Bluetooth Auto ON/OFF





Introduction: Bluetooth Auto ON/OFF


My car has aux and bluetooth - but only for phone calls. WEIRD :( So I decided to add another bluetooth for listening music and podcasts.

With little research I found that bluetooth receivers and headphones need "aptX" for high guality sound. The cheapest I found on Aliexpress "Link-485".

There is a little trick. BT receiver has battery inside and for pairing you need to press button for 5 sec. But I want this to be automatically, when I start a car.

The original instructions I found here

Step 1: Soldering

I needed 2 capacitors.

One small for switch and one "big" to replace battery. If I would leave battery inside, BT receiver would not shut down until battery would be empty. With capacitor it shuts down immediately with the car.

For replace battery I use capacitor 10V 3300µF but it was tested also with 10V 2200µF.

For switch is enough 0,47F.

Be careful with polarity - watch my pictures!

Step 2: Power Supply

I use Lithium Charger Step down 5A 5V-32V to 0.8V-30V Power Supply Module LED Drive 5A

and cable with fuse "add-a-circuit".

Step 3: Installation Into Car

You can see I had problems with too big capacitor. I use hot glue gun and fill gap with glue:)

I also glued receiver with the same glue under steering wheel.

It is "invisible" but still enough close if I need buttons.

Step 4: Thank You



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    16 Discussions

    Hi, very useful instructions.

    I have a doubt about the module you used here. i read you can adjust the output v from the module. my intention is to use it (or a couple) for the bt receiver and as a smartphone charger: how to adjust the output for the two devices, considering the input from the car would be about 13.7? tks.

    Great project

    1 reply


    Thank you!!

    If you need phone charger for phone, than I suggesting you to buy some quality phone charger. ( I use Aukey from aliexpress, 2x USB 3.0, quick charger for 10€).

    And for bluetooth module you can buy what I bought and you can find link in description.

    I think is better to use 2 diffrent chargers than experiment with phone battery. You can make fire if you are not realy sure what are you doing.

    Is it possible to use the 5v in car usb to power it like it does normally?

    So far I've only removed the battery - still need the capacitor.

    For switch you used 0.47 uF not 0.47F right ? 0.47uF also for 10v ?

    1 reply

    Because I prefer to power-ON BT when I need it.

    I don't need bluetooth everytime when I sit in a car. So I see that is better if I handle it by my self.

    I need this System because Long time is looking how can i do but i didnt find. Now is find. But I must learn Why you remove?

    I need this System because Long time is looking how can i do but i didnt find. Now is find. But I must learn Why you remove?


    2 years ago

    Done the same in my Volvo C30. Can you please let me know if the play/pause button is working after adding capacitor for auto on/off feature? I use it to answer calls so it's critical for me.

    2 replies


    Great instruction!

    I remove capacitor on play button. So I don't know if works.

    I prefer to power-on BT when I need it.

    In my case I'll will either change the BT unit to a different one (without battery so it turns on when powered) or find a way to reprogram this one.
    Anyways, thanks for sharing your guide! Keep up the good work!

    Can you explain why the USB-to-microUSB cable is in the picture sequence under Power Supply? It doesn't appear to be used for anything. The power cables wired into the power supply are much larger gauge, and it is not visible being used in any other sequence that follows. Great idea, though. Thank you!

    1 reply