Any rechargeable electronic device, from cordless power drills to cordless phones, has a battery pack. Often the replacement of these packs is extremely costly. The interesting facet to these battery packs is that they look like single, monolithic structures. This leads most people to believe that the entire battery pack is used for energy storage. Anyone with a screwdriver and a little time is able to deconstruct a battery pack to discover what once seemed to be a single object is actually a multitude of smaller objects — namely, rechargeable batteries — set into a housing. The housing is the costly part of any battery pack.
Whenever the battery packs on one of these devices fails, many corporations will tell you that you must replace it only with their patented materials, or risk harming your device. There is a grain of truth to this claim, and to be fully safe, one should not necessarily step outside of the bounds of company recommendation, especially if there are concerns about abiding by the rules of the product’s warrantee. If you are not worried about voiding the warrantee and want to both save some money and learn an invaluable new skill, then you can make your own battery packs.
Making battery packs is not very difficult, and it is certainly cheaper (usually about half the price) than buying a whole new battery — but up until recently, it was easy to do it wrong without extensive practice. Formerly, battery packs were made by soldering wires or small plates to the ends of the batteries to create a comprehensive whole. These wires would allow the power from one battery to flow into the next battery to create greater power.
Those days are long behind us.
These days, instead of buying rechargeable batteries as well as wires or plates, many rechargeable batteries come with things called solder tags. Solder tags have revolutionized the simplicity with which battery packs can be constructed. Simply put, solder tags are pieces of metal that come pre-attached to rechargeable batteries, instead of having to wrestle with loose wires or pieces of metal. By buying rechargeable batteries with solder tags, you eliminate the cost of also buying additional wires or metal solder points. Solder tags have truly taken the headache out of battery pack construction, so that anyone with hands can do it.
How to Build a Battery Pack Using Rechargeable Batteries With solder Tags
The first step to building your own battery pack is to figure out what kind of battery to use. This is a lot simpler than most people think. Commercial battery packs generally have the same power output. For instance, rechargeable batteries generally have a universal voltage of 1.2V. This means that a battery pack that produces 2.4V has two batteries contained in it. This is true no matter what size the battery is.
Battery size changes the amount of power held within a particular battery. Larger batteries last longer, but do not produce greater amounts of power. It is the combination of power or multiple batteries that determines how strong a battery pack is. This means that voltage does not vary across battery types. A AAA rechargeable battery produces the same 1.2V (actually, 1.25V to be exact) as a D cell battery. The D cell will just be able to produce those 1.2V for a longer period of time. Much longer, in fact.
What this means for making your own battery pack is the size of battery you will need depends entirely on the housing you are using. The power output will be the same, but how long the battery lasts depends on the size of battery you use. If you are making a battery pack for a device where the battery already has the complicated housing mentioned above, like a mobile piece of equipment, then you will need to use whatever size battery came out of the housing. If you are making a battery pack for a device where you have free reign over the size of the pack, then the only question you need to ask yourself is how long you want it to last. The longer you want the charge to go on before it needs recharging, the bigger the cell of battery. That is it for determining battery size.
Since you will want a battery pack that is rechargeable, you will almost always be using NiMH rechargeable batteries. As we have talked about before here on the blog, NiMH stands for for Nickel-Metal Hydride and are not only rechargeable, but also environmentally friendly. Since they are the most popular rechargeable battery, using NiMH rechargeable batteries will save you even more money, because they are sold from several retailers, from premium brands like Sanyo Eneloop to more affordable generic brands like Vapex..
Use Solder Tags to Quickly & Easily Assemble your Battery Pack
Now that you have picked out the size and type of battery, it is time to get down to the actual construction. This is where you will see how beneficial solder tags are to use. In the bad old days of battery pack construction, you would be bent over trying to keep the loose rechargeable batteries aligned while you juggled wires and solder and metal bits and batteries. The frustration involved would be enough to make you give up the project and pay the ridiculous prices for a brand new battery pack. No more. The solder tags give you a high conductivity attachment between the batteries of your pack, and they are mounted directly onto the batteries themselves. No need to juggle.
To construct the battery pack, all you need to do is sand the ends of the battery lightly, so as to give the solder an area to grip to. Once that is done, you melt a drip of solder onto each end of each battery in the pack. You then arrange the batteries into the form you want. Here is the big note you must not miss:
MAKE SURE ALL BATTERY CONNECTIONS GO FROM NEGATIVE TO POSITIVE.
In your battery pack, there needs to be a flow from negative to positive all the way around. The easiest way to accomplish this is to arrange the batteries with one right side up, the other upside down. Make sure that that the batteries are arranged bottom to top all the way with no two tops and no two bottoms beside each other, and you will be golden.
Battery packs are most easily arranged left to right and top to bottom. This means that you do not arrange the pack the same way you are reading this page. You begin at the left hand side of the top, with battery number 1. The battery chain should look like this:
And so on down with battery 8 flowing down into battery nine, and the row starting with nine connecting left to right, while the next row goes right to left.
The final step is to solder the batteries together. Now every battery should have a little dollop of solder on both ends. This again is where the solder tags have made life simple. Using a very hot soldering iron (recommended 100-Watt), you place the solder tags over the bit of solder on each battery and then place the iron against the top of the tag for 5 seconds. It is very important not to do it longer, because if you do, you will be heating the core of the battery. This can damage the battery, or it can excite the particles within the battery and turn it into a very small bomb.
While you would have once had to try to hold the batteries steady, the soldering iron, and the wire, all you need to do now is simply press with the soldering iron on the soldering tag and it will give you a perfect connection almost every time.
That is really all there is to making a battery pack. It can be hardwired into almost any mounting, all made so much simpler by the beauty of the solder tag. You can cut the cost of battery replacement by nearly half by buying the rechargeable batteries separately and then using the existing housing. Thanks to solder tags, it is no longer a difficult operation, but a cost effective solution, perfect for these dire economic times. Thanks to solder tags, homemade battery packs are not only possible, but easy and affordable. Happy Soldering!
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