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Questions about 5xx batteries

3lectr1cPPC

Well-known member
The PB 540 I just got in from eBay came with two batteries that are both detected by the system and pass all tests in EMMpathy/Lind/Apple's utilities, so they are certainly good candidates to rebuild. While they do hold enough charge to keep the system in sleep mode unplugged, they will not power the laptop itself while it's on. When I do eventually get around to rebuilding them, I'd like to know a few things:

1. What cells should I use? I'd like to get like-for-like replacements to the original cells if possible, not hacking up a pre-built pack and fitting it in like some have done.
2. How do I get the casing open with the least damage?
3. Is there anything that I need to do, like keeping the EMM powered while I install the new cells?

Here’s a picture of the packs. No visible external corrosion!
563821D4-4A0E-4E41-A550-24B194B05050.jpeg
 

aladds

Well-known member
I re-celled one in perhaps 2004 and I used tabbed AA cells, but they're certainly not the same as the originals. Pretty close in size, though, and usually higher capacity. They probably need doing again now actually.

As for opening the case nicely... the issue is that ridge in the middle. It's ultrasonically welded along that ridge as well as the outside, so it's very difficult to break that without warping the pack some. Your best bet would probably be to get it apart however you have to, then shave down the case some after and use epoxy and perhaps a jig to get it back to the "normal" shape.

As for your third question, the Apple Intelligent Battery Recondition software or EMMPathy (Actually lots of useful tools here, including the Apple tool) are what you need to reset the intelligent module. No need to keep it powered. If it doesn't work first time run the utility over and over until it does. The Apple utility asks for the serial number and this is an attempt to match the controller to the cells. I remember sometimes you had to try one setting and then the other and eventually the powerbook would recognise them.
 

3lectr1cPPC

Well-known member
Thanks for the reply! A couple more questions:

1. Tabbed AAs seem like a good way to go then. I've never recelled a battery before, about all I know is to get tabbed cells to avoid soldering directly to them. My main concern is figuring out how the whole thing is wired up, but assuming the insides are in good shape (which they seem to be from the fact that both are currently recognized) I could probably just study that to get an idea of things.
Edit: Found these on Amazon: https://www.amazon.com/Combo-Tenerg...ocphy=9015321&hvtargid=pla-570918665741&psc=1
(side note - I love how the Amazon page advertises these are perfect for rebuilding dead packs. right to repair FTW!)

2. What ridge are you referring to? Is it this: 6BFDDE47-C64C-416F-BBE0-7C88132A8914.jpeg

3. I think the fact that both packs are already recognized and charged is a good sign that I won't have to fight too much with the EMM, but we'll have to see. It will probably be a few months (or more) before I get around to this, just getting info now. I've already run EMMpathy, Lind BU, and Apple's software to try to revive the current cells, with no real luck, but the EMM tests good on both packs.

Finally, a forth question. What voltage is the pack supposed to be? Pack #1 charges to 9 volts and Pack #2 charges to 7.5. Which is correct?
 
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aladds

Well-known member
1. Yes they look good.

2. Should have clarified - I suppose it's more of a groove. The bit you're showing in that picture is actually a clip-on cover and you can pop it off with a spudger. I'd recommend you do that first, actually. The EMM PCB is underneath it. You essentially have to break the ultrasonic welds around the batteries which includes the bit behind that PCB.

3. Very true. I've never had a "factory working" 500 series battery so I can't speak for what you'll encounter with a working one.

4. There are 8 1.2v cells. If you look up NiMH charge & discharge curves you'll see that "full" is actually close to 1.45v per cell once the charger has settled, and "empty" is closer to 1.15v, so your 7.5v battery is in pretty bad shape (pretty much fully dead) and your 9v battery is just below "completely empty" but probably enough to register on the battery meter. NiMH cells are interesting in that you know when they're fully when they get warm, so batteries have temperature sensors inside to detect this.
 

3lectr1cPPC

Well-known member
4. There are 8 1.2v cells. If you look up NiMH charge & discharge curves you'll see that "full" is actually close to 1.45v per cell once the charger has settled, and "empty" is closer to 1.15v, so your 7.5v battery is in pretty bad shape (pretty much fully dead) and your 9v battery is just below "completely empty" but probably enough to register on the battery meter. NiMH cells are interesting in that you know when they're fully when they get warm, so batteries have temperature sensors inside to detect this.
Very interesting, I don't know much about how NiMH batteries work beyond the memory effect so this is all news to me! I guess that's why they're not running the computer! As for the heat factor - that's very interesting as I do have one single working NiMH laptop pack, the pack for my ThinkPad i1260. I've had some pretty bad calibration issues with it that seem to keep returning despite me recalibrating it twice. When it's properly calibrated, it will run the laptop for an hour and 20 minutes, and it gets very warm while charging. When it's having issues, it doesn't warm up and won't run the computer for even a second, although the lights do flash briefly when I attempt to power it on.

2. Should have clarified - I suppose it's more of a groove. The bit you're showing in that picture is actually a clip-on cover and you can pop it off with a spudger. I'd recommend you do that first, actually. The EMM PCB is underneath it. You essentially have to break the ultrasonic welds around the batteries which includes the bit behind that PCB.
Aha, that's what you meant. If that's the case, I'll probably try to get access to a small vice to use, as I don't have one. Maybe I should get one though, as I've got some dead PowerBook chargers I need to crack open to recap. Brute forcing it with a screwdriver would probably work but it would also completely destroy the fragile case.

Edit: My spudger isn't fitting into the groove over the EMM cover. Where are the clips located and where should I try to leverage it from?
 

3lectr1cPPC

Well-known member
Goodness me, I have no idea what I meant to say but it wasn’t glass. No idea how that autocorrect even happened!

Anyways, I got the cover off both batteries without cracking anything, 2 happy looking EMM boards!
18211997-2C84-46D4-976C-154E3A6D5039.jpeg
How should I go about opening the rest of the pack then? I’ll be at a local place this Friday that should have a vice, but the ultrasonic welds go behind the EMM board.
 
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