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WARNING!! NiCd and NiMH batteries are low resistance, high capacity devices. If the leads of even one cell are shorted together, very high currents can flow and the wires and battery can get quite hot. Exercise great care when assembling a pack.
The use of battery holders is not recommended. They take too much space and are not reliable. Ready-made battery packs are seldom suitable for building into many applications it seems these days. When they are available, use them-- it will save a lot of trouble. When they are not available for your setup then you will have to build them. This is not really very difficult provided you follow some simple guidelines. |
When buying the cells from us at mdbattery, it is often possible to specify that they come with solder tabs. These are strips of tinned material that are welded to the ends of the cell and they make soldering very much easier. (picture 1)
If solder tabs are not available, you must solder short wires to the ends of the cells. Good soldering practice and good solder are most important. The iron will have to be larger than usual or hotter or both. Solder guns do not have enough heat capacity for this. Be sure to use rosin core solder and it is a good idea to use fine sandpaper to polish the solder areas. Using as little heat as possible, tin an area on the end of the cell. Tin the end of the wire, then solder to the end of the cell. Insulated wire should be used and great care taken to prevent uninsulated wire from shorting to the edge of the cell at the positive terminal.
When assembling a battery pack of unusual dimensions, it is often useful to make a jig glued up from scrap plastic. Also, a hot melt glue gun can be of help for holding cells in alignment. Be sparing with the hot melt glue as you might want to take the battery apart some time. Before starting to solder, do a test package by placing the batteries in the engine or in an equivalent jig. When you are sure you have the assembly configuration that you want, then it is time to begin soldering. (picture 2)
Some packs are built whereby the cells are placed side by side with the head and tail ends alternating and others are aligned together. If your cells have solder tabs, first trim them so there is little excess, then tin the tabs where they will overlap and finally do the connection by holding the tabs together and heating with a soldering iron.
BE VERY CAREFUL NOT TO MELT THE PLASTIC BATTERY COVER AT THE POSITIVE END OR YOU MAY GET A SHORT IN THAT CELL.
To aid in preventing accidental shorts, it may be useful to use plastic tape or thin strips of plastic between clumps of cells in an assembly. One good idea is to make washers of non-melting paper masking tape to protect the positive ends of the cells. These washers can be mass produced by using a sharpened piece of brass tubing to drill into a roll of masking tape every inch or so. (picture 3)
THINK AHEAD ABOUT WHAT YOU ARE DOING AND WHETHER THERE MIGHT BE A SHORT CIRCUIT.
The comments on this page are simply suggestions and not to be used in place of a formal set of guidelines or assembly instructions manual.
MDBATTERY stocks a wide range of industrial cells used in the assembly of custom battery packs. Because of the diverse range of custom battery pack designs we have many types of industrial cells, whereby we can provide these cells either as plain cells or with tagged terminations to suit your application.
Please provide caution when assembling any pack yourself.
Manufacturers will advise that cells should not be soldered to directly because it would be easy to cause internal and possible unseen damage to the battery.
We sell nickel plated tabs or tags to the cells direct from the manufacturer whereby they use special resistance welding equipment. If you are going to solders cells then it is advisable to choose this type of cell. Please email or call us direct to request us to have the manufacturer make most configurations for your specific application.
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