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Battery Cell Swapping

posted Nov 8, 2010, 11:15 PM by Barrett Blackwood   [ updated Jul 22, 2011, 5:18 AM ]
So I went to use my camera the other day and It kept shutting down on me. I have a sony Cybershot T90. I looked at the battery and noticed it had swollen up some. I checked all my batteries and 3 out of 4 were toast. Sony typically charges $50 for these so I really didn't want to spend that kind of money to replace them.

I had some aftermarket batteries sitting around that were designed for a T70. Although Identical on the outside they are incompatible because Sony's camera uses some kind of authentication to detect aftermarket batteries and the camera will shut itself off if you try to use them. Thats right... battery DRM.


The solution? Swap the chips from the dead batteries to the aftermarket ones.

First step is to remove the labels, these batteries have no outer shell so the label is the only thing that holds all the parts inside.




The other side of this circuit board has a few IC chips and some other parts used for battery protection. They are Sony compatible however they updated the detection method on the T90's firmware. The camera will run for about a minute until the camera can identify the aftermarket battery, then it shuts down.

Next step: Warm up the soldering iron and desolder the positive and negative wires from the circuit board that holds the chips.


Now I soldered the circuit board from the Sony battery to the aftermarket battery. I had to trim the negative lead a bit.


Then I reinserted the components into the frame and wrapped it with scotch tape to seal it as the label was destroyed during removal (electrical tape is too thick)


The completed battery on the left, with the aftermarket battery in the centre and sony's battery on the right.

The batteries work exactly like the origionals (if not a little better) at a fraction of the cost. (I paid $10 each for the after-maket ones)

While I was at it, I decided to crack open my Logitech mouse (MX revolution) that has been acting up a bit lately. The battery inside was similar to the Sony batteries but a different shape. 

I opened the battery up and discovered it was intenally identical to the Sony batteries, but with a different circuit board. I used another one of the aftermarket Sony batteries I had and swapped the chip and put it into the logitech housing. Works perfectly. I figure many cameras use similar shape battery packs (600-650mah, 3.7 volt) and if you have some kicking around they are very easy to swap.

Additional notes:

When I bought the camera the Sony batteries were 80 dollars each at my local sony store. Unbelievable! After a bit of research I found that they are standard 3.7 volt lithium ion used by almost every device manufacturer under the sun and not worth much more than $10.

Just a couple of notes about battery chemistry: Its really important to match voltages. These batteries come in 2 flavours. 3.6 and 3.7 volt. Never replace a 3.7 volt with a 3.6 or kaboom! As long as your swapping packs of the same voltage and chemestry you should be safe :)

The batteries Sony shipped with this Camera are the older 3.6 volt flavour, however the Sony chargers are designed for newer 3.7 volt batteries. This probably explains why the battery packed failed so quickly (I had the camera about 1 year) the charging voltage is too high.
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