Thread
PowerBook Duo battery replacement
My personal inclination (when I get around to it) is to try the tab AAs. If it turns out they are too big for a Duo batt - hey, portable 12V powerpack, and that's always a handy thing to have.
I know the conversion for Klick <-> Mile and, having cut my teeth on slip-sticks, can easily do it between my ears.
Hence the:
) So: 
And: :lol:
My High Capacity BTI Battery Pack protrudes from the front edge of the Duo approximately the amount quoted earlier for fitting a set of AA Cells in place of the 4/5 AA Cells normally used in a standard size Duo BatPack. Therefore I'm assuming that when I crack the case, early this week, I'll find full sized AA Cells. Hopefully, they haven't eaten up the circuitry needed to install new Cells.
12v BatPack Hookup through the, now (and so far }
) useless, Modem Port opening would work nicely, as would the Docking Connector, if memory serves.
Hence the:
) So: And: :lol: My High Capacity BTI Battery Pack protrudes from the front edge of the Duo approximately the amount quoted earlier for fitting a set of AA Cells in place of the 4/5 AA Cells normally used in a standard size Duo BatPack. Therefore I'm assuming that when I crack the case, early this week, I'll find full sized AA Cells. Hopefully, they haven't eaten up the circuitry needed to install new Cells.
12v BatPack Hookup through the, now (and so far }
) useless, Modem Port opening would work nicely, as would the Docking Connector, if memory serves.
The problem with the 4/5AA cells is that they can't be acquired in 1600MAh capacities.
So the risk of overcharging is very much possible. Is there enough room for AAs in there?
Should be. Let's fill this out:
(dimensions are diameter x height or length, depending on orientation)
4/5 AF dimensions: 17x40mm (Battery Station says 16.5x42)
Fullsize A dimensions: 17x50mm (Wiki) (Battery station says 16.5x48)
4/5 AA dimensions: 14.5x43mm
Fullsize AA dimensions: 14.5x50.5mm (must be the button version)
Tabbed flat terminal AA: 14.2x50mm link, retardedly expensive)
AAA: 11x45 flat terminal, batterystation.com says 10x43.7. Like these. "We have a great supplier for these..." ...they all come from China, ya know...
Here's the issues:
AAA: Too small of a capacity. Maxes out at 1000-1200mAh.
AA: It won't even fit lengthwise. Capacity is not a problem.
4/5 AA: Not enough capacity. (1200mAh)
4/5 A: Original size yes, but it won't ever go in the same way. Not unless Apple had a spontaneous flashback and decided to retool and retrain everybody just to make some Duo batteries. (And you'll know they're charge for that)
A: Too big.
Confirmation of 1600mAh cells.
I suppose I could stagger the AAA cells. That's basically all I can think of that's left. I don't have the dimensions of the inner part of the Duo pack. But I think it could work that way. Since AAAs are about 6mm thinner than the AF size cells, and 6mm is about 50% of their thickness, this means it MIGHT work. I'll have to get 20 flat based 800mAh AAAs (with tabs, otherwise I'll have to pay for them to be done as there is NO way I can rig up a spot welder without spending $) and see what happens. A pair of paralleled cells should give me the 1600mAh I need x 10 pairs equals VICTORY!
The next step would be to know if the Duo will overcharge the batteries. I suppose it probably charges at 1 Coulomb then tapers off around 85%. As long as it doesn't go over that we MIGHT be fine.
So the risk of overcharging is very much possible. Is there enough room for AAs in there?
Should be. Let's fill this out:
(dimensions are diameter x height or length, depending on orientation)
4/5 AF dimensions: 17x40mm (Battery Station says 16.5x42)
Fullsize A dimensions: 17x50mm (Wiki) (Battery station says 16.5x48)
4/5 AA dimensions: 14.5x43mm
Fullsize AA dimensions: 14.5x50.5mm (must be the button version)
Tabbed flat terminal AA: 14.2x50mm link, retardedly expensive)
AAA: 11x45 flat terminal, batterystation.com says 10x43.7. Like these. "We have a great supplier for these..." ...they all come from China, ya know...
Here's the issues:
AAA: Too small of a capacity. Maxes out at 1000-1200mAh.
AA: It won't even fit lengthwise. Capacity is not a problem.
4/5 AA: Not enough capacity. (1200mAh)
4/5 A: Original size yes, but it won't ever go in the same way. Not unless Apple had a spontaneous flashback and decided to retool and retrain everybody just to make some Duo batteries. (And you'll know they're charge for that)
A: Too big.
Confirmation of 1600mAh cells.
I suppose I could stagger the AAA cells. That's basically all I can think of that's left. I don't have the dimensions of the inner part of the Duo pack. But I think it could work that way. Since AAAs are about 6mm thinner than the AF size cells, and 6mm is about 50% of their thickness, this means it MIGHT work. I'll have to get 20 flat based 800mAh AAAs (with tabs, otherwise I'll have to pay for them to be done as there is NO way I can rig up a spot welder without spending $) and see what happens. A pair of paralleled cells should give me the 1600mAh I need x 10 pairs equals VICTORY!
The next step would be to know if the Duo will overcharge the batteries. I suppose it probably charges at 1 Coulomb then tapers off around 85%. As long as it doesn't go over that we MIGHT be fine.
A Coulomb is a unit of charge, like a bucketfull of electrons. It's the amount of charge transferred by a 1 amp current in one second. (equivalent to 1/3600th of an amp-hour) Think of it this way - a full battery will have a lot of Coulombs in it; the flow rate in and out is the current, in amps.
I was befuddled about cell sizes when I cracked a pair of Batteries a little while ago. At the beginning of the thread, we were talking about 4/5 AAs and I forgot about the original cells being 4/5 A.
I can confirm that a 2" Chisel works like a charm on the standard Duo Batteries wit no damage at all to the Flex Circuit. However, the second one I tried was quite a different beastie. The BTI High Capacity BatPack lacks the slot running around the perimeter of the standard case. I got it open with minor cosmetic issues, but managed to cut 4 of the 5 wires that are placed where the flex circuit would be on the standard pack.
The oversized, 3/8" protruding, BTI High Capacity BatPack uses the same 10 4/5 A cells as the standard Duo BatPack! 8-o
The difference in depth allows for a bunch of spacers on the sides for two rows of higher capacity 4/5 A cells separated by a PCB running, front to back, between the rows. My working assumption is that this PCB makes the Battery Pack itself very intelligent, allowing higher capacity cells to be fully charged inside the Duo.
Pics and disassembly documentation to follow, along with details of the PCB. :approve:
BTW, the cracked open standard pack fits very nicely back into the Duo, so what's the problem in replacing the 4/5 A Cells? :?:
I can confirm that a 2" Chisel works like a charm on the standard Duo Batteries wit no damage at all to the Flex Circuit. However, the second one I tried was quite a different beastie. The BTI High Capacity BatPack lacks the slot running around the perimeter of the standard case. I got it open with minor cosmetic issues, but managed to cut 4 of the 5 wires that are placed where the flex circuit would be on the standard pack.
The oversized, 3/8" protruding, BTI High Capacity BatPack uses the same 10 4/5 A cells as the standard Duo BatPack! 8-o
The difference in depth allows for a bunch of spacers on the sides for two rows of higher capacity 4/5 A cells separated by a PCB running, front to back, between the rows. My working assumption is that this PCB makes the Battery Pack itself very intelligent, allowing higher capacity cells to be fully charged inside the Duo.
Pics and disassembly documentation to follow, along with details of the PCB. :approve:
BTW, the cracked open standard pack fits very nicely back into the Duo, so what's the problem in replacing the 4/5 A Cells? :?:
I stand by what I wrote earlier: the original cells were not 1600mA cells; they hovered around 800,900, 1000mA in the different versions of the Duo battery produced.
Is there a Developer's note, I wonder, on the Type 1, 2 and 3 batteries?
Is there a Developer's note, I wonder, on the Type 1, 2 and 3 batteries?
Are there any markings on any of the cells in either pack, Trash?
The reason why we're not in favor of using 4/5As is: 1) expensive, 2) a real tight fit on reassembly because the factory churns them out by the pallet and thus has the tooling/skills to pack it real nice and tight in there, 3) the mAh of today's batteries is not the same (likely) as the older ones, so they (likely) won't be fully charged.
If we could only get a solid pin down on the mAh: my vote is on 1600mAh because the Apple KB article says they're 1.6Ah batteries, and the 'fritter post says 1600mAh too.
What we can do, and i've been checking up on this, is for the mAh of the PowerBook 520/540 series for more "results in Google"...since they're sort of close on the chart to see what other people think/know:
The reason why we're not in favor of using 4/5As is: 1) expensive, 2) a real tight fit on reassembly because the factory churns them out by the pallet and thus has the tooling/skills to pack it real nice and tight in there, 3) the mAh of today's batteries is not the same (likely) as the older ones, so they (likely) won't be fully charged.
If we could only get a solid pin down on the mAh: my vote is on 1600mAh because the Apple KB article says they're 1.6Ah batteries, and the 'fritter post says 1600mAh too.
What we can do, and i've been checking up on this, is for the mAh of the PowerBook 520/540 series for more "results in Google"...since they're sort of close on the chart to see what other people think/know:
Dunno yet, I'm tired. I'm just taking some "before" pics of the still assembled, but open, battery packs tonight.
For the Apple Pack: no markings whatsoever. :-/
For the BTI Pack labeling: Panasonic Brand NiMh "Rechargeable Batteries" and they've also got the number 9711 on them, whether that designates a Lot# or Model# remains to be seen. It's a different printing process, so it's likely a Lot#.
What's interesting about the design of the BTI Pack is that it has paper thin labels covering grooved skeleton frames on both the Top and Bottom of the Pack. The Apple version has solid, if thin, plastic on the bottom side. Maybe tolerances can be eased just a hair by sanding away some more of the Apple Pack's grooved bottom plate.
Great news: one of my existing Duo Batteries is showing increasing charging/discharging times for conditioning cycles on the LIND SuperCharger II that jruschme donated to the cause!
Thanks again, jr! [
] ]'>
For the Apple Pack: no markings whatsoever. :-/
For the BTI Pack labeling: Panasonic Brand NiMh "Rechargeable Batteries" and they've also got the number 9711 on them, whether that designates a Lot# or Model# remains to be seen. It's a different printing process, so it's likely a Lot#.
What's interesting about the design of the BTI Pack is that it has paper thin labels covering grooved skeleton frames on both the Top and Bottom of the Pack. The Apple version has solid, if thin, plastic on the bottom side. Maybe tolerances can be eased just a hair by sanding away some more of the Apple Pack's grooved bottom plate.
Great news: one of my existing Duo Batteries is showing increasing charging/discharging times for conditioning cycles on the LIND SuperCharger II that jruschme donated to the cause!
Thanks again, jr! [
] ]'>
The challenge would be then sanding uniformly around the entire area of the Apple branded pack. This probably means something like a mill, and that should be possible with someone in the know. Even then, why? If you get 4/5A batteries today they're in excess of 2000mAh, which means they probably won't charge completely. Bad.
If you pull all the batteries out, does it look like it's possible to stagger AAAs in there? There should be enough room in there to do so, it's just a matter if 20 is possible to cram in there. I was going to think about layouts, but then I need dimensions and a program. At the moment only the SE/30 has a drawing application(s) on it. (I don't but should have AppleWorks on my Mac mini)
If you pull all the batteries out, does it look like it's possible to stagger AAAs in there? There should be enough room in there to do so, it's just a matter if 20 is possible to cram in there. I was going to think about layouts, but then I need dimensions and a program. At the moment only the SE/30 has a drawing application(s) on it. (I don't but should have AppleWorks on my Mac mini)
That's why the BTI Pack's PCB is of interest. It was a High Capacity Pack which sticks out the front of the Duo, yet it has the same config: 4/5 A batteries. So I'm thinking it may be a more intelligent battery pack, allowing for fully charging a ten-pack of higher Capacity A Cells.
After I wreck . . . erm . . . pull apart . . . the two Packs for documentation in the morning, I'll play with a couple of handfuls of AAA batteries! :approve:
Milling machine? :lol: Sand, fit . . . sand, fit . . . sand, fit . . . }
After I wreck . . . erm . . . pull apart . . . the two Packs for documentation in the morning, I'll play with a couple of handfuls of AAA batteries! :approve:
Milling machine? :lol: Sand, fit . . . sand, fit . . . sand, fit . . . }
Look, I really have to dispute this, but I suspect that without experimentation, we're both blowing smoke on the issue.
The Duo's inbuilt charger must be more than a simple timer, or else it would not be able to recharge partially-discharged batteries. It most likely uses the ΔV charging method - ie, measuring the voltage returned from the battery pack - to detect end-of-charge status. This return voltage will cross the threshold when the battery is nearing full, whatever its capacity is.
Case in point: your table shows the Duo 210 battery is 0.9Ah, and the 280c is 1.6Ah - yet you can use either battery in either machine. Second case in point: Trash80s extended-life pack. QED.
Excellent find on that table btw
I'll add it to the peripherals links thread.The first claim is probably correct, the second is likely also, and the third is wrong. The Apple source says that the 210 through 280 uses a 25W power supply which came with it, the 280c and 2300 use a 36W power supply although the 36W will work with the 210-280 series.
The charging circuit could use a delta-time method also, if it knows the discharge over time according to use cycles, then it can calculate what time to charge based on x number of charge-discharge cycles.
I dunno. I'm going for 1600mAh because that's the original capacity and the most safe. I'd love to have 2400mAh but that's not known at this time other than a prior post here which said he had problems with the higher capacity batteries being not fully charged AND Trash's BTI pack which has circuitry present which is not found in the standard 1.6Ah packs -- but has (likely) just higher capacity (1800, 1900, 2000mAh?) batteries with circuitry to manage or trick the Duo into fully charging them.
BTI IC = 7 discrete components & PIC on DS PCB
PIC "Output Side" = R1 + D
PIC "Input Side" = R2 + C2 + C1 + C2 + R4
PIC16C64
-RC/SO
9647CAW
Motorola Logo (99% sure on the logo)
PCB pics & layout to follow.
Same kinda boxie thingamahoozie on board as on Apple Battery Pack. :approve:
WAG: looks like the PCB could be wedged inside the Duo between the Battery contacts and the DUO MoBo! [}] ]'>
PIC "Output Side" = R1 + D
PIC "Input Side" = R2 + C2 + C1 + C2 + R4
PIC16C64
-RC/SO
9647CAW
Motorola Logo (99% sure on the logo)
PCB pics & layout to follow.
Same kinda boxie thingamahoozie on board as on Apple Battery Pack. :approve:
WAG: looks like the PCB could be wedged inside the Duo between the Battery contacts and the DUO MoBo! [}
] ]'>
Yep, like I guessed, intelligent battery pack PCB for higher capacity cells that could very likely be installed inside the Duo in order to fully charge a handful of High Capacity re-celled Standard Duo Bats.
] ]'>
[}
] ]'>
Well, youll still need to dump the code out of the PIC if you want to clone it.
Most likely since its a C, it was masked in the factory and its program prevention protection fuse set. So the only way to dump the code out of those PICs, is to either VCC or Clock glitch it during a read event.
Most likely since its a C, it was masked in the factory and its program prevention protection fuse set. So the only way to dump the code out of those PICs, is to either VCC or Clock glitch it during a read event.
Or just get in touch with Battery Technology, Inc. and ask, they're still around! )
Panasonic probably would tell us the capacity of that particular batch of 4/5A Cells.
Tweak the code on the PIC for variable capacity cells . . . }
) Panasonic probably would tell us the capacity of that particular batch of 4/5A Cells.
Tweak the code on the PIC for variable capacity cells . . . }
Or code up a new PIC from scratch.... it wouldn't have to do much; monitor one or two analog voltages from the pack (voltage, temperature), and spoof the appropriate signals at the appropriate times to the battery contacts.
Documenting/cloning the *rest* of that PCB would be a Good Thing, though
Documenting/cloning the *rest* of that PCB would be a Good Thing, though
That Battery Pack will be documented soup to nuts, the operative word being . . . NUTS! = 8-o
So you think a staggered array of AAAs will fit?
I measured a stack of staggered and they appear to total about 3/4", or close to 17mm.
I'd probably use glue to hold them together -- I'm banking there's not enough room for a nice battery holder array.
I measured a stack of staggered and they appear to total about 3/4", or close to 17mm.
I'd probably use glue to hold them together -- I'm banking there's not enough room for a nice battery holder array.
One thing I have never studied deeply, was "smart" charging circuitry. It wouldn't be hard to make a new PCB with new circuitry for charging batteries, the problem being is not too sure how charging systems work. Lets say I have a 7.2v battery pack, and i hit the pack with 8v or maybe 9v to charge it, Wouldn't it be 9V at the terminals of the batteries?
Almost need some sort of resistance between the pack and charging voltage to be able to measure the voltage drop across the resistor for current consumption, and then the voltage point at the batteries itself. I dunno about duo, but i know on the old 190/5300s they just had a simple serial ROM that told the machine the battery was installed and its type/capacity.
Almost need some sort of resistance between the pack and charging voltage to be able to measure the voltage drop across the resistor for current consumption, and then the voltage point at the batteries itself. I dunno about duo, but i know on the old 190/5300s they just had a simple serial ROM that told the machine the battery was installed and its type/capacity.
I need to get this circuit board documented and figure out if it can be implemented, preferably in the Duo, in the 2 Battery Charger Pack at worst, or in both.
I'm hoping osfjd will chime in, he's a power supply kinda EE Boffin. If he doesn't, I'll be PMin' him! :approve:
I'm hoping osfjd will chime in, he's a power supply kinda EE Boffin. If he doesn't, I'll be PMin' him! :approve:
I am an AVR fan myself, as thats the MCU I am most familiar with.
Here is a battery charger sheet that explains the different battery types, and how they are charged:
http://www.atmel.com/dyn/resources/prod_documents/doc1659.pdf
Here is a battery charger sheet that explains the different battery types, and how they are charged:
http://www.atmel.com/dyn/resources/prod_documents/doc1659.pdf
I just wanted to toss in some more tidbits:
Quote from a site:
http://www.powerstream.com/NiMH.htm
Good Read. If i were to ASSUME, the PB probably uses the dT/dt technique with 1C charge, besides, the current/voltage sensor used in a loop to keep the current level at 1C is used as the fuel gauge as well. But in order for this charging scheme to work, and to be able to calculate 1C, or 10C, or whatever charge mechanism you use, you MUST know the initial capacity. So, this is given by the battery's ROM, or by some other means. As mentioned, the -dV/dt method is better because it leaves the capacity out of the equasion, BUT it destroys NiMH because its more sensitive to this (less drop across threshold than NiCd). So its for NiCd and is probably used in the PB1XX series.
Quote from a site:
From site:
http://www.powerstream.com/NiMH.htm
Good Read. If i were to ASSUME, the PB probably uses the dT/dt technique with 1C charge, besides, the current/voltage sensor used in a loop to keep the current level at 1C is used as the fuel gauge as well. But in order for this charging scheme to work, and to be able to calculate 1C, or 10C, or whatever charge mechanism you use, you MUST know the initial capacity. So, this is given by the battery's ROM, or by some other means. As mentioned, the -dV/dt method is better because it leaves the capacity out of the equasion, BUT it destroys NiMH because its more sensitive to this (less drop across threshold than NiCd). So its for NiCd and is probably used in the PB1XX series.
technight: that battery charger PDF is a great resource. Thanks for posting that - it's filed away for later reference for many, non-Mac related projects
I have a little test I've brewed up to settle the capacity argument once and for all. If and when blah blah etc, I'll try it myself, but if anyone else feels like having a go, I'll document my thoughts here:
Above provided for entertainment porpoises only. BunsenLabs accepts no responsibility for personal injury, property damage, or the heat death of the universe.
NB, if one plans to later attempt to fit the cells inside a Duo battpack, one would of course need the solder-tab version, not the button-ended ones. If the tests fail, one still has a portable 12V power pack, or several smaller ones, for other uses.
I have a little test I've brewed up to settle the capacity argument once and for all. If and when blah blah etc, I'll try it myself, but if anyone else feels like having a go, I'll document my thoughts here:
- Dismantle a Duo battery pack
- Buy ten matching, reliable high capacity AAs
- Mount them in standard AA holders.
- Add the little thinggum from inside the battery pack in between the equivalent pair of cells to its original position inside the Duo battery.
- Wire from the AA holders to the contacts inside the gutted Duo battery.
- Use the Duo (or the Lind charger) to charge them
- Test them attached to the Duo
Above provided for entertainment porpoises only. BunsenLabs accepts no responsibility for personal injury, property damage, or the heat death of the universe.
NB, if one plans to later attempt to fit the cells inside a Duo battpack, one would of course need the solder-tab version, not the button-ended ones. If the tests fail, one still has a portable 12V power pack, or several smaller ones, for other uses.
Keep in mind though, according to my calculations (insert crazy scientist form here) AAs won't work inside the actual battery...
• 4/5 AF dimensions: 17x40mm (Battery Station says 16.5x42)
• Fullsize A dimensions: 17x50mm (Wiki) (Battery station says 16.5x48)
• 4/5 AA dimensions: 14.5x43mm
• Fullsize AA dimensions: 14.5x50.5mm (must be the button version)
• Tabbed flat terminal AA: 14.2x50mm
• AAA: 11x45 flat terminal, batterystation.com says 10x43.7.
I'd love to tap into 123a batteries but they're made only in alkaline ($$$$$) and Lithiums (reasonable).
I could jump into this foray right away but I'm awaiting a certain shipment from the Bermuda Triangle. Once you do get your setup rigged up, see if you can somehow measure the remaining capacity to see if the batteries did get indeed filled up completely. Given that...
• 4/5 AF dimensions: 17x40mm (Battery Station says 16.5x42)
• Fullsize A dimensions: 17x50mm (Wiki) (Battery station says 16.5x48)
• 4/5 AA dimensions: 14.5x43mm
• Fullsize AA dimensions: 14.5x50.5mm (must be the button version)
• Tabbed flat terminal AA: 14.2x50mm
• AAA: 11x45 flat terminal, batterystation.com says 10x43.7.
I'd love to tap into 123a batteries but they're made only in alkaline ($$$$$) and Lithiums (reasonable).
I'm quite interested in your aquamarine battery pursuits. :approve:
I could jump into this foray right away but I'm awaiting a certain shipment from the Bermuda Triangle.
Once you do get your setup rigged up, see if you can somehow measure the remaining capacity to see if the batteries did get indeed filled up completely. Given that...and considering that...
Well, so far I've identified two different versions of the standard, Type I Duo Battery pack, neither appear to have special markings to designate them as Type II or Type III. I'm sending both of those along with a Two Battery Charger unit for Mk.558 to pick apart, document here, and to determine if the charger's the place to put a clone of the High Capacity BTI Pack's PCB instead of inside the Duo.
My charger unit was freed up for this purpose when jruschme gifted me with his, thanks again, buddy! [] ]'>
I've also found a standard BTI Battery Pack amongst the sheep to crack open for comparison with the two standard Apple Pack revs along with the High Capacity BTI Pack.
My workbench is now clear for me to get crackin' on some more hackin' projects again! :approve:
My charger unit was freed up for this purpose when jruschme gifted me with his, thanks again, buddy! [
] ]'>I've also found a standard BTI Battery Pack amongst the sheep to crack open for comparison with the two standard Apple Pack revs along with the High Capacity BTI Pack.
My workbench is now clear for me to get crackin' on some more hackin' projects again! :approve:
New developments:
AAs won't work. You can only fit 7 of them in. That'd be fine if all we were looking for was 8.4v but that is not the case.
AAAs also won't work. You can't fit 20 of them in, not easily at least. The most I believe could fit is 15, and double-stacking is essentially ruled out because there's not enough height in the case.
For reference, the pack is about 13mm shorter in length than a 12" iBook G3 A1005 battery, and about the same height and width. (Except the iBook one is 4400mAh instead of 1600mAh)
The solution? 2/3 As. Not 2/3AAs -- those are about 700mAh.
Like these. Capacity correct: Yes. Size: Yes. Solution: Quite likely.
You'll still need solder tabs, though. You'll also need to properly re-wire the thing back together. Probably start by making a map of the circuit and battery polarities. Since I have two batteries, I could probably recell one for myself and sell the other one for cost + shipping (if there is interest). Not like I'll be taking notes with that dream keyboard all others aspire to be rough, coarse keyboard. It's just a hobby laptop that is retro for the fun of being retro.
AAs won't work. You can only fit 7 of them in. That'd be fine if all we were looking for was 8.4v but that is not the case.
AAAs also won't work. You can't fit 20 of them in, not easily at least. The most I believe could fit is 15, and double-stacking is essentially ruled out because there's not enough height in the case.
For reference, the pack is about 13mm shorter in length than a 12" iBook G3 A1005 battery, and about the same height and width. (Except the iBook one is 4400mAh instead of 1600mAh)
The solution? 2/3 As. Not 2/3AAs -- those are about 700mAh.
Like these. Capacity correct: Yes. Size: Yes. Solution: Quite likely.
You'll still need solder tabs, though. You'll also need to properly re-wire the thing back together. Probably start by making a map of the circuit and battery polarities. Since I have two batteries, I could probably recell one for myself and sell the other one for cost + shipping (if there is interest). Not like I'll be taking notes with that dream keyboard all others aspire to be rough, coarse keyboard. It's just a hobby laptop that is retro for the fun of being retro.
:lol: I think you're the first to complain of a Duo KBD being rough and course! ALL the early revs are like mushy, spongeboards, that's the real problem. You've got a late Rev KBD that just needs to be used a bit to get it broken back in shape . . .
. . . kind of like oiling up and working your ball glove after taking a few too many seasons off!)
. . . kind of like oiling up and working your ball glove after taking a few too many seasons off!
)
It's worth saving the removed 4/5A cells and testing them individually, if you can. One or two borked cells in a pack can render the whole pack useless, while the other cells may still have some life left in them.