I recently discovered a rather annoying problem with my FP2. It kind of reminds me of the Noise in headphones while charging topic- but not quite. Let me explain.
Not too long ago I bought a car (2006 Honda Jazz) with an aux socket. Using a male-male 3.5mm audio cable plugged into that socket, I can connect the phone to my sound system so that I can listen to music and hear my navigation. When I also plug in the USB charger ( The official and EC certified HP Pre/Pixi/Veer Car Charger & USB Cable ) my phone even starts to charge… a little. However, as soon as music playback pauses there is suddenly a lot of high pitched screechy noise on the speakers when music is paused. Even worse, although my FP2 is fairly stable rebooting about once a fortnight, it pretty much always crashes on a multi-hour journey when I plug in the charger, whether it’s playing music or not. More than once this has caused quite a stressful situation as I can’t operate the phone while on the go, and not sure where I’m going anymore!
I tried replacing all the cables. I ordered both a brand new aux cable and a sparkly new USB cable + car charger just last week. Unfortunately, replacing the cables had no noticable effect. I don’t quite know what the next step might be in troubleshooting this issue.
I don’t quite know what might be going wrong. Only having noise when music is paused sounds like it only happens when the audio subsystem is put in low-power/suspend mode. Crashes increasing in frequency when connected to the charger kind of sounds like the charging mechanism is not properly isolated from the phones power net. That in combination with a power source (car battery) that is not quite as reliable as a wall socket could well lead to instability.
To conclude, a couple of questions:
Can others confirm this kind of problematic behaviour?
To say it bluntly, I have absolutely NO experience whatsoever with daily use of car sound systems in combination with android devices. However, I heard that so-called ground loops can cause strange noises if you connect two devices in more than one way.
Here’s a imho good explanation on ground loops:
If that is indeed what you’re experiencing, a ground loop isolator may solve the problem.
That doesn’t sound like a bad explanation for the noise, I’ll definitely give that a try and report back.
Actually, come to think of it. This is the first set-up I’ve had where I use the phone under heavy load while charging. Considering the significant delay between unresponsive phone and reboot, I bet the kernel got stopped by a thermal-triggered interrupt. The reboot would then be caused by that kernel no longer bellyrubbing the watchdog for a few seconds. Perhaps this could give a good lead to the FPOS developers…
Have you also tried the same setup with another phone or simple mp3 player?
2006 is 12 years back. If the car has any active filter components installed such as low/high-pass for the 12V charging socket, audio system or else the capacitors may be spend by this period. So maybe any connected device could show this effect.
Plug (attached to a cable) or socket??
Perform some more tests and different combinations to separate if caused by the car (which I rather tend to believe) or the phone itself: so to find out if aux plug or 12V output causes this
With a different device too (should reveal if your individual FP2 problem)
Test Audio noise (pause/playback) while USB charging and while on battery (charger issue or not/maybe 12V dc output related; noise being introduced by the aux plug
Test internal phone speaker noise while pause/playback when USB charging and when on battery (aux plug / car HiFi system not involved).
Perform all tests with engine started and also with engine cut-off
Take off the phones cover and carefully connect to the cars HiFi system again. Some users have audio connection issues (with the slim covers).
I am using Bluetooth earbuds, but since I have a slim cover replacement I know for sure about this design flaw.
FP2 audio jack has a 4-pin design (for using audio equipment with microphone & controls). Conventional audio jacks/plugs only have 3 pins. Properly plugged things usually work fine, but if the connection is not matching well no one can tell for sure how results will be.
Not me.
Feel free to get your 12V dc output checked professionally with a multimeter or even oscillograph. The battery in idle-state should always deliver >12 volts otherwise its not fully charged or beginning to die. With running engine (properly operating and charging generator assumed) dc output may go up to 13,5 volts.
Depending on quality your USB charger should not pass through any noise and keep its 5v dc output constant depending on how much load is actually connected.
Assure to keep it somewhere where it is save from overheating and able to emit heat caused by charging and running processes.
Did you replace with the same HP USB charger?
It looks like some homework to be done. Good luck.