[atlau]

[IMG]c:\cd\picture.jpg[/IMG]

I want to make a cleaner install for my GPS (currently hooked into the cigarette lighter).

This may be a dumb questions... Is it possible to bypass the lighter alltogether with a mini-usb cable on one end and the other end directly into the wiring? (see picture).

Thanks,
Anthony

[atlau]

sorry picture didnt work on first post.. I meant this..

[HighVoltage]

Yes, in the end it is just wire. The important issue is going to be voltage. Ill bet that usb power connector for powering your GPS in the car is converting 12V (car) to 5V (gps). Presumably that molex is on the vehicle, so it will likely be 12V. You will need some kind of regulator or switching supply circuit to bring it down. You could either cannibalize the one that came with the GPS or make your own. I bet a simple L7805 would do...

[tintivilus]

The first thing I'd try is cutting apart a cheapo USB charger and seeing where I could cram the board.

I've been thinking about getting the OEM 6FL USB port and wiring it up as a charger, but haven't really had a need just yet.

[rolling18]

my friend uses the mini usb from his motorola cell phone car charger to run his Garmin gps..

[atlau]

thanks for the tip! I think I'll try to pick up a cigarette lighter to usb adaptor and tear it apart and wire it directly to the 12V connection and run the wire up through the console. That way the lighter should still be available.

[rolling18]

im waning to power my garmin through it mini usb also, and will be using the moto, car adapter as well

[HighVoltage]

Originally Posted by rolling18

im waning to power my garmin through it mini usb also, and will be using the moto, car adapter as well

Make sure it can meet the current (amps) requirements for both loads.

[atlau]

I picked up a cheapo motorala charger.. but it doesnt say what the output voltage is on it... I know the GPS is supposed to have a 5v input, but I'm wondering worst case what would happen if it got 12v instead of 5...

[Tegs4tugs]

I remember someone had a post where they simply bought that connector that has 2 wires that connects to any power source and has a simple cigarete lighter attached where you can plug in the charger but he mounted it under the center console so no need to cut into the charger just an addition charger port hidden under the console where he just ran the charger behind the dash and plug in there

[HighVoltage]

Originally Posted by atlau

I picked up a cheapo motorala charger.. but it doesnt say what the output voltage is on it... I know the GPS is supposed to have a 5v input, but I'm wondering worst case what would happen if it got 12v instead of 5...

If the GPS is expecting 5V, you'de cause catastrophic component failure(s) in the GPS.

If it has a mini usb plug it probably isnt 12V though.

Some bacrgound:

The mini usb plug on the device (GPS, phone, etc) is usually there to provide a USB data connection to a computer. While it is plugged in to the USB port on the computer it can also serve to charge the device since the USB physical layer requires there to be 5V for powering peripherals on the bus. Knowing this, manuafactures of devices like GPS, cell phones etc also provide chargers for our cars with 12V to 5V converters. One end of the cord is the cig lighter @ 12V and the other is the mini-usb @ 5V with some kind of voltage regulator in between.

If you bought a car charger meant to charge your phone for instance, it may not be able to power both the phone and the GPS. You need to look at the power output of the charger then compare that to the power consumption of the GPS + the power consumption of the phone.

Given the power requirements between these two devices I would imagine that a charger meant for a GPS would stand a better chance of working with both a GPS and a phone, then a charger designed for the phone....

[atlau]

Did a bit of research and it appears the Motorala charger should be a 5 or 5.5v output... anyway I'll try it out with the GPS tomorrow.

The 3pin molex has 1 brown wire, a red&black wire, and 2 smaller red&blue wires in one of the other pins. The smaller wires appear to be powering a small LED (lights up the cigarette lighter and ashtray). I am assuming the brown is the negative based on the way it is wired. It appears to be wired in parallel, so the smaller wires should also be 12v correct? Probably less amps as the there is a higher resistance. (It's been a while since I took electrical engineering

[HighVoltage]

Originally Posted by atlau

Did a bit of research and it appears the Motorala charger should be a 5 or 5.5v output... anyway I'll try it out with the GPS tomorrow.

The 3pin molex has 1 brown wire, a red&black wire, and 2 smaller red&blue wires in one of the other pins. The smaller wires appear to be powering a small LED (lights up the cigarette lighter and ashtray). I am assuming the brown is the negative based on the way it is wired. It appears to be wired in parallel, so the smaller wires should also be 12v correct? Probably less amps as the there is a higher resistance. (It's been a while since I took electrical engineering

I believe you're correct, thick brown for common and thick red/blk for +. Definitely dont use the wires for the led, that circuit is controlled by the LCM, so it is pulse width modulated just like the dash lights.

[atlau]

"so it is pulse width modulated just like the dash lights"

huh?? out of academic curiosity what does that mean?

[HighVoltage]

Originally Posted by atlau

"so it is pulse width modulated just like the dash lights"

huh?? out of academic curiosity what does that mean?

Its not a constant 12Vdc. They essentially generate a pulse at a frequency high enough to prevent the led from flickering and then vary the duty cycle (the pulse width) to control the brightness.

[atlau]

Interesting.. so instead of controlling the voltage to adjust brightness, they rapidly turn it on/off... is that how most LEDs work?

[HighVoltage]

Originally Posted by atlau

Interesting.. so instead of controlling the voltage to adjust brightness, they rapidly turn it on/off... is that how most LEDs work?

The only reason they are using this method is because they wanted the brightness to be regulated by the user. Its tied to the same circuit as the dash lights. Normally you would just supply a constant dc voltage and be done with it.