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Thread: Best source for small Li-Po with tabs and no protection?

  1. #1

    Default Best source for small Li-Po with tabs and no protection?

    I'm rebuilding a couple of old cell phone batteries, and am very limited in the parameters needed for this project. Been absolutely scouring the web for days looking for something in the 700 - 1000mAh range with solder tabs, and no protection circuit. Max dimensions of 45mm L (NOT counting the solder tabs) x 34mm W x 6.5mm H.

    The very few items I've found with suitable size and capacity either come with protection (and JST connectors) that is difficult to remove without harming the cell, or a large minimum qty. order. Honcell makes something that would be perfect, but they appear to be an OEM supplier only. I've looked everywhere I could find... hobby supply stores, retail battery houses, Digikey/Mouser, and more.

    Getting desperate here. One battery is already shot, and has been disassembled for studying/planning, and the one still in use is on it's last legs. For various reasons, I refuse to buy a new cell phone!

    Help!... lol.
    I'm an excellent driver. Of course I don't have my underwear... I'm definitely not wearing my underwear

  2. #2
    Flashaholic* Timothybil's Avatar
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    Default Re: Best source for small Li-Po with tabs and no protection?

    Have you checked LiIonWholesale.com? Otherwise Banggood and Gearbest sometimes have cells like that.

    Is the current battery a LiPO?
    Remember, Two is One, and One is None!.

  3. #3

    Default Re: Best source for small Li-Po with tabs and no protection?

    Thanks, Tim. Though they seem to only have cylindrical cells, that is an excellent link, and will come in quite handy for other things! I like their claim of verifying the authenticity of their supply.

    The old phone battery is a Li-Po encased in a metal shell with the "external" protection circuit spot welded on, just like the one in the video below. Only difference on mine is then it all goes into a fully enclosed plastic case that clicks into the back of the phone. I managed to open the plastic case with little damage so it closes again semi-properly, and retained the stock protection board.




    I aim to win the Oldest Cell Phone Still In Use award... haha. No reason to change it whatsoever, and every reason to keep it going.
    I'm an excellent driver. Of course I don't have my underwear... I'm definitely not wearing my underwear

  4. #4

    Default Re: Best source for small Li-Po with tabs and no protection?

    Facing exceedingly little choice, I've gone ahead and ordered a 603443 Li-po. It has the usual protection which will be very carefully removed, hopefully exposing a couple tabs to connect the stock LG protection to. If all goes well, I'll repeat the process with the other battery, and get a second 15 years out of my phone. Or, at least until CDMA is gone... lol.

    For anyone interested, I'll post pics of the phone battery rebuild.

    This effort also has a tangential relation to flashlights. By getting more familiar with the Li-po world, I hope to come up with a solution that will enable a couple of treasured lights to function well into the future.
    I'm an excellent driver. Of course I don't have my underwear... I'm definitely not wearing my underwear

  5. #5

    Default Re: Best source for small Li-Po with tabs and no protection?

    Well, I've royally screwed this up, and fried the protection circuit by hooking it up backwards. I'd like to blame LG, but it's my fault.

    SO CLOSE to having this restoration work like a charm. Got the PTC off the new batt with no problem, carefully worked the delicate tabs (especially the positive) into position to be soldered, hooked the new batt to the stock PTC, put it all into the plastic case, temporarily held it together with a little tape, and clicked it into the charger. CONTACT! The red charging light came on! Very excited to see my plan working, and finally have a well functioning battery. It all went downhill from there.

    I look 30 seconds later, and the light is blinking instead of solid, indicating a problem. Pop the battery out and click it back in, light starts blinking again and now I'm smelling burning electronics. Took it off, opened the plastic back up, Li-Po was fine but the PTC was hot. While investigating what I did wrong, I grabbed the old Li-Po and discovered the polarity was opposite from what I thought it was. This means I installed the new one backwards.

    As you'll see from the picture below, it's easy to assume the button in the middle is positive, and the metal case is negative. I knew this too, but had forgotten in the eight months since taking it out. By the time this pic was taken, I had already re-connected the PTC the correct way, but the damage was done. No voltage getting through now. Dead.

    Yes, it was my error, but to blow off some steam here.... STUPID F@%#ING BATTERY!!! Totally counter-intuitive.

    Click for large image.


    This whole thing almost went perfectly, and I could've been sitting here smiling about being able to use my dying phone as if it were new. I'm very frustrated about this, and am now facing even tougher odds in keeping the thing alive. I either need to get my hands on another old battery somehow, or risk surgery on the barely working one. Plotting what to do, and will report back.

    Moral of the story: Double or triple check everything before connecting power to something, especially if you don't do this stuff every day, and/or distracted by a thousand things in life. The dumbest of mistakes will ruin the whole shebang.
    I'm an excellent driver. Of course I don't have my underwear... I'm definitely not wearing my underwear

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