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Warning! Exploding Maxell PRAM Batteries

AwkwardPotato

Well-known member
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.

 

bibilit

Well-known member
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) 

 

techknight

Well-known member
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. 

 

Scott Baret

Well-known member
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.

 

Franklinstein

Well-known member
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.

 

Trash80toHP_Mini

NIGHT STALKER
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.

 
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Bolle

Well-known member
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?

 

tokyoracer

Well-known member
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.

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joshc

Well-known member
Not an LC/Performa but a Classic...I finally get to join the club, my first Maxell explosion...what do I win?

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ScutBoy

Well-known member
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.

 

joshc

Well-known member
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.

 

Torbar

Well-known member
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!

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Scott Baret

Well-known member
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...

 

Torbar

Well-known member
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

 
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