Chosen Solution
Hi guys, I have a MacBook Pro 2012 (non retina) with a swollen battery. The battery still worked fine, holding some charge for about an hour, but I decided to fix it. I opened the battery, discarded the swollen cells, and replaced them with healthy cells from a donor battery from another MacBook Pro 2012. I checked all six cells with a LiPo charger, and they all hold >90% of the original capacity, so they are very good. I charged all cells individually, double checked all connections, and soldered everything together. A multimeter shows 11.1 V at the battery terminals, so far so good… Unfortunately the MacBook Pro does not power up with this refurbished battery. It boots with the power adapter connected though. Both MacOS and CoconutBattery recongise the battery serial number, manufacturer, age, and so on, but show 0 mAh and the Mac does not charge or use the battery. As soon as I remove the power cord, the MacBook Pro shuts down. I have reset SMC and made no difference. Any clue of how to fix this? UPDATE 02/10/2021 CoconutBattery snapshot
I’ve never rebuilt a pack before, but I’ve tempted fate before so I have a bit of experience and know how downright dangerous charging 0V packs can be, and rebuilding. A lot of laptop batteries today have a one-way permanent failure flag, with some being more aggressive than others - even if you can safely rebuild it. In some cases, especially systems like the Lat E series and 3/5/7/9000 series, a custom TI chip combined with a sensitive BIOS (AFAIK the removable Lats are picky with the E Series, but not sure about the built-in series) also get in the way. That was not a problem on Lat D machines. Why the change? Shoot for Sony producing faulty cells, which led to a multiyear battery recall which went on from 2005-2008. Before those years, we used to be able to abuse batteries without a permanent failure flag that’s easily triggered; it was there, but you had to be incredibly bold to trip it. You could even swap cells without killing the BMS. On a lot of the older batteries, I’m still able to charge an unused pack from 0V even if it’s been sitting for years (Yes, this is a somewhat dangerous game to play. I DO MONITOR THESE!) and has been the case for over 10 years. The way I see it is if the pack is probably bad, why not try? The manufacturers removed that endurance with cheaper cells and trigger happy BMS boards which trip a permanent failure way more easily then they used to. In addition, a lot of post Sony packs block charging below 3.5-3.7V. You can still tell the thing you mean it, but you need to trick the computer OR use an external charger that tells it where to shove the complaint. The closest we have to that time is Samsung SDI, which can take a similar beating as the Sony cells (but cannot charge a 0V pack, thanks to the modern BMS issues). If it can be done, I’ve found a way. Sadly, you may need to give in and buy a new pack. The days of taking an old pack from something like a pre-2005 HP and early PB G4 packs where there were no nannies are over, and so are packs that last 10+ years and still work even if they sit thanks to Sony.
I’m suspecting you will need to reprogram the batteries microcontroller or at least see what it is telling you. Frankly, its just best to replace the full assembly as the sensor logic within the battery could have been damaged which is causing the microcontroller not to work properly.
The battery management IC inside the battery pack will produce a permanent failure when it sees a severe cell imbalance. You created that imbalance when you reworked the stack. This is 100% correct behavior by the management IC, since a severe imbalance can lead to fire/explosion. Also, replacing some of your cells with cells from another pack guarantees a cell imbalance, since it is pretty certain the new cells don’t have the same use history and aging. Cells are matched at production time so that they are all the same. You should never replace individual cells in a lithium battery stack. Make no further attempt to use this battery. Buy a new one.
