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B S Magnet

macrumors 603
Original poster
This question seems kind of far-fetched, but I have to ask nevertheless, especially considering the prevalence of Li-ion batteries being prone to damage (including swelling) or failure, when left plugged in to a charger at maximum charge for extended periods of time.

Also, considering the strategy of both phones and hybrid/plug-in Li-ion batteries in cars running a “fast charge” to a “mostly charged” state, this got me to thinking about third-party hardware controllers for components like fans (like G4fancontrol/MacsFanControl/iStat Menu) and pondering whether any such means to control the charge of a battery on a laptop has ever existed (or, for that matter, ever been tried).

I say this as I shop for replacement batteries for a few of my laptops, both PPC (the PowerBooks) and Intel (a couple of MacBook Pros).

I realized it would be handy to, say, be able to set a custom charging regime for which the usual (re-)charging would halt at, say, 80 per cent (or some other custom threshold), followed by a kind of intermittent charging (on five minutes, off for ten, repeat) above that threshold, as a way to maximize a battery’s longevity and health.

Has anything like this ever existed? Nothing comes to mind, and a few broad searches didn’t turn up anything, either. At this point, I ask more as an idle curiosity than anything urgent.
 

repairedCheese

macrumors 6502a
Jan 13, 2020
632
835
Sorry, this is not what I was referring to in my original post.
Would this be more along the lines of the sort of thing you would be looking for?
Screenshot_20210422-185309.jpg

I know it's for Android, but it sounds like the kind of thing you'd want, only for Mac instead.
 
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B S Magnet

macrumors 603
Original poster
Would this be more along the lines of the sort of thing you would be looking for? View attachment 1762394
I know it's for Android, but it sounds like the kind of thing you'd want, only for Mac instead.

Yes, this would be a lot closer to what I’d be looking for — a utility which would enable you to be able to set how long the battery will charge before either halting re-charge (easier, but simpler) or switching to a trickle re-charge above 80 per cent (more involved, possibly well beyond the limit of what older DC-in board logic would be able to do).

Something tells me the problem with achieving this is that each generation of PPC and (early) Intel Mac used different boards with different logic circuits which were not designed to be controlled or altered outside their pre-programmed core function (located on some kind of EEPROM on the charging board).

That is to say: my wondering aloud here is whether the charging circuitry specific to the PPC laptops, mated with the power brick specific to the PPCs, run with a chip set which is different from the Intel laptops that use MagSafe1 and that series’ power brick. If so, then that might make a software-based utility to control charging (as, say, a Universal Binary) either impractical or impossible. Also, unlike fan control on Intel Macs and G4 ’Books, there may not be any kind of low-level way for a user-executed utility to access control over the charging board (which might, for all I know, not be “smart” enough to receive and execute commands from outside the board’s very basic programming).

Frankly, there are times when I just want to leave the power adapter plugged into a laptop and not have to worry over things like the health of the battery. I’d be fine with keeping a laptop battery only four-fifths’ charged while it’s left plugged in and running if it meant preserving the overall health of a battery (especially so for PPC laptops, whose batteries are now much tougher to find affordably).
 
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AphoticD

macrumors 68020
Feb 17, 2017
2,283
3,466
IOKit Power management is where one would find a way to control this.

Some searching reveals this tool for mostly 2015+ Intel and Apple Silicon:

It is written in Swift, with some support dating back to 2010 model MacBooks.

Digging through the code it looks like some pretty simple SMC Byte writing to control max charge capacity. Which would be persistent between reboots.

Perhaps Open Firmware has similar capabilities for our PowerPC Macs?
 
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