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Warning! Exploding Maxell PRAM Batteries
Posted by: AwkwardPotato on 2018-03-19 09:42:46
There really isn't a "safe" battery you can install in one of these systems, at least one that won't leak. The safest alternative would simply be to not install a battery at all, however many Macs won't boot without one. The IIGS can boot without the battery, although you'll lose all your settings, and from what I can gather the LC III can as well.
Posted by: bibilit on 2018-03-19 09:51:56
I agree.

Most of them don't need batteries.

Only a few are required to boot (Macintosh II range except the IIsi / The LC 475 will need one IIRC or will not display any video) 
Posted by: techknight on 2018-03-19 15:15:29
I like to re-locate mine to the outside/rear of the computer using a AAA battery holder, and do it that way. In case it does leak or go bad, its on the outside and not inside, plus its easy to replace and off the shelf. 
Posted by: Scott Baret on 2018-04-08 18:56:12
I'm planning on buying a bulk pack of batteries for the lab I use with the kids and installing them, then replacing them in 4 years.

The ones I have at home are easier since I can keep a closer eye on them. As soon as the battery fails, out it comes.
Posted by: Franklinstein on 2018-10-11 21:39:21
Just to add a bit:

Yes, the Maxells seem to be the worst of the 1/2 AA lithiums, but the white-and-green ones are also pretty bad. Tadirans (purple and black) usually fail the least catastrophically but given enough time and/or poor storage conditions they too will leak.

If you notice, on the models with the square battery packs with the leads, the wires act as wicks when the batteries leak: the electrolyte travels from the bad battery all the way to the connector where it begins corroding the logic board connector and beyond. It's usually visible as a greenish blue tint on one of the wires at the connector.  If the leakage spills beyond the battery pack the velcro usually absorbs a lot of it which thankfully localizes and reduces the damage done.

This mode of failure also happens when PowerBook backup batteries leak. Yes, they will and do leak. The electrolyte will not only leak out of the battery pack and corrode anything around it, but is also wicked to the terminal of the connector where it inflicts damage to the logic board.

If you collect PowerBooks of any vintage, I highly recommend removing the backup batteries from all of them. Some still have replacement battery packs available, if you really need to be able to sleep-swap the main battery. I have yet to see one of the soldered backup batteries from the original 1x0 series cause any problems but it's likely only a matter of time before they do. Also, do not store the PowerBook with its main battery installed. This should be common knowledge but from as many ruined models as I've seen it apparently isn't.
Posted by: Trash80toHP_Mini on 2018-10-12 09:32:53
If it's lithium, which I suspect it is, it probably will eventually do so. Hmmm, wonder if that battery could be adapted to a Mac Plus, since the original 4.5 volt alkaline Eveready #523 batteries are almost impossible to find these days.


The ones you do find, are actual "hacks" using button cells or something of the like, and a homebrew wrap to make that particular battery.
Dunno about the size issues, but it sounds like it might be possible to design a printable replacement battery cover to hold button cells using springy copper (brass/whatever) strips for the contacts. Maybe a two part design that with an outer portion that acts as a cup with the lead for the bottom contact looping up and out of the cup? Maybe put V notches thinning the strips to the point that they corrode away within the cup in case of failure before strip wicking can get to the machine contacts?

Yep... I guess I could see about machining a brass (or copper) spacer, then just use three PX76's...
Your suggestion's what got me musing about printable holders. Even a hunchback cover for the Plus- series wouldn't be unsightly. A platinum painted 3 AAA holder would Velcro nicely over the squarish copy panel of my Quadras with Kynar leads looped through the security slot to a printed battery dummy with MAXELL and olePigeon's skull & crossbones in "raised" letters in a sunken panel. [}🙂]

Picturing printed PowerBook holders for smaller modern cells, but that's blur filtered  .  .  .

Coffee mug needs a warmup, I'll decide how dumb all this sounds later when I wake up  .  .  .  after a third mug or so. :🙂

edit: fixed some typos and now wondering if only a platinum snap-on cup/cover for a stock 3 AAA holder might work on the modular Macs? SE/SE/30 would need a color coded or keyed header lead setup? Copy panel location works there as well.
Posted by: Bolle on 2018-10-15 00:09:50
And here we go with another one:

View attachment 25060

Good thing is only one of the two went off. Looking at the metal shield I was wondering how those batteries actually go off - more like slowly leaking or are they gassing out explosion-like once the sealing is getting weak enough?
Posted by: Solvalou on 2018-10-17 18:37:40
This reminds me of the IIfx I received 8 years ago along with a II (that survived albeit with no signs of life).

Sadly both batteries went on a killing spree.

IMG_3624.jpg

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Posted by: joshc on 2021-01-03 08:30:12
Not an LC/Performa but a Classic...I finally get to join the club, my first Maxell explosion...what do I win?

IMG_0952.jpeg

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Posted by: ScutBoy on 2021-01-03 09:59:56
Win? Sorrow and woe

🙂

PS - that might be survivable - won't know until you get the crud cleared off and can bet a better look.
Posted by: joshc on 2021-01-03 10:19:52
Win? Sorrow and woe

🙂

PS - that might be survivable - won't know until you get the crud cleared off and can bet a better look.
I have started the process, I will start a restoration thread in due course. So far it's looking like ~10 traces are damaged. This is a multi layer board so I'm not massively hopeful for it to be honest.
Posted by: Torbar on 2021-02-01 07:51:03
Didn't realize they were still using Maxell's in the G3 Era, but I opened up my Blue and White yesterday to a tasty treat.  Luckily it seemed to clean up fairly well and I was able to boot to the flashing question mark at least.  Not sure if the drive in there works or not, or if there's an OS on it.  This week I'll remove the motherboard, desolder battery holder, make sure it's all cleaned up below it, and clean the rust/acid that made its way to the hinge, and pop in a new holder.  Also check on my iMacs and remove the batteries in them I guess!
Posted by: Scott Baret on 2021-02-01 13:17:05
They used them even later than that...I have an iMac G4 I really need to open up sometime; it's been in storage for a few years and I know it's only on its second battery...
Posted by: Torbar on 2021-02-01 16:26:48
They used them even later than that...I have an iMac G4 I really need to open up sometime; it's been in storage for a few years and I know it's only on its second battery...


*nervously looks at the iMac g4 in my projects pile*

Guess I know how I'm spending my weekend
Posted by: joshc on 2021-07-06 04:44:56
Here's another one...

96933317-F8A0-4860-BFAC-73BCFB3F3BFB_1_105_c.jpeg

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Posted by: joshc on 2021-10-11 23:52:04
Got a battery bombed Q950 on the way but it only seems to have taken out some RAM and maybe a few RAM slots...

1634021499928.png
Posted by: mg.man on 2023-02-27 08:51:55
Pretty sure I mentioned elsewhere... but might as well here :

20230215_120851.jpg

RIP little IIsi. 😢
Posted by: LaPorta on 2023-02-27 09:05:45
My SE find 2019:


Crusty.

Machine was totally restored and works well.
Posted by: bilbomacuser on 2023-05-06 12:21:36
Has anyone had a relatively new replacement 1/2AA leak? I’ve got a few computers that I use occasionally that I’ve put replacement batteries in, with the plan of replacing them every five years. However, I’ve had loads of AA batteries leak over the years, and some before their expiry dates - so tend to replace those every year (not in computers). Just trying to decide what is safe vs wasteful?

Any computers on longer term storage have batteries removed - I learnt my lesson a while back with a Mac SE that I stored without removing the battery, and it damaged areas including the ram slots. Was still able to repair it enough to get it to boot, though probably ought to replace the motherboard if I see one.
Posted by: Phipli on 2023-05-06 12:48:09
Has anyone had a relatively new replacement 1/2AA leak? I’ve got a few computers that I use occasionally that I’ve put replacement batteries in, with the plan of replacing them every five years. However, I’ve had loads of AA batteries leak over the years, and some before their expiry dates - so tend to replace those every year (not in computers). Just trying to decide what is safe vs wasteful?

Any computers on longer term storage have batteries removed - I learnt my lesson a while back with a Mac SE that I stored without removing the battery, and it damaged areas including the ram slots. Was still able to repair it enough to get it to boot, though probably ought to replace the motherboard if I see one.
There were stories of them leaking even back in the 90s and early 2000s, so those must have been about 10 years old. Just not worth leaving 1/2 AAs in stored computers. Coin Cells are a better option, but still.
Posted by: joshc on 2023-05-06 12:54:27
Just not worth leaving 1/2 AAs in stored computers.
This. Though I have been foul to it myself...it's easy to forget or think you'll be coming back to a machine sooner than you actually end up doing.
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