Remove.IT – failed bulging lithium battery from Mio C520 GPS

Last night, we went for a drive into the city as my wife wanted to visit a couple of friends from China. My car had been parked outside in the sun and my GPS mount had come off the windscreen. As I was remounting the GPS, I found that the GPS was bulging where the battery is situated – not a good sign, as it means that the battery is failing and could explode any minute.

Ok – maybe not necessarily, but it is possible – it didn’t explode on the way to the city and it didn’t explode on the way home, so after getting home, I took the GPS back into the house with me. It was a Mio C520 GPS which was bought in December 2007 before our family holiday driving down to Melbourne for the new year. I had replaced the battery in June 2009 after its capacity went very low, like a few minutes.


Mio C520 with original battery

This is the original battery.


Mio C520 with failing, bulging battery

This is what it looks like now. Lithium battery can swell up, due to increase in gas pressure – which can happen due to over charging or due to internal failure. Most reputable lithium batteries come with an overcharge protection circuit – the problem is that over time, and due to heat, that this protection circuit may fail to be effective and the end result is a battery that starts to swell up like a balloon that can eventually pop with disastrous results.

Normally there is no metallic lithium in these batteries, however during overcharging, the metallic lithium may accumulate on the anode faster than it can be dissipated – and can anyone remember high school chemistry where the teacher cuts off a piece of lithium metal and drops it into a pan of water? If not, I will remind you – lithium reacts intensely with water, forming lithium hydroxide and hydrogen gas – the result means a bright flame if the amount of lithium is small – that is why you don’t want to puncture the battery – even though you can feel that it is like a balloon, there is a reason why it is sealed to avoid ingress of humidity, i.e. water in air.


Battery from Mio C520

Ok – after removing the battery, this is what it looks like – before I put it somewhere safe in my garage.

What should I do? Order a replacement battery or get a new GPS? This battery lasted more than 6 years, whereas the original battery only lasted 1.5 years. This Mio C520 GPS does not have upgradeable maps, so there are places in Western Sydney that I cannot navigate to because it doesn’t have the street maps. The cheapest replacement battery I can get is from Netherlands for $15 or from China for $18. There are a number of GPS’s like Garmin, TomTom and Navman available with free lifetime maps for under $200, so question is new battery or new toy?



Remove.IT – dust in desktop PC, that is!

Yesterday, a neighbour from down the road knocked on my door. He asked if I could have a look at his PC that wasn’t working properly. I had previously fixed up a laptop for his mum, which is why he came to me. I said, “Sure, bring it over”.

So, he goes back and brings back the PC in his ute. He says he thinks there is a virus or something on it. Now, I remember that his mum had contacted me some time ago about his computer, but he never brought it to me, so it looks like things are worse now.

What I usually do is to open up the computer and have a look inside. When I did this, I noticed a fair amount of dust, so got the vacuum cleaner out and went around the insides with a brush and got most of the dust out. This is when I noticed something about the cpu heatsink, it looked like more dust inside. Fortunately, this heatsink fan, could be popped off by levering a couple of small latches, then pulling off the fan.

What I saw could best be described by thinking of something Crocodile Dundee might have said, if he was a computer repairman – “That isn’t dust, this is dust!”.


I took a photo for you people to look at – it wouldn’t be surprising if the cpu was getting hot and maybe shutting down at times. It would have been worse in summer. I vacuumed all of that dust out, and brushed the fan as well, so now it looks almost like new. There were two hard disk drives in it, a 1TB drive and a 80GB drive. I took both out, and checked them on my test machine – I found a bad sector on the 80GB drive, and some directory problems on the 1TB drive which will have to wait.

Anyway, installing it back together and powering on, showed the screen that Windows tells you if it didn’t start properly, so I chose to go to Safe Mode with Command Prompt. From the command prompt, I did a chkdsk /f of the 80gb drive that had the bad sector – it fixed a few minor errors. Next, I rebooted and let it start up normally. The desktop came up and there were a number of invalid pop-ups which I closed, and left it for a while. The PC was still ok, no signs of sudden crashing, so I decided to do a thorough check of both disks.

chkdsk /R will fix any errors and also check free space for bad sectors. I did this for both drives, except that of course, it cannot lock the drives to do this, so chose to have it run automatically on next startup. Reboot, and let the disk scan run – several hours later, all errors were corrected on both disks, the bad sector was mapped out on the second drive, and all seemed well. So it looks like, this dust was the culprit – how about you check your PC now?