Instructables

How to solder ni-cad batteries together for battery pack.


I want to replace a bad battery in an eighteen volt pack, but can't seem to get the solder to adhere to ends of battery. I thought about welding, but don't want to damage batteries. Any suggestions.?

blfinche3 years ago
You can solder nicad batteries, but you must first sand the ends of the batteries. You don't have to do anything else. You will also need a powerful enough soldering iron with the right tip. You will need at least a 40 watt iron. A hammerhead tip works best for me. I use solder braid to solder the batteries together. You need to use good technique when soldering. Only hold the soldering iron on the batteries for 1 - 3 seconds to tin the ends of the battery.
fserban3 years ago
Here's a a solution. Pick a piece of very fine sandpaper and scratch the metal ends. Then take a tablet of Aspirin (acetylsalicylic acid), heat your soldering iron, melt a small bit from the Aspirin tablet then rub the scratched metal parts. After this, the solder will adhere much easier. DO NOT INHALE THE ASPIRIN SMOKE !. It's very nasty!
As per Frollards comments, weld if possible, but soldering needs an ACID flux to do it - we have one here called "Baker's fluid" which is great for difficult materiala (not aluminium though)

Steve
frollard3 years ago
Most tabs are welded to batteries using a spot welder that only puts current thru the end cap, not thru the battery itself.

it is possible but dangerous to solder nicads -- make sure you get the end hot enough, and use flux to clean the surface first. Beware, this may explode and kill you and your neighborhood. (really recommend spot welding)