How to Modify RC Transmitter With Rechargeable Li-Po Battery

Hello! In this brief and easy guide, I will go over how to power a normal 12v RC transmitter using a rechargeable lithium-ion battery pack.

2.4 GHz RC transmitters are very useful for tons of uses. However, they typically need AA batteries to work, and rip through them pretty quick. So rather than wasting tons of batteries and having to replace them all the time, why not replace them for good with a rechargeable lithium battery?

Step 1: Materials

In order to do this modification, you will need

- RC transmitter

- soldering iron and solder

- wire stripper/cutter

- 2 wires with standard male pin connector

- 3s (11.1v) Li-Po battery (see below)

- Li-Po battery charger

You will need a 3s Li-Po that is compact enough to fit in the compartment of the transmitter. Measure the inside of the battery compartment, and find a battery that will fit but also leave sufficient space for the wires to be stuffed in.

I got a "BQY 11.1v 2200mAh Li-Po" from AliExpress. The battery I got has a small servo-sized connector, which is optimal because it does not take up much room. The dimensions of my battery is 110mm x 40mm x 12mm, which fits snugly in the compartment with just enough room for the connector.

Step 2: Prepare the Materials

You'll need to cut the negative/black wire quite short, but leave the positive/red wire quite long. Strip the ends of the wires you there is about ~6 mm of exposed wire. This step will vary depending on the setup and size of your transmitter. Just be sure to adjust accordingly, as the pins need to be able to plug into the battery, but not have too much excess wire.

Step 3: Get Ready to Solder...

Open up the battery compartment, and rest the transmitter on a stable surface where you can easily see the compartment. You will need to identify the negative and positive battery terminals. The picture above shows the terminals for a regular 8-AA battery compartment.

Negative/ground (circled in black), is usually a protruding tab or spring. Positive/power (circled in red), is usually just a flat round metal contact. These are where you will be soldering the wires.

You might want to take the edge of a screwdriver or other tool to scratch up the electrical contacts, because the solder will stick better to the uneven surface.

Step 4: Attach the Wires

Now simply solder the red wire to the positive terminal, and the black wire to the negative terminal. It helps to tape the connector to the inside of the compartment to hold the wire in place. Just be careful to not melt the plastic on the transmitter.

Once you have finished, it should look something like the picture above.

Step 5: Success!

Now take your battery, place it in the compartment, plug the connectors to the battery, and tuck the wires into the extra space. Now just put the cover back on, and done! Try turning on the transmitter, and it should work!

Most certainly remember to turn off the transmitter when you are done with it, and it is recommended to also unplug the battery when you're done as well. Li-po batteries can be extremely volatile and dangerous when damaged.

An alternate method of doing this would be to unscrew the body of the transmitter, and solder the wires directly to the motherboard, then thread the connectors into the battery compartment. This works too, but this method is easier to do and undo if needed.

I hope you enjoyed my first Instructable! Thanks for reading!