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aplmak

Powerbook 100 Battery Rebuild

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Ok... so on this board I have not seen a PB100 battery rebuild.. But I did see another forum with a solution someone did... Any help here is greatly appreciated... Any ideas on where to get a thin enough battery to work... a AAA size is just a little too big... Perhaps connect multiple flat cell phone batts together?? Also I am not sure what to use for a battery and the resistance and where to place the resistors... (duhh.. I know)... The old ones are these little rectangular black cells... strange.. probably custom..

 

Here is my disassembled pack.. It says that it is a 6V 1600mah NI-MH battery in my battery pack... but the other guy put a 7.2V 1000mah

 

post-2150-0-18615300-1443197027_thumb.jpg

 

 

The other guy's battery which he has a 7.2V 1000mah

 

post-2150-0-01290700-1443196870_thumb.jpg

 

 

ANY HELP OR INPUT GREATLY APPRECIATED!!!

 

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I know the charger outputs 7.5v and 2 amps but that is the charger which is always a little more... The PB I think calls for 6V at 1600mah

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I am assuming each cell is 1.2v and totaling 5 is your 6v... so there are two 6v sets in the battery pack.. but to find 1.2v flat batteries... hmmm... or another solution?

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Exactly Mike & Charles.. Sorry just thinking aloud.. But I hope this helps anyone who wants to rebuild a PB100 battery... I'll do more editing moving forward.. Lol.. Since you two are the EXPERTS.. Any suggestions???

Edited by aplmak

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Monologging isn't necessarily bad, especially if it's thought process, a worklog, or if new information comes up before anybody else posts.

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I thought I'd resurrect this old thread rather than starting a new one, hope that's OK. I have a plan to cannibalise a PB100 battery pack so that 5 x 1.2V AAA Eneloops can be clicked in and out and recharged using an external charger. This would permit carrying extra AAA cells in the field (for those times when you take your 28 year old Powerbook out on field assignments).

 

Apparently Eneloops (NiMh) have a nominal voltage of 1.2V, but actually they start out at 1.45v (x 5 = 7.25v) and then settle down to 1.3v (6.5v) which would seem to mirror the range seen out there in the wild - if the original battery contained 3 x 2V cells, then presumably one can extrapolate from this discharge graph for lead acid batteries similar behaviour for 2v cells. If roughly 6.5v-5.5v is the range for the SLA batteries and the Nominal 7.2V 3rd party NiMh battery that aplmak disassembled apparently also works fine then it sounds like 5 x Eneloops (nominal 6v) would work just fine. In fact judging from the fact that the 3rd party battery pack contained 6 x nominal 1.2V NiMh cells it looks like I could install 6 Eneloops and get away with it but the idea makes me nervous. What do you guys reckon?

 

I expect I would have to look into the diode installation idea to prevent the SLA charger from destroying the NiMh Eneloops. That said if there were original 3rd party powerbook batteries available which used NiMh then maybe the internal charging circuitry works fine with NiMh?

leadacid-discharge-characteristic.jpg

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Well, @elemenoh, I decided to take a few steps forward in my little project. I don't have a 3d printer to fabricate a dummy battery but I do have a few dead Powerbook 100 lead acid batteries so I decided to cannibalise one to make a NiMh battery pack - main priority is that the powerbook looks legit from the outside. Couldn't find any images online of what's inside the pack so decided to break out the Dremel with the reinforced cutting wheel and dissect an original powerbook 100 battery for the benefit of mankind.

 

IMG_1482.thumb.jpg.216e4b3459c42e843d5d751b9c95c97c.jpg

 

It appears I cut into the cells themselves rather than cutting off the top. I wondered why it smelt like vinegar and my nose was tingling. Never mind. I would have had to cut it open to remove the innards anyway.

 

IMG_1483.thumb.jpg.412e74c08b6d20c7e4c11c7c78950fa6.jpg

 

I pulled out the lead plates & totally dried-up matting and chucked them in a bucket of baking soda solution which proceeded to fizz a bit.

 

Now I have three empty cells and the top section of the battery completely loose. There’s a different, entirely unmolested PB100 battery in the background just to confuse you.

 

IMG_1485.thumb.jpg.68b7f41584ec5a207f467f7447a38345.jpg

 

Turns out there's actually a plastic cap on the top. When you crack it open you see three rubber caps sealing up the three cells (one is missing in photos), a couple of wires going to the contacts and a thermistor or whatever it's called - a thing that cuts off the current if the temp gets too high. With those little holes covered with removable rubber caps you could theoretically try to restore the lead acid cells to semi-working order with Epsom salts I guess. I didn’t want to because I doubt that they would ever hold much charge again even if you did manage to get them working again.

 

IMG_1487.thumb.jpg.3cce0f9f5ebcf8feb9168c9c42384f90.jpg

 

My plan from here was to cut those wires, solder longer wires to them, feed them through the cell ports and attach them to a AAA battery pack. I will short one of the battery slots to make a 5-battery pack. 5 x NiMh batteries at 1.45V start voltage per cell means just over 7.25 volts. Actual measured start voltage once NiMh batteries were charged was just over 7 volts which seems reasonable if the range of the Lead Acid battery was 6.5-5.5 volts.

 

IMG_1505.thumb.jpg.d59a45fd63e621a298b3a43271b08ee1.jpg

 

I hacked a hole in the battery to install the battery packs, fed the wires through, inserted the bisected battery into the battery into the slot and hooked the wires up to a bench power supply set to 7V/1A in order to test it. I had to reset the powerbook power manager (http://www.jacsoft.co.nz/Tech_Notes/PP_Manage.shtml) to get it working otherwise I kept getting a "there is no battery reserve" error. But then it still wouldn’t boot from the “battery” power, only from the AC adapter! It was at this point I realised I had forgotten to re-install the battery terminals so there was an air gap. Oops.

 

IMG_1507.thumb.jpg.019fe4437c04457be2789e2617a6cab2.jpg


Note the 40V 3A diode to stop the laptop from trying to charge the power supply. Will install this in my rebuilt/modded battery pack.

 

Oh well, I'll have to resume work on this again later in the week. I’m keen to see if it works. Note that this powerbook has a SCSI2SD installed and I have left off the palm rests for testing.

 

So far so good though. I totally recapped it and the removal of surface mount components was greatly aided by my nice new hot air rework station. Accidentally melted one of the plastic ribbon cable sockets a bit when soldering a new tantalum cap nearby but the socket still works thankfully. The socket only latches on one side now but it doesn’t seem to have any great inclination to work itself free - will tape it up with electrical tape when I’m done.
 

The screen looks great but it has a few subtle dark lines here and there so I'll need to recap it at some point to see if that improves things. May have to actually learn how to solder new surface mount components for that.

 

P.S. sorry for the messy desk

Edited by electricmonk

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Well, I was wrong. I had actually re-installed the battery terminals. Don't understand what the problem is - when I attach the benchtop power supply, the bank of 5 x AAA batteries or my spare very dead lead-acid battery to the terminals the same message comes up: "No battery reserve power remains. The Macintosh will go to sleep within 10 seconds to preserve the contents of memory. Good Night." The message doesn't appear when running under AC power only, but it does appear if running on AC power with the "battery" connected.

 

There's a reference to this error message in a thread about a Macintosh portable here. I know that the PB100 is just a miniaturised portable but the solution they reached in that thread was achieved by careful testing and I'm sure there are any number of reasons why that error message would come up. Hmm.

 

It is a bit disconcerting that there are several errors in the maccaps PB100 reference page with respect to capacitance & voltage values. I was reasonably careful to go by what was printed on the capacitors rather than that page but maybe I missed something. It all works fine although the sound does appear to have stopped working which could possibly be connected - or not.

Edited by electricmonk

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Can't believe I missed this project! Gotta read it through carefully. Right off the bat, I'm wondering if there might  be a difference in the way lead/acid appears to the sensor mechanism. Second thought would be hacking away at my (oh so very dead) VST ThinPack that feeds power to the power plug. Given enough cells to match the power adapter input, mimicking the ThinPack circuitry and hotwiring to the power input plug from the jumpered power plug assy and the disconnected from logic board battery bay contacts, a better than original setup might be achieved? Such would circumvent the battery bay sensing setup?

Edited by Trash80toHP_Mini

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That is a good idea although you would need some means of turning off the internal battery to allow you to run off mains when desired.

 

Thing is this problem does have a solution and it will be a logical one, it's just a question of figuring it out. Unfortunately one would need a non-dead PB100 battery to test whether the issue is the logic board or the battery itself, and those aren't exactly easy to come by.

 

I'm guessing it is the logic board itself - the thing just doesn't boot when only the dummy battery is connected. I suppose I could recap my spare logic board and try that. Quite a lot of effort though.

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Further on that subject, @Trash80toHP_Mini, the sensor mechanism is just a switch that gets pressed when the battery gets shoved in... presumably the laptop measures the voltage of the battery but I don't see how that would make a difference.

 

Maybe I'll scrutinise that Macintosh portable thread again and try and figure it out.

 

Found the developer notes here. Here goes nothing:

 

http://powerbook.micahgartman.com/

 

The PB100 developer notes say that the powerbook 100 power manager is identical to that of the portable which is described in this document:

 

https://macintoshgarden.org/apps/apple-guide-the-macintosh-family-hardware

 

This may also be useful. Wish me luck

 

https://macintoshgarden.org/apps/apple-mac-technical-reference-and-repair-manuals

Edited by electricmonk

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Have some great luck in this. I'm curious to see if running the PB100 off the adapter without a good battery in the bay is as harmful as trying to run the Portable with no good battery in its bay?

 

On 4/3/2020 at 12:59 AM, electricmonk said:

That is a good idea although you would need some means of turning off the internal battery to allow you to run off mains when desired.

The VST ThinPack resides between power adapter and power plug of the computer, Adapter plugs into one side of the ThinPack and the ThinPack comes with cable to plug into the PB100's power jack.

 

It's very late, hope this makes some sense.

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I understood you - it just strikes me that you would have to either have a cable travelling from the battery bay to the outside of the computer and snaking round the back to the power plug... or you’d have to cobble together some means of switching between the “Internal thinpack” and the mains power adapter. I suppose if you just disconnected the internal battery cells you could run off mains but if the battery and the AC were connected at the same time would that be bad? I suppose they’d be running in parallel.

Edited by electricmonk

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Anyway good news for anyone following this saga - sat down with a multimeter to investigate tonight and it was actually a mechanical problem. My disembowelled dummy battery wasn’t making contact with the positive and negative terminals at the same time - only one or the other depending on which way it was nudged. Because the end with the terminals was physically separate to the rest of the battery (just basically free floating) and there’s a bit of spare height up that end of the battery bay it just wasn’t pressing down hard enough.


So that error message was, needless to say, coming up regardless of what kind of power source was connected to the dummy battery - the tech docs say the powerbook goes to sleep when the battery drops past 5.74v and it looks like you get the same error message whether it’s zero volts or 5.7v. The computer knows that the battery is inserted because it presses on a switch and if the voltage is below the lower threshold you get the error and it goes to sleep.

 

So I’ve done a quick and dirty job of rebuilding the battery pack by tacking the end back on with superglue and then filling in the jagged cut with epoxy putty. That should be nice and solid when it dries and the battery should exert sufficient force on the terminals to make good contact.

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Hmm so this doesn’t appear to have fixed the problem. I can now read 6.73v across the battery terminals on the logic board with my 5 x AAA cells attached but it still won’t boot without the mains power adapter, and if I attach my benchtop power supply to the dummy battery it delivers zero current.

 

The logic board can obviously READ the battery voltage because I no longer get the “No battery reserve power remains” error with my dummy battery, but if I pull the DC plug from the back it just turns off instantly rather than running off battery.

 

I’m not entirely sure where to start measuring voltages on the board as I don’t want to short something out.

 

I read 5.8v across the fuse. With no cells attached and with the power brick plugged in and battery bay switch pushed in I read 4.62v (jumps around a bit) across the battery terminals. Same reading with a dead battery attached. That seems very low for a charging voltage but I’m hesitant to draw too many conclusions from this because I ain’t no EE.

 

Incidentally I get infinite ohms across the speaker so I think that explains why there is no sound. Audio works fine through the headphones.

 

I’ve attached an image of the dummy battery brutally patched together with epoxy putty. As you can see the computer runs reasonably well off mains.

 

 

F675C794-077F-4B44-915D-34A2CEB59FF8.jpeg

Edited by electricmonk

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