Recharge.IT – Samsung phone batteries

What happens when you are trying to fix a Samsung phone but the battery is flat, and won’t charge in the phone – for various reasons? Of course, find an identical working phone – put the battery in and charge it on that phone.

A while ago, my brother gave me a Samsung Galaxy S2 to look at. The touch-screen wasn’t working, and also the battery was flat. I also have a S2 but his battery also wouldn’t charge in my phone, so I put that aside. I opened up his S2 and was able to locate the display cable, which I think also included the touch-screen – so when I removed that connector and plugged it back in, the touch-screen started working again, so he got the phone back minus the battery.

Some time later, he gave me a Samsung Galaxy S3 to look at. This one had just stopped and would not boot up. It powers up but then stays at the Samsung Galaxy SIII GT-I9300 screen. I wrote about it here.

I have the battery for the S3 here still, so I thought about charging it. If the phone doesn’t boot up, then it will not charge the battery – very unlike a laptop. While doing a few Google searches, I came across mention of a TP4056 chip that would charge Lithium batteries. On eBay, these are very cheap – so cheap, that I ordered a few, as in five. I have this idea of getting those Lithium cells, like the 16550’s and converting everything to use Lithium instead of NiCad etc.

Of course, not everything works from 3.7 Volts, so I also ordered a few DC-DC boost converters, which will take the 3.7V and get 9V or even 12V etc. Again, not everything wants 5V, so for some things, it might like 3.3V so I also got some DC-DC buck converters. Oh, wouldn’t it be nice to have boost-buck converters?

In converter nomenclature, boost means to get higher voltage, and buck is to get lower voltage – from the input voltage – got? A boost-buck converter would be able to take any input, within reason and produce any output – within certain limits of course. They are available, but not as cheap as the boost or buck converters. Anyway, I am getting off topic.

So, these TP4056 chargers came in eventually. They can take an input voltage and produce up to 4.2V to charge a lithium cell. The charger also has a mini-USB connector on it, so I plugged in my GPS charger that can output 5V at 1A and tried it out.

I made a little jig to fit the battery and some copper wire, sort-of spring loaded to connect to the battery terminals, then used a couple of jury-rig wire clips to connect the battery to the charger. The TP4056 is set to charge at 1A which should be fine, since most phone batteries are more than 1Ah in size.


Jury rigged lithium battery charging system

The S3 battery charged ok, even though it is a 3.8V Lithium-Ion battery. Now I have a fully charged S3 battery – what do I do with it, ok – later. I thought I would try the dead S2 battery, so I connected that one, and to my surprise – it started charging. I had previously tried to charge that battery with a specialized battery charger that could handle lithium batteries, but it had failed to charge.

Now, those of you who are know something about lithium batteries will say that this won’t fully charge a 3.8V battery. Of course, the end-point full charge of a 3.8V lithium battery will be about 4.35V whereas the 4.2V is for a 3.7V lithium battery – I certainly agree, however the difference in charge level is only small – perhaps 90+% of charge, and not 100%.

Let me tell you a little secret, which most of you know anyway. A lithium battery has a certain lifetime – defined as the number of full charge cycles. Let us say, for instance that it is 1000. Most of us, will need to charge the phone almost daily – which means that in about 3 years, if we left it to charge overnight, and in the morning – the phone was fully charged, that is a charge cycle. I didn’t finish, in about 3 years or so, the capacity of the battery will be diminished – it may start to happen in 2 years, and if you are lucky, in 3 years or so. By then of course, most people have already upgraded the phone.

So if everyone knows this, how is it a secret? The secret is – what if we don’t fully charge the battery? I.e. for a 3.7V battery that has a full charge voltage at 4.2V – what if we charged it only to 4.1V – and similarly for a 3.8V battery that has a full charge voltage at 4.35V, what if we only charged it to 4.2V? We actually wouldn’t be using up charge cycles – it’s like driving without the odometer clicking over. Theoretically, that battery would still be in top condition even after 10 years! The reason is business – we want you to replace the battery, so that we can sell batteries. We want you to replace the phone since it is getting old, and the new phone can run a lot more apps than the old one. It is just that simple.

Recondition.IT – Thurlby LA-160A Logic Analyzer – Part 1

Towards the end of last year, I came across an interesting circuit board on eBay. It was the CY7C68013A-56 EZ-USB development board – made by Lcsoft. Perhaps made is too strong a word, let’s say “designed” by Lcsoft, and copied by the myriad of asian suppliers. Anyway, it was less than AU$8 including shipping, so I ordered one. In due course, it came, but by then – as usual – I was tied up with other things.

Over the last couple of days, I was sorting things out, and I pulled out my Thurlby LA-160A Logic Analyzer from my cupboard. This logic analyzer was bought at great expense back in either 1985 or 1986. This one was badged by RS Components and was 16-bit capable, with various clock and trigger inputs – very versatile and economical at the time, compared with others that there were available and completely unaffordable, at least to a small business.

I was doing repairs on computers at the time, mainly Commodore 64’s and the IBM PC/XT clones. From memory, it didn’t get used a lot, and still has the plastic that covered the display. Being on a small budget, I elected to make the data pods for it instead of buying them. Ok – to stop digressing, I powered the LA-160A up and could see the display go through a check of all the segments, then LA160A .32 was displayed, telling me that it says that it is a LA-160A and the rom version is 32. Shortly afterwards, it said ready – but then a short while later, started checking the display again, then coming back to LA160A…

It looks like something is slightly amiss with it, so I had a quick check of Google, as we usually do, and found an article about the Nicad battery, and how it could leak. Definitely after 30 years or so, a Nicad battery will most likely have self-destructed, so it was time to open it up and take a look.


Nicad failure

For sure, the battery looked a bit worse for wear – the negative terminal was corroded. Not only that, it looks like the electrolyte leaking out of the battery has travelled quite a distance.


Under the board

Here the tracks under the battery appear also to be corroded, as in eaten away under the PCB coating. I had to remove the battery, which was easier said than done – the positive terminals were easy to desolder, but the negative terminal wouldn’t. I did manage to get it out finally and then it was time to inspect the damage.


LA-160A controller board

The top of the board shows where the electrolyte has followed the path of corrosion, a process called wicking where the liquid moves into small gaps, caused by corrosion. I could see that the corrosion has reached pin 11 of the 74LS02N chip on the right, then the track in the other direction has gone under the two resistors, under the 6116 static ram, then all the way to the empty 28-pin socket (for an option rom) where pin two is corroded.

The corrosion will not stop and must be cleaned. I cleaned the bottom of the board first, since there was not much to be done, except that the tracks were larger.


Corroded ground tracks cleaned (sort of)

I removed the 6116 chip, then desoldered the 74LS20 and both the 6116 socket and the option rom socket. After doing this, I continued the cleaning process – by using methylated spirits with cotton tips to clean the tracks that were corroded – to try to neutralize the electrolyte. Once it was dry, I used a small flat screwdriver, and a fibreglass pen to remove the majority of the corrosion, then cleaned again with metho. Once I was happy with it, I gave the board a clean using isopropyl alcohol cleaning wipes (as the metho leaves a white deposit).


controller board after cleaning

Now it looks better. I could see that the corrosion had been moving in the direction of the LA160 32 eprom, so it looks like I caught it in time to prevent any major damage.

The next steps to do will be as follows:

  1. Repaint the cleaned tracks with a PCB Resist Touch Up paint, preferably in green. This will protect the tracks.
  2. Refit the 24-pin ic socket for the static ram and install the 6116 chip again.
  3. Fit a 14-pin ic socket for the 74LS02N.
  4. Check if I have stock of the 74LS02N, if not – then order a couple – I like to keep spares.
  5. Check continuity for all connections relating to the damaged tracks. Jumper wires to be soldered in place as needed to fix damaged connections.
  6. Order a replacement battery 2.4V 100mAh. Nicad ones are not available, but a NiMH 2.4V 140mAh battery is available at one of my usual suppliers. If I do this, then I need to ensure that the logic analyzer is turned on every couple of months or so, to keep the battery charged up. It is usually a flat battery that starts leaking, plus of course – old age.

I have decided not to install a 28-pin option rom socket for the simple reason that I don’t have the LR-64 option rom for this logic analyzer. If I do get hold of one and want to install this, it would be a simple matter of installing the socket at that time. Also leaving the socket out would allow me to inspect the corroded tracks to confirm that the corrosion is no longer progressing.

By the way, the LA-160A will capture 16-bit data at 10MHz sampling rate. The little CY7C68013A board will be able to capture 8-bit data at 25MHz – an example of new technology at less than a hundredth of the cost of the LA-160A. For about $100 I could get a logic analyzer that can capture 34 bits at 125MHz – maybe that is for another day.

Anyway, this is part 1, with more to follow.

P.S. During my Google search, I found a site that talked about the battery and had a newer rom version 50 available for download, and from another site

found a service manual for this LA-160A. To try out the version 50, I will need a 2764A eprom or perhaps a 2864A eeprom. The 2764A is uv-erasable, but I don’t have a uv eraser, so the 2864A being electrically-erasable would probably be better. Anyway, it depends on what is available and from where.

[Edit]  After checking my stock of integrated circuits and finally finding a 74LS20N, I found that I had misread the IC and actually needed a 74LS02N, of which I do have plenty. Updated the above article with 74LS02N. I should wear my glasses.

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?



Review.IT, Remake.IT – BMW Z3 Battery Clamp Stud Bolt

Last night while I was in bed about to go to sleep, I had a thought.  The bolt I used to fix the battery clamp – I could machine the original bolt in the same manner.  In this way, instead of buying a replacement stud bolt, I can end up with a bolt that does the same thing, slightly shorter than the original.  I had fished out the end of the bolt that had broken off in the hole.


Here is the original bolt, with the broken piece at the end, and an identical bolt that I had used.  By the way, those bolts came from a barbecue that was dismantled.  I can turn down the original bolt and extend the thread so that I can put a nut on it to press down on the clamp.  Ok – put the original stud bolt into my lathe, turn it down to 6mm diameter.  Some of the corrosion came off – which appears to be battery acid corrosion.  Then I put my hand crank onto the lathe spindle to manually turn the bolt, while I use a M6 die to cut the thread.


Here it is with the clamp assembled.  Prior to installing it, I sprayed some white lithium grease onto the thread to protect it from corrosion and rust.  We just have to check that it is tight – from time to time.  This is my “review.IT” and “remake.IT” of the battery clamp stud bolt.

[NOTE] When working on the lathe, and on cars, it is quite remarkable that no matter how hard you try, you get grease on your hands.  I use a “Tuff Stuff” hand cleaner that is fantastic at removing grease and grime, and keeps my hands soft and smooth – as it is non-abrasive.  It has fine granulated polymer beads and has a fresh lime fragrance.

Retap.IT or Rethread.IT – BMW Z3 battery clamp mounting

A week or so ago, my son’s BMW Z3 had its battery replaced.  The car hadn’t been in use much – and we had charged the battery occasionally, but we must have left it too long, so the last time we tried charging, the battery charger indicated a battery failure.  Battery voltage was about 8V – much too low, hence a battery replacement was needed.  I got a good price from Onlinebatteries, with a great price on delivery – only $10.  What was even better was that the battery was delivered that afternoon, and the guy even helped with removing the old battery.  Here was the problem – he showed me that the battery clamp bolt would not loosen.  The bolt is about 7.5 inches long, and after some fiddling, it broke off in the hole.  Ok – no matter, at least the faulty battery can come out and within a short time, the new battery was installed.

Now, unless the battery is fastened properly – if the car goes over a bump, the battery might jump around – not good, and would invalidate the warranty.  That was a week or so ago.  This morning, I had a bit of time, so drove the Z3 down the road to our local mechanic.  He said that it is very fiddly to fix, and suggested that we just drill out the bolt, and either rethread it, or (like some people on the internet have done), put a bolt in through the bottom of the car, and have a nut on the other end.  Since I have most of the necessary tools, I decided to have a go at it.

Of course, the spare wheel – a space saver, is mounted under the car, so this needs to be released and dropped down.  I don’t want to drill the bolt, then go through the tyre.  I center punched the end of the bolt, which fortunately had snapped off flush with the mounting plate.  I drilled it out with a 3mm drill first – keeping the drill as vertical as possible.  Then followed up with a 4mm drill, and lastly a 5mm drive – which jammed in the hole.  Life was not meant to be easy – I hear that sometimes.  With a bit of wiggling and some WD40, the drill came loose, and this time I drilled, pushing gently and eventually went through.  It appears that I didn’t quite drill it centrally – or the hole wasn’t vertical, one or the other.  I poked around the hole, and the remainder of the bolt came loose, and I was able to push it out the bottom of the hole.  It was time to clean up the thread – or time to “” or ““.  The bolt was a Metric 6mm bolt, so I began tapping with a M6 starting tap, which I was able to do by hand.  Next was an intermediate tap, followed by a finishing tap. Great – I tried a handy M6 bolt and it threaded ok – just a bit looser than usual.

Since I didn’t have a replacement bolt on hand, I decided to put everything back in, after vacuuming the battery compartment, removing a lot of debris – that accumulated with time. A thought then occurred to me, the M6 bolt I had tried, it is similar to the original bolt, but without the flange that presses on the battery clamp.  I could put a nut in place and that would be the flange.  The bolt is much too short, but my 10mm nut driver would reach the bolt even with the battery in place.  So, I inserted the bolt with the clamp, and was able to tighten it so that the battery didn’t move.  It could well be serviceable for a time at least.


In the photo above, you can see the new battery and to the left (in the middle), the clamp with the improvised bolt to keep it fastened.  The plastic panel is still to be mounted, which covers all of the tail light wiring.   The plastic panel had been removed in order to get my drill to be able to drill vertically – as it was getting in the way.  I had carefully put all 9 assorted screws and bits and pieces into a plastic bag, and remembered in which order everything went back together.  All well and good!  Another successful repair.  I don’t think my son will be paying me for the 2 hours or so that I spent on this.

[Note] I was able to get the remainder of the bolt out, during the vacuuming. It showed me that the drill went in at quite an angle, yet I was holding the drill very much vertically. It turns out that the original bolt was tightened so much, that the mounting plate was warped to one side, so by drilling vertically, it went into the side of the hole.  Since only part of the thread is intact, this might explains the looseness – but it does tighten up, so we could leave it.  If in the future, I want to fix this properly – I would be best to use a thread repair kit, this is one where the hole is drilled out, and threaded then a M6 threaded insert is screwed in place.  This would then give a proper M6 hole for the bolt to go into.  Maybe that is a job for later, since I don’t have those repair kits on hand – but they are available locally.

Recharge.IT – The saga of the Nexus 7 battery continues

The Nexus 7 battery being charged by my Swallow Advance battery charger completed charging this morning.


3328mAh of charge was accepted by the battery – this is a little higher than the 3300mAh charge from the previous day.  If the rated capacity of the 1st generation Nexus 7 is 4375mAh, then this battery’s condition is at about 76% of new.  Each full charge/discharge cycle has a tendency to reduce the lifespan and capacity of a battery.  Most batteries of this type should provide 100% capacity during the first year of its life.  However due to shelf life and storage before use, this capacity may be lower than the rated capacity.  As this battery is at least 2 years old by now, a 76% capacity is actually not too bad and is reasonable for its age.

If you wish to prolong Lithium batteries, you should charge them frequently, but not to full charge, and don’t discharge them all the way.  By having shallow charging and discharge cycles, the life of the battery can be extended.  The downside is that you won’t be able to run the whole day on them otherwise they will go flat.  Always there are advantages and disadvantages, so it is best just to use your normal routine.

Ok – I reconnected the battery to the Nexus 7, and put the back cover on.  I had to press the power button for 30 seconds before it would turn on.  After waiting a while for the screen colour blobs to go around and around, the normal screen came up.  I plugged in the Asus charger and the Nexus displayed “Charging 93%”.  The other applications started up, together with the wireless, and the display was now “Charging 92%”, etc.

After an hour, I noticed that it wasn’t charging, so disconnected the charger and reconnected.  An hour later it is now saying “Charging 82%”.  This is what many Nexus 7 owners are complaining about.  I did vacuum the micro-USB socket – to get rid of dust and lint, which can get in the way of a good connection.  Dust and lint are good at attracting moisture – which then leads to corrosion.  Corrosion is the bane of all electrical connections, so keeping connectors clean is a good idea.  I just vacuumed my Samsung Galaxy S2.

I don’t know the pin code to unlock the tablet – I will have to get that.

Recharge.IT – Nexus 7 tablet battery not charging

My sister popped by yesterday with a couple of items.  A Dell 2408WFP monitor and a Nexus 7 tablet.  The Nexus 7 has been having a history of intermittent charging. Sometimes it will charge, other times it seems to discharge – so what could be wrong?  We have tried already, a different charger – most people suggest that the charger needs to be able to supply at least 2A.  A look on Google shows that this is a problem faced by many Nexus 7 owners.  This Nexus 7 has been so frustrating that a little while ago, they went out and bought one of those 10″ tablets that I think was on special at Aldi.  I said at the time that if they don’t want the Nexus 7, they can bring it over some time and I will see what I can do with it.

First thing was to pop the back off.  This is quite simple – just using a fingernail – slide it between the plastic and the metal bezel, and work your way around – the clips should easily disengage.  Having longer fingernails works better.  Once the back is off – you can see this large flat black item with a six wire cable coming out and plugging into a socket.  The black is negative and the red is positive.  I used a multimeter to connect to the socket pins and measured 0.4V – not good.  The battery being a Lithium Polymer battery is a 3.7V battery.  Wikipedia indicates that the first generation Nexus 7 (which this is) was powered by a 4325mAh battery.  A check on eBay shows that the cheapest battery for this is a 4270mAh for just over $20 delivered.

Now, what to do with the battery – I need to ““.  Perhaps I should say to charge it, but recharge sounds better.  I have a battery charger that can charge LiPo batteries.  I connected it up to the battery using some small clips – the contacts are quite small.  Here is a photo of the setup.


I set the capacity of the battery to be 3000mAh and the voltage to 3.7V – as being a single cell.  The charger is powered by a small 12V battery.  I started it and let it charge overnight.

This morning I had a look at it – it had finished charging.  So I am now testing the battery.  I am doing a discharge test at 0.3A – this is what the photo is showing.  When the battery voltage drops to about 3.7V, the charger will automatically stop.  The number at the top right hand of the display would be a number that relates to the capacity of the battery.  If I charge and discharge the battery a number of times, this number should be either similar or increasing each time.  The purpose of this charge, discharge test is to verify if the battery is able to retain charge.  Retaining a reasonable amount of charge indicates that the battery is still good.  I will come back with an update later.