A question about power draw from the 2595LMT

The answer really depends on the state of the unit when you plug it in. If the battery is charged or nearly so, then the charging rate isn't that important if it is going to be plugged in for any length of time. The only time I can think of it mattering is if the unit is low on charge and you are looking at a rapid recharge because you will be running it on the internal battery. Most of the time it will be just plugged in while you are driving, so the charge rate isn't that important.

My vehicle power/traffic cord is a GTM 26 and its fused at 1 amp. If you have this cord there should
be no problem using it with either vehicle connecter.
If you have another traffic cord they may be fused
at a higher amperage. The GTM 35 and 60 are
both fused at 2 amps. Look at the end of the cord
that goes into your vehicle power it will give you
the fuse rating for example the GMY 35 is
Fuse 1A/250V.

I don't have the answer to your question, but to adjust understanding of some of the other comments I'll point out that if your 12V USB charger meets USB specs then it is putting out 5V on the power wire of the USB connector. So the 12V fuse value is not the place to consult for maximum draw.

If the port you choose makes any difference in Garmin charging rate at all, it would not be in the late stages of charging--when any lithium-ion charger which does not destroy batteries reduces the charging rate to keep the maximum voltage on the battery within prudent bounds. Maybe it would allow a faster charging rate in the early stages of charging a deeply discharged battery, or maybe not.

Out of curiousity--why are you considering plugging it into the USB port rather than using the 2595LMT's own 12V cord?

Thanks everyone. I have this dual USB port lighter adapter in my vehicle lighter socket. I wanted to use it to be able to connect both the Garmin and my cell phone as needed. I like the fact I can do both and plus, my Samsung S2 connects and charges as AC. Some chargers are only recognized as USB charging.

http://www.amazon.com/Lighter-Charger-Adapter-Android-BlackB...

I currently couldn't find my 2595LMT's own cord so I didn't know the output of it. From the sounds of it, it appears to be 2A.

I have a bad habit of using the Garmin on battery even in the car, and only connect it when the battery runs low. Seeing some of these posts, has given me the thought of changing my ways and always run it connected and also save wear on the lithium-ion cells.

There is one issue you may have in using a USB cord with the unit. Garmin requires a special configuration to prevent the unit from going into mass storage mode. You may have more success using an adapter giving you two female lighter outlets. You can use one for the dual USB plug and the other to run the Garmin. It should need less than 1/2 an amp if the battery is charged and about an amp if it's drawing its full charge power.

I tried the Garmin on the dual USB lighter adapter, I actually have two for separate vehicles and it worked as expected on one of the two, didn't go into mass storage mode on one, did on the other on the 2.1A port, 1.0A port works fine on both. Something strange going on with those cheap adapters, may be some sloppy soldering inside. Waiting for Amazon on an exchange.

I have considered going with a dual female lighter outlets. I still may do so, undecided at the moment.

My 2595 is plugged in to a mini "power bar" with three female lighter outlets. The other two outlets are for a dual USB charger for the Nexii and an inverter for everything else. Been working well for going on a year.

This has not been the case for me and I'm coming to think just the opposite. I used my nuvi 250 for about 4 years mostly on battery, charging in the car on on the computer when needed. I didn't use the device constantly, mostly just on trips or when navigating to someplace new around the city. After four years it was still holding a good charge and could run for some time (multiple hours) on battery.

In January I got a new car and changed my usage pattern. I kept it in the car and pretty much ran it everywhere I went, plugged into the switched lighter socket all of the time. This still isn't a lot of usage, less than 1000 miles in the first three months. But a couple of weeks ago I had occasion to run the nuvi on battery and found that it warned me the battery was low in just about two minutes, rather than the couple of hours it would have taken in January!

I realize that the receiver is getting older, but I can only attribute this very sharp drop off in battery capacity to running the device under a constant charging state (which I pretty much have to do now). I'm hard pressed to think that it would have dropped off this fast if I had used it on battery, the way I did the first four years. Rechargeable batteries do have a finite life, but they are meant to be recharged, not run constantly full. And rough calculations tell me that I should be nowhere near the expected cycle count on the battery.

I should also add that I've been good to the device and the battery, I always take it out of the car, I don't leave it in the vehicle to experience freezing or baking in the sun, which would be extremes beyond the recommend range for storage in the Garmin manual.

Your experience makes sense. What I believe kills batteries prematurely is 3 things, excessive heat, constantly draining the battery down to the minimum, and maybe what you just posted, constant topping off on a full charge?

For lithium-ion batteries more important than any of these is excessive voltage on the battery. This is awkward, as a higher voltage gives faster recharge times during the bulk charge phase, and higher total capacity during the end phase, both of which are things users value, and customers punish the cautious folks who build chargers which will give longer total service life.

If it is really true that the previous poster had a battery that was killed off by constant topping-off, the fault is not in the constant topping-off, but in a charger which allowed too high a voltage on the battery in that circumstance. Not all of them do that, as shown by the many Garmin users who leave their units plugged in nearly all the time, yet have meaningfull capacity after several years when unplugged.

The extreme sensitivity of battery capacity and even frank failure to even momentary maximum voltage excess is a characteristic in which lithium-ion cells differ materially from the general run of other cell chemistries.

Since the 3.7 volt lithium battery in a nuvi can be recharged by plugging the USB cord directly into a computer USB port (5 volt), I'm expecting and hoping that Garmin has some sort of voltage regulation and protection in the unit. Under voltage protection would sure be nice too, as discharging such a battery too far can also make irreversible chemistry changes. Even most simple rechargeable lion batteries sold to consumers such as the 18650 cell usually include this type of protection circuit internally, cutting the battery off when the voltage gets too high or too low before harm is done.

Anyway, I used both the Garmin provided charger and occasionally my laptop (when I was going to load new POI files) for 4 years with no noticeable ill effect.

The sharp drop off in capacity that I saw came after using the Garmin provided 12 volt cigarette lighter adapter/charger that came with the nuvi, pretty much what I expect others will be using too. I can't say for certain that it was the constant topping off that caused the sharp drop, but normally I would expect a much less drastic change in charge capacity over just 3 months or so.

The internal battery protections are last-ditch emergency measures aimed at preventing severe events (and not always succeeding--as the videos of burning laptops show). They are NOT aimed at, nor capable of, preventing all harm. A charger which takes the battery just a few tens of millivolts higher will shorten battery lifetime materially compared to another otherwise identical one.

This is all really basic Lithium-ion stuff.

Just curious but is the 12v charger you use from Garmin, a 1A or 2A output?