Stripdown of faulty Toshiba laptop battery

[Lorenzo_1]

I mentioned sometime ago (I can't locate the old post) that I bought a Toshiba laptop battery (Labeled Replace PA39050U-18RS) from China and it showed poor battery 'health' from day 1 and would simply shut down ungracefully (crashing my laptop) when it ran low on charge.  Finally got a genuine Toshiba replacement at a high price and opened up the Chinese one to see if they used recycled batteries or had an obviously dodgy control board.  The manual for it said not to allow it to discharge completely to avoid damage, while I expected a proper control system would prevent that.  Anyway, turns out the innards do include a seemingly adequate control board and what appear to be new batteries (attached photo).  The batteries are labelled "PH Great Power Li-Ion ICR18650 2000mAh 3.7V 20160926" - I've taken the latter to be the manufacture date, which is close to when I bought them.  The control board has a 20 pin IC SA1414SE (Li-battery protection chip) and an ATMEL414 24C04N which appears to be a serial EEprom.  All the cells measured 3.8V with no load, so no obviously dead cells.  So it doesn't appear to be lacking obvious material parts.  I assume the poor performance from new is down to bad construction or quality control.  Unless they rewrapped old batteries with new plastic covers and invented dates - I guess that's not out of the question.

Posted in case others are looking at trying cheap Chinese batteries - 1/3 the cost of Toshiba parts in Oz but not worth the hassle in this case.

[amyk]

You can do a charge/discharge test on the cells to see if they're really 2Ah. The 5.2Ah rating on the case is obviously a lie, although it suggests there should be 2.6Ah cells inside if this is a 3S2P pack.

[Armadillo]

FeedbackLoop has a lot of videos on battery capacity testing and plotting.
Recommended to watch.   

[Lorenzo_1]

Would be good to test them but I don't have an electronic load at present and my other loads are pretty crude. Test video was useful - thanks. Also have five or six other repairs in progress and limited time for any of them at present.  They'll go in the drawer for a rainy day. They did give a rather interesting demonstration of rapid flammability while being dismantled!    Not hard to why they're high risk items on planes.