# Sunday, 20 December 2009

As our phones and portable media players become more and more powerful, and we start using them more and more, more often than not our devices will run out of power on us more and more frequently. One way is to get more batteries, but usually that's either expensive or your device might not even HAVE a removable battery! The other is to find alternate sources for charging your device when you're out and about. Most of the device now have some way of receiving power through USB, and most of us travel around in cars so today I'll just talk about the car cigarette lighter USB adapters.

It sounds like a no brainer, all USB ports are the same right? So a person could just head into a shop and easily buy an off the shelf cigarette plug to USB adapter. If only it was so easy... here I have 4 cigarette lighter USB adapters.

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They all perform the same function, but they all have their own quirks.

Before you even think of buying something like this, first you have to find out if your device can actually receive power through the USB port. The easiest way to do that is to just find a USB charge cable for your device, plug it into a USB port then plug it into your device and see if it indicates that it's charging or not. BUT... that's still not confirmed that your device can charge using these adapters. Some devices, like say... and iPod or some phones, WILL NOT charge from a USB port unless it detects a proper USB host on the other end. ie. A computer. These might require more specialized car charges. The only way to test this is to find some form of a USB power supply like this and then plug the USB cable in and see if it charges.

Now let's take a look at the different plugs that I amassed throughout the years.

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This is what I've been using for a few years, it's what you find all over the place. Just a cigarette lighter plug on one end, and a USB socket on the other. And it was cheap too! RM15 only! Everything was nice and dandy when I used this with my first few Windows Mobile phones, until I got phones with built in GPS. Then I learnt about current and amperage.

This is the most important thing you need to know when using ANY external USB power source.  When all of them deliver a charge at 5V (I'm not sure if I'm using the right terms, but I didn't exactly study Eletronic Engineering) they deliver it at a certain rate this is usually identified by the A beside the charger. Go pick up any power adapter and read the OUTPUT column it'll look something like 5V 1A or 12V 2A that means that the power adapter can deliver N volts at a rate of X amps. (I'm gonna stress this one last time, the terms but be wrong cause I don't know what's the right term) From my understanding, the higher the A the more quantity of power can be delivered.

So what does this have to do when we charge our devices with a external USB source? Let's say for example that this generic cigarette adapter's output is 5V 0.25A, then you plug your phone into the thing and it says it's charging so... feeling secured that your phone is charging you use it more.. maybe you use it to play music... use GPS for navigation... surf the web... play games... and then you get a low power warning even though your phone says it's charging!

What just happened? Remember that the adapter's output is 5V 0.25A so it's pushing current at that rate. But... your phone isn't idle, let's say that when it's idle your phone draws 5V 0.05A so the adapter has a chance of pusing juice in at a higher rate than you're using it. But then when you start using the phone to do other things your phone draws more power let's say at 5V 0.5A. Your phone is now using power at a higher rate that is supplied by the charger, hence the charger cannot add charge to the battery but is merely able to prolong it's lifespan for a while.

This logic told me that I needed to find something with a higher A rating if I wanted to be absolutely sure that my device was being charged. But that's a bit hard, cause first of all the cheap adapters might not come with the label (like this one I got) or... they have a very deceptive label of 5V1AMAX. When I saw the word I just paused for a moment, that should mean that the adapter is capable of deliver 1A but it might not be capable of sustaining it for long periods. Since I couldn't trust a cheap unmarked adapter, I put my faith in a branded one instead.

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This adapter is from the battery company Uniross. There's a nice clear marking that says that it outputs 5V1A. I assumed that as a battery company this should be real. This was bought at RM45 so it's definitely NOT CHEAP! It seem to work well, was charging my Diamond pretty well, until one day on my way back from Ipoh with my phone plugged in and GPS running the battery warning came up. I then looked at the battery information screen and it said that it WASN'T CHARGING. I removed the phone from the cradle and it was HOT! The phone was hot because of the combined scenario of Battery being charged, GPS in use, sun shining on it while it's stuck on the windscreen. (This is before I changed the location of my holder) 

Why did it stop charging? Lithium Ion batteries EXPLODE in high temperatures. That's why proper Li Ion batteries have a cut off to ensure that they don't get too hot when charging. Technically you can't reach that high a temperature when you're just using the device cause there's not enough energy to generate the heat, but when you're charging it that's when it's possible to reach the danger threshold.

Thinking that maybe this Uniross one also might be lying about it's capacity I recently acquired this small little thing.

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This is a low profile Belkin auto charger, it ALMOST sits flush with the cigarette socket. And it doesn't look like anything else at all.

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If it does looks like anything else to you, it's just YOU! So anyway this one again has a rating of 1A. And I always thought that was good enough, since your computer's USB port is also rated at 5V1A. This was again NOT CHEAP, after all it has the Belkin product name on it! That was until I bought a new Taiwan made PMP player a few months back, and I plugged it in and it DIDN'T CHARGE! At first I thought it was one of those things that needed a USB host before charging. But I finally dug this out of my drawer.

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This is a genuine HTC car charger. I got this free when I got my HTC Touch Diamond, I didn't really gave it a second thought until the incident with the PMP player. So I fished this out of my drawer plugged it into the socket, then plugged the PMP into it.

And it started charging! This is when I truly understood that not all car adapters and devices are made to be used together. Why? Because I can only find one reason why the HTC would charge the player so effortlessly while the others failed.

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The output of the HTC charger is rated at 5V 2A. I have yet to be able to find another car adaptor that can push out current at this high a rating. But because of this, I do believe that the amps make a difference, and if you can. You should probably try to find something that has a trustable high rating. Maybe not 2A, maybe at 1A it's enough for you. Just remember to do some prelim testing first before committing to an expensive unit.


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