Rechargeable batteries are more expensive to purchase, but they save you money over time. This is particularly true if you need a battery pack to regularly power equipment such as remote controlled (RC) cars or aeroplanes. Batteries such as nickel cadmium (NiCad) or nickel metal hydride (NiMH) are popular choices for RC car enthusiasts, while lithium polymer (LiPo) batteries are chosen by RC aeroplane enthusiasts, due to the that battery's lighter weight and higher output voltage. Build a rechargeable battery pack wired in series to increase output voltage: RC models need about 10-volts to operate, although it varies by type. Wiring in series combines the output voltage of each battery in the pack.
Calculate the voltage needed to operate your equipment. NiCad and NiMH batteries provide 1.5 volts; LiPo batteries provide 3.5 volts. To calculate, if your equipment operates on 10 volts, you need three LiPo batteries or seven NiCad or NiMH batteries.
Lay your batteries on a flat surface---as many as necessary to make a rechargeable battery pack to power your equipment. Alternate the batteries' terminals so you have a negative then a positive terminal alternating each end. If you are making a battery pack using four batteries you have two positive and two negative terminals each end.
Label the batteries numerically; so with four batteries, label them 1 through 4. Wrap electrical insulating tape around the batteries so that they form a neat tight battery pack.
Cut strips of AWG gauge 16 wire using a knife. You need two strips long enough to go from your battery pack to your equipment and then short strips of wire, long enough to attach to each battery terminal. The number of short strips you need depends on the number of batteries you are using to build your battery pack. If you are using four batteries, you need three short strips. The number of short strips is always one less than the number of batteries.
Remove ¼-inch of plastic coating from the ends of each strip of wire using wire strippers or a small knife. Attach a long strip of wire to the positive terminal of the battery you labelled "1." Use a piece of electrical insulating tape to keep the wire securely attached. Attach the second long piece of wire to the negative terminal of your last labelled battery.
Attach a short strip of wire to the negative terminal of battery 1 then attach the opposite end to the positive terminal of battery 2.
Continue attaching a short piece of wire to the negative then positive terminals of each battery in numerical sequence until you reach the positive terminal of the last battery. Ensure that only one wire is attached to each terminal.
Connect the opposite end of the long wire attached to the positive terminal of battery 1 to the positive terminal of your equipment and then attach the long piece of wire attached to the negative terminal of your last labelled battery to the negative terminal of your equipment.
Rechargeable batteries should be handled with care. Use according to the manufacturer's instructions. When the batteries need charging ensure your charger matches the voltage requirements of your battery pack. It is dangerous to connect two different types of battery such as LiPo and NiCad.