Everyone knows that a lithium polymer battery cannot be overheated or soldered with a regular soldering iron. But what to do if you still need to connect two batteries. This will be discussed in the article.
When I was building the Cessna, site users advised me to buy at least two batteries so that I wouldn’t have to go out into the field to fly for a few minutes.
We ordered two of these batteries .jpg)
Battery Turnigy 1300mAh 3S 20C Lipo Pack
Product http://www.site/product/9272/
One of them categorically did not want to take the charger. Sometimes it immediately gave a burst error, sometimes during charging. I soon discovered that the contacts inside it were shorting. So I started flying with just one battery.
Now I got around to taking it apart. After removing the outer wrapper, it was discovered that the iron plate between the first and second cans was torn and contact was ensured only due to the “tightness” in this place.
When I started poking around and completely broke away. 
But everyone knows that LiPo batteries cannot be overheated above 60 degrees Celsius. Regular solder melts at about 200 degrees Celsius. Moreover, the solder practically does not stick to these plates due to the sticky layer, which means you will have to tin for a long time. As luck would have it, only a couple of millimeters of this plate remained on one can.
Then I remembered about Rose’s alloy. Its melting point is only 95 degrees Celsius. Those. it can even be melted in boiling water. 
I didn’t have an adjustable soldering iron at hand, so I had to solder with a regular one. The temperature was regulated by “undocking” the soldering iron from the socket. Rosin melts at about 70 degrees, so ten seconds after heating until the rosin melts, you can safely turn off the soldering iron.
I first clamped all three “antennae” with steel wire that needed to be soldered together (two from adjacent stickers, the third with a white wire for the balancing connector) and started soldering. This wire later helped me very well - as I wrote earlier, the native plates very diligently repel the alloy, at first the solder stuck just to this wire, and then slowly transferred to the plates. 
The rest of the wires can be clamped with a rubber band, otherwise they interfere very much with this “jewelry work”. 
After soldering, I cut off the excess steel wire, took care of the insulation, and reassembled everything. At the end I wrapped everything with regular electrical tape. Now I have it white. 
I ran 5 charge/discharge cycles. The charge shows normal.
Tomorrow I'm going to test it on a Cessna.
I also want to add that disassembling and soldering LiPo batteries are associated with great health risks and this article is in no way a guide to action!
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To collect the simplest scheme powered by a battery, we have to resort to various tricks to ensure that the wires fit snugly to the poles of the battery itself. Some people make do with electrical tape and adhesive tape, others come up with various kinds of clamping devices. But the contact in this case will be imperfect, which ultimately affects performance assembled circuit. Often the contact disappears or becomes loose, and the device works intermittently. To avoid this, it is best to simply solder the wires to the poles. In our article we will tell you how to solder wires to a battery so that the contact is perfect.
The simplest example of a device
The most a simple device, powered by a battery, is an ordinary electromagnet. Using his example, we will check the performance of our student soldering. We take an ordinary nail, for example a weave, and wrap it around it copper wire in tight rows. We insulate the turns on top with electrical tape. The electromagnet is ready. Now all that remains is to power the device from the battery.
Of course, you can simply press the wires at each end of the battery, and the device will start working. But it is inconvenient to use. Therefore, it is best to ensure constant contact of the wires with the power source. This can be done by adding an ordinary switch (toggle switch) to the network and soldering the wires directly to the battery poles. The device will become more reliable, it will be more convenient to use, and if it is not needed, you can always turn it off by opening the circuit using the switch so that the battery does not run out. But how to solder the wires to the battery so that they do not fall off after five minutes of using the device?
Tools and consumables required for soldering
In order to reliably solder the wires to the battery poles, you need necessary set tools. Since soldering a wire to a battery is a more difficult task than simply soldering a pair together copper wires, we will do everything exactly with the instructions posted below. In the meantime, let's prepare everything you need:
- An ordinary household hand-held soldering iron. We will use it to solder the wires to the poles of the battery.
- Sandpaper or file to clean the soldering iron tip from slag and carbon deposits.
- Sharp knife. We will use it to strip wires if they are braided.
- Flux or rosin. Which soldering flux is suitable for in this case? Let’s not rack our brains here, let’s take simple soldering acid, it is sold in any store that sells radio products. Well, rosin, although it often differs in color and shade, is always the same in properties.
- Brush for applying flux.
- Solder. It can be purchased in the same place as flux.
Solder the wires to a regular battery
So, how to solder wires to a 1.5V battery? This task is not difficult if everything you need is already at hand. We act according following instructions:
That's it, the wires are properly soldered to the battery.
Solder the wires to the crown
How to solder a wire to a Krona battery? Here, soldering is carried out almost in the same way as in the case of a conventional battery. The only difference is that in the Krona battery the 9V plus and minus are located side by side on one top side of the battery. The nuances are as follows:
- In the case of flux, we treat the Krona contacts on opposite sides with acid. There we will solder the wires.
- In the case of rosin, you will need to tin the Krona contacts, also on opposite sides. Why from the opposite ones? Because in this case the risk of a short circuit between the wires is practically reduced to zero.
- The Krona 9V battery has contacts (poles) that are very inconvenient for soldering. At the top they open wider, and therefore for high-quality tinning and soldering from the side of such a contact, it is necessary for the soldering iron tip to be narrower or pointed.
In general, the whole process is similar to the previous one. We treat the contacts and edges of the wires with acid (or tin in the case of rosin), press the wires to the contacts, take a little solder with a soldering iron and solder them. The process is complete.
Quad batteries 4.5 V
It is even easier to solder wires to such batteries. They have flat, folding contacts that can be easily tinned. And soldering to them is easier and faster. The main thing is not to move the wires during the soldering process. Otherwise they will simply come off.
Here you can not hold the wire at all, but wrap it around the plane of the contact strip. And then, having collected tin with a soldering iron, carry out soldering.
Rechargeable batteries
It is better not to solder batteries, but to make a special container for them, in which the contacts of the elements will be in close contact with the polar contacts of the container. The material of the batteries consists of alloys that are even worse for soldering than conventional lithium ones. But if you really need it, then soldering is carried out as in the case of a regular 1.5 V battery, just use flux and not rosin. Plus, soldering should be done as quickly as possible, keeping the contact of the soldering iron to the poles to a minimum, since such batteries are afraid of overheating.
Conclusion
Of the two options - rosin or flux - it is better to choose flux. It will provide the soldering with greater durability and reliability. Such soldering will not fall off even if the device is used very often. The only caveat is that the acid vapors released during soldering are very harmful, so it is not recommended to inhale them, and after the procedure you should wash your hands thoroughly.
When working with mobile household devices or special tool With a built-in power supply, there is often a need to solder a wire to the battery.
Before you begin this seemingly simple procedure, you should carefully prepare, which will guarantee that you will receive a reliable and high-quality connection at the end of the work.
Both the alkaline or lithium battery itself and the one soldered to it need preparation. connecting wire Nick.
These procedures also include preparing the necessary consumables, including such important components as solder, rosin and flux mixture.
The most difficult and crucial moment of the upcoming work is stripping the battery terminal to which the connecting wire is supposed to be soldered. This procedure may seem simple only to those who have never tried to do this.
The problem in this case is that the aluminum contacts of power supplies (finger or other type - it doesn’t matter) are susceptible to oxidation and are constantly covered with a coating that interferes with soldering.
To clean them and subsequently isolate them from air you will need:
- sandpaper;
- medical scalpel or well-sharpened knife;
- low-melting solder and neutral flux additive;
- not a very “powerful” soldering iron (no more than 25 watts).
After all the specified components are prepared, the following operations must be performed. First, you need to carefully clean the place where you intend to solder, using first a scalpel or knife, and then fine sandpaper (it will provide more high-quality removal oxide films from the contact zone).
At the same time, the bare part of the soldered wire should undergo the same stripping.
Immediately after preparation you should proceed to protective treatment terminals of a AA or any other battery.
Flux treatment
To prevent subsequent oxidation of the contact, the surface of the battery, cleared of plaque, should be immediately treated with a flux mixture made from ordinary rosin.
If the phone battery contacts, for example, are missing greasy spots from oils - just wipe them with a soft flannel soaked in ammonia.
After this, you will need to warm up the soldering iron well and solder the contact area with a few quick touches. At this point, preparation for soldering can be considered complete.
Soldering process
After each of the connected parts has been cleaned and treated with flux, they proceed to directly soldering the wires to the contact area of the battery.
To carry out this final procedure, you can use the same 25-watt soldering iron that was used to prepare the battery terminals from NI or CD.
As a solder, you should choose a low-melting composition, and for good spreading, use a rosin-based flux.
The final soldering procedure should take no more than 3 seconds. This applies to any type of battery (both NI and CD).
The most important thing is to prevent overheating of the terminal part of the element, as a result of which it can be seriously damaged. The possibility of its complete destruction (rupture) during the soldering process cannot be ruled out.
When considering how to solder a wire and a battery, it should be noted that this situation occurs much more often than it seems. First of all, this concerns special construction tools(if it is necessary to solder screwdriver batteries, for example).
There are often cases when the built-in power supply of the tool used is completely destroyed for some reason, and there is nothing to replace this screwdriver with. In this situation, the conductors powering the device are soldered to a spare battery designed for the same voltage.
The considered technique can be used when you just need to solder two batteries together.
It should be noted that instead of soldering, spot welding is used in production for batteries. But not everyone has a device for this type of connection, while a soldering iron is a more common device. That’s why soldering comes to the rescue at home.
When it comes to converting a battery to 18650 (for a screwdriver with Ni-Cd/Ni-MH or for a home emergency DIY power supply like a Tesla Powerwall), many manuals and instructions are silent about how to connect the batteries. Not all of them are suitable for durability and even safety.
Is it possible to solder 18650 batteries?
When assembling several cells for a laptop or as part of a large battery (under various purposes ensuring autonomy right up to vehicles) the task is to connect 18650 batteries. And many lovers of DIY crafts are considering soldering as one of the options.
Remember, lithium-ion batteries (18650 and any other Li-Ion) when heated from soldering station(and even a low-power soldering iron) are destroyed in their structure and irreversibly lose part of the capacity!
That is solder 18650 batteries should not be done unless absolutely necessary. Either you have to put up with the change chemical composition and deterioration of performance. In addition, the solder connection is unreliable if the battery overheats. The metal is also impractical for compact assembly due to random solder shapes and vulnerability to external influence.
The installers themselves rightly note in the comments that when exposed to temperature lithium ion battery you also run the risk of deformation safety valve . This key element 18650 battery safety is located under the positive terminal and is made of polymer that can withstand maximum operating temperatures no more than 120°C.
What do professionals use to properly connect 18650?
You can achieve reliability and safety in assembling a battery from several batteries professional methods or at least proven to be practical and safe.
How to properly connect 18650 batteries:
resistance welding(dot);
using factory holders (holders);
neodymium magnets (powerful eternal magnets);
gluing;
liquid plastic.
Professionals use the spot welding method - this method is also recommended for industrial assembly of products with 18650 batteries. An example of budget spot welding for the home was discussed in detail not long ago on Geektimes.
Popular in the DIY community are rare earth neodymium magnets that hold pins tightly and allow you to quickly construct temporary or small household items. For long-term, compact projects, liquid plastic or even glue is best.
To quickly assemble a configuration of several 18650 batteries, you can buy holders with a plastic case and factory contacts for manual soldering without fear of overheating of the lithium-ion batteries.
Only in certain cases, when other options are not suitable or impractical (depending on the conditions), soldering should be performed by professionals. Their responsibility falls on the choice of low-temperature solder, as well as guaranteeing the performance and safety of the battery during further operation.