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I need to solder a wire on each of the terminals on the battery shown below. They are approx. 15mm large.

Should I solder the wires, of use some sort of clamp? It looks like the terminals are made of aluminum, so soldering would not hold well.

enter image description here

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  • \$\begingroup\$ Those terminals are intended to be soldered down to a PCB, so they won't be aluminum. But they are flexible and somewhat fragile (easily torn) so you will want to use care to provide for lots of mechanical strain relief. Also the battery itself is fairly fragile, and is expecting to be protected from mechanical abuse by a surrounding case. So don't poke it with a pencil or drive a nail through it by accident. \$\endgroup\$ – RBerteig Jun 25 '14 at 20:50
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    \$\begingroup\$ The positive terminal of a Lipo cell is made of Aluminum, but manufacturers usually spot-weld a nickel tab onto it for easier soldering. You should solder only onto the nickel tab, and avoid stressing the soft Aluminum. \$\endgroup\$ – Bruce Abbott Aug 19 '14 at 10:52
  • \$\begingroup\$ Not really a solder job, but I have used these crimps successfully for similar battery tabs before \$\endgroup\$ – user2813274 Sep 27 '16 at 21:53
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Soldering battery terminals is usually a bad idea anyways because the heating process of soldering tends to damage the battery near the terminals, but apparently on Li-Po battery tabs, there's special zinc solder to do so. See here for more info.

The standard way it's done is with a spot welder or ultrasonic welder which gets the heat in and out fast. The downside is that you only need a grand or two to buy one of those...

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Solder as per normal, but you need to really clean the tag first - can't remember what the metal is of the tags but oxidises rapidly which will stop the solder wetting. There is appropriate flux about, but make sure you get the right stuff! Otherwise just work carefully and swiftly, to keep cell temp down, and do consider the physical constraints to - support those tags, protect the cell from bangs etc. When making up multi cell packs make sure air can circulate between the cells, or the middle cells will get hot and go out of balance (or indeed fail).I've done 80mAh up to 4Ah cells successfully.

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  • \$\begingroup\$ Needs more explanation of which flux to use. I've attempted soldering aluminum many times, ruining my tip each time, and occasionally getting something to stick at all, yet I have many dozens of hrs of experience in normal electronic and RC soldering. Despite this, I have yet to reliably solder any sort of aluminum. I'm still missing something. \$\endgroup\$ – Gabriel Staples Sep 25 '15 at 3:50
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I did some searching around and found a few things. Since the tabs are aluminum, try soldering them with zinc flux and zinc solder. Watch out though, as I've heard this stuff eats through solder tips. I recommend using an old tip, or designating a new tip to become your "old tip" after one use.

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I've been looking into soldering these batteries myself and this is what I'm going to do:

  • contact Manufacturer (Turningy in this case) and ask what the terminal's material is.
  • when the material is established, experiment soldering on strips of that material that you can get into the hardware store and test the conductivity of the final product. You should be looking for the methods that take the least amount of time.
  • Precautions: as you know that LiPo batteries are highly susceptible to heat and risk setting on fire or exploding if overheated. I've come across a few threads where people were suggesting that one finds a cooling method while doing soldering or spot welding. It could be as easy as directing a fan at the battery's surface (below and above) to dissipate heat (just be sure not expose the leads to dissipation as that will result in a bad solder).
  • I would try soldering before spot welding.
  • if you decide to spot weld, you must not give too much amperage.This thread has a very nice table that tells you how much Amperage you need for each material at a given gauge or thickness: https://endless-sphere.com/forums/viewtopic.php?f=14&t=68005
  • If you want to take a chance with it, there this variable amperage spot welder on aliexpress: www.aliexpress.com /item/Hand-held-Spot-Welder-Machine-Welding-Laptop-Battery-Button-battery-Battery-Pack/594538510.html?recommendVersion=1 -There is also nice tutorial on how to make a cheap one with a 12V battery that you can find here: https://www.youtube.com/watch?v=Gk3vrKc4Y1w

    To sum it up, you'll need two 3-4mm thick copper rods, a piece of wood (10mm x 20mm x 40mm), a car battery/booster batter and some electrical wire. Carve a groove on each side of the 20x40 sides of the wood, it should be enough so that the rods fit through the groove. Connect or solder the electrical wires to rods. Run wires through grooves and make sure the rods stick out by 10mm at bottom of piece of wood. Put electrical tape around piece of wood to keep a hold on rods. Bend rods so that they're 2-3mm apart. Attach wires to battery when you want to weld and put extended tips against surface where you want to do the welding. You can control the wattage going through that system via a potentiometer, knowlege of the batteries Amperage and Ohm's law. The table I gave you that gives the recommended amperage for welding assumes you're using a spotwelder which typically run at 1-1.5V (let's assume 1.25) on the welding terminal. You can convert the amperage to P=Ix1.25 to get the Wattage you need for the weld.

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I usually solder these cells by

  1. Cleaning the contacts
  2. Roughen the surface (e.g. with rough sanding paper) to remove the oxidised top layer
  3. Using aluminium solder (contains special flux) for the aluminium contact, normal solder for the tinned copper contact and a high power soldering iron (250 W or above) to be able to exploit the heat resistance instead of heating up the whole cell (which is really really bad)
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Please read the datasheet of the cells. I have some cells where the manufacturer warns strongly agains to high temperature during soldering. It is even recommended to let the solderjoint and therefore the element cool down before continuing to the second lug. The cells are mostly combined to a complete battery where the lugs of the individual cells are soldered against a special header pcb. That pcb is then also used to connect the wires from the bms (Battery Management System). Use large and sufficiently hot soldering iron in order to reduce the soldering time. Make sure that the soldering temperature stays below 300 C. Follow the instructions in the datasheet and make sure not to damage the container of the cell in any way.

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