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| PowerBook G4 12” Battery Re-cell possible? |
Posted by: croissantking on 2026-01-06 08:27:43
A friend has asked me to re-cell his G4 12” battery. Just wanted to check if there were any gotchas with the BMS before I do this. Anyone else successfully rebuild one? |
Posted by: mdeverhart on 2026-01-06 08:35:15
I’m afraid I don’t know, but I have one that needs to be recelled too and I’ll be eagerly watching the feedback here and your results if you attempt it! |
Posted by: Durosity on 2026-01-06 10:05:35
Not a topic I have much experience on, but I vaguely recall that these units will “die” if the cells are disconnected/drop below a certain voltage as a component on the BMS is designed to only ever power up once. As I’m writing this I’m now starting to doubt myself though.. I don’t have the ability to google it where I am right now, but might be worth looking into? |
Posted by: croissantking on 2026-01-06 10:07:22
I googled it but didn’t come up with anything hence posting here 🙂 |
Posted by: zigzagjoe on 2026-01-06 10:20:00
Depending on the exact model of the main BMS IC it might entirely lack the lockout feature. If it does have lockout, it's a bit in EEPROM rather than anything truly irreversible. Sometimes the eeprom is external to the chip, other times it's internal, but usual TI BQ ICs mostly have known reset procedures. |
Posted by: nyef on 2026-01-06 10:40:55
From my own notes last February (and, no, I haven't actually finished rebuilding the thing, it's sitting, shelled, on my workbench):
So, a bit more on the iBook G4 battery pack: Chips provisionally
identified as bq29311PW, bq20851DBT, two TPC8107 (8-pin, turns out to
be a P-channel MOSFET), and a 451A 516 (8-pin, motorola?, probably an
N-channel MOSFET). Datasheets found for the bq29311 "three- and
four-cell lithium-ion or lithium-polymer battery protection ic" and
bq2085 "sbs-compliant gas gauge ic for use with the bq29311". The
latter uses flash storage for configuration information, so I believe
that this BMS board is not the type to suicide if it loses power. I'd be glad to know if I'm wrong about this, and if anyone has advice on recovering (even if it's "replace the ICs on the BMS") if it is locked out. |
Posted by: croissantking on 2026-01-06 11:00:20
From my own notes last February (and, no, I haven't actually finished rebuilding the thing, it's sitting, shelled, on my workbench):
I'd be glad to know if I'm wrong about this, and if anyone has advice on recovering (even if it's "replace the ICs on the BMS") if it is locked out. Is the 12” iBook battery the same as the 12” G4? |
Posted by: Durosity on 2026-01-06 12:36:28
I googled it but didn’t come up with anything hence posting here 🙂 Oh I assumed you’d looked already.. I more meant specifically about the battery BMS lockout if you hadn’t already done that! 😅 |
Posted by: AlpineRaven on 2026-01-07 01:46:41
Following - keen to find out!
Cheers
AP |
Posted by: 3lectr1cPPC on 2026-01-14 21:13:23
Let us know what the main BMS chip is. As Joe said, the BQ series chips are generally able to be made to work after a recell. Gets tricky with some of the stuff Panasonic was using, and anything proprietary of course. |
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