Remove battery from bluetooth receiver - how to do it and get rid of humming sound

[snoopios]

Hi all,

I have a TaoTronics bluetooth receiver (https://www.amazon.co.uk/dp/B07CJ9PWSJ/?tag=fdoc-21) and I want to disconnect the battery from it so that when the car turns off, so does the receiver.

I've managed to crack it open and I have now removed the battery.

I'm not an electrician so I don't really know what I'm doing however, I kind of understand circuits so what I've done after removing the battery is to connect the positive and negative sides of where the battery use to connect, together to complete the circuit now that the battery is removed. See the picture below where it says "B-" and B+".

I've plugged this setup into the car and for the most part, it works. I plugged it into my USB charging port that's in the cigarette lighter and when the car ignition is turned on, the receiver fires up and my phone starts to play music (the receiver has auto play on it).

The issue I'm having is that there is a high pitched humming noise and my guess is because that now the battery has gone, resistance/capacitance in the circuit is gone. Does anyone know what I would need to do to remove that humming noise?

Thanks in advance

 

[Paulm]

I have a similar issue when using some usb ports in the car. I find if i use the more expensive wilko usb (about £4.50) its ok, if i use the cheap one (£2.50) i get a lot of buzzing when charging the phone

 

[snoopios]

I have a similar issue when using some usb ports in the car. I find if i use the more expensive wilko usb (about £4.50) its ok, if i use the cheap one (£2.50) i get a lot of buzzing when charging the phone

Thing is, I've got a really expensive one (£20) from TomTom....

 

[Paulm]

There normally pretty good iirc. Its just an issue ive had on a few cars. I have a couple of the wilko ones in each car, never had a problem. But you may have a different problem. Bit like the old suppressors we had to fit on the old cars with dizzys other wise the radio was terrible

 

[jack.am]

You could have messed up the DC offset by taking the battery out of the loop. You could try measuring the resistance of the battery and putting a similarly rated resistor inline?

 

[snoopios]

You could have messed up the DC offset by taking the battery out of the loop. You could try measuring the resistance of the battery and putting a similarly rated resistor inline?

That was my thought and I’m going to give it a go.

 

[MisterEman]

That was my thought and I’m going to give it a go.

What was the outcome? (not to revive a dead thread, but I'm in a similar situation)

 

[Jake_rorx7]

What was the outcome? (not to revive a dead thread, but I'm in a similar situation)

You could always use a small relay in the battery loop to close the circuit when ignition is switched on. Wouldnt be a particularly tight solution, but it would work.
Alternatively, you could choose to remove the battery and power the device on ignition on - but youd need a small unit to drop the voltage from 12v (car) to roughly 3.7v (1s lipo). 3.7v is just the average, I think they range from 4.5-3v. IMO I would remove the LiPo, those things can be quite dangerous, especially inside a hot car!