# Electronic soldering...super simple low level battery repair **URL:** \ **Category:** Factual Questions\ **Created:** [November 10, 2015, 2:24am UTC](https://boards.straightdope.com/t/electronic-soldering-super-simple-low-level-battery-repair/737160 "2015-11-10T02:24:29Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![Stoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/stoid/32/272_2.png) [@Stoid](https://boards.straightdope.com/u/Stoid)\ **Post date:** [November 10, 2015, 2:24am UTC](https://boards.straightdope.com/t/electronic-soldering-super-simple-low-level-battery-repair/737160/1 "2015-11-10T02:24:29Z")
I now have four batteries for two bike lights. Three are busted, but only “busted” in the sense that the wires have split and pulled away from the batteries. I have solder and a soldering iron. The wires are a bundle of copper looking in red wrap and a bundle of copper looking in black wrap. So do I just make sure that hot solder covers all possible wires and attaches them to the battery, do I have to solder the wires to each other… any tips or cautions? I use my bike lights constantly, I just want a steady supply of energy and I’m tired of having to spend money replacing them just because of wires… ---
**Author:** ![DinoR](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dinor/32/2821_2.png) [@DinoR](https://boards.straightdope.com/u/DinoR)\ **Post date:** [November 10, 2015, 2:34am UTC](https://boards.straightdope.com/t/electronic-soldering-super-simple-low-level-battery-repair/737160/2 "2015-11-10T02:34:14Z")
Depending on battery chemistry there can be issues of heat damage from a typical hobbyist soldering iron. Lithium Ion cells especially can present problems and even dangers. Here’s a description of a [technique](https://xaeus.wordpress.com/2014/04/20/safely-soldering-li-ion-cells-without-causing-any-thermal-damage-en/) for them. ---
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [November 10, 2015, 2:40am UTC](https://boards.straightdope.com/t/electronic-soldering-super-simple-low-level-battery-repair/737160/3 "2015-11-10T02:40:11Z")
As long as you are fixing this, seems like a more permanent solution would be to solder the wires from the led lights to a standard battery holder. Then you can just insert regular batteries, and the contacts at the ends of the batteries connect to the battery holder. Then you can use any standard battery in the holder, even rechargeable ones. (On a bike, you probably want battery holders that secure the batteries in tightly, with a cover or strap or something, given the bumps of the terrain.) Whenever I see non-standard batteries like this, I see it as a company’s way of suckering more money out of you, by forcing you to by their proprietary battery pack, instead of the much cheaper standard batteries. ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [November 10, 2015, 3:06am UTC](https://boards.straightdope.com/t/electronic-soldering-super-simple-low-level-battery-repair/737160/4 "2015-11-10T03:06:57Z")
> [@Stoid](#): > > So do I just make sure that hot solder covers all possible wires and attaches them to the battery, do I have to solder the wires to each other… Nope. The mechanical and electrical property of the wire adds to the same whether the strands are separated or bundled. In fact splaying the strands out is a good way to increase mechanical strength of the solder bond to the electrode. (its a single cell if its 1.1 to 2.0 volts…Pedant will come along to echo me, but a battery is an array of similar items. 6 volt ? 4 zinc or Nickel cells. 9 volt ? 6 zinc or nickel cells. 12 volts , often six lead acid cells…) ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [November 10, 2015, 3:15am UTC](https://boards.straightdope.com/t/electronic-soldering-super-simple-low-level-battery-repair/737160/5 "2015-11-10T03:15:44Z")
Use some fine sandpaper and clean both the wires and the battery terminals before soldering. When soldering, get the wires nice and hot first, and “tin” them with the solder. Then, tin the battery terminal, and let everything cool. Then, quickly solder the two together, to minimize heating of the battery. ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [November 10, 2015, 2:46pm UTC](https://boards.straightdope.com/t/electronic-soldering-super-simple-low-level-battery-repair/737160/6 "2015-11-10T14:46:06Z")
Remember that the goal is not to glob hot solder on the metal, it’s to heat the metal workpiece and then use the workpiece to melt the solder. That ensures that the rosin core will properly flow over the metal and remove the oxide layers that will otherwise prevent a solid mechanical and electrical connection. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [November 10, 2015, 2:58pm UTC](https://boards.straightdope.com/t/electronic-soldering-super-simple-low-level-battery-repair/737160/7 "2015-11-10T14:58:37Z")
I like tbonham’s idea of installing battery holders. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [November 10, 2015, 4:08pm UTC](https://boards.straightdope.com/t/electronic-soldering-super-simple-low-level-battery-repair/737160/8 "2015-11-10T16:08:42Z")
If you’ve not soldered before you definitely want to practice on some spare wire and small hunks of copper to simulate batteries. As said above , the goal is to get the parts hot enough to melt and flow the solder BUT no hotter. The longer you fumble, the more damage you do to the batteries. And another vote for replacing soldered-in batteries with a standard holder and standard replaceable batteries. Fix it once, not every time you exhaust the batteries. ---
**Author:** ![Kevbo](https://avatars.discourse-cdn.com/v4/letter/k/e47774/32.png) [@Kevbo](https://boards.straightdope.com/u/Kevbo)\ **Post date:** [November 10, 2015, 5:04pm UTC](https://boards.straightdope.com/t/electronic-soldering-super-simple-low-level-battery-repair/737160/9 "2015-11-10T17:04:53Z")
During the repair, and the first time you charge them, have a bucket of water and some pot holders handy, and don’t turn your back on them. Damaged cells can get hot enough to start a fire, if they start getting hot, use pot holders to drop them into a bucket of water. I had this happen once. I carried the battery outside by a wire, and dropped it into a rain-catch barrell. It was emitting noxious smoke by the time I got outside. It was pretty scary. Things were fine until I tried to charge them. It took about 3-5 minutes before I knew there was trouble. A large, high wattage iron or soldering gun will allow the connection to be made with less heat to the battery than a small, low watt iron. A better way to make up batteries is spot welding. There are several articles online on homemade spot welders for this purpose. Spot welding gives intense, but momentary heat, so the total heat put into the cell is a tiny fraction of what it takes to solder cells. ---
**Author:** ![Stoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/stoid/32/272_2.png) [@Stoid](https://boards.straightdope.com/u/Stoid)\ **Post date:** [November 12, 2015, 12:28am UTC](https://boards.straightdope.com/t/electronic-soldering-super-simple-low-level-battery-repair/737160/10 "2015-11-12T00:28:15Z")
Well, I appreciate everyone’s help. Turns out not so simple. At least not the first of the two batteries, because this one has a torn wire, and all attempts to join the wires result in tiny little fires. Fun. I know this would be a cinch for someone who had the slightest comfort level. WAH. ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [November 12, 2015, 1:33am UTC](https://boards.straightdope.com/t/electronic-soldering-super-simple-low-level-battery-repair/737160/11 "2015-11-12T01:33:10Z")
I’ve been soldering for 42 years. It’s a science for sure, but it’s also an art. A person who is experienced at soldering has a intuitive feeling for the wattage of the iron, the size & geometry of the tip, how to tin the tip, how long to apply heat, and how to add the solder. I suggest emailing your local amateur radio (“ham”) club, and ask one of the members if they can help you. ---
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [November 12, 2015, 3:38am UTC](https://boards.straightdope.com/t/electronic-soldering-super-simple-low-level-battery-repair/737160/12 "2015-11-12T03:38:58Z")
> [@Stoid](#): > > … because this one has a torn wire, and all attempts to join the wires result in tiny little fires. Fun. If I understand this right, you have a wire that is torn in half, and you are trying to solder those pieces back together? I wouldn’t bother trying to do that, just get a phone wire crimp connector ([3M Scotchlok UR3 or similar](http://www.summitsource.com/scotchlok-type-button-phone-wire-crimp-connector-pack-modular-telephone-conductor-data-signal-cable-squeeze-audio-connectors-part-920101-p-4855.html)) to connect them. They’ll cost you about 10¢ each (maybe more at someplace like Lowes or HomeDepot), and get the job done in about 5 seconds – well worth it. (This is assuming the wire is smaller than #18 AWG. Also, many of these connectors are designed for solid wires only – make sure you can use one with your stranded wire.) And I still recommend replacing soldered-in batteries with a standard holder, for a long-lasting fix. ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [November 12, 2015, 7:35am UTC](https://boards.straightdope.com/t/electronic-soldering-super-simple-low-level-battery-repair/737160/13 "2015-11-12T07:35:45Z")
> [@Isilder](#): > > In fact splaying the strands out is a good way to increase mechanical strength of the solder bond to the electrode. It depends but I doubt this is usually good advice. If you splay the strands out then very often when the wire is pulled in a particular direction tension will come onto the one strand furthest from the direction of pull. That lone strand will (immediately or eventually) break. Then the next strand will come under tension, and so on. If the strands are all together, they all take the tension and the load is spread. ---
**Author:** ![Stoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/stoid/32/272_2.png) [@Stoid](https://boards.straightdope.com/u/Stoid)\ **Post date:** [December 2, 2015, 8:27am UTC](https://boards.straightdope.com/t/electronic-soldering-super-simple-low-level-battery-repair/737160/14 "2015-12-02T08:27:33Z")
> [@t-bonham@scc.net](#): > > If I understand this right, you have a wire that is torn in half, and you are trying to solder those pieces back together? No, they had torn in half and I was going to remove the bits from the battery and solder the wires still connected to the plug back to the battery. All the wires kept bumping into each other and sending up tiny little sparks and flames and smoke. I managed to remove most of the wires attached to the battery, but they appear to have been topped with wax or something and I’m hesitant to pry them off. Don’t know why, really…hardly makes a difference at this point. > [@](#): > > And I still recommend replacing soldered-in batteries with a standard holder, for a long-lasting fix. > [@t-bonham@scc.net](#): > > seems like a more permanent solution would be to solder the wires from the led lights **to a standard battery holder**. > [@carnivorousplant](#): > > I like tbonham’s idea of installing battery holders. > [@LSLGuy](#): > > And another vote for replacing soldered-in batteries with a standard holder and standard replaceable batteries. Fix it once, not every time you exhaust the batteries. So can y’all give a gal some guidance about what you mean? I’m googling but I’m not sure I’m finding what your’e thinking of. ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [December 2, 2015, 9:14am UTC](https://boards.straightdope.com/t/electronic-soldering-super-simple-low-level-battery-repair/737160/15 "2015-12-02T09:14:26Z")
Standard battery holders are readily available. [This](http://www.amazon.com/Philmore-Battery-Holder-Standard-Connector/dp/B000LFVFT4)is one example. ---
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [December 2, 2015, 9:47am UTC](https://boards.straightdope.com/t/electronic-soldering-super-simple-low-level-battery-repair/737160/16 "2015-12-02T09:47:03Z")
[Here is](https://cdn.shopify.com/s/files/1/0953/5270/products/02700401_00_e47397f0-eca6-4134-a65b-dcf4a49dddb7_large.jpeg?v=1446835877) another example that might be clearer (it shows the wires on it. You connect those wires to the wires on your light. Then you just replace the battery in that holder whenever it runs down. Note that this photo shows a single “AA” size holder. You will need to get one that holds the appropriate number of batteries, and the right size ones. Just go to a nearby RadioShack store to get them – shouldn’t cost more than $2-$3. (You can probably get it cheaper online, but actually being there you can make sure you get one that will work for this.)