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  • replacing battery pack?

    My rotating laser won't hold a charge. It has five batteries in the pack. It looks like four are connected together to output six volts and the fifth is independent. The wall-wart charger outputs 12v.

    Presuming I can bux duplicate batteries is there anything I need to do special soldering up the new pack?
    Location: The Black Forest in Germany

    How to become a millionaire: Start out with 10 million and take up machining as a hobby!

  • #2
    Originally posted by Black Forest View Post
    My rotating laser won't hold a charge. It has five batteries in the pack. It looks like four are connected together to output six volts and the fifth is independent. The wall-wart charger outputs 12v.

    Presuming I can bux duplicate batteries is there anything I need to do special soldering up the new pack?
    Buy the replacement batteries with soldering tabs, otherwise you need to "cook" the battery terminals with unwanted heat.

    If its AA battery size these are good:
    https://eu.nkon.nl/rechargeable/aa-s...deerlipje.html
    Location: Helsinki, Finland, Europe

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    • #3
      I've rebuilt battery packs in a lot of my cordless power tools. Just buy good quality tab batteries and solder them up. You may have to build some little jig / fixture to group all the batteries together to hold them in place while you solder.

      JL.......

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      • #4
        Here is a picture
        The aaa batery is for reference.
        Location: The Black Forest in Germany

        How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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        • #5
          as above. All you need to find out is the size of the battery - bespoke packs use funky size batteries. Those look like 3/4C or something along those lines. Most likely you'll only be able to find them tabbed. If not, you can solder directly to the terminals, you just have to be quick and then wick the heat away immediately afterwards. I've direct soldered a bunch of li-ion cells over many years without issues (one pack is going on 8yrs old!).

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          • #6
            I've replaced my drill battery packs three times. I bought batteries the first time with tabs on them. Maybe in the configuration you have the tabs will work out, but they didn't on mine. You still have to solder the other end. I used a small coil of electronics solder, came in a plastic tube, and a soldering iron. Of course only heat as much as needed, but I had no issues.

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            • #7
              Here are some pics of the packs that I've rebuilt. The easiest way to do this is to make a fixture like I did for each pack. Make it to snugly fit the original pack as you probably won't have
              much wiggle room. The fixture will hold all the batteries in place and allow you to rotate each battery for the best tab alignment. They won't ever all fall right into place so your going to have to fold the tabs over in various directions to meet the mating battery. Be careful no to mess up the polarity. The tabbed batteries usually don't mark them + or - and on some batteries it's hard to tell the difference between the + end and the - end.
              On a final note...... don't buy any cheap ebay batteries or you'll be doing this again in about 6 months.

              When your done soldering and connecting any thermal protective devices get a small tube of silicone and squeeze a little dab in between each battery, let it cure over night before you take the pack out of the fixture. This will hold them all together.

              JL................







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              • #8
                Not worth if you are only making one battery pack but the (chinese) battery pack spot welders are pretty cheap nowadays if you want to build battery packs more often. And nickel strip is also easy to find, unlike some 5 years ago...
                Location: Helsinki, Finland, Europe

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                • #9
                  If you're good at soldering so you can get onto the cell ends and off again rapidly then there's little or no damage to be done. I've soldered cells directly for my RC models for many years and literally hundreds of cells without issue.

                  If you go this route keep in mind that you want a really hot iron with a fat tip. The key is a good thermal mass at the wedge faces of the iron which a big heavy fat tip gives you. That way you can dab on then off again to tin the ends of the cells in only about a second. Then have a wet but not dripping rag to touch to the end to draw out the heat.

                  Don't try to do the entire joint in one go. Clean then tin the ends to leave a slight puddle. Then tin the ends of the connecting wires. And finally "sweat" the tinned wire to the pool in another short 1 second dab of the iron. No additional solder or flux for this is needed or wanted. Then cool with the rag again.

                  If you're not sure about doing that then by all means buy the pre-tabbed cells. Just don't expect the tabs to point to each other. You'll end up just folding them over on themselves and soldering wire to them.

                  As for identifying the cells you have there's specs on the web for all the sizes. Just search for them and compare the sizes. At a glance I'd say your cells are some length of "C" size diameter. Very likely the popular "sub C" which I believe are 2/3C. But there's also 3/4C and 1/2C. But start with comparing the diameter so you know.
                  Chilliwack BC, Canada

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                  • #10
                    My batteries arrived today. They have the tabs on them for soldering. Anything special I need to do to solder them together? Do I tin the indiviual tabs first and then over lap them and touch the soldering iron to the top tab?
                    Location: The Black Forest in Germany

                    How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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                    • #11
                      pretty much. If you have a variable temp soldering iron, set it a bit hotter than usual as you want to solder it quickly. Once the solder sets on the joint, touch a pair of pliers (or similar lump of metal) to the join to wick the heat away.

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                      • #12
                        You DO need to know what type of batteries they are. NiCad? Lithium? Nickle Metal Hydride? Lead Acid? or ??
                        Paul A.
                        SE Texas

                        Make it fit.
                        You can't win and there IS a penalty for trying!

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                        • #13
                          Originally posted by Paul Alciatore View Post
                          You DO need to know what type of batteries they are. NiCad? Lithium? Nickle Metal Hydride? Lead Acid? or ??


                          They are NiMh
                          Does that make a difference how I solder them?
                          Location: The Black Forest in Germany

                          How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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                          • #14
                            Originally posted by Black Forest View Post
                            They are NiMh
                            Does that make a difference how I solder them?
                            Yes and no. My own experience has shown me that I can solder directly NiCd and NiMH cells with no damage using the method I gave earlier to minimize the heat put into the cells during each of my two step process. But I'd want to do more checking on the idea of soldering DIRECTLY to lithium based cells.


                            But that doesn't matter to you since you bought tabbed cells. The tabs pretty well insulate the cells from the heat. Just don't take forever to get things joined though.

                            Where the tabs can overlap you can solder them directly to each other. But some of the joints will require a fold back and use connecting wires.

                            Do NOT fold the tabs with joints down the side of the cells. If you do you run the risk of them wearing through the thin insulating covers. And if that happens in the wrong place it could lead to at the very least a pack failure. And at worst a meltdown and possible fire.
                            Last edited by BCRider; 03-25-2018, 10:59 AM.
                            Chilliwack BC, Canada

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                            • #15
                              I bought some sub C’s off of eBay several years ago, they didn’t seem to last. Where would you buy the good ones?

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