Unsolved PowerPC mysteries: The “well, that’s not swell” edition

[B S Magnet]

This is a terrible question. I’m neither an electrical engineer nor a chemist, which makes this all the more clumsy of me for asking it.

Every swelling lithium battery I’ve experienced over the years has come from Intel Macs and other devices (such as phones and other makers’ laptops).

The odd thing, however (minding how most of the batteries within iBooks and most PowerBooks are a bunch of cylindrical 18650 cells joined in a series), is not only have I never run across many, if any mentions of 17-inch PowerBook G4 batteries swelling up, but also, in thinking about my own 17-inch G4, the almost-dead, OEM battery (which has been with said laptop since it was assembled in a factory, in Shanghai, in March 2006) has neither swelled nor has it ever died completely.

In fact, for the nearly four years I’ve had it running, a fraction of the power coming from the OEM A1149 battery has remained the same — discharging almost the same amount of power now as it did in early 2019 when I bought the laptop. Were the components inside the 17-inch battery a bunch of 18650 form factor cells, then I would describe its behaviour as if, say, seven out of eight cells were dead, but one remained healthy (Coconut Battery shows about 12 per cent of the original capacity, give or take, and I can unplug it and run with battery-only, even though at 12 per cent, it amounts to having a kind of built-in UPS and not much more).

We know the battery construction inside the 17-inch PowerBooks had to be thinner than what a 18650 cell, on its side, could accommodate. As far as I’m aware, the 17-inch models have a layered cell design, much like batteries found in most complex electronics since the aughts.

And yet… the hecking thing, despite being connected to the mains constantly, has never swelled up or altogether stopped holding a charge, much as a lot of OEM and replacement batteries are wont to do with other gear — including Intel Macs with both user-replaceable and glued batteries. It’s also flatter, on both sides, than southeast Texas, Nebraska, or even an iced-over pond.

I also have a 17-inch aluminium MacBook Pro from ’08, so although it’s a different battery size, it’s basically the same thickness and form factor as what’s in the 17-inch PowerBooks. It would also be a layered Li-ion battery. I’ve had that MBP running for less than two years, and it’s already almost through with its second replacement battery (both of which, unfortunately, weren’t Apple-branded, and both having that vexatious trait of abruptly shutting off the system around 35–40 per cent of alleged charge remaining).

Although I know quality control can explain away much of the failure rate on third-party MBP batteries, it doesn’t give one much to go on when it comes to the PowerBook battery not swelling — or in having not run across many, if any user reports of swollen PowerBook 17-inch batteries.

So I feel like I’m either missing data (or even anecdata), or else there’s something fundamentally different with how Li-ion layered batteries are managed by the built-in power management board within PowerBook 17-inch batteries.

Can anyone, particularly anyone with some applied insight on chemo-electrical processes, charge management, and modern Li-ion battery tech, shed some light here?

Cheers!

 

[AphoticD]

Loving this discussion (and title) @B S Magnet

I have nothing scientific to contribute, only my personal observation and I can concur; 3 out of 3 PowerBook 17” batteries in my collection have not become swollen. But also out of a dozen or so MacBook Pro 15” and 1 MBP 17”, only one of the 15” batteries has ballooned up.

Compare this to the cells used in all the white polycarbonate MacBooks, where possibly half of these batteries on hand did swell up, either at the time I purchased (2nd hand) or over time.

Then everything “unibody” (MB white, alu, MBP 13, 15, and the “retina” models) have an even higher chance of swelling, from the dozens of units I’ve worked on. So what changed between the materials used in a 17” PowerBook G4 flat cell battery and these later models? or as you are leading toward, is it entirely within the power management of said models?

From what I have seen, the cylindrical 18650 cell houses rolled up sheets of the same material as the flat battery packs, however they include a literal chamber of air down the center of the battery and a venting hole at the tip, which allow the cell’s gasses to escape without warping the housing of the battery pack (and in turn cracking trackpads, warping bottom cases, etc)

So in the race for thinness, these simple logical failsafes are deemed unnecessary. It makes me wonder if EV manufacturers are as arrogant as Apple when it comes to venting and swelling factors or if the risk of cell damage and the resulting potentials for injury or death outweigh the drive to maximize space?

 

[GMShadow]

A lot of PC makers have similar swelling battery issues - Dell's been pretty notable with problems the last few years.

Most EV car batteries are just bundles of the little round cells - of which the failed ones can be replaced individually by someone with the time and motivation, something that will become more important as these age.

 

[B S Magnet]

Loving this discussion (and title) @B S Magnet

I have nothing scientific to contribute, only my personal observation and I can concur; 3 out of 3 PowerBook 17” batteries in my collection have not become swollen. But also out of a dozen or so MacBook Pro 15” and 1 MBP 17”, only one of the 15” batteries has ballooned up.

Compare this to the cells used in all the white polycarbonate MacBooks, where possibly half of these batteries on hand did swell up, either at the time I purchased (2nd hand) or over time.

Then everything “unibody” (MB white, alu, MBP 13, 15, and the “retina” models) have an even higher chance of swelling, from the dozens of units I’ve worked on. So what changed between the materials used in a 17” PowerBook G4 flat cell battery and these later models? or as you are leading toward, is it entirely within the power management of said models?

From what I have seen, the cylindrical 18650 cell houses rolled up sheets of the same material as the flat battery packs, however they include a literal chamber of air down the center of the battery and a venting hole at the tip, which allow the cell’s gasses to escape without warping the housing of the battery pack (and in turn cracking trackpads, warping bottom cases, etc)

So in the race for thinness, these simple logical failsafes are deemed unnecessary. It makes me wonder if EV manufacturers are as arrogant as Apple when it comes to venting and swelling factors or if the risk of cell damage and the resulting potentials for injury or death outweigh the drive to maximize space?

If they’re still around, have a look at your old aluminium MBP Apple-made batteries to see where they‘re made and what their serial numbers are. Only after I posted this topic did I notice I’d somehow overlooked how my OEM A1149 battery was manufactured in Japan. Whether that was Sony or Toshiba, I’m not sure. But its prefix, Y9, was new to me, and despite thinking I’d covered all the computers I own and Mac parts I have lying about, it was not an entry in my continuing wikipost list. Something tells me that the OEM A1181 (the A1185, I think) batteries and the aluminium MBP batteries which did bloat might have originated in factories which isn’t the Y9 one in Japan. But this is a hypothesis, nothing more.

It’s baffling that battery packs for laptops weren’t engineered with any kind of venting whatsoever. This is something especially egregious when examining the cells in the unibody and retina MBPs. Part of me has long wanted to take one of my old batteries destined for recycling and to carefully puncture that soft underbelly in the unibody battery design, just for the heck of it. But I haven’t, simply because I don’t have enough sand at the ready outside to have the whole assembly immersed in it in the event of… a sudden, catastrophic failure.