Remote control, or RC, enthusiasts often use nickel metal hydride, or NiMH, power tool battery packs to power their RC models. NiMH batteries are considered better than nickel cadmium batteries, or NiCAD, as they don’t suffer from “memory effect,” which is when you charge your battery fully and find it only lasts a short time before going dead. Factory-made NiMH battery packs can be expensive, so make your own battery pack if you want to save money.
Check the label on your RC model to find out the voltage it needs to operate. This determines the number of NiMH batteries you need to make your NiMH battery pack. You are wiring your battery pack in series, so you need to divide the input voltage of your RC model by 1.2. NiMH batteries produce 1.2 volts. For example, if your RC model requires 6 volts, then divide 6 by 1.2. The answer is 5, so you need five batteries.
Visit an electrical store to get the numbers of NiMH batteries you need based on your calculation. If the answer you calculated is not a whole number, round the number up or down to get the nearest whole number. For example if your RC model requires 6.5 volts, then 6.5 divided by 1.2 equals 5.4, so round it down to 5. However, if your RC model requires 7 volts, then 7 divided by 1.2 equals 5.8, so round it up to 6.
Put the NiMH batteries you need to make your power tool battery for Ryobi on a work bench and lay them flat. Rotate the batteries so you have alternating battery terminals at each end. For example, if you’re using five batteries, you have three positive terminals and two negative terminals on one end and two positive and three negative on the other end. The battery terminals are labeled “+” for positive and “-” for negative.
Mark each NiMH battery with a pen, If you have five batteries, mark then A through E. You need to be able to identify each battery so you attach the correct wires in series.
Wrap some electrical insulating tape around the NiMH batteries a few times so you hold them neatly together in a battery pack. It makes wiring easier and allows you to move them to where you need to when you want to connect them to your RC model.
Use AWG 18-gauge wire and cut two strips with a small knife long enough to reach between the NiMH battery pack and the motor in your RC model. Cut short strips of AWG 18-gauge wire: each strip needs to be about 2 inches long. The number of short strips you need is based upon the batteries you are using. A simple rule to follow when wiring in series is to calculate based on the number of batteries minus one. So if you’re using five batteries, you need to cut four strips of wire.
Use wire strippers to remove ¼ inch of plastic from the ends of each strip of wire. If you’re wiring five batteries, you have two long strips and four short strips, so you need to remove ¼ inch 12 times.
Attach the end from one long strip of wire to the positive terminal of the battery you labeled “A” using a 2-inch strip of electrical insulating tape to hold the wire on the terminal. The other end connects to your RC model.
Attach the end of a short strip of wire to the negative terminal of battery “A” using a 2-inch strip of tape. Attach the opposite end of the short strip of wire to the positive terminal of battery “B” by using tape.
Repeat attaching the short strips of wire to the negative and then positive battery terminals sequentially until you attach the end of the last strip of wire to the positive terminal of the last battery in your pack. If you are using five batteries, then the end of the last short strip of wires attaches to the positive terminal of battery “E.”
Attach the end of the remaining long strip of wire to the negative terminal of the last labeled battery in your pack. The opposite end connects to your RC model.
Use electrical insulating tape and carefully wrap it around the whole battery pack. This ensures that all the short wires and battery terminals are covered completely. However, make certain you leave the two long wires outside the pack as you need to connect them to your RC model.
Cut a piece of paper 2 inches by 1 inch using scissors. Write NiMH on the paper, then write the voltage output, number of batteries and the date on the paper. For example, if you used five batteries, write 6 volts and five batteries on the paper, plus the date. This ensures you don’t mix up other packs, if you decide to make more in the future.
Attach with clear adhesive tape the label prominently on the side of the battery pack so you can see through to read the label.
If you’re making a power tool battery pack for Metabo model airplane, consider using lithium polymer, or LiPo, batteries. Each battery produces 3.7 volts. So, as weight is important when flying model airplanes, you get more power using fewer batteries, meaning your airplane can fly faster, longer and higher.