The Nuvi uses the USB +5V supply to charge and by the USB standard it will provide at least 500mA (0.5 Ampere) of charging current. This is sufficient to charge the Nuvi. The real reason why your Nuvi went into the data mode (computer mode) is the Product ID pin of the mini USB connector is not configure for the Nuvi. There are two possible configurations. The original Nuvi car charge has a 17.3K Ohms resistor from Pin x to Ground (Pin 5). This according to some Internet sources would allow the Nuvi to draw 1 Amp for charging. The other configuration is what I have done to my home modified generic charger/cable where Pin X is directly connected to Ground (pin 5). This configuration will set the current to 500mA. You can verify this by going to the diagnostic screen for battery charging where it states the 500mA ILimit. The mini USB connector is molded and to change its configuration you have to 'tear it up' and re-wire Pin X. Why do all this when the original works... money....
How do you get into charge and navigation mode with a generic charger in the car without any modification? Here is the procedure:-
- Plug in your charger to the Nuvi
- Wait for it to get into the Data mode
- Remove the USB connector and wait for it to reboot (the screen change). Immediately plug in the mini USB connector. Note:- You can also unplug and plug in the charger.
- Your Nuvi will boot up in the Navigation mode
I have the mini USB connector modification procedure but due to my posting problem here.... I can't do it...
Hope this helps... cheers!