This information comes from an article published in the July / August 1978 issue of Race Car World. It should be used for research and entertainment only!
“Racing Tips”is a regular column where any advertising manufacturer can express new ideas involving their products or tell racers the latest tips. This column is not a new products listing but rather a pipeline of information from those who should know to those that want the knowledge.
Greetings from the quality world of BOLink! We’re here to give you ideas and tips to make your car run faster and more reliably.
Our intent is to do these columns on a regular basis and would appreciate hearing from you, both as to what you would like to hear about and any tips you would care to share.
For a beginning we will start with a very simple task, which isn’t quite as simple as it seems. We are going to replace a battery in your motor power supply.
But first let’s give you some background on these batteries. Most of our cars have either 4 or 6 sub ‘C’ size nicads (except for you cheaters out there who run 8 cells to surprise your friends).
We don’t use just any old nicads, they are internally welded, low impedance, cells with an almost instantaneous collapse rate. They are only made by G.E. All other nicads have a higher impedance to make them run longer but they will not pull more than 8 amps so they do not get the torque that the G.E. cells will. We are telling you this so you don’t rush down to your nearest war surplus store and buy a mystery cell because it looks the same.
“…do not solder a new cell into an already charged pack.”
Now before you go ripping off wires, make sure you have a dead cell and not a broken wire. Push, pull and wiggle everything to see if it might start working. If you have a Volt Meter it’s easy to run down the individual cells. If not, then we are going to have to work some magic. If you have a flashlight bulb, hang a wire off one side and see if it will light by putting the center to one pole and running the wire over to the other pole and see if it lights. These batteries are rated at 1.2 VDC and when charged will show a plate voltage of about 1.4 VDC.
Okay, you’ve determined one cell is a dud and you know which it is. Before you unfasten it we want to discharge your pack.
Whatever you do, do not solder a new cell into an already charged pack. What happens is the charged batteries will seek an average so will all discharge into the one new uncharged battery. More good cells are ruined this way.
If you have a charger with a discharge setting, then use it. If not, then run the car until the motor dies. If the bad cell has infinite resistance, then put a jumper around it. Just get the good cells down.
The bad cell is now out and the new cell is ready to go in. Be sure and check the polarity. The negative side is flat and the positive has the little button. All the batteries are wired in series, that means positive to negative. A battery put in backward can be driven into reverse, not helping matters at all.
You’ve determined the direction, got your soldering iron hot and are ready. So take your Xacto knife, or whatever you have, and scrape off the goo that always seems to be on the end of these things, then heat up the tabs and tin them. That means run a little solder around them. Do not use an acid core solder or acid flux on an electrical joint. Sooner or later it will corrode things and boy will you be sorry. I prefer Ersin 60/40 tin, lead.
A couple of things for you to watch out for: First, on the positive side, notice the black ring outside the button. Don’t let solder get across that ring and to the case because it shorts out the works. Also notice outside that ring, a tiny hole. Do not, for any reason, plug that hole. As a byproduct of charging, these batteries give off hydrogen. That hole is the vent and if you block it, you will have a bomb on your hands.
Okay, the battery is tinned, now tin the inside of the jumper tab, set it against the battery and heat the outside until the solder melts. Hold until it cools and you are ready for recharging.
One note on recharging.The manufacturers recommend that you discharge these batteries to the point they no longer run the car before each charging. They will take the rapid charge very well but will not take an overcharge.
Overcharging is taken up in heat. At 115 to 120 degrees Fahrenheit the plates will start warping, internally shorting the battery, thereby ruining it.
Also the hydrogen gas buildup can be great enough to overpower the vent, thereby causing an explosion.
So now you know the tricks to replacing batteries, let’s hope you don’t need to use them.
As we said in the beginning, drop us a line as to anything you would like to hear about or tips you may have. The address is: BOLink Race Tips, P.O. Box 80653, Atlanta, CA 30341.