I had the occasion to rummage around in my PC parts box this week and besides a nifty heat sink for my controller project I found a laptop battery for my 18 year old Sony Vaio!!! 
Now these are not the original batteries, I sold those to a German guy years ago, he wanted to re-cell them. I regret not knowing then what I know now because the interesting bit in those is the original Sony BMS. There was another one of these after market cheap Chinese batteries in the Vaio but it no longer accepts charge too. So I tool them appart and... not a pretty sight. Very close to leakage, god only knows how old these things are, I don't remember when I bought them only that they were dirt cheap in the range of 25 something USD.
Out comes the multimeter and the oldest and nastiest one has zero charge, not only that the BMS has no continuity. Second one 0.019v no wonder the computer doesn't boot from it and the BMS has continuity on all three cells.
A project! Grab the 3 cheapest cells from nkon and put it back together. The cheapest are Samsung 22P and with soldering tabs and shipping costs 11.85€. First I have to de-solder the cells from the BMS and see how they are put together, soldered via tabs I can handle but it seems they are spot welded in series. No clues from the one that fell apart, the nickel tabs are long gone.
Now these are not the original batteries, I sold those to a German guy years ago, he wanted to re-cell them. I regret not knowing then what I know now because the interesting bit in those is the original Sony BMS. There was another one of these after market cheap Chinese batteries in the Vaio but it no longer accepts charge too. So I tool them appart and...
not a pretty sight. Very close to leakage, god only knows how old these things are, I don't remember when I bought them only that they were dirt cheap in the range of 25 something USD.Out comes the multimeter and the oldest and nastiest one has zero charge, not only that the BMS has no continuity. Second one 0.019v no wonder the computer doesn't boot from it
and the BMS has continuity on all three cells.A project! Grab the 3 cheapest cells from nkon and put it back together. The cheapest are Samsung 22P and with soldering tabs and shipping costs 11.85€. First I have to de-solder the cells from the BMS and see how they are put together, soldered via tabs I can handle but it seems they are spot welded in series. No clues from the one that fell apart, the nickel tabs are long gone.