Nuts & Volts - January 2005

Near Space

need to watch what you are doing.

This modification involves soldering two #12 AWG gauge wires to the battery’s tabs and then covering the exposed connection with tape and heat shrink.

So, begin by firing up your soldering iron. After it warms up, apply a thin coat of solder to the entire exposed surface of the electrical contacts of the lithium-ion battery. Do this quickly, as you don’t want to heat the metal contacts any longer than necessary. The battery chemistry may not respond favorably to high heat and you certainly do not want to melt the plastic case. I found that the gold-colored contacts soldered very easily.

Cut a red and a black wire to the same length. These wires will become the battery’s new power cable, so select the power connectors you plan to use and crimp and/or solder them to one end of each wire. It’s easier to terminate your wires now than later, when the battery is hanging from the other end. In my example, I cut my wires 4” long and crimped Anderson Power Poles on the ends.

Strip between 1/8” and 1/4” of insulation from the other ends of the two wires. Bend the ends of the exposed wires at right angles where the insulation ends and tin the exposed ends with solder. Watch out — the wires will stay hot for a while, so be careful when you handle them.

Look at the front of the battery and beneath the tinned electrical contacts. There, you’ll see a small positive and a small negative mark imprinted on the plastic battery case. These represent the polarization of the electrical contacts. After determining the polarization of the tinned contacts, solder the wires onto the battery contact. Be sure you solder the red wire to the positive contact and the black wire to the negative contact.

To solder the wires to the battery, I recommend laying a 12 gauge wire on the front of the battery case with its tinned end touching a tinned battery contact. Wrap a strip of masking

JANUARY 2005

tape around the battery and wire to hold them together while you solder the wire to the battery contact. When soldering the wire to the contact, quickly apply a well-tinned soldering iron to the wire and battery contact. The solder in the tinned wire and battery contact will melt and fuse together. Remove the soldering iron as soon as the connection is made. Repeat the process on the other wire.

Once the solder has cooled, cut two pieces of electrician’s tape and cover the exposed solder joints on the top of the battery. Cut the tape long enough to not only cover the top of the battery, but also to partially cover the sides of the battery. For good measure, wrap a strip of electrician’s tape around the top of the battery and cover the ends of the first two strips.

Finish the battery modification by cutting a 2-1/2” length of 2” diameter heat shrink tubing. Slide the tubing over the battery and fully cover both the body of the battery and the ends of the electrician’s tape that was used to cover the solder on the battery. Shrink the tubing down.