoldering braid, a heavy duty D battery, a buck spent on a Radio Shack battery holder to scavenge, and you're on your way.

    BTW, I forgot to address your question about dissecting the batteries. The ones I use aren't alkaline, they're carbon zinc. Sometimes called "dry cells," usually labelled as "heavy duty" batteries. Repeat these words to yourself: NOT ALKALINE. [img]/ubbthreads/images/graemlins/jpshakehead.gif[/img] If you use a carbon zinc cell, there won't be any need to clean the tools.

    As far as how to do it, you basically peel the skin, sort of like peeling an orange. Start at a corner, pry up a little of the outer casing (which might be cardboard, plastic, or even thin sheet metal), grab it with some needlenose pliers or perhaps a small Vise Grip, and continue peeling. Inside will be an unmarked steel canister with a black ('cause it's carbon) rod sticking out the top a little. There will probably also be a couple plastic spacers, and of course the endcaps themselves. At some point in your peeling, the endcaps should pretty much fall out on their own. That's it! [img]/ubbthreads/images/graemlins/grin.gif[/img]

  12. #12

    Default Re: Yet another EL 3AA-to-D battery holder rebuild

    hi, I just wanted to share/post my battery holder build FAIL (btw you actually learn more from mistakes and fails than from posers showing you perfection, think about it), without opening a new thread for it ...
    What i wanted is a 4s1p 18650 battery holder in block format, i.e. with quadratic cross section (profile). CN etailers like FT have a selection of 4x18650 battery holders in "flat" format, so i got two of them, cut and glued them to block format. Well, the build itself worked out really nice:



    However the performance of the holder is poor!
    I would want this battery pack to work in my portable vacuum cleaner, but compared to the "original" 4x18650 battery holder it just underperforms, delivering a lower current draw. No need to investigate any further, to me it is clear that the electrical resistance (could be the springs or the thin wires) of my FT build is too high for my vaccum cleaner application which draws about 4 or 6 amps.

    In theory i could substitute thicker leads or buy the other SKU to learn if that solves the performance problem. But no, i am leaving the situation like that and will continue to use the "original" 4x18650 battery holder which has superior performance, just looks ugly wtf cares. My point of trying was to roll the dice and see how far i could get with 1 quick shot, i.e. without soldering/crimping/help/efforts 3011. Now i know. Good enough for me. Moving on.

    Anyway, shame on the Chinese manufacturer imho. How can they release a 4x18650 product if it can't deliver the electrical power (current draw) which 4x18650 products typically demand? I am sure that there are 4x18650 applications out in the world which require a 0.3A current only ... but geez …
    Last edited by kreisl; 07-12-2020 at 08:50 AM.
    ~ bitterness about poor quality remains long after sweetness of low price is forgotten ~

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