How Long to Charge a Garmin Via USB?by Fred Decker
Garmin's nuvi GPS devices are designed to be lightweight, portable and easy to use. They can be charged while you're at home or on the road, using the supplied AC and car chargers. If you should find yourself away from both chargers, but have a computer or other device with a USB connection, you can use that USB connection to charge your nuvi. However, it is slower than a normal charge.
When connected to an AC or DC power outlet through one of the standard chargers, most nuvi models will charge in four hours or less. The screen will display an icon to show that the battery's charging. Once it's fully charged, the on-screen battery strength meter on most models provides a usable estimate of your remaining power. If you're charging from USB instead, the available current is much lower than it is with the standard chargers. Rather than four hours, a full charge might take as long as eight to 12 hours.
Trickle-charging through the USB connector is not the best available option when you need to charge your battery in a hurry, but it does have its uses. If you're on the road and have forgotten your chargers, trickle-charging overnight -- or all day, while you're busy with other things -- can still bring you back up to full capacity. Alternatively, leave your nuvi connected to the USB port all day, while it's in use. The trickle charge will offset your battery usage, and prolong the life of your existing charge dramatically. If your schedule is flexible, plug in your nuvi for a top-up whenever you take a break .
Limitations and Considerations
There are a few things to bear in mind if you're trickle-charging your nuvi on the road. If you're connected to a laptop or other portable device, it probably needs to be turned on before it will charge your nuvi. Some portable computers are an exception, providing a USB port that's wired to remain active even when the computer itself is turned off. They're intended specifically for charging duties, or powering other accessories. If you're in below-freezing or unusually hot surroundings, your nuvi might refuse to charge. This is normal, and protects the unit from damage. Provide warmth or shade, as appropriate, and the unit will charge as usual.
Battery-Powered USB Chargers
If you're going to be away from your home or vehicle chargers for an extended period, such as a weekend wilderness hike, you might benefit from a battery-powered portable USB charger. Several manufacturers make these, in a wide range of sizes and capacities. Smaller units will fit in a pocket or backpack and charge your GPS three to five times. Larger ones have higher-capacity batteries and multiple outlets, and are suitable for recharging several devices. Your nuvi will charge at full speed with these products, usually reaching a full charge in four hours or less.