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Power Macintosh G3 Beige Tower Battery Blow up solution

Z

Zippy Zapp

Experienced Member
Joined
Dec 13, 2014
Messages
259
Location
USA:CA
Hi,

I recently picked up a Tower G3 beige that was classified as working and no problems. It works, except the drive is dead and the battery was corroded and it looks like it corroded part of the case frame in a 3 inch diameter with some nasty rust. Very irritating. The battery holder literally disintegrated when I attempted to remove the spewed battery.

No problem, ordered one of these and figured I would desolder the old one and install a new one of these:
https://www.digikey.com/short/3zh47w

The positive side came out easy enough. But the negative side refused and the pad broke in the process.

What do people do in these cases? I'll show you my solution but maybe there is a better way?

I solder blobbed both sides of the negative side and checked for continuity to the negative vias and capacitor sides and it seemed fine so that was a relief. I then took the battery holder and a I2C 4 pin cable and removed two wires, red and black from one end of the connecter and the crimp side slides perfectly over the pins in the battery holder. A little bit of solder and some heat shrink and it is sound.

I used some header pins to solder into the positive side of the motherboard battery pads and a wire from a header pin to the negative battery pad/blob. A little velcro and it seems to do the trick.

What do you think?

FullSizeRender.jpg
 
Were this my G3, I'd move the batter off the motherboard; i.e. leave a wired connection. PCBs and batteries were never made to co-exist in proximity.
 
I've started potting my batteries and locating them elsewhere in the machine. The mac guys have been collectively losing their minds saying it's a fire/high pressure explosion hazard but what do they know? They're mac users.
 
There are always problems with larger batteries near PCB, so I remove them when computer comes, especially rechargeable ones may end with corrosive chemicals on PCB. I usually install wires to put the battery to casing, using nearby holes and zip-ties to keep it in place. Some of computer's BIOS/RTC keeping batteries can be replaced with variations of CR2032.
It is always important to remember about a diode if replacing rechargeable with non-rechargeable battery. Without it, even CR2032 may spit its chemicals.

->NeXT
It may be true in some conditions. I've seen two Powerbooks with internals literally flooded with chemicals from batteries. The battery packs looked like they were blasted out from inside and could be removed only when the computer was disassembled.

Last time I had quite interesting discovery in an old Siemens computer: Two AA batteries made in West Germany around 1992 (best-before 1994). They were still in perfect visual condition and haven't discharged very much (still have ca. 1.33V each).
 
Chuck(G) said:
Were this my G3, I'd move the batter off the motherboard; i.e. leave a wired connection. PCBs and batteries were never made to co-exist in proximity.
Click to expand...

Perfect. That is exactly what I did. The battery is located a bit away from the logic board and velcro'd to the chassis inside the holder I showed. I am using the batteries that OWC sells. Supposed to be fresh so I don't know if they are prone to spewing or not as I have only used them for a few years.
 
MCbx said:
->NeXT
It may be true in some conditions. I've seen two Powerbooks with internals literally flooded with chemicals from batteries. The battery packs looked like they were blasted out from inside and could be removed only when the computer was disassembled.
Click to expand...

Powerbooks are something different entirely. You don't have the luxury of a large case. In that instance I'd remove the battery permanently and keep the main battery topped up as that will also keep the PRAM alive.
 
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