HowTo: Power your USB GPS from the bike for about £5

TheJoker · 26-04-06, 16:38

Guys,

If you, like me, have a GPS (or any other gadget) that's got a USB connector and charges through that you can connect it to the bike using a £5 USB Car Charger.

I did this on my K1200R and took some pictures of it and did a write up on my home page. Have a look here for full details: http://jocke.selincite.com/bikes/usb-power

The short version is:
- Get cheap USB Car Charger off eBay
- Butcher it and attach power cables
- Mount on bike
- Ride with powered GPS

TheJoker · 26-04-06, 16:47

Just added another pic of the cockpit view so you can see how it's all mounted

STUBBS · 26-04-06, 16:56

cheers for the link was wondering how to do it for a pda

TheJoker · 26-04-06, 17:06

Quote:

Originally Posted by STUBBS

cheers for the link was wondering how to do it for a pda

My pleasure!

PDA will do fine - in fact, anything you can get a car charger for would do really.

I was amazed how cheaply you can get those things off eBay.

ebbo · 26-04-06, 17:13

Well done Joker, nicely done

Wapping · 26-04-06, 18:39

I think Blowzorn had a similar home made device on his 'Angry bike' for the Moroccan dash.

There again he had a million other wires, as well as excrutiating feedback (but it could have been wind) so I could be wrong.

TheJoker · 26-04-06, 19:19

ebbo: Thanks

Wapping: I'd be surprised if I'd be the first one to do this simple hack!

PaulW · 26-04-06, 20:26

I have done the same for my 1200GS but if you leave it plugged in you should take note of this . . .
All of these chargers use buck/boost switching regulators. If your PDA is not connected, the switching regulator with no-load will keep the socket live AFTER you have turned the ignition off. The continuous drain of 100mA is sufficient to drain the battery over a period of several days.
The simple solution is to solder a resistor (1kohm) across the output. Failing that you must remember to unplug the charger or leave the PDA connected (not always convenient).

Hope this helps
paul

TheJoker · 26-04-06, 21:13

Quote:

Originally Posted by PaulW

I have done the same for my 1200GS but if you leave it plugged in you should take note of this . . .
All of these chargers use buck/boost switching regulators. If your PDA is not connected, the switching regulator with no-load will keep the socket live AFTER you have turned the ignition off. The continuous drain of 100mA is sufficient to drain the battery over a period of several days.
The simple solution is to solder a resistor (1kohm) across the output. Failing that you must remember to unplug the charger or leave the PDA connected (not always convenient).

Hope this helps
paul

Paul, that's very interesting, and thanks for the heads up. However, I fail to see how the charger can draw power from the battery when the on-board motorbike computer has turned off the power from the socket.

Could you explain that to me, please.

PaulW · 26-04-06, 21:53

The charger doesn't draw any significant power but the switching pulses generated by the regulator when off-load, fools the CANBUS and keeps the socket LIVE (similar to the way the BMW charger works). I measured the drain on the battery in this condition and found it to be approx 100mA. The 'normal' drain current was about 5mA as I remember.

TheJoker · 26-04-06, 22:13

Quote:

Originally Posted by PaulW

The charger doesn't draw any significant power but the switching pulses generated by the regulator when off-load, fools the CANBUS and keeps the socket LIVE (similar to the way the BMW charger works). I measured the drain on the battery in this condition and found it to be approx 100mA. The 'normal' drain current was about 5mA as I remember.

Is there anyway of verifying this other than measuring the drain (where should I measure that, btw?)? My GPS turns itself off, so does the Geodesy that's connected to the same power source. The hazard light switch also turns itself off at the same time..?

Quote:

The simple solution is to solder a resistor (1kohm) across the output.

At the output of the charger, I presume..?

Thanks Paul!

PaulW · 26-04-06, 22:26

The hazard switch light is what alerted me to the problem in the first place - it stayed on after 1 min after fitting the 5V charger. Don't know about the K1200R, all my comments refer to the 1200GS. Yes, the resistor is on the output of the charger but since your hazard light switch goes out, I think you are ok. I measured the drain directly at the battery terminals.

TheJoker · 27-04-06, 07:40

Quote:

Originally Posted by PaulW

The hazard switch light is what alerted me to the problem in the first place - it stayed on after 1 min after fitting the 5V charger. Don't know about the K1200R, all my comments refer to the 1200GS. Yes, the resistor is on the output of the charger but since your hazard light switch goes out, I think you are ok. I measured the drain directly at the battery terminals.

Aaahaa! Looks like I might have gotten away with it!

However, I do appreciate your insight on this and will amend the article accordingly! Thanks!