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PowerBook 500 series Battery Rebuild

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Has anyone rebuilt a PowerBook 500 series battery?  If so, are there any decent guides or documentation of this in 68kmla?  I tried searching around a bit but nothing jumped out right away.


I'm guessing I could just rebuild it with NiMH AA cells?  Does the smart part of the battery need to be reset or replaced in any way?


I'm hoping that with modern NiMH cells the computer will see even better run times than when it was new.  I have 4 of them in decent condition, and one that has a lot of corrosion on the connector/leaked a bit.  I'd like to rebuild the 4 that are still in good shape (though all dead).



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I started this very project in 2013:

- Tore open a 500 battery and took pictures

- Bought tabbed AA NiMH cells on Amazon

- Bought 3" wide Capton tape on Amazon to tape the battery back up (and to cut masks for adjacent parts during hot air rework)

- Both my PowerBook 540c and my 520 stopped booting, even after 24hrs on the charger and SMC resets

- Final two years of BSEE

- 2nd child

- Today


I have not found a successful Powerbook 500 520c 540c battery recell teardown tear down repair walk through on the internet (Google: see what I did there).


From what I recall: The battery is tricky to get into, and I would start with the corroded one to get the method down (assuming you haven't already). It's not welded all the way around, but where it's not welded vs where it is welded is not always obvious. The battery will likely need to be taped back to together, unless you want to get fancy with some sort of plastics adhesive.


Using AA NiMH batteries appears to be a good thing because they are smaller, lighter weight, and longer lasting than what you're replacing. However, you may want to find some sort of non-conductive spacer. I charged the tabbed batteries on my regular Energizer charger to check that this would work and it did, but now that I look at it, I can't recall if I ever verified that 11V from 8 cells was enough or if you need to add a cell or two to reach 12V. 


It would be good for someone to document/explain the two inline components shown in the pictures I've attached. I'm not sure what they are but I assume they are part of the health assesment. I've never gotten too far researching them but also haven't tackled it with passion.


I assume you know this, but: Use tabbed batteries and don't attempt to solder non-tabbed batteries. I also read somewhere that the batteries should be charged before assembly so that the battery health circuit/software has a full cycle to track. Again, soldering fully charged NiMH batteries would not be wise.


I could be talked into sharing the new AA cells I have for you to finish the job and report your results to the community.


Pictures attached below.











Edited by danpoarch
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I have one that was sold to me as rebuilt, although I don't know what procedure was used. Since I bought the computer(and battery) form a member here, perhaps he can provide some details. I haven't looked at it TOO closely but it don't recall any scars being overly obvious. 


BTW, a number of years back I had a decent business rebuilding a certain model of Canon battery pack-it was the large rechargeable pack for the motor drive on the New F-1(F-1N). I did several of them-I'd buy the dead ones on Ebay for $20-30 and then flip them for $80 or so. I quit when someone else started driving up the price of dead packs to where it wasn't profitable :) . In any case, though, those packs took 12 AA batteries, and I bought ones identical to the ones pictured above. I did a mix of both Ni-Cd and NiMH rebuilds-the one I kept for myself(and still have is Ni-Cd). These are "dumb" packs, though-my preference for using Ni-Cds was that they have lower internal resistance. In the camera, this translated to Ni-Cds running the motor drive faster in "high speed" mode-it would keep the advertised 5 frames per second, while the NiMHs dropped it down to 4.5 frames per second(the same as an AA pack with alkalines). Mine is still good 8 years later, although I don't use it much and always run it down all the way.

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Thank you everyone for the input :) I read every reply and have a bit of take away to get started.  I'll try to document what I do as best as possible over the next few weeks.


-Start with corroded battery to examine how the battery is structured and how best to take apart a "good" unit without physically destroying it too much


-Use tabbed AAs.  I'm going to go with NiMH as that is what the battery was originally and what the charging circuitry was designed for.  Additionally, while I do think that NiCd has longer shelf life, NiMH batteries should hold up better for daily use and partial drain and recharge cycles that commonly happen with laptop usage


-Charge the cells externally to ensure that they are all at the same level, and charged enough to be recognized by the computer (I have an Eneloop NiMH set and charger, I'm confident I can get the cells to charge using that)


-Looking at danpoarch's photos, it looks like there is room for 8 cells, so I'll start with that


-danpoarch, which cells did you purchase, and what were their specs in regards to mAh rating?  Do you know what the orginial cells were rated at?


-bunnspecial, who was the member that rebuilt that battery?  Can you PM them and see if they would be willing to comment into this thread?


-Last but not least, take my time to ensure that I'm not over-heating the cells


Depending on what danpoarch has laying around and if they are still in good shape, I'm also considering these:

20 pack: http://a.co/7wKXsq5

10 pack: http://a.co/hVbFQtP

(Amazon short links, both appear to be from the same seller (not shipped by Amazon :( ), and are supposedly identical)

They are Tenergy 2000mAh units.  Unfortunately I'm not finding any (at least with any reviews) that are over 2000mAh.  Shame, since the standard, non-tabbed versions go up to 2800mAh.  Unfortunately my soldering skills are pretty low, so I'll need those tabs to help me not over-heat the cells.

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Oh I couldnt help but notice the battery controller has a 93C46 Microwire eeprom. that may need dumped and taken a look at. 


As the battery ages, and the microcontroller recomputes capacity and charging time, those values get stored in the EEPROM just like modern lithium batteries. So, it may need re-virginizing either using a known good image/software, or even some manual hacking if you want the battery to work properly again after rebuild. 


The EEPROM also contains the battery model/serial number as well as the cell's "State of life" and the batteries over all capacity. 

Edited by techknight
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As I just discovered one of my batteries has leaked (thankfully not in the machine at the time), I have a renewed interest in rebuilding the batteries.

Ages ago I came across this website where they replaced the cells with (at the time available) Sony batteries, then ran Lind Electronics' BU500 Deluxe 2.01 to reset the charging circuit settings and switch them to the Sony type.


...Since it only has charging profiles for either the Sony or the Panasonic batteries, would you be able to use other brands/types? Perhaps that's why the rebuild above didn't work.

Edited by lameboyadvance
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Yeah, I sent it off to Battery Refill, they opened it up and replaced the cells.  Sadly, I don't have the email receipt any more. It took them like four months, though.  I had them do two at once (and got a slight discount for it,) and got about 10 hours between the two batteries when they were fresh.  They did replace the cells with new NiMH.  And obviously they did a GREAT job in opening/resealing them.  One of them was slightly more "bulged" than original. I'm 99% sure I kept that one and sent you the good one.  The bulgey one is a bit tough to get out of the right-side battery bay, but seemed to be fine to use in the left-side one.

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I will have to give that Intelligent Battery Recondition a go.  It's actually already installed on the 540c, so that's convenient :)


My understanding is that danpoarch should have a chance to drop the cells in the mail this coming week.  The following week I should be able to get to work on it.


Thank you techknight for the details on that eeprom in the battery.  I'm hopeful that the 4 "good" batteries haven't actually leaked inside and damaged it.  I'm expecting battery 5 (the one that is corroded at the contacts/leaked a bit) to be a complete loss aside from the learning experience of how to best open and re-seal the battery.


Bunnspecial and Anonymous Freak, thank you for the info on the third party battery rebuilders.  While I normally have the logic boards recapped by someone else, I'm going to try this one myself first.  I will consider Battery Refill as a fall back plan :)


lameboyadvance, I'm not sure what the source of these cells are.  I'm hoping the Intelligent Battery Recondition program will handle all that.

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  • 2 weeks later...

...Any chance those of you with refilled batteries would want to crack them open and see what batteries they used? Also (if they did use different batteries than the original ones), dump the battery settings to see if they changed anything?

Only do this to a rebuilt one that is dead (again).  Getting into these things is a bit of a pain.  My post of cracking open the bad one to follow in a bit.

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Finally had some time to play around with these batteries.  This will be a three part post.


1)How to tear down an old battery

2)Recell a battery

3)How to reset the eeprom, if necessary.


Part 1 is tonight.  I somehow went from having 1 PowerBook 520c and no batteries for it to 2 PowerBook 520c units, a PowerBook 540c, and lastly a PowerBook 540 as well as EIGHT batteries for these things all in the span of a few months after having owned the first 520c for over a decade.


The eight batteries vary in condition.  The absolute best one actually shows up when in the computer, shows a full charge, fails communications, and the charge dies the moment you unplug the cable.  Not even 1 full second of power.  It will however sustain sleep mode for ~30 minutes.  The next best battery doesn't show up, but does have a measurable charge of around 3 volts.  The other six batteries are all flat 0 when tested.


One of those 0volt batteries shows substantial signs of corrosion, and actually pulled a few of the battery pins out from the second 520c when I went to remove it (aside from the few missing pins, the second PowerBook 520c seems to operate how a PowerBook with no battery installed would operate, amazingly enough).


So we have our Guinea Pig for the battery rebuild series:


Start by removing the contact cover and the part that holds the battery in the computer.  The contact cover will slide off easily.  The large part that holds the battery in will have to be rocked a few times and will naturally want to pop off one direction more so than the other.


Remove the Intelligence circuitry cover:



There's no other way of saying this.  This part sucks and will be a bit on the difficult side.  You really have to muscle the plastic around while at the same time being careful not to let your tool (in my case, a small flat-head screw driver) slip too far in, striking the circuit board.  Mine had 8 clips for sure as you can see in the above photos.  Surprisingly, the plastic (at least on this one) was not brittle at all.  It put up quite the fight.  A LOT of patience is needed here.  Just try to pop off one section and leave the first tool there, and then get a second tool (another small flat head screw driver) and work the rest of that side off.  Eventually it will pop right off when you are down to just a clip or two.


Dremmel the remaining three sides:




The key hear is to run the Dremmel at a slow speed, and just work slowly.  You can always go back and make another pass if the cut didn't quite go deep enough through the plastic to see the batteries.  Use caution when you are doing the plastic in front of the connection pins.  You don't want to cut through the metal.


Don't worry about the built up excess plastic from the Dremmel.  In my case, it brushed off easily enough by running my finder over it a few times.


Once you have all three sides cut, using a wide flat head screwdriver, insert into the space of the cut, and turn left and right a few times to finish popping the seal.  Move around all three sides you just cut until the casing is nice and loose.


Time to open it:



Facing the battery with the Apple logo downwards and the serial number and/or barcode facing up, very gently open it, treating the circuit board area like a loose hinge.  While doing so you may hear a piece of plastic from the "hinge" area breaking.  From what I can tell, there is no getting around that.  Just take care to not put pressure on the circuit board and be gentle with the area near the connecting pins as the plastic there is thin.



Finally, we have have the actual battery cells exposed:





From here, the battery was an absolute mess.  In fact, there was literally battery fluids still in there.  I had to wash my hands off after handling it just for peace of mind.


I'm 99% sure that the polarity for the individual cells is going to be positive at the end with the indent wrapped along the side about 1 or 2 mm back, and negative at the smooth end.  However, to appease that 1% of me that isn't sure, we will be using the battery that still retains ~3volts for part 2 and 3 of this guide since I can use my voltmeter to verify at the cell which pole is which.

Edited by just.in.time
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I've been following along as you do this-- using one of my 540C batteries. I used an X-Acto knife and slowly / carefully cut it along the seams and inside the compartment for the circuit board until it popped open. The plastic is pretty soft and I was able to work my way through.  It took about an hour to open it up.


I'll be placing an order for some of the cells on Amazon.

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Oh cool :) I'm a bit behind because work has been insane busy the past month.


That battery I opened in the first part of this series is absolutely done. The corrosion was extensive, as I expected.


On the next battery I open I will give your method of using an exacto knife a try. The cleaner the cut the nicer it will seal back up, and I imagine that will result in a cleaner cut than the Dremel.


If I don't get dragged into work Saturday I should be able to do part two then.

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