LiPo for 3DR IRIS R/C transmitter

IRIS pilots will quickly get tired of buying Alkaline AA batteries for the R/C transmitter and will also realize that this can turn into a costly part of our hobby. Time to replace these batteries with a Lipo.

Required materials and tools

The following materials are required.

The following tools are required:

  • Very small flat-head screwdriver

How-to assemble

Important: The discharge leads of the above pack is reversed for the use in the 3DR IRIS R/C transmitter. Read these steps carefully to fix this!

Follow these steps to change the polarization of the above LiPo and install it into your RC transmitter:

  • The Turnigy 2650mAh 3S 1C LLF Tx Pack comes with 3 leads that can be used for charging and discharging (See Figure 1). Lead 1: Balance lead for charging. Lead 2: Discharge lead for R/C controller (More later). Lead 3: Charge lead.
    Figure 1: Lipo Charge/Discharge Leads

    Figure 1: Lipo Charge/Discharge Leads

  • For the discharge lead (See Figure 1, Lead 2.) use a very small flat-head screwdriver and carefully remove the metal pins from the plastic plug. As an alternative you can also use the Futuba plug (See Figure 1, Lead 3) and place the battery sideways into the bay.

Important: Ensure that the metal pins don’t touch each other! This will shorten the battery and can cause damage.

Figure 2: Removing the metal pins from underneath the plastic clip

Figure 2: Removing the metal pins from underneath the plastic clip

In Figure 2, Sequence 3 you can see circled in red the small barb on the metal pin. You need to carefully lift the plastic tooth under which the metal pin is locked in (See Figure 2, Sequence 1). While lifting the plastic tooth you have to carefully and gently pull the wire towards the back (See Figure 2, Sequence 2).

  • Notice that you can only insert the plug of the discharge plug in one way, with the plastic locking the pins facing down. Re-insert the cables, so that the red wire is on the right and the black wire is on the left, while the plug is facing down with the plastic locking mechanism (See Figure 2).
Figure 3: Discharge lead of the LiPo

Figure 3: Discharge lead of the LiPo

  • Insert the discharge plug into the 3DR IRIS R/C controller. Red (+) on the middle pin and Black (-) on the left pin (See Figure 2).
  • Place the Lipo inside the 3DR IRIS R/C controller to the right of the battery bay and store the remaining cables.
Figure 4: Lipo stored in 3DR IRIS radio

Figure 4: Lipo stored in 3DR IRIS radio

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  • I placed a small strip of foam between the Lipo and the battery door, before closing the battery door. When doing so, be careful to not squeeze any of the cables.

Charging

While Lead 2 is connected to the R/C transmitter, Lead 1 and Lead 3 are not (See Figure 1). This means that you can charge your radio Lipo via Lead 1 and Lead 3, while the Lipo is in the R/C transmitter and without disconnecting Lead 2. Just open the battery door, carefully remove Lead 1 and Lead 3 and connect them to your charger. Ensure that your R/C transmitter is turned off while charging.

Results

The 3DR IRIS R/C transmitter is a re-branded Flysky / FrSkY transmitter and usually works with 12V (8x 1.5 AA cells). With the backlight installed it needs about 120-140mA. Since the above Lipo provides 12.6V when freshly charged, you might be scared by this difference. No need for this as the voltage will drop pretty fast below 12V.

In contrary to some of the other proposed batteries, this Lipo can be charged with the stock 3DR charger or any other Lipo charger.

You will notice that the R/C transmitter becomes very lightweight with the Lipo installed. Also with 2650 mAh it will last for month on regular flying.