GPS 3790LMT

That's what it sounds like to me. Are you plugging into a USB port directly on the chassis of your computer or going thru a USB hub? Some hubs do not provide enough power to charge the nuvi battery, so it continues to discharge even though you are plugged in to USB.

I plug USB straight into the computer. But I might have another problem, the gps will not turn on. I even plugged it into the cig adapter in the car and would not come on, and even tried the wall adapter, no jucice. Will have to return it, will try Best Buy where I bought in June 2011.

If the battery is completely dead, you may have to leave it plugged in to the charger for a while before it will turn on. I have this problem occasionally on my 855 nuvi. After it charges for an hour or so, it will turn on.

Does not sound like a dead battery. The usb connector and where the unit powers up in the car are two different places. The unit should work just fine with out a battery at all plugged into the car cradle.

Try holding the power button down for 30 seconds. Then plug into the computer. If it powers on allow it to charge for 8-12 hours. It sounds like the battery got very low.

The above is the reply I received from Garmin. I tried it and it worked. I fully recharge the battery.

same thing happenned to me once on an earlier unit the nuvi 680 i think. I plugged it in overnight using a wall adapter and it came back.

In most cars the accessory outlets go off when the engine is turned off. USB from the PC does not supply enough current to charge the nuvi in a reasonable time, and if the PC goes into sleep mode the charging will stop. For sufficient current, use a cell phone charger that has a mini-USB connector and charging will take at least 5 hours. This has been well-covered in past threads.

Cold weather makes it worse. The battery's capacity can be reduced by 50% when cold.

I agree with holding down the power button for 30 seconds. Take these steps before concluding that the nuvi needs service.

dobs108