paulr

I have a USB socket in my car, and would like to use it to power my Garmin Sat Nav. However when i plug it in an icon appears on the sat nav requesting data transfer. It thinks it is being linked to a PC. Is it possible, somehow, to power my Sat Nav, in my car, using a USB lead.

(i know i can use a cigarette lighter socket, thats not what i want)

Garmin Nuvi 1210

AndyC_772

iTrader: (2)

If it works OK with a cigarette lighter USB port, try snipping the D+ and D- wires (green & white), but leave the red & black ones intact. That will break communication between the sat nav and the car, and should allow it to charge without thinking it's plugged into a PC.

paulr

Or could i buy a USB connector and the connection to fit the Garmin and wire it up myself connecting only the power wires. Is there any issue of voltage/current from a car USB being different to the one from a PC.

A normal USB lead is only a lead, there are no resitors or anything, i'd imagine.

AndyC_772

iTrader: (2)

Can't see a problem with that, USB is 5V and has a 500mA current limit, so if your car provides a USB port at all it should conform to that spec and be OK. A normal USB lead is indeed just wires.

paulr

Interesting.....

From Maplins there are two types of USB adaptor that fit in car cigarette sockets. One is a micro DC to USB and the other is a mini DC to USB. One outputs 1A and the other outputs 2A. My standard cigarette lighter car charger outputs 1A.



http://www.maplin.co.uk/home-and-car...power-adaptors

joey_turbo

iTrader: (26)

I think the problem is the cable is only supplying the 500mA, which makes it think its a computer. Some systems will use more than that whilsts working, so it'll actually drain whilst plugged in still.
I've got one of those flush fit ones (much cheaper on ebay) and they supply the full 1A.
Get one of those, you hardly notice them if you leave it plugged in.

oobyJu

iTrader: (2)

some usb leads only have the power connections, how long does it have to be? i might have one somewhere but i think it's quite short was from a solar charger.

RobsyUK

iTrader: (2)

have you looked at the FAQ's on the Garmin website? They might have an adaptor..

paulr

Okay, my Garmin requires 5V 1A. I bought a USB adaptor for my car socket but it is rated at 2A. The guy in Maplins said the 2A rating is not the output, but the max that can be drawn. Is that right. If something is rated at 2A, it wont push 2A into the Sat Nav (unlike voltage).

scoobeenut

The rating is usually the max that any cable is rated for, if you try to draw any more current the cable is likely to melt or sustain damage, thats why you have fuses in the circuit to prevent overload.

paulr

Cheers. Its what the guy in Maplins said, but i dont always trust shop assistants.

AndyC_772

iTrader: (2)

On this occasion, he's right. If a power supply is rated at 2A, then it *can* supply 2A. That doesn't mean it *will* supply 2A.

paulr

Thanks Andy.