Battery and Audio for SkyView-AMOLED 1.75" on LilyGO T-Display S3

[Sasa Mihajlovic]

Hi everyone,

I recently got a LilyGO T-Display S3 AMOLED 1.75" and I plan to use it with the SkyView-AMOLED-round-1.75-TFT_eSPI project. I have a few questions regarding battery and sound:

1. Which Li-Po battery do you use (mAh capacity)? What capacities have you tried, and what worked best in terms of runtime and charging stability?

2. Does the SkyView-AMOLED hardware expect a speaker, buzzer, or any audio output for alarms (e.g., thermal, altitude), or is the project designed to be just a display without sound?

3. If you have added sound, what did you use exactly (piezo buzzer, small speaker + amplifier), and how did you connect it?

Any suggestions or links to batteries available from AliExpress would also be appreciated.

Thanks in advance for your help!

[Vlad Belayev]

Hi Sasa, 
Thanks for questions, I still need to add some comprehensive documentation on battery and how to add Speaker and AMP , but here is some quick answers to your question.
Please keep an eye on the repository for updates. 

1. Which Li-Po battery do you use (mAh capacity)? What capacities have you tried, and what worked best in terms of runtime and charging stability?
   

1. - The battery originally used is 50x30x40 600mAh battery, like below
   Battery 
   

   This form factor fits inside the round 50 mm case design (the corners need to be slightly rounded).

   In testing, this 600 mAh cell provides around 6 hours of runtime, which is also confirmed by the built-in battery logger (available in my version of the SkyView AMOLED firmware).
   The LilyGO T-Display S3 AMOLED 1.75" itself draws roughly 100 mA, which matches the expected runtime.

   Although 6 hours is achievable, in practice this can feel a bit short:

   • Many pilots arrive at launch with the battery only partially charged—for example 50%—which isn’t enough for a longer XC flight.

   • Previously, the board also consumed ~5 mA in standby, which could drain the battery overnight before takeoff.
     This happened because the power button had to be monitored continuously.

   This issue is now solved with the BATFET cutoff implementation.
   When the device is shut down using BATFET disable, the battery is electronically disconnected from the processor and standby drain becomes effectively zero.

   (Just note: to power the unit back on after BATFET cutoff, you need to briefly plug in USB power, because in that state the button can’t wake the board.)

     Another pilot tested a larger Li-Po cell, which provides significantly longer runtime.
   However, it doesn’t fit the standard round case — a redesigned, slightly bigger 3D-printed enclosure is required.
   He is currently working on an updated case to accommodate that pack.  
   
   This battery code is  UF553450ZF . It punches 1100 mAh and still quite "thin" 5.2mm. But the toot print is larger than a AMOLED display. He is designing the 3D case for it and hopefully I ll be able to share it once it finished. It looks rather nice.
   With this battery the SkyView LilyGo AMOLED lasts 11 hours, while fully operating.
   
   

   
   

1. Does the SkyView-AMOLED hardware expect a speaker, buzzer, or any audio output for alarms (e.g., thermal, altitude), or is the project designed to be just a display without sound?

The project does support audio, and the firmware already includes the original SkyView traffic-alert sounds.
These were further improved by Moshe, including:

• Spoken traffic distance announcements

• “Danger” proximity warnings when another aircraft gets too close

• Alerts triggered by incoming $PFLAA sentences whenever the reported alarm level is greater than 0

So the software side is ready for audio output.

However, the SkyView-AMOLED hardware does not include a built-in speaker or buzzer by default — you must add your own small speaker plus an amplifier board if you want audible alarms.
I will provide proper documentation describing how to connect the speaker/amp, recommended small modules, and suitable power routing.

3.  Audio support is implemented as an add-on to the LilyGO T-Display S3 AMOLED 1.75" board.
I’m using a small I2S class-D amplifier board   ( MAX 98357 AMP) aliexpress link . 

To make installation clean and compact, I aligned the AMP’s pinout with the AMOLED board’s I2S pins, so the module can be soldered almost directly, with minimal or no wiring.
To do this:

• The AMOLED’s header connector needs to be carefully removed.

• The MAX98357 board must be trimmed slightly so it fits the available space.

• Once aligned, the I2S pins (BCLK, LRCLK, DOUT ) solder straight across.

I’ll include detailed pictures and step-by-step instructions in the documentation, but here’s a preview:

• AMP on LilyGo 1.75 AMOLED (soldered)

• Speaker module used for audio

The speaker I chose is surprisingly powerful for its size and works very well with the MAX98357A. It’s compact enough to fit inside the enclosure and can be sourced easily online. from here 
Here is the demo of the voice alerts - Youtube video

Currently, only traffic alerts are implemented — no altitude announcements or thermal tones yet.
But I’m planning to add:

• Altitude callouts (every 500 ft or 100–200 m)

• Airspace warnings

• Possibly other safety-related voice cues

More details will be added in the documentation soon.

[Sasa Mihajlovic]

Thanks for the explanation, Vlad! Just to clarify, the third wire on the battery is only for monitoring purposes, right? So I can safely connect the battery to the 2-wire connector on the device without using the third wire?

[Vlad Belayev]

That's, correct only two wires are used , positive and negative the sensor wire can be disconnected.