Rewire flashlight jack to USB

[ashori]

I've noticed several people use the aux power adapter to connect their flashlight jack to devices (gps, phone, etc.). However, most of these devices run on a USB interface, which is 5V.

If I have read the forums correctly, the light jack already outputs 5V, so what people are doing is actually wiring the 5V jack to a 12V amp (the aux input), which is stepped back down to a 5V supply (car charger that plugs into the jack).

I have not verified if the flashlight jack outputs 5V, but if it does, shouldn't you be able to wire the jack directly to a USB port? I was thinking I might add a female usb output so I can just plug in any device I like.

Nevermind... The jack outputs 12 V

[jknj]

The BMW adapter for the flashlight jack is pretty cheap,($9.50 on BMWUSA.COM) and a cigarette lighter to USB adapter is also really cheap (< $5 at Radio Shack). While it may seem overly complicated, it is all pretty cheap and easy to pull off, In additon, the USB is supped to have a specific protection limit, which may not be present in the scheme you describe, making it less safe. Further, there are a lot of things that could use the cigarette plug in a pinch, like GPS units and radar detectors, making the 12V plug useful. And last, the easist way to get the flashlight connector is to buy the 12V connector cable. You would then have to tear it apart to make the cable.

[ashori]

Originally Posted by jknj

The BMW adapter for the flashlight jack is pretty cheap,($9.50 on BMWUSA.COM) and a cigarette lighter to USB adapter is also really cheap (< $5 at Radio Shack). While it may seem overly complicated, it is all pretty cheap and easy to pull off, In additon, the USB is supped to have a specific protection limit, which may not be present in the scheme you describe, making it less safe. Further, there are a lot of things that could use the cigarette plug in a pinch, like GPS units and radar detectors, making the 12V plug useful. And last, the easist way to get the flashlight connector is to buy the 12V connector cable. You would then have to tear it apart to make the cable.

I agree with what you are saying, but it seems like it would be a cleaner install if you skipped the adapter. Also, I'm not entirely sure if you would need to get the adapter, since the flashlight plug is prewired into the glove box and outputs 5V (I think). As far as protection, I believe all you would need is to wire in a low pass filter (a resistor and a capacitor from Radio Shack should work) and a fuse. One of the problems I've found with cigarette lighter to USB adapters is they often don't have enough juice to charge up all phones, GPS units, etc. The only reason I can think that is the case is their power output is simply too low, and the protection circuitry kicks in.

That being said, I think I'll probably end up doing what you suggested and simply buy the adapter from BMW. The more I think of it, the more I realize that while my solution would probably work, it would probably blow up my GPS and/or set fire to my dashboard. Still, it would be nice if BMW just added a USB interface to their cars.

[Boston X5 4.4]

Is the flash light power sourced switched? - i.e. on when ignition on only

[ashori]

Originally Posted by Boston X5 4.4

Is the flash light power sourced switched? - i.e. on when ignition on only

Yes. Otherwise the flash light would be draining the battery when the car is off.

[jknj]

I would be really surprised if the adapter converted 5V to 12V, and also surprised if the jack has 5V in the first place.

[Boston X5 4.4]

Originally Posted by ashori

Yes. Otherwise the flash light would be draining the battery when the car is off.

Duh, my bad