USB Cigarette adapter

[bel4_20]

I am looking at getting a 12V to USB cigarette lighter adapter for my one XL so I can use the USB cable in my wife's car as I'm hard wiring my factory tt adapter in my truck. My question is I found this adapter pictured below @ walmart and the specs are 12Vinput to 5V output but it claims only 1Amp I noticed my tt is 5V 2Amps Is 1 amp sufficient? or should I search for one with 2 amps

TIA

 

[SShadow]

If you trust the rating as stated on the GPS, then look for a 2amp one. If you use the 1 amp, it may work for a while - but it will get hot and will either fail or melt and catch fire.

The rating on the GPS is probably specced high, but what it's saying is it could possibly draw up to 2amps in current - but the adapter is only rated at providing 1amp of current.

 

[bel4_20]

That's a good point sshadow, it's just that I thought I read here somewhere that these guys were using Motorola adapters(for the razor cell phone) and there only rated at 500 milliamps or something. If anyone can confirm please let me know.

 

[bel4_20]

anyone?........

 

[SShadow]

To tell you the truth, I can't see a USB port being able to provide 1amp worth of current in the first place - so if a USB port can support the powering/charging of the GPS, I would think that the 1amp rating on that cigarette lighter would suffice.
This is just my opinion though...

Accoding to this .PDF - the maximum current draw for a USB port is 500mA... http://www.edn.com/contents/images/220400t1.pdf
This one says the same: http://focus.ti.com/lit/an/slyt118/slyt118.pdf

 

[bel4_20]

To tell you the truth, I can't see a USB port being able to provide 1amp worth of current in the first place - so if a USB port can support the powering/charging of the GPS, I would think that the 1amp rating on that cigarette lighter would suffice.
This is just my opinion though...

According to this .PDF - the maximum current draw for a USB port is 500mA... http://www.edn.com/contents/images/220400t1.pdf
This one says the same: http://focus.ti.com/lit/an/slyt118/slyt118.pdf

So in theory, that plug i got pictured should do the job with no problems, I guess what we really need to know is why the original adapter that came with the unit is rated at 2Amps, I'm sure there's a reason but does it really matter? and to be honest I have searched my brains out today and have not found a car 12V to USB that had over 1Amp...interesting.

 

[flyer1024]

So in theory, that plug i got pictured should do the job with no problems, I guess what we really need to know is why the original adapter that came with the unit is rated at 2Amps, I'm sure there's a reason but does it really matter? and to be honest I have searched my brains out today and have not found a car 12V to USB that had over 1Amp...interesting.

Any electrical device will draw only the amperage it needs. Your power supply could be 100 amps and the tomtom wouldn't even burp. It's voltage you have to be careful about.

The original adaptor is probably 2 amps because it's widely available to tomtom.

 

[SShadow]

I concur with Flyer1024. I don't think you'll have any problems with it at all.
But honestly, you can get a replacement car charger for cheap on eBay... So if you are REALLY concerned, just go that route.

 

[bel4_20]

I'm not "super" concerned, what Flyer1024 says makes perfect sense and I'm not looking to charge it from the car I just don't want it to go dead while using it in my wife's car for the odd couple of times we take that vehicle out on an outing.

 

[Birdman]

I'm not "super" concerned, what Flyer1024 says makes perfect sense and I'm not looking to charge it from the car I just don't want it to go dead while using it in my wife's car for the odd couple of times we take that vehicle out on an outing.

I cannot find the current draw spec for the TomTom ONE XL (you said 2A in your original post, but I don't buy it).

Taken directly from the USB2.0 spec, the cables that connect to a USB port are to have a maximum constant current draw spec of 0.5A:

The USB specification provides a 5 V (volts) supply on a single wire from which connected USB devices may draw power. The specification provides for no more than 5.25 V and no less than 4.75 V (5 V?5%) between the positive and negative bus power lines.[10] Initially, a device is only allowed to draw 100 mA. It may request more current from the upstream device in units of 2 mA up to a maximum of 500 mA.

So, the absolutely maximum the XL is allowed to draw is 500mA per the USB spec (1/2 of your 1A rating of that plug)

Now, if the plug itself is designed as an hihg-powered port, the TomTom could ask for more than 500mA, but that is a protocol that is all handled via the handshaking between the plug and the TomTom as addressed in the paragraph below:

A main issue addressed in this new specification (the USB Charging Specification) includes defining a mechanism that detects whether a particular device is hooked to an AC charger, host, or hub. If it is connected to a hihg-powered port, the device in question can then ask for more than 500mA of power, otherwise, a cap is set at 2.5mA, 100mA, or 500mA. The new specs will also enable portable devices to juice up at 100mAh if they're unable to start.


SUMMARY: You should be fine

 

[TDK1044]

I got a replacemrnt car charger/adapter on e-bay for my TomTom One 3rd edition. It cost $3.99 plus $4 shipping. It's much better than the one that came with the TT, because it has a coiled cable and so the cable is not in the way at all and is hardly noticable. The original had a cable that was way too long. I use the new one all the time.

 

[flyer1024]

I cannot find the current draw spec for the TomTom ONE XL (you said 2A in your original post, but I don't buy it).

[/B]

I don't either. The battery in the tomtom is rather small, and I saw somewhere it was 1200 or 1400mah....can't remember which.

anyway, let's take the higher value 1400 mah or 1.4 amps max available over one hour.

Tomtom says and some people report two hour operating time. that would mean a max operating current draw of 700 mah or .7 of an amp.

However, in reality, it would be even lower as any battery which is "dead" has a fair bit of unusable residual power. I'd guesstimate that the max usable power in the internal battery would be more in the area of 1000maH or one amp over one hour. operating for two hours would mean a consumption of 500 mah or .5 amp.

people reporting lesser operating time doesn't mean higher current consumption, but rather a battery that is not up to snuff and doesn't have full current capacity. seems to happen rather quickly with the tomtom batteries.

of course, changing some preferences such as the backlight brightness would mean less consumption.

 

[bel4_20]

I cannot find the current draw spec for the TomTom ONE XL (you said 2A in your original post, but I don't buy it).

Well here is a picture i just took 10seconds ago of the cigarette lighter adapter that came with my xl.

 

[Birdman]

I cannot find the current draw spec for the TomTom ONE XL (you said 2A in your original post, but I don't buy it).

Well here is a picture i just took 10seconds ago of the cigarette lighter adapter that came with my xl.

That spec means the output capability of the adapter is 5VDC and can handle up to 2A current draw. That doesn't mean the TomTom is actually drawing that amount of current.

 

[bel4_20]

I agree with what your saying, so I'm saying that the adapter i have pictured in my first post although rated at 5V 1 amp should work. Am I right by assuming that?

 

[SShadow]

Should work, yes. 100% guarentee - I won't go that far.

 

[Birdman]

I agree with what your saying, so I'm saying that the adapter i have pictured in my first post although rated at 5V 1 amp should work. Am I right by assuming that?

Based on what I know about the USB specifications, I would say YES. Ideally, we would know the TomTom spec for current draw, but I've spent quite some time searching on the web for this and cannot find it.

 

[bel4_20]

bummer to bad we could not find the spec.

 

[StewNTexas1]

A USB cable is a USB cable. From what I can tell, the only difference is the configuration of the 'small' plug that goes into the TT unit.

My older Olympus digital camera has the same size 'socket', and my TT cable works well on the camera, and the camera cable works well on my TT.

From this I conclude that this is a somewhat standard, though unusual, USB cable. I plan to search through a few electronics catalogs to see what I can find.

 

[Birdman]

A USB cable is a USB cable. From what I can tell, the only difference is the configuration of the 'small' plug that goes into the TT unit.

My older Olympus digital camera has the same size 'socket', and my TT cable works well on the camera, and the camera cable works well on my TT.

From this I conclude that this is a somewhat standard, though unusual, USB cable. I plan to search through a few electronics catalogs to see what I can find.

The discussion here is geared toward the elecrical specifications of the AC/DC charging adapter in the first post and the how much current the TomTom ONE XL will draw. The AC/DC adapter in the 1st post can support up to 1A of current draw @ 5VDC. We need to insure the TomTom doesn't draw more than 1A or the AC/DC adapter may be destroyed, or worse, destroy the TomTom due to a short.

The cable itself is pretty standard, even the plug that goes into the bottom of the TomTom...I have an MP3 player, a digital camera, and a digital media player that all use the same cable.