Nuvi Charger

Are you just trying to charge the Nuvi's battery? If so you should have also got a USB cable with the 2450 and that will charge the Nuvi if connected to the GPS and your computer.

Yes you can use the .550Ma on your 2450, but it will charge slower than the Garmin OEM 1.0 amp that you would connect to your power cradle.

1.0 is 1 amp
0550MA is a little more than half an amp
1000Ma = 1 amp

Thanks for the above chart. I was thinking the 550ma was larger than 1 amp but don't know much about electrical terms. Thanks

I am just trying to charge the battery. I did get the usb cable but thought it was just for file management.

When I plug it in to the computer it goes into the computer mode. Is it charging when it does that?

Better safe then sorry

it is charging and ready for data access

Use a 500mA USB charger will take considerable longer if your GPS battery is running low. I would only consider use it for overnight charge.

However, I usually have an old 2.5A USB charger on my desk to charge everything USB. It works out great for many years, and I have had no device damaged yet.

It will charge my GPS from no battery power to full in about one hour.

500 MA is what the USB port on your computer supplies. Using an external charger rated at 500 MA will take no longer to fully charge a unit than it would if it were connected directly to the computer.

Since Garmin OEM wall charger is listed at 1.0 amps to work with all their units, I would be very reluctant to use a 2.5 amp charger. I'm sure you have not had any problems, but I'd be nervous that it potentially could shorten the batteries life span.

Maybe somebody on the forum has expertise with electronic charging characteristics and could enlighten us.

The 2.5 A charger was probably designed to power a 5 port USB hub or something similar. Unless something in the device connected to the charger fails, it will only draw the current (amps) needed up to the limit of the charger.

A better example would be a table lamp in your house. It only draws enough current to light the bulb to its maximum. If it's a 60W bulb, it draws that amount of current. If it's a 30W, then it only draws enough to light that one. The socket the lamp is plugged into can provide up to 20A normally so the amount used is less than what can be provided.

Sounds logical to me. Thanks for the education.

I agree with your analogy to an extent.

However, electronic devices have a maximum input load that shouldn't exceed design limits. The load on the PCB components are the limiting factor.

Inputting 2.5 amps on a 1 amp circuit is not a good idea. You're still overloading the device, even if it only draws what it needs.

That's why table lamps will say 'maximum 60 watt bulbs', as their design specs, and current draw, only allow that for safety.

Boxcar is right - you could use a 100 amp power supply and it wouldn't make a difference - too many VOLTS would be another matter. The supply capacity in Amps is a measure of the amount of current available.

The load determines how much is taken. It could care less how much is available, it takes only what it needs when things operate normally.

The Motorola charger is another matter, however. Despite the U in USB meaning Universal, I think both Motorola and BlackBerry need a Motorola or Blackberry charger. That isn't what the original post asked about, but for some people this cane be good to know. For example, if we have an HTC and Motorola phone and micro USB chargers at home, the HTC phone can be charged by either charger, BUT the Motorola phone has to be charged by the Motorola charger!

Your table lamp that specs a maximum 60 watt bulb does so because of heat. A 100 watt bulb will get a lot hotter than a 60 watt bulb. The lamp's socket can only take so much heat, more that what it is rated to stand will cause insulation to soften or melt and might start a fire.

Your house is connected to a power grid that is capable of supplying millions of amps to your home but only 240 volts. The appliances in your home decide how much current they need to do the job and only draw that much from the available millions of amps. The same holds true with your GPS, if it only needs 0.2 amps (200 Ma) then it will only draw that amount even if the supply can give it 2.5 amps. If the supply's voltage doesn't exceed the rating of the GPS (usually 5 volts) then you are safe.

We're getting off track here, but Bramfrank is correct. It all comes down to Ohm's Law in that the voltage equals current times resistance (E=IR). Voltage can be thought of as the force behind the current. The higher the voltage or potential, the more force behind the current and, for a fixed resistance or load, the lower the available current. But we're also getting into the power specs and their formulas as well. Power is either voltage times current or the square of the current times resistance. (P=IE or P=I^2R) So in the Nuvi's case as long as the voltage is constant and the load (the unit) doesn't change, the amount of current draw will remain the same.

takes substantially longer than using an AC or DC charger. Also, the unit will appear as a hard drive on your desktop when connected via USB.

I never used the 550ma.

I ordered a 5V 1A ac charger from Amazon. The ad said for the Nuvi 2450.

The AC charger that came in the mail is 4.85V-5.4V and 850mA.

I emailed Amazon and told them they sent an 850mA and not a 1A. Amazon said to reorder and sent me the same link I ordered from. They again sent the 850mA with the listing saying 1A.

I now have two AC adapters 850mA.

Is 850mA the same as 1A?

Do you think the AC charger is safe to use or should I order from somewhere else?

I got a nuvi 2495 lmt and use a Motorola ac adapter is 5 volt 550ma it works great.

One Amp is 1000 milliamps or mA so an 850 mA charger is 85% of the advertised value. Contact Amazon again and state they are flirting with what some prosevutors would call Bait and Switch where the item advertised is not the item advertised nor is it equivalent.

No 850ma is a little bit more than 3/4 amp. 1000ma = 1A.
It's certainly safe to use, and probably close enough that the you wouldn't notice a difference in charge time between 1A and 850ma, but I'd tell Amazon that their listing is wrong if it says 1A and you keep getting 850ma.

(I guess I type slower than Box Car! lol)

I'm sorry I didn't see your original post. There are a lot of replies here with a lot of extraneous and irrelevant information that must have been confusing to you.

I assume that you just want an AC charger to charge your Garmin unit from a normal 120vAC receptacle (without having to use the OEM 12vDC car charger) and you probably also might like to do trip planning on the unit without having to sit in the car. Is that about correct?

The difference between 850milliAmp and 1 amp (1,000 milliAmp) is fairly insignificant. In any case, the charge controller for the internal GPS battery is also inside the GPS unit, so having extra power output available does not normally pose any risk to the battery. But normally, there's not much reason to have a high-powered charger either.

Matter of fact, even a 500 milliAmp (one-half amp) charger will work too, but it will take about twice as long as a 1 amp charger to charge the battery, IF the unit is turned off. With the unit turned ON, the charge rate is dependent upon the available power above the consumption of the unit. For example, with the unit turned ON, let's say that IF the unit itself consumes 0.4 amps, with a small 500 milliAmp (0.5 amp) charger, that would only leave about 0.1 amp available to charge the battery. With the unit turned OFF, almost all of the available power goes toward charging the battery. Most GPS units have a battery with about 1500 milliAmp-Hour capacity (though the actual capacity varies widely), so 500milliAmp (0.5amp) charger can charge a typical powered-off GPS unit in less than four hours (taking charge efficiency into account, which is over 85% on this type of battery).

This means that "A charger from a Motorola phone, with the mini usb has 5.0V - 550mA" has enough power output to charge the battery in a few hours with the unit turned off. Just make sure it is actually charging your Garmin unit, as shown in the youtube videos I linked below.

Whatever AC charger you decide to use, you just need to make sure it actually is charging the battery, rather than just powering the unit. Plug it into the AC charger, then go to whatever screen you need to see the battery bar graph. If it's charging, the little bars should "cycle" (the nearly universal method of showing that the battery is filling up) in the same way as it does when plugged into the OEM Garmin car charger.

When SOME devices are connected to a computer's USB port (or to some AC chargers), they treat that as a "data only" connection, and are merely powered by that connection, but do not charge the battery. These videos show exactly what happens with a Magellan 1412:

OEM car charger (powers the unit and charges the battery): http://www.youtube.com/watch?v=ZPAjoDy6-p8

generic USB AC charger (powers the unit but does not charge battery): http://www.youtube.com/watch?v=o-qMwtx-p1Y

There is a specific reason why this happens (which is too technical to get into here). But as far as I know (and I can't speak authoritatively about all Garmin units), most GPS units & other devices DO NOT behave like the Magellan unit shown in the videos above. Most units will charge from any powered USB connection, whether it's from a computer or a generic USB charger.

FYI: Most cell phones now come with Micro-USB connections, but usually the chargers they now come with have USB ports instead of a built-in cable like they did in the past. Anyone who already has a charger like that needs only a standard USB "A Male" to Mini-USB male cable to use that charger with a GPS nav unit.

If you now have two AC adapters 850mA, then maybe you can take advantage of the fact that they aren't what you thought you ordered. But are you sure they were sold by Amazon, or from one of their merchants?

In any case, you should not need to go to the extent of telling them that they are "flirting with what some prosecutors would call Bait and Switch" because in my experience, Amazon is also very good about making it easy for a customer to return something that wasn't what they expected. But it also depends on whether or not Amazon sold it, or one of their merchants.

If you can return the charger(s) you just got from Amazon without paying for return shipping, that's probably the thing to do. I guess it depends on how much you paid for it. You can get chargers like these off of ebay very cheap, if you want to wait for them to come from China. Here's an example: http://www.ebay.com/itm/US-Battery-AC-Power-Adapter-2-0-USB-... As difficult as it may be to believe, this one sold for $0.32 (delivered). I've bought stuff off of ebay from China before, and it always arrives, but sometimes things have been broken (but the sellers always quickly gave a full refund too). Personally, I'd prefer to get something like this from a US seller, but even they are selling these for under two bucks, delivered.

Amazon is a great place to buy from.

When I bought the first adapter I emailed them and told them what happened. They refunded my money and sent me the link to order again.

The link stated 5V 1A.

I ordered again and got the same charger. 4.8V-5.4V and 850mA.

I emailed Amazon again, they again refunded my money and told me they were pulling the ad to correct it and to order another one if I could find the one I needed.

They said to just dispose of the two adapters as I wished.

There are not many companies that are that great.

I started not to even email them because I did not want the hasstle of mailing back the adapters. They said they wanted to make it as hasstle free for me as they could and they did.

I am now surffing Amazon to see if they have another listing with the 5V 1A that my Nuvi needs.

You may want to check out Monoprice. They carry a large selection of electronics at really cheap prices. Shipping is very reasonable and their customer service is the best I've encountered with an online retailer.

Here's a link to some of the usb chargers they carry http://www.monoprice.com/products/subdepartment.asp?c_id=108...

I like the fold down one. Will the short usb cord that came with the Nuvi 2450 work with it? It is a mini usb for data on the computer but I don't know if it will be ok to use it to charge?

re: "I am now surffing Amazon to see if they have another listing with the 5V 1A that my Nuvi needs."

Why keep looking for something else?

There is no reason to do that if the one you have now charges your Nuvi.

Just make sure the battery is charging (see the videos I posted above). If it is, you really don't need to waste any more time on this issue.

I have never used the 850ma on my Nuvi 2450.

When I need to charge the Nuvi 2450 I go to the car and get the power stand you plug into and use my Nuvi 750 charger, 5V 1A, that came from Garmin.

If the unit needs a 1A and the one I have is 850ma this will not charge like it should???

From what I found, can't remember where, the Nuvi 2450 needs 5V and 1A to charge for proper use. Aren't you suppose to always charge things at the stated V and A?

I was afraid if I used a slower than required charger it might cause the battery to not work as it was inteded to. And when we go on vacation I have to take the car stand to have something to plug into. The new Nuvi needs a micro usb and the old Nuvi charger has a mini usb. So to make it work it needs its power stand.

Am I correct that the Nuvi 2450 needs a 5V 1A charger? I can't remember where I saw this.

Keep in mind that the slower the charge rate the longer the battery life. So if you have the time to charge it overnight you are better off slow charging it.

So, it doesn't matter what the charger is? It won't hurt the unit?

OK, I couldn't resist commenting.

From my own personal experience. Never use a charger that is rated LESS than what the manufacturer says. They always are short lived when used for long periods of time. All wall chargers that are UL rated have some sort of "thermal fuse" in the transformer. This helps prevent it from catching fire when over-loaded or shorted. Continually pushing the device to the maximum capacity will eventually cause the thermal fuse to fail, even though the transformer is not getting hot enough to ignite. The extreme temperature swings will cause the little metal strip inside it's holder to flex and flex and flex until it fails from metal fatigue - not from getting too hot (melting).

You can buy the little thermal fuses, but unless you have an expensive charger, it's not worth taking the charger apart (some are glued together) then digging into the protective wrapping on the transformer and carefully un-soldering the old fuse and soldering in a new one. Then you have to put it back together.

Always use a charger at or slightly above the recommended amperage. I would get a true 1.0 Amp or 1.2 amp charger. Yes, you could get a larger charger to work just fine, but then you run the risk of the device being charged having something fail, like it's built-in current limiting circuit that would allow the battery to overcharge, then overheat and start to leak or worse - EXPLODE. Not a pretty sight.

The 850 mA charger will work just fine. The only affect will be a slightly longer time to bring the battery to a full charge. The only time the charger most likely has a full output is when the Nuvi battery is depleted and the charger is first connected, The battery will then draw all the available current (mA) and as the battery charges, the amount of current will decrease until the battery reaches full charge.

No, it doesn't matter. No it won't hurt either the charger or the Garmin Nuvi.

What Box Car said is correct. Any given charger will put out its rated output independently of the device connected to it.

You can ignore what the other commenter above said warning about the transformer getting hot and melting something. Unless the chargers are big heavy cubes, they don't even have transformers in them. Almost all chargers now have transistorized "switching" power supplies, not conventional magnetic transformers.

If there is any problem with failure, it will be due to a poor quality charger, not the fact that it's 850mA vs. 1000mA. I have boxes full of old failed chargers, and every single one of them failed not because they were undersized (they are all OEM tool chargers used for their OEM application) but because they were simply poor quality chargers, and not one of them "blew up" - they just stopped working.

Remember that these units are designed to operate and charge from a USB port on a computer. Computer USB ports are limited to 1/2 amp (500 ma) @ 5 volts. My 750 has two charge rates 1/2 amp and 1 amp. But the only time it will draw 1 amp is when it is in the cradle. The USB port will only draw 1/2 amp regardless of what it is hooked to. So use your 850 ma charger, it will charge at the same rate as your computer.

I just didn't want to hurt my Nuvi.

I appreciate all your help.

We don't know what type of charger the op has -switching or transformer.

Not all "new" chargers are "Switching". My wife's new Laptop has a charger that weighs over 2 lbs, that I could use as a Billy Club in a bind. It's definately a Transformer. Our fairly new Cable Modem has an inline transformer type Power Supply. Our recently updated Cell Phones have chargers that weigh only a few ounces and are obviously "Switching" chargers.

At any rate, they are all fused somehow, otherwise they would never get a UL listing.

I can't tell you how many electronic devices I have repaired that had an open fuse (not obviously "Blown") that worked fine after just replacing the fuse. No obvious reasons other than the fuse was "Open". Careful examination of the metal strip with a magnfying glass would sometimes show a hairline crack near the middle of the strip, causing an Open circuit. The others I assumed lost the bond at one end or the other of the strip. I'm talking about the little glass tube fuses that you don't see in cars much any more.

Constantly pushing any electronic/electrical device to the maximum design ratings and then letting it cool down will cause an early failure due to thermal cycles and flexing. Anybody that has repaired electronic devices for any length of time will tell you that. It could be that's why you have so many that don't work. They were Maxed out just one too many times.

Don't take this as being snarky, I'm just speaking from experience.

Speaking from my experience, it's been well over 20 years since I've seen one of the "wall warts" that had replaceable parts. Most are "potted" in that they are sealed in a resin that can't be opened. If there was an external current limiter in the form of a fuse, it was always in line as part of the output and on extremely rare instances on the input. Internal fusing is often done with a current limiting diode and not a traditional "fuse." If the diode fails, throw the device away. You can't open it to replace it and a replacement is relatively inexpensive.

As to "stressing" a charger, the only time a charger such as we are talking about here is "stressed" is when it is first connected between the source (the wall outlet) and the load (the Nuvi in this case). The electronics within the charger will draw greater amounts of power from the wall and output a higher than rated output for an extremely short time - like in the thousandths of a second. Once the electronics stabilize, they will then put out their maximum rated power until the load begins to reach saturation (the battery becomes more fully charged) and taper off until only a small amount of current flows in a trickle. Some of us that have been around a few years remember those trickle chargers we had for car batteries. They had a 13.8 volt output but the current was only about 2 to 3 amps instead the 6 or 12 amps used in a rapid charge.

In this case, we have a wall wart with a 5 volt nominal output voltage and a limited amount of current. If using a lower current charger was so dangerous, then why would Garmin state you can use the USB port on your computer? These are limited by the USB standards to providing about half the desired 1000 mA at 500 or so mA and they work just swell. The only drawback is the increased charging time.

Mary's concern is more with the rated output and the specification from her old charger rather than the prolonged discussion of the difference between a charger rated at 850 mA vice 1000 mA and how well it functions in charging her unit. As long as the output current of the charger is greater than the amount of power used by the Nuvi when running, the battery WILL charge.

I have a cheapie 100-240VAC adapter. I also have a 12V splitter that allows me to use 2 Garmins in the car.
I purposely let the battery run down on both my Garmins. I connected both to my cheapie adapter. One booted up. The other did not. I umplugged the first, and the second one booted up.
Next experimeent: Both batteries still depleted. I connected both Garmins into a better adapter. It states: Class 2 Power Supply
Input 100-240VAC
Output 12VDC 1A
When I plug it into the wall socket, both Garmins power up. The 295w has an icon that shows when the battery at full charge.
I note the time is 91 minutes. Both units show a full charge when on battery power.
The adapter remained cool to the touch as did both car chargers.
I don't have a theory.

Using a power supply with 12VDC 1A Output and the OEM Garmin car chargers is not relevant to the original question, which is will a 120vAC input, 850mA 5vDC output USB power adapter charge a Garmin Nuvi.

Most standard USB devices can be charged with an adapter like this, but a few, such as some Magellan units, will not (as shown in the youtube videos linked above). Step one is to make sure the adapter is charging the battery, not just powering the unit. Assuming that is the case, the typical user need fret no further over this issue.

Any atypical user who wants to know for sure how much load is on the USB power adapter can simply measure the load in milliamps on the output side while it is charging the Garmin Nuvi. Since any decent multimeter has this function, there is no need to speculate what might or might not happen.

One reason why Box Car just got a "COW" is due to detailed and understandable posts like this one.

Thanks, Box Car